android: stability fixes and xposed api v101 (#531)

android/app/src/xposed/cpp/l2c_fcr_hook.cpp

@@ -0,0 +1,394 @@
+/*
+    LibrePods - AirPods liberated from Apple’s ecosystem
+    Copyright (C) 2025 LibrePods contributors
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <android/log.h>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <elf.h>
+#include <atomic>
+#include <jni.h>
+
+#include "l2c_fcr_hook.h"
+
+extern "C" {
+    #include "xz.h"
+}
+
+#define LOG_TAG "LibrePodsHook"
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
+#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
+
+static HookFunType hook_func = nullptr;
+
+static uint8_t (*original_l2c_fcr_chk_chan_modes)(void*) = nullptr;
+static tBTA_STATUS (*original_BTA_DmSetLocalDiRecord)(
+        tSDP_DI_RECORD*, uint32_t*) = nullptr;
+
+static std::atomic<bool> enableSdpHook(false);
+
+uint8_t fake_l2c_fcr_chk_chan_modes(void* p_ccb) {
+    LOGI("fake_l2c_fcr_chk_chan_modes called");
+    uint8_t orig = 0;
+    if (original_l2c_fcr_chk_chan_modes)
+        orig = original_l2c_fcr_chk_chan_modes(p_ccb);
+
+    LOGI("fake_l2c_fcr_chk_chan_modes: orig = %d, returning 1", orig);
+    return 1;
+}
+
+tBTA_STATUS fake_BTA_DmSetLocalDiRecord(
+        tSDP_DI_RECORD* p_device_info,
+        uint32_t* p_handle) {
+
+    LOGI("fake_BTA_DmSetLocalDiRecord called");
+
+    if (original_BTA_DmSetLocalDiRecord && enableSdpHook.load(std::memory_order_relaxed)) original_BTA_DmSetLocalDiRecord(p_device_info, p_handle);
+
+    LOGI("fake_BTA_DmSetLocalDiRecord: modifying vendor to 0x004C, vendor_id_source to 0x0001");
+
+    if (p_device_info) {
+        p_device_info->vendor = 0x004C;
+        p_device_info->vendor_id_source = 0x0001;
+    }
+
+    LOGI("fake_BTA_DmSetLocalDiRecord: returning status %d", original_BTA_DmSetLocalDiRecord ? original_BTA_DmSetLocalDiRecord(p_device_info, p_handle) : BTA_FAILURE);
+    return original_BTA_DmSetLocalDiRecord ? original_BTA_DmSetLocalDiRecord(p_device_info, p_handle) : BTA_FAILURE;
+}
+
+static bool decompressXZ(
+        const uint8_t* input,
+        size_t input_size,
+        std::vector<uint8_t>& output) {
+
+    LOGI("decompressXZ called with input_size: %zu", input_size);
+
+    xz_crc32_init();
+#ifdef XZ_USE_CRC64
+    xz_crc64_init();
+#endif
+
+    struct xz_dec* dec = xz_dec_init(XZ_DYNALLOC, 64U << 20);
+    if (!dec) {
+        LOGE("decompressXZ: xz_dec_init failed");
+        return false;
+    }
+    LOGI("decompressXZ: xz_dec_init succeeded");
+
+    struct xz_buf buf{};
+    buf.in = input;
+    buf.in_pos = 0;
+    buf.in_size = input_size;
+
+    output.resize(input_size * 8);
+
+    buf.out = output.data();
+    buf.out_pos = 0;
+    buf.out_size = output.size();
+
+    LOGI("decompressXZ: entering decompression loop");
+    while (true) {
+        LOGI("decompressXZ: xz_dec_run iteration, buf.in_pos: %zu, buf.out_pos: %zu", buf.in_pos, buf.out_pos);
+        enum xz_ret ret = xz_dec_run(dec, &buf);
+
+        LOGI("decompressXZ: xz_dec_run returned %d", ret);
+
+        if (ret == XZ_STREAM_END)
+            break;
+
+        if (ret != XZ_OK) {
+            LOGE("decompressXZ: xz_dec_run error");
+            xz_dec_end(dec);
+            return false;
+        }
+
+        if (buf.out_pos == buf.out_size) {
+            size_t old = output.size();
+            LOGI("decompressXZ: resizing output to %zu", old * 2);
+            output.resize(old * 2);
+            buf.out = output.data();
+            buf.out_size = output.size();
+        }
+    }
+
+    output.resize(buf.out_pos);
+    xz_dec_end(dec);
+    LOGI("decompressXZ: decompression successful, output size: %zu", output.size());
+    return true;
+}
+
+static bool getLibraryPath(const char* name, std::string& out) {
+    LOGI("getLibraryPath called with name: %s", name);
+
+    FILE* fp = fopen("/proc/self/maps", "r");
+    if (!fp) {
+        LOGE("getLibraryPath: fopen failed");
+        return false;
+    }
+
+    char line[1024];
+
+    LOGI("getLibraryPath: scanning /proc/self/maps");
+    while (fgets(line, sizeof(line), fp)) {
+        if (strstr(line, name)) {
+            LOGI("getLibraryPath: found line containing %s", name);
+            char* path = strchr(line, '/');
+            if (path) {
+                out = path;
+                out.erase(out.find('\n'));
+                LOGI("getLibraryPath: path found: %s", out.c_str());
+                fclose(fp);
+                return true;
+            }
+        }
+    }
+
+    fclose(fp);
+    LOGI("getLibraryPath: failed to find path for %s", name);
+    return false;
+}
+
+static uintptr_t getModuleBase(const char* name) {
+    LOGI("getModuleBase called with name: %s", name);
+
+    FILE* fp = fopen("/proc/self/maps", "r");
+    if (!fp) {
+        LOGE("getModuleBase: fopen failed");
+        return 0;
+    }
+
+    char line[1024];
+    uintptr_t base = 0;
+
+    LOGI("getModuleBase: scanning /proc/self/maps");
+    while (fgets(line, sizeof(line), fp)) {
+        if (strstr(line, name)) {
+            base = strtoull(line, nullptr, 16);
+            LOGI("getModuleBase: found base at 0x%lx", base);
+            break;
+        }
+    }
+
+    fclose(fp);
+    LOGI("getModuleBase: failed to find base for %s", name);
+    return base;
+}
+
+static uint64_t findSymbolOffset(
+        const std::vector<uint8_t>& elf,
+        const char* symbol_substring) {
+
+    LOGI("findSymbolOffset called with symbol_substring: %s", symbol_substring);
+
+    auto* eh = reinterpret_cast<const Elf64_Ehdr*>(elf.data());
+    auto* shdr = reinterpret_cast<const Elf64_Shdr*>(
+            elf.data() + eh->e_shoff);
+
+    const char* shstr =
+            reinterpret_cast<const char*>(
+                    elf.data() + shdr[eh->e_shstrndx].sh_offset);
+
+    const Elf64_Shdr* symtab = nullptr;
+    const Elf64_Shdr* strtab = nullptr;
+
+    LOGI("findSymbolOffset: parsing ELF sections");
+    for (int i = 0; i < eh->e_shnum; ++i) {
+        const char* secname = shstr + shdr[i].sh_name;
+        if (!strcmp(secname, ".symtab"))
+            symtab = &shdr[i];
+        if (!strcmp(secname, ".strtab"))
+            strtab = &shdr[i];
+    }
+
+    if (!symtab || !strtab) {
+        LOGE("findSymbolOffset: symtab or strtab not found");
+        return 0;
+    }
+    LOGI("findSymbolOffset: found symtab and strtab");
+
+    auto* symbols = reinterpret_cast<const Elf64_Sym*>(
+            elf.data() + symtab->sh_offset);
+
+    const char* strings =
+            reinterpret_cast<const char*>(
+                    elf.data() + strtab->sh_offset);
+
+    size_t count = symtab->sh_size / sizeof(Elf64_Sym);
+
+    LOGI("findSymbolOffset: scanning %zu symbols", count);
+    for (size_t i = 0; i < count; ++i) {
+        const char* name = strings + symbols[i].st_name;
+
+        if (strstr(name, symbol_substring) &&
+            ELF64_ST_TYPE(symbols[i].st_info) == STT_FUNC) {
+
+            LOGI("findSymbolOffset: matched symbol %s at 0x%lx", name, (unsigned long)symbols[i].st_value);
+
+            return symbols[i].st_value;
+        }
+    }
+
+    LOGI("findSymbolOffset: no match found for %s", symbol_substring);
+    return 0;
+}
+
+static bool hookLibrary(const char* libname) {
+    LOGI("hookLibrary called with libname: %s", libname);
+
+    if (!hook_func) {
+        LOGE("hook_func not initialized");
+        return false;
+    }
+
+    std::string path;
+    if (!getLibraryPath(libname, path)) {
+        LOGE("Failed to locate %s", libname);
+        return false;
+    }
+    LOGI("hookLibrary: located path: %s", path.c_str());
+
+    int fd = open(path.c_str(), O_RDONLY);
+    if (fd < 0) {
+        LOGE("hookLibrary: open failed");
+        return false;
+    }
+
+    struct stat st{};
+    if (fstat(fd, &st) != 0) {
+        LOGE("hookLibrary: fstat failed");
+        close(fd);
+        return false;
+    }
+    LOGI("hookLibrary: opened file, size: %lld", (long long)st.st_size);
+
+    std::vector<uint8_t> file(st.st_size);
+    read(fd, file.data(), st.st_size);
+    close(fd);
+
+    auto* eh = reinterpret_cast<Elf64_Ehdr*>(file.data());
+    auto* shdr = reinterpret_cast<Elf64_Shdr*>(
+            file.data() + eh->e_shoff);
+
+    const char* shstr =
+            reinterpret_cast<const char*>(
+                    file.data() + shdr[eh->e_shstrndx].sh_offset);
+
+    LOGI("hookLibrary: parsing ELF header and sections");
+    for (int i = 0; i < eh->e_shnum; ++i) {
+
+        if (!strcmp(shstr + shdr[i].sh_name, ".gnu_debugdata")) {
+            LOGI("hookLibrary: found .gnu_debugdata section");
+
+            std::vector<uint8_t> compressed(
+                    file.begin() + shdr[i].sh_offset,
+                    file.begin() + shdr[i].sh_offset + shdr[i].sh_size);
+
+            std::vector<uint8_t> decompressed;
+
+            if (!decompressXZ(
+                    compressed.data(),
+                    compressed.size(),
+                    decompressed)) {
+                LOGE("hookLibrary: decompressXZ failed");
+                return false;
+            }
+            LOGI("hookLibrary: decompressed debug data, size: %zu", decompressed.size());
+
+            uintptr_t base = getModuleBase(libname);
+            if (!base) {
+                LOGE("hookLibrary: getModuleBase failed");
+                return false;
+            }
+            LOGI("hookLibrary: module base: 0x%lx", base);
+
+            uint64_t chk_offset =
+                    findSymbolOffset(decompressed,
+                                     "l2c_fcr_chk_chan_modes");
+
+            uint64_t sdp_offset =
+                    findSymbolOffset(decompressed,
+                                     "BTA_DmSetLocalDiRecord");
+
+            LOGI("hookLibrary: chk_offset: 0x%lx, sdp_offset: 0x%lx", chk_offset, sdp_offset);
+
+            if (chk_offset) {
+                void* target =
+                        reinterpret_cast<void*>(base + chk_offset);
+
+                hook_func(target,
+                          (void*)fake_l2c_fcr_chk_chan_modes,
+                          (void**)&original_l2c_fcr_chk_chan_modes);
+
+                LOGI("hookLibrary: hooked l2c_fcr_chk_chan_modes");
+            }
+
+            if (sdp_offset) {
+                void* target =
+                        reinterpret_cast<void*>(base + sdp_offset);
+
+                hook_func(target,
+                          (void*)fake_BTA_DmSetLocalDiRecord,
+                          (void**)&original_BTA_DmSetLocalDiRecord);
+
+                LOGI("hookLibrary: hooked BTA_DmSetLocalDiRecord");
+            }
+
+            return true;
+        }
+    }
+
+    LOGI("hookLibrary: failed for %s", libname);
+    return false;
+}
+
+static void on_library_loaded(const char* name, void*) {
+    LOGI("on_library_loaded called with name: %s", name);
+
+    if (strstr(name, "libbluetooth_jni.so")) {
+        LOGI("Bluetooth JNI loaded");
+        hookLibrary("libbluetooth_jni.so");
+    }
+
+    if (strstr(name, "libbluetooth_qti.so")) {
+        LOGI("Bluetooth QTI loaded");
+        hookLibrary("libbluetooth_qti.so");
+    }
+}
+
+extern "C"
+[[gnu::visibility("default")]]
+[[gnu::used]]
+NativeOnModuleLoaded native_init(const NativeAPIEntries* entries) {
+    LOGI("native_init called with entries: %p", entries);
+    hook_func = (HookFunType)entries->hook_func;
+    LOGI("LibrePodsNativeHook initialized, sdp hook enabled: %d", enableSdpHook.load(std::memory_order_relaxed));
+    return on_library_loaded;
+}
+
+extern "C"
+JNIEXPORT void JNICALL
+Java_me_kavishdevar_librepods_utils_NativeBridge_setSdpHook(
+        JNIEnv*, jobject thiz, jboolean enable) {
+    LOGI("setSdpHook called with enable: %d", enable);
+    enableSdpHook.store(enable, std::memory_order_relaxed);
+
+    LOGI("sdp hook enabled: %d", enable);
+}

android/app/src/xposed/cpp/l2c_fcr_hook.h

@@ -0,0 +1,52 @@
+/*
+    LibrePods - AirPods liberated from Apple’s ecosystem
+    Copyright (C) 2025 LibrePods contributors
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+#include <cstdint>
+
+typedef int (*HookFunType)(void *func, void *replace, void **backup);
+
+typedef void (*NativeOnModuleLoaded)(const char *name, void *handle);
+
+typedef struct {
+    uint32_t version;
+    void* hook_func;
+    void* unhook_func;
+} NativeAPIEntries;
+
+typedef NativeOnModuleLoaded (*NativeInit)(const NativeAPIEntries *entries);
+
+typedef enum : uint8_t {
+    BTA_SUCCESS = 0, /* Successful operation. */
+    BTA_FAILURE = 1, /* Generic failure. */
+    BTA_PENDING = 2, /* API cannot be completed right now */
+    BTA_BUSY = 3,
+    BTA_NO_RESOURCES = 4,
+    BTA_WRONG_MODE = 5,
+} tBTA_STATUS;
+
+typedef struct t_sdp_di_record {
+    uint16_t vendor;
+    uint16_t vendor_id_source;
+    uint16_t product;
+    uint16_t version;
+    bool primary_record;
+    char client_executable_url[400];
+    char service_description[400];
+    char documentation_url[400];
+} tSDP_DI_RECORD;

android/app/src/xposed/cpp/xz/xz.h

@@ -0,0 +1,448 @@
+/* SPDX-License-Identifier: 0BSD */
+
+/*
+ * XZ decompressor
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <https://7-zip.org/>
+ */
+
+#ifndef XZ_H
+#define XZ_H
+
+#ifdef __KERNEL__
+#	include <linux/stddef.h>
+#	include <linux/types.h>
+#else
+#	include <stddef.h>
+#	include <stdint.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* "#define XZ_EXTERN static" can be used to make extern functions static. */
+#ifndef XZ_EXTERN
+#	define XZ_EXTERN extern
+#endif
+
+/**
+ * enum xz_mode - Operation mode
+ *
+ * @XZ_SINGLE:              Single-call mode. This uses less RAM than
+ *                          multi-call modes, because the LZMA2
+ *                          dictionary doesn't need to be allocated as
+ *                          part of the decoder state. All required data
+ *                          structures are allocated at initialization,
+ *                          so xz_dec_run() cannot return XZ_MEM_ERROR.
+ * @XZ_PREALLOC:            Multi-call mode with preallocated LZMA2
+ *                          dictionary buffer. All data structures are
+ *                          allocated at initialization, so xz_dec_run()
+ *                          cannot return XZ_MEM_ERROR.
+ * @XZ_DYNALLOC:            Multi-call mode. The LZMA2 dictionary is
+ *                          allocated once the required size has been
+ *                          parsed from the stream headers. If the
+ *                          allocation fails, xz_dec_run() will return
+ *                          XZ_MEM_ERROR.
+ *
+ * It is possible to enable support only for a subset of the above
+ * modes at compile time by defining XZ_DEC_SINGLE, XZ_DEC_PREALLOC,
+ * or XZ_DEC_DYNALLOC. The xz_dec kernel module is always compiled
+ * with support for all operation modes, but the preboot code may
+ * be built with fewer features to minimize code size.
+ */
+enum xz_mode {
+	XZ_SINGLE,
+	XZ_PREALLOC,
+	XZ_DYNALLOC
+};
+
+/**
+ * enum xz_ret - Return codes
+ * @XZ_OK:                  Everything is OK so far. More input or more
+ *                          output space is required to continue. This
+ *                          return code is possible only in multi-call mode
+ *                          (XZ_PREALLOC or XZ_DYNALLOC).
+ * @XZ_STREAM_END:          Operation finished successfully.
+ * @XZ_UNSUPPORTED_CHECK:   Integrity check type is not supported. Decoding
+ *                          is still possible in multi-call mode by simply
+ *                          calling xz_dec_run() again.
+ *                          Note that this return value is used only if
+ *                          XZ_DEC_ANY_CHECK was defined at build time,
+ *                          which is not used in the kernel. Unsupported
+ *                          check types return XZ_OPTIONS_ERROR if
+ *                          XZ_DEC_ANY_CHECK was not defined at build time.
+ * @XZ_MEM_ERROR:           Allocating memory failed. This return code is
+ *                          possible only if the decoder was initialized
+ *                          with XZ_DYNALLOC. The amount of memory that was
+ *                          tried to be allocated was no more than the
+ *                          dict_max argument given to xz_dec_init().
+ * @XZ_MEMLIMIT_ERROR:      A bigger LZMA2 dictionary would be needed than
+ *                          allowed by the dict_max argument given to
+ *                          xz_dec_init(). This return value is possible
+ *                          only in multi-call mode (XZ_PREALLOC or
+ *                          XZ_DYNALLOC); the single-call mode (XZ_SINGLE)
+ *                          ignores the dict_max argument.
+ * @XZ_FORMAT_ERROR:        File format was not recognized (wrong magic
+ *                          bytes).
+ * @XZ_OPTIONS_ERROR:       This implementation doesn't support the requested
+ *                          compression options. In the decoder this means
+ *                          that the header CRC32 matches, but the header
+ *                          itself specifies something that we don't support.
+ * @XZ_DATA_ERROR:          Compressed data is corrupt.
+ * @XZ_BUF_ERROR:           Cannot make any progress. Details are slightly
+ *                          different between multi-call and single-call
+ *                          mode; more information below.
+ *
+ * In multi-call mode, XZ_BUF_ERROR is returned when two consecutive calls
+ * to XZ code cannot consume any input and cannot produce any new output.
+ * This happens when there is no new input available, or the output buffer
+ * is full while at least one output byte is still pending. Assuming your
+ * code is not buggy, you can get this error only when decoding a compressed
+ * stream that is truncated or otherwise corrupt.
+ *
+ * In single-call mode, XZ_BUF_ERROR is returned only when the output buffer
+ * is too small or the compressed input is corrupt in a way that makes the
+ * decoder produce more output than the caller expected. When it is
+ * (relatively) clear that the compressed input is truncated, XZ_DATA_ERROR
+ * is used instead of XZ_BUF_ERROR.
+ */
+enum xz_ret {
+	XZ_OK,
+	XZ_STREAM_END,
+	XZ_UNSUPPORTED_CHECK,
+	XZ_MEM_ERROR,
+	XZ_MEMLIMIT_ERROR,
+	XZ_FORMAT_ERROR,
+	XZ_OPTIONS_ERROR,
+	XZ_DATA_ERROR,
+	XZ_BUF_ERROR
+};
+
+/**
+ * struct xz_buf - Passing input and output buffers to XZ code
+ * @in:         Beginning of the input buffer. This may be NULL if and only
+ *              if in_pos is equal to in_size.
+ * @in_pos:     Current position in the input buffer. This must not exceed
+ *              in_size.
+ * @in_size:    Size of the input buffer
+ * @out:        Beginning of the output buffer. This may be NULL if and only
+ *              if out_pos is equal to out_size.
+ * @out_pos:    Current position in the output buffer. This must not exceed
+ *              out_size.
+ * @out_size:   Size of the output buffer
+ *
+ * Only the contents of the output buffer from out[out_pos] onward, and
+ * the variables in_pos and out_pos are modified by the XZ code.
+ */
+struct xz_buf {
+	const uint8_t *in;
+	size_t in_pos;
+	size_t in_size;
+
+	uint8_t *out;
+	size_t out_pos;
+	size_t out_size;
+};
+
+/*
+ * struct xz_dec - Opaque type to hold the XZ decoder state
+ */
+struct xz_dec;
+
+/**
+ * xz_dec_init() - Allocate and initialize a XZ decoder state
+ * @mode:       Operation mode
+ * @dict_max:   Maximum size of the LZMA2 dictionary (history buffer) for
+ *              multi-call decoding. This is ignored in single-call mode
+ *              (mode == XZ_SINGLE). LZMA2 dictionary is always 2^n bytes
+ *              or 2^n + 2^(n-1) bytes (the latter sizes are less common
+ *              in practice), so other values for dict_max don't make sense.
+ *              In the kernel, dictionary sizes of 64 KiB, 128 KiB, 256 KiB,
+ *              512 KiB, and 1 MiB are probably the only reasonable values,
+ *              except for kernel and initramfs images where a bigger
+ *              dictionary can be fine and useful.
+ *
+ * Single-call mode (XZ_SINGLE): xz_dec_run() decodes the whole stream at
+ * once. The caller must provide enough output space or the decoding will
+ * fail. The output space is used as the dictionary buffer, which is why
+ * there is no need to allocate the dictionary as part of the decoder's
+ * internal state.
+ *
+ * Because the output buffer is used as the workspace, streams encoded using
+ * a big dictionary are not a problem in single-call mode. It is enough that
+ * the output buffer is big enough to hold the actual uncompressed data; it
+ * can be smaller than the dictionary size stored in the stream headers.
+ *
+ * Multi-call mode with preallocated dictionary (XZ_PREALLOC): dict_max bytes
+ * of memory is preallocated for the LZMA2 dictionary. This way there is no
+ * risk that xz_dec_run() could run out of memory, since xz_dec_run() will
+ * never allocate any memory. Instead, if the preallocated dictionary is too
+ * small for decoding the given input stream, xz_dec_run() will return
+ * XZ_MEMLIMIT_ERROR. Thus, it is important to know what kind of data will be
+ * decoded to avoid allocating excessive amount of memory for the dictionary.
+ *
+ * Multi-call mode with dynamically allocated dictionary (XZ_DYNALLOC):
+ * dict_max specifies the maximum allowed dictionary size that xz_dec_run()
+ * may allocate once it has parsed the dictionary size from the stream
+ * headers. This way excessive allocations can be avoided while still
+ * limiting the maximum memory usage to a sane value to prevent running the
+ * system out of memory when decompressing streams from untrusted sources.
+ *
+ * On success, xz_dec_init() returns a pointer to struct xz_dec, which is
+ * ready to be used with xz_dec_run(). If memory allocation fails,
+ * xz_dec_init() returns NULL.
+ */
+XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);
+
+/**
+ * xz_dec_run() - Run the XZ decoder for a single XZ stream
+ * @s:          Decoder state allocated using xz_dec_init()
+ * @b:          Input and output buffers
+ *
+ * The possible return values depend on build options and operation mode.
+ * See enum xz_ret for details.
+ *
+ * Note that if an error occurs in single-call mode (return value is not
+ * XZ_STREAM_END), b->in_pos and b->out_pos are not modified and the
+ * contents of the output buffer from b->out[b->out_pos] onward are
+ * undefined. This is true even after XZ_BUF_ERROR, because with some filter
+ * chains, there may be a second pass over the output buffer, and this pass
+ * cannot be properly done if the output buffer is truncated. Thus, you
+ * cannot give the single-call decoder a too small buffer and then expect to
+ * get that amount valid data from the beginning of the stream. You must use
+ * the multi-call decoder if you don't want to uncompress the whole stream.
+ *
+ * Use xz_dec_run() when XZ data is stored inside some other file format.
+ * The decoding will stop after one XZ stream has been decompressed. To
+ * decompress regular .xz files which might have multiple concatenated
+ * streams, use xz_dec_catrun() instead.
+ */
+XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
+
+/**
+ * xz_dec_catrun() - Run the XZ decoder with support for concatenated streams
+ * @s:          Decoder state allocated using xz_dec_init()
+ * @b:          Input and output buffers
+ * @finish:     This is an int instead of bool to avoid requiring stdbool.h.
+ *              As long as more input might be coming, finish must be false.
+ *              When the caller knows that it has provided all the input to
+ *              the decoder (some possibly still in b->in), it must set finish
+ *              to true. Only when finish is true can this function return
+ *              XZ_STREAM_END to indicate successful decompression of the
+ *              file. In single-call mode (XZ_SINGLE) finish is assumed to
+ *              always be true; the caller-provided value is ignored.
+ *
+ * This is like xz_dec_run() except that this makes it easy to decode .xz
+ * files with multiple streams (multiple .xz files concatenated as is).
+ * The rarely-used Stream Padding feature is supported too, that is, there
+ * can be null bytes after or between the streams. The number of null bytes
+ * must be a multiple of four.
+ *
+ * When finish is false and b->in_pos == b->in_size, it is possible that
+ * XZ_BUF_ERROR isn't returned even when no progress is possible (XZ_OK is
+ * returned instead). This shouldn't matter because in this situation a
+ * reasonable caller will attempt to provide more input or set finish to
+ * true for the next xz_dec_catrun() call anyway.
+ *
+ * For any struct xz_dec that has been initialized for multi-call mode:
+ * Once decoding has been started with xz_dec_run() or xz_dec_catrun(),
+ * the same function must be used until xz_dec_reset() or xz_dec_end().
+ * Switching between the two decoding functions without resetting results
+ * in undefined behavior.
+ *
+ * xz_dec_catrun() is only available if XZ_DEC_CONCATENATED was defined
+ * at compile time.
+ */
+XZ_EXTERN enum xz_ret xz_dec_catrun(struct xz_dec *s, struct xz_buf *b,
+				    int finish);
+
+/**
+ * xz_dec_reset() - Reset an already allocated decoder state
+ * @s:          Decoder state allocated using xz_dec_init()
+ *
+ * This function can be used to reset the multi-call decoder state without
+ * freeing and reallocating memory with xz_dec_end() and xz_dec_init().
+ *
+ * In single-call mode, xz_dec_reset() is always called in the beginning of
+ * xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in
+ * multi-call mode.
+ */
+XZ_EXTERN void xz_dec_reset(struct xz_dec *s);
+
+/**
+ * xz_dec_end() - Free the memory allocated for the decoder state
+ * @s:          Decoder state allocated using xz_dec_init(). If s is NULL,
+ *              this function does nothing.
+ */
+XZ_EXTERN void xz_dec_end(struct xz_dec *s);
+
+/**
+ * DOC: MicroLZMA decompressor
+ *
+ * This MicroLZMA header format was created for use in EROFS but may be used
+ * by others too. **In most cases one needs the XZ APIs above instead.**
+ *
+ * The compressed format supported by this decoder is a raw LZMA stream
+ * whose first byte (always 0x00) has been replaced with bitwise-negation
+ * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is
+ * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
+ * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
+ * marker must not be used. The unused values are reserved for future use.
+ */
+
+/*
+ * struct xz_dec_microlzma - Opaque type to hold the MicroLZMA decoder state
+ */
+struct xz_dec_microlzma;
+
+/**
+ * xz_dec_microlzma_alloc() - Allocate memory for the MicroLZMA decoder
+ * @mode:       XZ_SINGLE or XZ_PREALLOC
+ * @dict_size:  LZMA dictionary size. This must be at least 4 KiB and
+ *              at most 3 GiB.
+ *
+ * In contrast to xz_dec_init(), this function only allocates the memory
+ * and remembers the dictionary size. xz_dec_microlzma_reset() must be used
+ * before calling xz_dec_microlzma_run().
+ *
+ * The amount of allocated memory is a little less than 30 KiB with XZ_SINGLE.
+ * With XZ_PREALLOC also a dictionary buffer of dict_size bytes is allocated.
+ *
+ * On success, xz_dec_microlzma_alloc() returns a pointer to
+ * struct xz_dec_microlzma. If memory allocation fails or
+ * dict_size is invalid, NULL is returned.
+ */
+XZ_EXTERN struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
+							  uint32_t dict_size);
+
+/**
+ * xz_dec_microlzma_reset() - Reset the MicroLZMA decoder state
+ * @s:          Decoder state allocated using xz_dec_microlzma_alloc()
+ * @comp_size:  Compressed size of the input stream
+ * @uncomp_size:  Uncompressed size of the input stream. A value smaller
+ *              than the real uncompressed size of the input stream can
+ *              be specified if uncomp_size_is_exact is set to false.
+ *              uncomp_size can never be set to a value larger than the
+ *              expected real uncompressed size because it would eventually
+ *              result in XZ_DATA_ERROR.
+ * @uncomp_size_is_exact:  This is an int instead of bool to avoid
+ *              requiring stdbool.h. This should normally be set to true.
+ *              When this is set to false, error detection is weaker.
+ */
+XZ_EXTERN void xz_dec_microlzma_reset(struct xz_dec_microlzma *s,
+				      uint32_t comp_size, uint32_t uncomp_size,
+				      int uncomp_size_is_exact);
+
+/**
+ * xz_dec_microlzma_run() - Run the MicroLZMA decoder
+ * @s:          Decoder state initialized using xz_dec_microlzma_reset()
+ * @b:          Input and output buffers
+ *
+ * This works similarly to xz_dec_run() with a few important differences.
+ * Only the differences are documented here.
+ *
+ * The only possible return values are XZ_OK, XZ_STREAM_END, and
+ * XZ_DATA_ERROR. This function cannot return XZ_BUF_ERROR: if no progress
+ * is possible due to lack of input data or output space, this function will
+ * keep returning XZ_OK. Thus, the calling code must be written so that it
+ * will eventually provide input and output space matching (or exceeding)
+ * comp_size and uncomp_size arguments given to xz_dec_microlzma_reset().
+ * If the caller cannot do this (for example, if the input file is truncated
+ * or otherwise corrupt), the caller must detect this error by itself to
+ * avoid an infinite loop.
+ *
+ * If the compressed data seems to be corrupt, XZ_DATA_ERROR is returned.
+ * This can happen also when incorrect dictionary, uncompressed, or
+ * compressed sizes have been specified.
+ *
+ * With XZ_PREALLOC only: As an extra feature, b->out may be NULL to skip over
+ * uncompressed data. This way the caller doesn't need to provide a temporary
+ * output buffer for the bytes that will be ignored.
+ *
+ * With XZ_SINGLE only: In contrast to xz_dec_run(), the return value XZ_OK
+ * is also possible and thus XZ_SINGLE is actually a limited multi-call mode.
+ * After XZ_OK the bytes decoded so far may be read from the output buffer.
+ * It is possible to continue decoding but the variables b->out and b->out_pos
+ * MUST NOT be changed by the caller. Increasing the value of b->out_size is
+ * allowed to make more output space available; one doesn't need to provide
+ * space for the whole uncompressed data on the first call. The input buffer
+ * may be changed normally like with XZ_PREALLOC. This way input data can be
+ * provided from non-contiguous memory.
+ */
+XZ_EXTERN enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s,
+					   struct xz_buf *b);
+
+/**
+ * xz_dec_microlzma_end() - Free the memory allocated for the decoder state
+ * @s:          Decoder state allocated using xz_dec_microlzma_alloc().
+ *              If s is NULL, this function does nothing.
+ */
+XZ_EXTERN void xz_dec_microlzma_end(struct xz_dec_microlzma *s);
+
+/*
+ * Standalone build (userspace build or in-kernel build for boot time use)
+ * needs a CRC32 implementation. For normal in-kernel use, kernel's own
+ * CRC32 module is used instead, and users of this module don't need to
+ * care about the functions below.
+ */
+#ifndef XZ_INTERNAL_CRC32
+#	ifdef __KERNEL__
+#		define XZ_INTERNAL_CRC32 0
+#	else
+#		define XZ_INTERNAL_CRC32 1
+#	endif
+#endif
+
+/*
+ * If CRC64 support has been enabled with XZ_USE_CRC64, a CRC64
+ * implementation is needed too.
+ */
+#ifndef XZ_USE_CRC64
+#	undef XZ_INTERNAL_CRC64
+#	define XZ_INTERNAL_CRC64 0
+#endif
+#ifndef XZ_INTERNAL_CRC64
+#	ifdef __KERNEL__
+#		error Using CRC64 in the kernel has not been implemented.
+#	else
+#		define XZ_INTERNAL_CRC64 1
+#	endif
+#endif
+
+#if XZ_INTERNAL_CRC32
+/*
+ * This must be called before any other xz_* function to initialize
+ * the CRC32 lookup table.
+ */
+XZ_EXTERN void xz_crc32_init(void);
+
+/*
+ * Update CRC32 value using the polynomial from IEEE-802.3. To start a new
+ * calculation, the third argument must be zero. To continue the calculation,
+ * the previously returned value is passed as the third argument.
+ */
+XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc);
+#endif
+
+#if XZ_INTERNAL_CRC64
+/*
+ * This must be called before any other xz_* function (except xz_crc32_init())
+ * to initialize the CRC64 lookup table.
+ */
+XZ_EXTERN void xz_crc64_init(void);
+
+/*
+ * Update CRC64 value using the polynomial from ECMA-182. To start a new
+ * calculation, the third argument must be zero. To continue the calculation,
+ * the previously returned value is passed as the third argument.
+ */
+XZ_EXTERN uint64_t xz_crc64(const uint8_t *buf, size_t size, uint64_t crc);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

android/app/src/xposed/cpp/xz/xz_config.h

@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: 0BSD */
+
+/*
+ * Private includes and definitions for userspace use of XZ Embedded
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ */
+
+#ifndef XZ_CONFIG_H
+#define XZ_CONFIG_H
+
+/* Uncomment to enable building of xz_dec_catrun(). */
+/* #define XZ_DEC_CONCATENATED */
+
+/* Uncomment to enable CRC64 support. */
+/* #define XZ_USE_CRC64 */
+
+/* Uncomment as needed to enable BCJ filter decoders. */
+/* #define XZ_DEC_X86 */
+/* #define XZ_DEC_ARM */
+/* #define XZ_DEC_ARMTHUMB */
+/* #define XZ_DEC_ARM64 */
+/* #define XZ_DEC_RISCV */
+/* #define XZ_DEC_POWERPC */
+/* #define XZ_DEC_IA64 */
+/* #define XZ_DEC_SPARC */
+
+/*
+ * Visual Studio 2013 update 2 supports only __inline, not inline.
+ * MSVC v19.0 / VS 2015 and newer support both.
+ */
+#if defined(_MSC_VER) && _MSC_VER < 1900 && !defined(inline)
+#	define inline __inline
+#endif
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "xz.h"
+
+#define kmalloc(size, flags) malloc(size)
+#define kfree(ptr) free(ptr)
+#define vmalloc(size) malloc(size)
+#define vfree(ptr) free(ptr)
+
+#define memeq(a, b, size) (memcmp(a, b, size) == 0)
+#define memzero(buf, size) memset(buf, 0, size)
+
+#ifndef min
+#	define min(x, y) ((x) < (y) ? (x) : (y))
+#endif
+#define min_t(type, x, y) min(x, y)
+
+#ifndef fallthrough
+#	if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311
+#		define fallthrough [[fallthrough]]
+#	elif (defined(__GNUC__) && __GNUC__ >= 7) \
+			|| (defined(__clang_major__) && __clang_major__ >= 10)
+#		define fallthrough __attribute__((__fallthrough__))
+#	else
+#		define fallthrough do {} while (0)
+#	endif
+#endif
+
+/*
+ * Some functions have been marked with __always_inline to keep the
+ * performance reasonable even when the compiler is optimizing for
+ * small code size. You may be able to save a few bytes by #defining
+ * __always_inline to plain inline, but don't complain if the code
+ * becomes slow.
+ *
+ * NOTE: System headers on GNU/Linux may #define this macro already,
+ * so if you want to change it, you need to #undef it first.
+ */
+#ifndef __always_inline
+#	ifdef __GNUC__
+#		define __always_inline \
+			inline __attribute__((__always_inline__))
+#	else
+#		define __always_inline inline
+#	endif
+#endif
+
+/* Inline functions to access unaligned unsigned 32-bit integers */
+#ifndef get_unaligned_le32
+static inline uint32_t get_unaligned_le32(const uint8_t *buf)
+{
+	return (uint32_t)buf[0]
+			| ((uint32_t)buf[1] << 8)
+			| ((uint32_t)buf[2] << 16)
+			| ((uint32_t)buf[3] << 24);
+}
+#endif
+
+#ifndef get_unaligned_be32
+static inline uint32_t get_unaligned_be32(const uint8_t *buf)
+{
+	return (uint32_t)((uint32_t)buf[0] << 24)
+			| ((uint32_t)buf[1] << 16)
+			| ((uint32_t)buf[2] << 8)
+			| (uint32_t)buf[3];
+}
+#endif
+
+#ifndef put_unaligned_le32
+static inline void put_unaligned_le32(uint32_t val, uint8_t *buf)
+{
+	buf[0] = (uint8_t)val;
+	buf[1] = (uint8_t)(val >> 8);
+	buf[2] = (uint8_t)(val >> 16);
+	buf[3] = (uint8_t)(val >> 24);
+}
+#endif
+
+#ifndef put_unaligned_be32
+static inline void put_unaligned_be32(uint32_t val, uint8_t *buf)
+{
+	buf[0] = (uint8_t)(val >> 24);
+	buf[1] = (uint8_t)(val >> 16);
+	buf[2] = (uint8_t)(val >> 8);
+	buf[3] = (uint8_t)val;
+}
+#endif
+
+/*
+ * To keep things simpler, use the generic unaligned methods also for
+ * aligned access. The only place where performance could matter is
+ * SHA-256 but files using SHA-256 aren't common.
+ */
+#ifndef get_le32
+#	define get_le32 get_unaligned_le32
+#endif
+#ifndef get_be32
+#	define get_be32 get_unaligned_be32
+#endif
+
+#endif

android/app/src/xposed/cpp/xz/xz_crc32.c

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: 0BSD
+
+/*
+ * CRC32 using the polynomial from IEEE-802.3
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <https://7-zip.org/>
+ */
+
+/*
+ * This is not the fastest implementation, but it is pretty compact.
+ * The fastest versions of xz_crc32() on modern CPUs without hardware
+ * accelerated CRC instruction are 3-5 times as fast as this version,
+ * but they are bigger and use more memory for the lookup table.
+ */
+
+#include "xz_private.h"
+
+/*
+ * STATIC_RW_DATA is used in the pre-boot environment on some architectures.
+ * See <linux/decompress/mm.h> for details.
+ */
+#ifndef STATIC_RW_DATA
+#	define STATIC_RW_DATA static
+#endif
+
+STATIC_RW_DATA uint32_t xz_crc32_table[256];
+
+XZ_EXTERN void xz_crc32_init(void)
+{
+	const uint32_t poly = 0xEDB88320;
+
+	uint32_t i;
+	uint32_t j;
+	uint32_t r;
+
+	for (i = 0; i < 256; ++i) {
+		r = i;
+		for (j = 0; j < 8; ++j)
+			r = (r >> 1) ^ (poly & ~((r & 1) - 1));
+
+		xz_crc32_table[i] = r;
+	}
+
+	return;
+}
+
+XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
+{
+	crc = ~crc;
+
+	while (size != 0) {
+		crc = xz_crc32_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
+		--size;
+	}
+
+	return ~crc;
+}

android/app/src/xposed/cpp/xz/xz_crc64.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: 0BSD
+
+/*
+ * CRC64 using the polynomial from ECMA-182
+ *
+ * This file is similar to xz_crc32.c. See the comments there.
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <https://7-zip.org/>
+ */
+
+#include "xz_private.h"
+
+#ifndef STATIC_RW_DATA
+#	define STATIC_RW_DATA static
+#endif
+
+STATIC_RW_DATA uint64_t xz_crc64_table[256];
+
+XZ_EXTERN void xz_crc64_init(void)
+{
+	/*
+	 * The ULL suffix is needed for -std=gnu89 compatibility
+	 * on 32-bit platforms.
+	 */
+	const uint64_t poly = 0xC96C5795D7870F42ULL;
+
+	uint32_t i;
+	uint32_t j;
+	uint64_t r;
+
+	for (i = 0; i < 256; ++i) {
+		r = i;
+		for (j = 0; j < 8; ++j)
+			r = (r >> 1) ^ (poly & ~((r & 1) - 1));
+
+		xz_crc64_table[i] = r;
+	}
+
+	return;
+}
+
+XZ_EXTERN uint64_t xz_crc64(const uint8_t *buf, size_t size, uint64_t crc)
+{
+	crc = ~crc;
+
+	while (size != 0) {
+		crc = xz_crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
+		--size;
+	}
+
+	return ~crc;
+}

android/app/src/xposed/cpp/xz/xz_dec_bcj.c

@@ -0,0 +1,738 @@
+// SPDX-License-Identifier: 0BSD
+
+/*
+ * Branch/Call/Jump (BCJ) filter decoders
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <https://7-zip.org/>
+ */
+
+#include "xz_private.h"
+
+/*
+ * The rest of the file is inside this ifdef. It makes things a little more
+ * convenient when building without support for any BCJ filters.
+ */
+#ifdef XZ_DEC_BCJ
+
+struct xz_dec_bcj {
+	/* Type of the BCJ filter being used */
+	enum {
+		BCJ_X86 = 4,        /* x86 or x86-64 */
+		BCJ_POWERPC = 5,    /* Big endian only */
+		BCJ_IA64 = 6,       /* Big or little endian */
+		BCJ_ARM = 7,        /* Little endian only */
+		BCJ_ARMTHUMB = 8,   /* Little endian only */
+		BCJ_SPARC = 9,      /* Big or little endian */
+		BCJ_ARM64 = 10,     /* AArch64 */
+		BCJ_RISCV = 11      /* RV32GQC_Zfh, RV64GQC_Zfh */
+	} type;
+
+	/*
+	 * Return value of the next filter in the chain. We need to preserve
+	 * this information across calls, because we must not call the next
+	 * filter anymore once it has returned XZ_STREAM_END.
+	 */
+	enum xz_ret ret;
+
+	/* True if we are operating in single-call mode. */
+	bool single_call;
+
+	/*
+	 * Absolute position relative to the beginning of the uncompressed
+	 * data (in a single .xz Block). We care only about the lowest 32
+	 * bits so this doesn't need to be uint64_t even with big files.
+	 */
+	uint32_t pos;
+
+	/* x86 filter state */
+	uint32_t x86_prev_mask;
+
+	/* Temporary space to hold the variables from struct xz_buf */
+	uint8_t *out;
+	size_t out_pos;
+	size_t out_size;
+
+	struct {
+		/* Amount of already filtered data in the beginning of buf */
+		size_t filtered;
+
+		/* Total amount of data currently stored in buf  */
+		size_t size;
+
+		/*
+		 * Buffer to hold a mix of filtered and unfiltered data. This
+		 * needs to be big enough to hold Alignment + 2 * Look-ahead:
+		 *
+		 * Type         Alignment   Look-ahead
+		 * x86              1           4
+		 * PowerPC          4           0
+		 * IA-64           16           0
+		 * ARM              4           0
+		 * ARM-Thumb        2           2
+		 * SPARC            4           0
+		 */
+		uint8_t buf[16];
+	} temp;
+};
+
+#ifdef XZ_DEC_X86
+/*
+ * This is used to test the most significant byte of a memory address
+ * in an x86 instruction.
+ */
+static inline int bcj_x86_test_msbyte(uint8_t b)
+{
+	return b == 0x00 || b == 0xFF;
+}
+
+static size_t bcj_x86(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	static const bool mask_to_allowed_status[8]
+		= { true, true, true, false, true, false, false, false };
+
+	static const uint8_t mask_to_bit_num[8] = { 0, 1, 2, 2, 3, 3, 3, 3 };
+
+	size_t i;
+	size_t prev_pos = (size_t)-1;
+	uint32_t prev_mask = s->x86_prev_mask;
+	uint32_t src;
+	uint32_t dest;
+	uint32_t j;
+	uint8_t b;
+
+	if (size <= 4)
+		return 0;
+
+	size -= 4;
+	for (i = 0; i < size; ++i) {
+		if ((buf[i] & 0xFE) != 0xE8)
+			continue;
+
+		prev_pos = i - prev_pos;
+		if (prev_pos > 3) {
+			prev_mask = 0;
+		} else {
+			prev_mask = (prev_mask << (prev_pos - 1)) & 7;
+			if (prev_mask != 0) {
+				b = buf[i + 4 - mask_to_bit_num[prev_mask]];
+				if (!mask_to_allowed_status[prev_mask]
+						|| bcj_x86_test_msbyte(b)) {
+					prev_pos = i;
+					prev_mask = (prev_mask << 1) | 1;
+					continue;
+				}
+			}
+		}
+
+		prev_pos = i;
+
+		if (bcj_x86_test_msbyte(buf[i + 4])) {
+			src = get_unaligned_le32(buf + i + 1);
+			while (true) {
+				dest = src - (s->pos + (uint32_t)i + 5);
+				if (prev_mask == 0)
+					break;
+
+				j = mask_to_bit_num[prev_mask] * 8;
+				b = (uint8_t)(dest >> (24 - j));
+				if (!bcj_x86_test_msbyte(b))
+					break;
+
+				src = dest ^ (((uint32_t)1 << (32 - j)) - 1);
+			}
+
+			dest &= 0x01FFFFFF;
+			dest |= (uint32_t)0 - (dest & 0x01000000);
+			put_unaligned_le32(dest, buf + i + 1);
+			i += 4;
+		} else {
+			prev_mask = (prev_mask << 1) | 1;
+		}
+	}
+
+	prev_pos = i - prev_pos;
+	s->x86_prev_mask = prev_pos > 3 ? 0 : prev_mask << (prev_pos - 1);
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_POWERPC
+static size_t bcj_powerpc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+
+	size &= ~(size_t)3;
+
+	for (i = 0; i < size; i += 4) {
+		instr = get_unaligned_be32(buf + i);
+		if ((instr & 0xFC000003) == 0x48000001) {
+			instr &= 0x03FFFFFC;
+			instr -= s->pos + (uint32_t)i;
+			instr &= 0x03FFFFFC;
+			instr |= 0x48000001;
+			put_unaligned_be32(instr, buf + i);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_IA64
+static size_t bcj_ia64(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	static const uint8_t branch_table[32] = {
+		0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0,
+		4, 4, 6, 6, 0, 0, 7, 7,
+		4, 4, 0, 0, 4, 4, 0, 0
+	};
+
+	/*
+	 * The local variables take a little bit stack space, but it's less
+	 * than what LZMA2 decoder takes, so it doesn't make sense to reduce
+	 * stack usage here without doing that for the LZMA2 decoder too.
+	 */
+
+	/* Loop counters */
+	size_t i;
+	size_t j;
+
+	/* Instruction slot (0, 1, or 2) in the 128-bit instruction word */
+	uint32_t slot;
+
+	/* Bitwise offset of the instruction indicated by slot */
+	uint32_t bit_pos;
+
+	/* bit_pos split into byte and bit parts */
+	uint32_t byte_pos;
+	uint32_t bit_res;
+
+	/* Address part of an instruction */
+	uint32_t addr;
+
+	/* Mask used to detect which instructions to convert */
+	uint32_t mask;
+
+	/* 41-bit instruction stored somewhere in the lowest 48 bits */
+	uint64_t instr;
+
+	/* Instruction normalized with bit_res for easier manipulation */
+	uint64_t norm;
+
+	size &= ~(size_t)15;
+
+	for (i = 0; i < size; i += 16) {
+		mask = branch_table[buf[i] & 0x1F];
+		for (slot = 0, bit_pos = 5; slot < 3; ++slot, bit_pos += 41) {
+			if (((mask >> slot) & 1) == 0)
+				continue;
+
+			byte_pos = bit_pos >> 3;
+			bit_res = bit_pos & 7;
+			instr = 0;
+			for (j = 0; j < 6; ++j)
+				instr |= (uint64_t)(buf[i + j + byte_pos])
+						<< (8 * j);
+
+			norm = instr >> bit_res;
+
+			if (((norm >> 37) & 0x0F) == 0x05
+					&& ((norm >> 9) & 0x07) == 0) {
+				addr = (norm >> 13) & 0x0FFFFF;
+				addr |= ((uint32_t)(norm >> 36) & 1) << 20;
+				addr <<= 4;
+				addr -= s->pos + (uint32_t)i;
+				addr >>= 4;
+
+				norm &= ~((uint64_t)0x8FFFFF << 13);
+				norm |= (uint64_t)(addr & 0x0FFFFF) << 13;
+				norm |= (uint64_t)(addr & 0x100000)
+						<< (36 - 20);
+
+				instr &= (1 << bit_res) - 1;
+				instr |= norm << bit_res;
+
+				for (j = 0; j < 6; j++)
+					buf[i + j + byte_pos]
+						= (uint8_t)(instr >> (8 * j));
+			}
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARM
+static size_t bcj_arm(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t addr;
+
+	size &= ~(size_t)3;
+
+	for (i = 0; i < size; i += 4) {
+		if (buf[i + 3] == 0xEB) {
+			addr = (uint32_t)buf[i] | ((uint32_t)buf[i + 1] << 8)
+					| ((uint32_t)buf[i + 2] << 16);
+			addr <<= 2;
+			addr -= s->pos + (uint32_t)i + 8;
+			addr >>= 2;
+			buf[i] = (uint8_t)addr;
+			buf[i + 1] = (uint8_t)(addr >> 8);
+			buf[i + 2] = (uint8_t)(addr >> 16);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARMTHUMB
+static size_t bcj_armthumb(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t addr;
+
+	if (size < 4)
+		return 0;
+
+	size -= 4;
+
+	for (i = 0; i <= size; i += 2) {
+		if ((buf[i + 1] & 0xF8) == 0xF0
+				&& (buf[i + 3] & 0xF8) == 0xF8) {
+			addr = (((uint32_t)buf[i + 1] & 0x07) << 19)
+					| ((uint32_t)buf[i] << 11)
+					| (((uint32_t)buf[i + 3] & 0x07) << 8)
+					| (uint32_t)buf[i + 2];
+			addr <<= 1;
+			addr -= s->pos + (uint32_t)i + 4;
+			addr >>= 1;
+			buf[i + 1] = (uint8_t)(0xF0 | ((addr >> 19) & 0x07));
+			buf[i] = (uint8_t)(addr >> 11);
+			buf[i + 3] = (uint8_t)(0xF8 | ((addr >> 8) & 0x07));
+			buf[i + 2] = (uint8_t)addr;
+			i += 2;
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_SPARC
+static size_t bcj_sparc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+
+	size &= ~(size_t)3;
+
+	for (i = 0; i < size; i += 4) {
+		instr = get_unaligned_be32(buf + i);
+		if ((instr >> 22) == 0x100 || (instr >> 22) == 0x1FF) {
+			instr <<= 2;
+			instr -= s->pos + (uint32_t)i;
+			instr >>= 2;
+			instr = ((uint32_t)0x40000000 - (instr & 0x400000))
+					| 0x40000000 | (instr & 0x3FFFFF);
+			put_unaligned_be32(instr, buf + i);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARM64
+static size_t bcj_arm64(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+	uint32_t addr;
+
+	size &= ~(size_t)3;
+
+	for (i = 0; i < size; i += 4) {
+		instr = get_unaligned_le32(buf + i);
+
+		if ((instr >> 26) == 0x25) {
+			/* BL instruction */
+			addr = instr - ((s->pos + (uint32_t)i) >> 2);
+			instr = 0x94000000 | (addr & 0x03FFFFFF);
+			put_unaligned_le32(instr, buf + i);
+
+		} else if ((instr & 0x9F000000) == 0x90000000) {
+			/* ADRP instruction */
+			addr = ((instr >> 29) & 3) | ((instr >> 3) & 0x1FFFFC);
+
+			/* Only convert values in the range +/-512 MiB. */
+			if ((addr + 0x020000) & 0x1C0000)
+				continue;
+
+			addr -= (s->pos + (uint32_t)i) >> 12;
+
+			instr &= 0x9000001F;
+			instr |= (addr & 3) << 29;
+			instr |= (addr & 0x03FFFC) << 3;
+			instr |= (0U - (addr & 0x020000)) & 0xE00000;
+
+			put_unaligned_le32(instr, buf + i);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_RISCV
+static size_t bcj_riscv(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t b1;
+	uint32_t b2;
+	uint32_t b3;
+	uint32_t instr;
+	uint32_t instr2;
+	uint32_t instr2_rs1;
+	uint32_t addr;
+
+	if (size < 8)
+		return 0;
+
+	size -= 8;
+
+	for (i = 0; i <= size; i += 2) {
+		instr = buf[i];
+
+		if (instr == 0xEF) {
+			/* JAL */
+			b1 = buf[i + 1];
+			if ((b1 & 0x0D) != 0)
+				continue;
+
+			b2 = buf[i + 2];
+			b3 = buf[i + 3];
+
+			addr = ((b1 & 0xF0) << 13) | (b2 << 9) | (b3 << 1);
+			addr -= s->pos + (uint32_t)i;
+
+			buf[i + 1] = (uint8_t)((b1 & 0x0F)
+					| ((addr >> 8) & 0xF0));
+
+			buf[i + 2] = (uint8_t)(((addr >> 16) & 0x0F)
+					| ((addr >> 7) & 0x10)
+					| ((addr << 4) & 0xE0));
+
+			buf[i + 3] = (uint8_t)(((addr >> 4) & 0x7F)
+					| ((addr >> 13) & 0x80));
+
+			i += 4 - 2;
+
+		} else if ((instr & 0x7F) == 0x17) {
+			/* AUIPC */
+			instr |= (uint32_t)buf[i + 1] << 8;
+			instr |= (uint32_t)buf[i + 2] << 16;
+			instr |= (uint32_t)buf[i + 3] << 24;
+
+			if (instr & 0xE80) {
+				/* AUIPC's rd doesn't equal x0 or x2. */
+				instr2 = get_unaligned_le32(buf + i + 4);
+
+				if (((instr << 8) ^ (instr2 - 3)) & 0xF8003) {
+					i += 6 - 2;
+					continue;
+				}
+
+				addr = (instr & 0xFFFFF000) + (instr2 >> 20);
+
+				instr = 0x17 | (2 << 7) | (instr2 << 12);
+				instr2 = addr;
+			} else {
+				/* AUIPC's rd equals x0 or x2. */
+				instr2_rs1 = instr >> 27;
+
+				if ((uint32_t)((instr - 0x3117) << 18)
+						>= (instr2_rs1 & 0x1D)) {
+					i += 4 - 2;
+					continue;
+				}
+
+				addr = get_unaligned_be32(buf + i + 4);
+				addr -= s->pos + (uint32_t)i;
+
+				instr2 = (instr >> 12) | (addr << 20);
+
+				instr = 0x17 | (instr2_rs1 << 7)
+					| ((addr + 0x800) & 0xFFFFF000);
+			}
+
+			put_unaligned_le32(instr, buf + i);
+			put_unaligned_le32(instr2, buf + i + 4);
+
+			i += 8 - 2;
+		}
+	}
+
+	return i;
+}
+#endif
+
+/*
+ * Apply the selected BCJ filter. Update *pos and s->pos to match the amount
+ * of data that got filtered.
+ *
+ * NOTE: This is implemented as a switch statement to avoid using function
+ * pointers, which could be problematic in the kernel boot code, which must
+ * avoid pointers to static data (at least on x86).
+ */
+static void bcj_apply(struct xz_dec_bcj *s,
+		      uint8_t *buf, size_t *pos, size_t size)
+{
+	size_t filtered;
+
+	buf += *pos;
+	size -= *pos;
+
+	switch (s->type) {
+#ifdef XZ_DEC_X86
+	case BCJ_X86:
+		filtered = bcj_x86(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_POWERPC
+	case BCJ_POWERPC:
+		filtered = bcj_powerpc(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_IA64
+	case BCJ_IA64:
+		filtered = bcj_ia64(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_ARM
+	case BCJ_ARM:
+		filtered = bcj_arm(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+	case BCJ_ARMTHUMB:
+		filtered = bcj_armthumb(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_SPARC
+	case BCJ_SPARC:
+		filtered = bcj_sparc(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_ARM64
+	case BCJ_ARM64:
+		filtered = bcj_arm64(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_RISCV
+	case BCJ_RISCV:
+		filtered = bcj_riscv(s, buf, size);
+		break;
+#endif
+	default:
+		/* Never reached but silence compiler warnings. */
+		filtered = 0;
+		break;
+	}
+
+	*pos += filtered;
+	s->pos += filtered;
+}
+
+/*
+ * Flush pending filtered data from temp to the output buffer.
+ * Move the remaining mixture of possibly filtered and unfiltered
+ * data to the beginning of temp.
+ */
+static void bcj_flush(struct xz_dec_bcj *s, struct xz_buf *b)
+{
+	size_t copy_size;
+
+	copy_size = min_t(size_t, s->temp.filtered, b->out_size - b->out_pos);
+	memcpy(b->out + b->out_pos, s->temp.buf, copy_size);
+	b->out_pos += copy_size;
+
+	s->temp.filtered -= copy_size;
+	s->temp.size -= copy_size;
+	memmove(s->temp.buf, s->temp.buf + copy_size, s->temp.size);
+}
+
+/*
+ * The BCJ filter functions are primitive in sense that they process the
+ * data in chunks of 1-16 bytes. To hide this issue, this function does
+ * some buffering.
+ */
+XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
+				     struct xz_dec_lzma2 *lzma2,
+				     struct xz_buf *b)
+{
+	size_t out_start;
+
+	/*
+	 * Flush pending already filtered data to the output buffer. Return
+	 * immediately if we couldn't flush everything, or if the next
+	 * filter in the chain had already returned XZ_STREAM_END.
+	 */
+	if (s->temp.filtered > 0) {
+		bcj_flush(s, b);
+		if (s->temp.filtered > 0)
+			return XZ_OK;
+
+		if (s->ret == XZ_STREAM_END)
+			return XZ_STREAM_END;
+	}
+
+	/*
+	 * If we have more output space than what is currently pending in
+	 * temp, copy the unfiltered data from temp to the output buffer
+	 * and try to fill the output buffer by decoding more data from the
+	 * next filter in the chain. Apply the BCJ filter on the new data
+	 * in the output buffer. If everything cannot be filtered, copy it
+	 * to temp and rewind the output buffer position accordingly.
+	 *
+	 * This needs to be always run when temp.size == 0 to handle a special
+	 * case where the output buffer is full and the next filter has no
+	 * more output coming but hasn't returned XZ_STREAM_END yet.
+	 */
+	if (s->temp.size < b->out_size - b->out_pos || s->temp.size == 0) {
+		out_start = b->out_pos;
+		memcpy(b->out + b->out_pos, s->temp.buf, s->temp.size);
+		b->out_pos += s->temp.size;
+
+		s->ret = xz_dec_lzma2_run(lzma2, b);
+		if (s->ret != XZ_STREAM_END
+				&& (s->ret != XZ_OK || s->single_call))
+			return s->ret;
+
+		bcj_apply(s, b->out, &out_start, b->out_pos);
+
+		/*
+		 * As an exception, if the next filter returned XZ_STREAM_END,
+		 * we can do that too, since the last few bytes that remain
+		 * unfiltered are meant to remain unfiltered.
+		 */
+		if (s->ret == XZ_STREAM_END)
+			return XZ_STREAM_END;
+
+		s->temp.size = b->out_pos - out_start;
+		b->out_pos -= s->temp.size;
+		memcpy(s->temp.buf, b->out + b->out_pos, s->temp.size);
+
+		/*
+		 * If there wasn't enough input to the next filter to fill
+		 * the output buffer with unfiltered data, there's no point
+		 * to try decoding more data to temp.
+		 */
+		if (b->out_pos + s->temp.size < b->out_size)
+			return XZ_OK;
+	}
+
+	/*
+	 * We have unfiltered data in temp. If the output buffer isn't full
+	 * yet, try to fill the temp buffer by decoding more data from the
+	 * next filter. Apply the BCJ filter on temp. Then we hopefully can
+	 * fill the actual output buffer by copying filtered data from temp.
+	 * A mix of filtered and unfiltered data may be left in temp; it will
+	 * be taken care on the next call to this function.
+	 */
+	if (b->out_pos < b->out_size) {
+		/* Make b->out{,_pos,_size} temporarily point to s->temp. */
+		s->out = b->out;
+		s->out_pos = b->out_pos;
+		s->out_size = b->out_size;
+		b->out = s->temp.buf;
+		b->out_pos = s->temp.size;
+		b->out_size = sizeof(s->temp.buf);
+
+		s->ret = xz_dec_lzma2_run(lzma2, b);
+
+		s->temp.size = b->out_pos;
+		b->out = s->out;
+		b->out_pos = s->out_pos;
+		b->out_size = s->out_size;
+
+		if (s->ret != XZ_OK && s->ret != XZ_STREAM_END)
+			return s->ret;
+
+		bcj_apply(s, s->temp.buf, &s->temp.filtered, s->temp.size);
+
+		/*
+		 * If the next filter returned XZ_STREAM_END, we mark that
+		 * everything is filtered, since the last unfiltered bytes
+		 * of the stream are meant to be left as is.
+		 */
+		if (s->ret == XZ_STREAM_END)
+			s->temp.filtered = s->temp.size;
+
+		bcj_flush(s, b);
+		if (s->temp.filtered > 0)
+			return XZ_OK;
+	}
+
+	return s->ret;
+}
+
+XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call)
+{
+	struct xz_dec_bcj *s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (s != NULL)
+		s->single_call = single_call;
+
+	return s;
+}
+
+XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
+{
+	switch (id) {
+#ifdef XZ_DEC_X86
+	case BCJ_X86:
+#endif
+#ifdef XZ_DEC_POWERPC
+	case BCJ_POWERPC:
+#endif
+#ifdef XZ_DEC_IA64
+	case BCJ_IA64:
+#endif
+#ifdef XZ_DEC_ARM
+	case BCJ_ARM:
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+	case BCJ_ARMTHUMB:
+#endif
+#ifdef XZ_DEC_SPARC
+	case BCJ_SPARC:
+#endif
+#ifdef XZ_DEC_ARM64
+	case BCJ_ARM64:
+#endif
+#ifdef XZ_DEC_RISCV
+	case BCJ_RISCV:
+#endif
+		break;
+
+	default:
+		/* Unsupported Filter ID */
+		return XZ_OPTIONS_ERROR;
+	}
+
+	s->type = id;
+	s->ret = XZ_OK;
+	s->pos = 0;
+	s->x86_prev_mask = 0;
+	s->temp.filtered = 0;
+	s->temp.size = 0;
+
+	return XZ_OK;
+}
+
+#endif

android/app/src/xposed/cpp/xz/xz_dec_stream.c

@@ -0,0 +1,984 @@
+// SPDX-License-Identifier: 0BSD
+
+/*
+ * .xz Stream decoder
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ */
+
+#include "xz_private.h"
+#include "xz_stream.h"
+
+#ifdef XZ_USE_CRC64
+#	define IS_CRC64(check_type) ((check_type) == XZ_CHECK_CRC64)
+#else
+#	define IS_CRC64(check_type) false
+#endif
+
+#ifdef XZ_USE_SHA256
+#	define IS_SHA256(check_type) ((check_type) == XZ_CHECK_SHA256)
+#else
+#	define IS_SHA256(check_type) false
+#endif
+
+/* Hash used to validate the Index field */
+struct xz_dec_hash {
+	vli_type unpadded;
+	vli_type uncompressed;
+	uint32_t crc32;
+};
+
+struct xz_dec {
+	/* Position in dec_main() */
+	enum {
+		SEQ_STREAM_HEADER,
+		SEQ_BLOCK_START,
+		SEQ_BLOCK_HEADER,
+		SEQ_BLOCK_UNCOMPRESS,
+		SEQ_BLOCK_PADDING,
+		SEQ_BLOCK_CHECK,
+		SEQ_INDEX,
+		SEQ_INDEX_PADDING,
+		SEQ_INDEX_CRC32,
+		SEQ_STREAM_FOOTER,
+		SEQ_STREAM_PADDING
+	} sequence;
+
+	/* Position in variable-length integers and Check fields */
+	uint32_t pos;
+
+	/* Variable-length integer decoded by dec_vli() */
+	vli_type vli;
+
+	/* Saved in_pos and out_pos */
+	size_t in_start;
+	size_t out_start;
+
+#ifdef XZ_USE_CRC64
+	/* CRC32 or CRC64 value in Block or CRC32 value in Index */
+	uint64_t crc;
+#else
+	/* CRC32 value in Block or Index */
+	uint32_t crc;
+#endif
+
+	/* Type of the integrity check calculated from uncompressed data */
+	enum xz_check check_type;
+
+	/* Operation mode */
+	enum xz_mode mode;
+
+	/*
+	 * True if the next call to xz_dec_run() is allowed to return
+	 * XZ_BUF_ERROR.
+	 */
+	bool allow_buf_error;
+
+	/* Information stored in Block Header */
+	struct {
+		/*
+		 * Value stored in the Compressed Size field, or
+		 * VLI_UNKNOWN if Compressed Size is not present.
+		 */
+		vli_type compressed;
+
+		/*
+		 * Value stored in the Uncompressed Size field, or
+		 * VLI_UNKNOWN if Uncompressed Size is not present.
+		 */
+		vli_type uncompressed;
+
+		/* Size of the Block Header field */
+		uint32_t size;
+	} block_header;
+
+	/* Information collected when decoding Blocks */
+	struct {
+		/* Observed compressed size of the current Block */
+		vli_type compressed;
+
+		/* Observed uncompressed size of the current Block */
+		vli_type uncompressed;
+
+		/* Number of Blocks decoded so far */
+		vli_type count;
+
+		/*
+		 * Hash calculated from the Block sizes. This is used to
+		 * validate the Index field.
+		 */
+		struct xz_dec_hash hash;
+	} block;
+
+	/* Variables needed when verifying the Index field */
+	struct {
+		/* Position in dec_index() */
+		enum {
+			SEQ_INDEX_COUNT,
+			SEQ_INDEX_UNPADDED,
+			SEQ_INDEX_UNCOMPRESSED
+		} sequence;
+
+		/* Size of the Index in bytes */
+		vli_type size;
+
+		/* Number of Records (matches block.count in valid files) */
+		vli_type count;
+
+		/*
+		 * Hash calculated from the Records (matches block.hash in
+		 * valid files).
+		 */
+		struct xz_dec_hash hash;
+	} index;
+
+	/*
+	 * Temporary buffer needed to hold Stream Header, Block Header,
+	 * and Stream Footer. The Block Header is the biggest (1 KiB)
+	 * so we reserve space according to that. buf[] has to be aligned
+	 * to a multiple of four bytes; the size_t variables before it
+	 * should guarantee this.
+	 */
+	struct {
+		size_t pos;
+		size_t size;
+		uint8_t buf[1024];
+	} temp;
+
+	struct xz_dec_lzma2 *lzma2;
+
+#ifdef XZ_DEC_BCJ
+	struct xz_dec_bcj *bcj;
+	bool bcj_active;
+#endif
+
+#ifdef XZ_USE_SHA256
+	/*
+	 * SHA-256 value in Block
+	 *
+	 * struct xz_sha256 is over a hundred bytes and it's only accessed
+	 * from a few places. By putting the SHA-256 state near the end
+	 * of struct xz_dec (somewhere after the "index" member) reduces
+	 * code size at least on x86 and RISC-V. It's because the first bytes
+	 * of the struct can be accessed with smaller instructions; the
+	 * members that are accessed from many places should be at the top.
+	 */
+	struct xz_sha256 sha256;
+#endif
+};
+
+#if defined(XZ_DEC_ANY_CHECK) || defined(XZ_USE_SHA256)
+/* Sizes of the Check field with different Check IDs */
+static const uint8_t check_sizes[16] = {
+	0,
+	4, 4, 4,
+	8, 8, 8,
+	16, 16, 16,
+	32, 32, 32,
+	64, 64, 64
+};
+#endif
+
+/*
+ * Fill s->temp by copying data starting from b->in[b->in_pos]. Caller
+ * must have set s->temp.pos and s->temp.size to indicate how much data
+ * we are supposed to copy into s->temp.buf. Return true once s->temp.pos
+ * has reached s->temp.size.
+ */
+static bool fill_temp(struct xz_dec *s, struct xz_buf *b)
+{
+	size_t copy_size = min_t(size_t,
+			b->in_size - b->in_pos, s->temp.size - s->temp.pos);
+
+	memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size);
+	b->in_pos += copy_size;
+	s->temp.pos += copy_size;
+
+	if (s->temp.pos == s->temp.size) {
+		s->temp.pos = 0;
+		return true;
+	}
+
+	return false;
+}
+
+/* Decode a variable-length integer (little-endian base-128 encoding) */
+static enum xz_ret dec_vli(struct xz_dec *s, const uint8_t *in,
+			   size_t *in_pos, size_t in_size)
+{
+	uint8_t byte;
+
+	if (s->pos == 0)
+		s->vli = 0;
+
+	while (*in_pos < in_size) {
+		byte = in[*in_pos];
+		++*in_pos;
+
+		s->vli |= (vli_type)(byte & 0x7F) << s->pos;
+
+		if ((byte & 0x80) == 0) {
+			/* Don't allow non-minimal encodings. */
+			if (byte == 0 && s->pos != 0)
+				return XZ_DATA_ERROR;
+
+			s->pos = 0;
+			return XZ_STREAM_END;
+		}
+
+		s->pos += 7;
+		if (s->pos == 7 * VLI_BYTES_MAX)
+			return XZ_DATA_ERROR;
+	}
+
+	return XZ_OK;
+}
+
+/*
+ * Decode the Compressed Data field from a Block. Update and validate
+ * the observed compressed and uncompressed sizes of the Block so that
+ * they don't exceed the values possibly stored in the Block Header
+ * (validation assumes that no integer overflow occurs, since vli_type
+ * is normally uint64_t). Update the CRC32 or CRC64 value if presence of
+ * the CRC32 or CRC64 field was indicated in Stream Header.
+ *
+ * Once the decoding is finished, validate that the observed sizes match
+ * the sizes possibly stored in the Block Header. Update the hash and
+ * Block count, which are later used to validate the Index field.
+ */
+static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	s->in_start = b->in_pos;
+	s->out_start = b->out_pos;
+
+#ifdef XZ_DEC_BCJ
+	if (s->bcj_active)
+		ret = xz_dec_bcj_run(s->bcj, s->lzma2, b);
+	else
+#endif
+		ret = xz_dec_lzma2_run(s->lzma2, b);
+
+	s->block.compressed += b->in_pos - s->in_start;
+	s->block.uncompressed += b->out_pos - s->out_start;
+
+	/*
+	 * There is no need to separately check for VLI_UNKNOWN, since
+	 * the observed sizes are always smaller than VLI_UNKNOWN.
+	 */
+	if (s->block.compressed > s->block_header.compressed
+			|| s->block.uncompressed
+				> s->block_header.uncompressed)
+		return XZ_DATA_ERROR;
+
+	if (s->check_type == XZ_CHECK_CRC32)
+		s->crc = xz_crc32(b->out + s->out_start,
+				b->out_pos - s->out_start, s->crc);
+#ifdef XZ_USE_CRC64
+	else if (s->check_type == XZ_CHECK_CRC64)
+		s->crc = xz_crc64(b->out + s->out_start,
+				b->out_pos - s->out_start, s->crc);
+#endif
+#ifdef XZ_USE_SHA256
+	else if (s->check_type == XZ_CHECK_SHA256)
+		xz_sha256_update(b->out + s->out_start,
+				b->out_pos - s->out_start, &s->sha256);
+#endif
+
+	if (ret == XZ_STREAM_END) {
+		if (s->block_header.compressed != VLI_UNKNOWN
+				&& s->block_header.compressed
+					!= s->block.compressed)
+			return XZ_DATA_ERROR;
+
+		if (s->block_header.uncompressed != VLI_UNKNOWN
+				&& s->block_header.uncompressed
+					!= s->block.uncompressed)
+			return XZ_DATA_ERROR;
+
+		s->block.hash.unpadded += s->block_header.size
+				+ s->block.compressed;
+
+#if defined(XZ_DEC_ANY_CHECK) || defined(XZ_USE_SHA256)
+		s->block.hash.unpadded += check_sizes[s->check_type];
+#else
+		if (s->check_type == XZ_CHECK_CRC32)
+			s->block.hash.unpadded += 4;
+		else if (IS_CRC64(s->check_type))
+			s->block.hash.unpadded += 8;
+#endif
+
+		s->block.hash.uncompressed += s->block.uncompressed;
+		s->block.hash.crc32 = xz_crc32(
+				(const uint8_t *)&s->block.hash,
+				sizeof(s->block.hash), s->block.hash.crc32);
+
+		++s->block.count;
+	}
+
+	return ret;
+}
+
+/* Update the Index size and the CRC32 value. */
+static void index_update(struct xz_dec *s, const struct xz_buf *b)
+{
+	size_t in_used = b->in_pos - s->in_start;
+	s->index.size += in_used;
+	s->crc = xz_crc32(b->in + s->in_start, in_used, s->crc);
+}
+
+/*
+ * Decode the Number of Records, Unpadded Size, and Uncompressed Size
+ * fields from the Index field. That is, Index Padding and CRC32 are not
+ * decoded by this function.
+ *
+ * This can return XZ_OK (more input needed), XZ_STREAM_END (everything
+ * successfully decoded), or XZ_DATA_ERROR (input is corrupt).
+ */
+static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	do {
+		ret = dec_vli(s, b->in, &b->in_pos, b->in_size);
+		if (ret != XZ_STREAM_END) {
+			index_update(s, b);
+			return ret;
+		}
+
+		switch (s->index.sequence) {
+		case SEQ_INDEX_COUNT:
+			s->index.count = s->vli;
+
+			/*
+			 * Validate that the Number of Records field
+			 * indicates the same number of Records as
+			 * there were Blocks in the Stream.
+			 */
+			if (s->index.count != s->block.count)
+				return XZ_DATA_ERROR;
+
+			s->index.sequence = SEQ_INDEX_UNPADDED;
+			break;
+
+		case SEQ_INDEX_UNPADDED:
+			s->index.hash.unpadded += s->vli;
+			s->index.sequence = SEQ_INDEX_UNCOMPRESSED;
+			break;
+
+		case SEQ_INDEX_UNCOMPRESSED:
+			s->index.hash.uncompressed += s->vli;
+			s->index.hash.crc32 = xz_crc32(
+					(const uint8_t *)&s->index.hash,
+					sizeof(s->index.hash),
+					s->index.hash.crc32);
+			--s->index.count;
+			s->index.sequence = SEQ_INDEX_UNPADDED;
+			break;
+		}
+	} while (s->index.count > 0);
+
+	return XZ_STREAM_END;
+}
+
+/*
+ * Validate that the next four or eight input bytes match the value
+ * of s->crc. s->pos must be zero when starting to validate the first byte.
+ * The "bits" argument allows using the same code for both CRC32 and CRC64.
+ */
+static enum xz_ret crc_validate(struct xz_dec *s, struct xz_buf *b,
+				uint32_t bits)
+{
+	do {
+		if (b->in_pos == b->in_size)
+			return XZ_OK;
+
+		if (((s->crc >> s->pos) & 0xFF) != b->in[b->in_pos++])
+			return XZ_DATA_ERROR;
+
+		s->pos += 8;
+
+	} while (s->pos < bits);
+
+	s->crc = 0;
+	s->pos = 0;
+
+	return XZ_STREAM_END;
+}
+
+#ifdef XZ_DEC_ANY_CHECK
+/*
+ * Skip over the Check field when the Check ID is not supported.
+ * Returns true once the whole Check field has been skipped over.
+ */
+static bool check_skip(struct xz_dec *s, struct xz_buf *b)
+{
+	while (s->pos < check_sizes[s->check_type]) {
+		if (b->in_pos == b->in_size)
+			return false;
+
+		++b->in_pos;
+		++s->pos;
+	}
+
+	s->pos = 0;
+
+	return true;
+}
+#endif
+
+/* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */
+static enum xz_ret dec_stream_header(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE))
+		return XZ_FORMAT_ERROR;
+
+	if (xz_crc32(s->temp.buf + HEADER_MAGIC_SIZE, 2, 0)
+			!= get_le32(s->temp.buf + HEADER_MAGIC_SIZE + 2))
+		return XZ_DATA_ERROR;
+
+	if (s->temp.buf[HEADER_MAGIC_SIZE] != 0)
+		return XZ_OPTIONS_ERROR;
+
+	/*
+	 * Of integrity checks, we support none (Check ID = 0),
+	 * CRC32 (Check ID = 1), and optionally CRC64 (Check ID = 4).
+	 * However, if XZ_DEC_ANY_CHECK is defined, we will accept other
+	 * check types too, but then the check won't be verified and
+	 * a warning (XZ_UNSUPPORTED_CHECK) will be given.
+	 */
+	if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX)
+		return XZ_OPTIONS_ERROR;
+
+	s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1];
+
+	if (s->check_type > XZ_CHECK_CRC32 && !IS_CRC64(s->check_type)
+			&& !IS_SHA256(s->check_type)) {
+#ifdef XZ_DEC_ANY_CHECK
+		return XZ_UNSUPPORTED_CHECK;
+#else
+		return XZ_OPTIONS_ERROR;
+#endif
+	}
+
+	return XZ_OK;
+}
+
+/* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */
+static enum xz_ret dec_stream_footer(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE))
+		return XZ_DATA_ERROR;
+
+	if (xz_crc32(s->temp.buf + 4, 6, 0) != get_le32(s->temp.buf))
+		return XZ_DATA_ERROR;
+
+	/*
+	 * Validate Backward Size. Note that we never added the size of the
+	 * Index CRC32 field to s->index.size, thus we use s->index.size / 4
+	 * instead of s->index.size / 4 - 1.
+	 */
+	if ((s->index.size >> 2) != get_le32(s->temp.buf + 4))
+		return XZ_DATA_ERROR;
+
+	if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->check_type)
+		return XZ_DATA_ERROR;
+
+	/*
+	 * Use XZ_STREAM_END instead of XZ_OK to be more convenient
+	 * for the caller.
+	 */
+	return XZ_STREAM_END;
+}
+
+/* Decode the Block Header and initialize the filter chain. */
+static enum xz_ret dec_block_header(struct xz_dec *s)
+{
+	enum xz_ret ret;
+
+	/*
+	 * Validate the CRC32. We know that the temp buffer is at least
+	 * eight bytes so this is safe.
+	 */
+	s->temp.size -= 4;
+	if (xz_crc32(s->temp.buf, s->temp.size, 0)
+			!= get_le32(s->temp.buf + s->temp.size))
+		return XZ_DATA_ERROR;
+
+	s->temp.pos = 2;
+
+	/*
+	 * Catch unsupported Block Flags. We support only one or two filters
+	 * in the chain, so we catch that with the same test.
+	 */
+#ifdef XZ_DEC_BCJ
+	if (s->temp.buf[1] & 0x3E)
+#else
+	if (s->temp.buf[1] & 0x3F)
+#endif
+		return XZ_OPTIONS_ERROR;
+
+	/* Compressed Size */
+	if (s->temp.buf[1] & 0x40) {
+		if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
+					!= XZ_STREAM_END)
+			return XZ_DATA_ERROR;
+
+		s->block_header.compressed = s->vli;
+	} else {
+		s->block_header.compressed = VLI_UNKNOWN;
+	}
+
+	/* Uncompressed Size */
+	if (s->temp.buf[1] & 0x80) {
+		if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
+				!= XZ_STREAM_END)
+			return XZ_DATA_ERROR;
+
+		s->block_header.uncompressed = s->vli;
+	} else {
+		s->block_header.uncompressed = VLI_UNKNOWN;
+	}
+
+#ifdef XZ_DEC_BCJ
+	/* If there are two filters, the first one must be a BCJ filter. */
+	s->bcj_active = s->temp.buf[1] & 0x01;
+	if (s->bcj_active) {
+		if (s->temp.size - s->temp.pos < 2)
+			return XZ_OPTIONS_ERROR;
+
+		ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]);
+		if (ret != XZ_OK)
+			return ret;
+
+		/*
+		 * We don't support custom start offset,
+		 * so Size of Properties must be zero.
+		 */
+		if (s->temp.buf[s->temp.pos++] != 0x00)
+			return XZ_OPTIONS_ERROR;
+	}
+#endif
+
+	/* Valid Filter Flags always take at least two bytes. */
+	if (s->temp.size - s->temp.pos < 2)
+		return XZ_DATA_ERROR;
+
+	/* Filter ID = LZMA2 */
+	if (s->temp.buf[s->temp.pos++] != 0x21)
+		return XZ_OPTIONS_ERROR;
+
+	/* Size of Properties = 1-byte Filter Properties */
+	if (s->temp.buf[s->temp.pos++] != 0x01)
+		return XZ_OPTIONS_ERROR;
+
+	/* Filter Properties contains LZMA2 dictionary size. */
+	if (s->temp.size - s->temp.pos < 1)
+		return XZ_DATA_ERROR;
+
+	ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]);
+	if (ret != XZ_OK)
+		return ret;
+
+	/* The rest must be Header Padding. */
+	while (s->temp.pos < s->temp.size)
+		if (s->temp.buf[s->temp.pos++] != 0x00)
+			return XZ_OPTIONS_ERROR;
+
+	s->temp.pos = 0;
+	s->block.compressed = 0;
+	s->block.uncompressed = 0;
+
+	return XZ_OK;
+}
+
+static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	/*
+	 * Store the start position for the case when we are in the middle
+	 * of the Index field.
+	 */
+	s->in_start = b->in_pos;
+
+	while (true) {
+		switch (s->sequence) {
+		case SEQ_STREAM_HEADER:
+			/*
+			 * Stream Header is copied to s->temp, and then
+			 * decoded from there. This way if the caller
+			 * gives us only little input at a time, we can
+			 * still keep the Stream Header decoding code
+			 * simple. Similar approach is used in many places
+			 * in this file.
+			 */
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			/*
+			 * If dec_stream_header() returns
+			 * XZ_UNSUPPORTED_CHECK, it is still possible
+			 * to continue decoding if working in multi-call
+			 * mode. Thus, update s->sequence before calling
+			 * dec_stream_header().
+			 */
+			s->sequence = SEQ_BLOCK_START;
+
+			ret = dec_stream_header(s);
+			if (ret != XZ_OK)
+				return ret;
+
+			fallthrough;
+
+		case SEQ_BLOCK_START:
+			/* We need one byte of input to continue. */
+			if (b->in_pos == b->in_size)
+				return XZ_OK;
+
+			/* See if this is the beginning of the Index field. */
+			if (b->in[b->in_pos] == 0) {
+				s->in_start = b->in_pos++;
+				s->sequence = SEQ_INDEX;
+				break;
+			}
+
+			/*
+			 * Calculate the size of the Block Header and
+			 * prepare to decode it.
+			 */
+			s->block_header.size
+				= ((uint32_t)b->in[b->in_pos] + 1) * 4;
+
+			s->temp.size = s->block_header.size;
+			s->temp.pos = 0;
+			s->sequence = SEQ_BLOCK_HEADER;
+
+			fallthrough;
+
+		case SEQ_BLOCK_HEADER:
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			ret = dec_block_header(s);
+			if (ret != XZ_OK)
+				return ret;
+
+#ifdef XZ_USE_SHA256
+			if (s->check_type == XZ_CHECK_SHA256)
+				xz_sha256_reset(&s->sha256);
+#endif
+
+			s->sequence = SEQ_BLOCK_UNCOMPRESS;
+
+			fallthrough;
+
+		case SEQ_BLOCK_UNCOMPRESS:
+			ret = dec_block(s, b);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->sequence = SEQ_BLOCK_PADDING;
+
+			fallthrough;
+
+		case SEQ_BLOCK_PADDING:
+			/*
+			 * Size of Compressed Data + Block Padding
+			 * must be a multiple of four. We don't need
+			 * s->block.compressed for anything else
+			 * anymore, so we use it here to test the size
+			 * of the Block Padding field.
+			 */
+			while (s->block.compressed & 3) {
+				if (b->in_pos == b->in_size)
+					return XZ_OK;
+
+				if (b->in[b->in_pos++] != 0)
+					return XZ_DATA_ERROR;
+
+				++s->block.compressed;
+			}
+
+			s->sequence = SEQ_BLOCK_CHECK;
+
+			fallthrough;
+
+		case SEQ_BLOCK_CHECK:
+			if (s->check_type == XZ_CHECK_CRC32) {
+				ret = crc_validate(s, b, 32);
+				if (ret != XZ_STREAM_END)
+					return ret;
+			}
+			else if (IS_CRC64(s->check_type)) {
+				ret = crc_validate(s, b, 64);
+				if (ret != XZ_STREAM_END)
+					return ret;
+			}
+#ifdef XZ_USE_SHA256
+			else if (s->check_type == XZ_CHECK_SHA256) {
+				s->temp.size = 32;
+				if (!fill_temp(s, b))
+					return XZ_OK;
+
+				if (!xz_sha256_validate(s->temp.buf,
+							&s->sha256))
+					return XZ_DATA_ERROR;
+
+				s->pos = 0;
+			}
+#endif
+#ifdef XZ_DEC_ANY_CHECK
+			else if (!check_skip(s, b)) {
+				return XZ_OK;
+			}
+#endif
+
+			s->sequence = SEQ_BLOCK_START;
+			break;
+
+		case SEQ_INDEX:
+			ret = dec_index(s, b);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->sequence = SEQ_INDEX_PADDING;
+
+			fallthrough;
+
+		case SEQ_INDEX_PADDING:
+			while ((s->index.size + (b->in_pos - s->in_start))
+					& 3) {
+				if (b->in_pos == b->in_size) {
+					index_update(s, b);
+					return XZ_OK;
+				}
+
+				if (b->in[b->in_pos++] != 0)
+					return XZ_DATA_ERROR;
+			}
+
+			/* Finish the CRC32 value and Index size. */
+			index_update(s, b);
+
+			/* Compare the hashes to validate the Index field. */
+			if (!memeq(&s->block.hash, &s->index.hash,
+					sizeof(s->block.hash)))
+				return XZ_DATA_ERROR;
+
+			s->sequence = SEQ_INDEX_CRC32;
+
+			fallthrough;
+
+		case SEQ_INDEX_CRC32:
+			ret = crc_validate(s, b, 32);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->temp.size = STREAM_HEADER_SIZE;
+			s->sequence = SEQ_STREAM_FOOTER;
+
+			fallthrough;
+
+		case SEQ_STREAM_FOOTER:
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			return dec_stream_footer(s);
+
+		case SEQ_STREAM_PADDING:
+			/* Never reached, only silencing a warning */
+			break;
+		}
+	}
+
+	/* Never reached */
+}
+
+/*
+ * xz_dec_run() is a wrapper for dec_main() to handle some special cases in
+ * multi-call and single-call decoding.
+ *
+ * In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we
+ * are not going to make any progress anymore. This is to prevent the caller
+ * from calling us infinitely when the input file is truncated or otherwise
+ * corrupt. Since zlib-style API allows that the caller fills the input buffer
+ * only when the decoder doesn't produce any new output, we have to be careful
+ * to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only
+ * after the second consecutive call to xz_dec_run() that makes no progress.
+ *
+ * In single-call mode, if we couldn't decode everything and no error
+ * occurred, either the input is truncated or the output buffer is too small.
+ * Since we know that the last input byte never produces any output, we know
+ * that if all the input was consumed and decoding wasn't finished, the file
+ * must be corrupt. Otherwise the output buffer has to be too small or the
+ * file is corrupt in a way that decoding it produces too big output.
+ *
+ * If single-call decoding fails, we reset b->in_pos and b->out_pos back to
+ * their original values. This is because with some filter chains there won't
+ * be any valid uncompressed data in the output buffer unless the decoding
+ * actually succeeds (that's the price to pay of using the output buffer as
+ * the workspace).
+ */
+XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
+{
+	size_t in_start;
+	size_t out_start;
+	enum xz_ret ret;
+
+	if (DEC_IS_SINGLE(s->mode))
+		xz_dec_reset(s);
+
+	in_start = b->in_pos;
+	out_start = b->out_pos;
+	ret = dec_main(s, b);
+
+	if (DEC_IS_SINGLE(s->mode)) {
+		if (ret == XZ_OK)
+			ret = b->in_pos == b->in_size
+					? XZ_DATA_ERROR : XZ_BUF_ERROR;
+
+		if (ret != XZ_STREAM_END) {
+			b->in_pos = in_start;
+			b->out_pos = out_start;
+		}
+
+	} else if (ret == XZ_OK && in_start == b->in_pos
+			&& out_start == b->out_pos) {
+		if (s->allow_buf_error)
+			ret = XZ_BUF_ERROR;
+
+		s->allow_buf_error = true;
+	} else {
+		s->allow_buf_error = false;
+	}
+
+	return ret;
+}
+
+#ifdef XZ_DEC_CONCATENATED
+XZ_EXTERN enum xz_ret xz_dec_catrun(struct xz_dec *s, struct xz_buf *b,
+				    int finish)
+{
+	enum xz_ret ret;
+
+	if (DEC_IS_SINGLE(s->mode)) {
+		xz_dec_reset(s);
+		finish = true;
+	}
+
+	while (true) {
+		if (s->sequence == SEQ_STREAM_PADDING) {
+			/*
+			 * Skip Stream Padding. Its size must be a multiple
+			 * of four bytes which is tracked with s->pos.
+			 */
+			while (true) {
+				if (b->in_pos == b->in_size) {
+					/*
+					 * Note that if we are repeatedly
+					 * given no input and finish is false,
+					 * we will keep returning XZ_OK even
+					 * though no progress is being made.
+					 * The lack of XZ_BUF_ERROR support
+					 * isn't a problem here because a
+					 * reasonable caller will eventually
+					 * provide more input or set finish
+					 * to true.
+					 */
+					if (!finish)
+						return XZ_OK;
+
+					if (s->pos != 0)
+						return XZ_DATA_ERROR;
+
+					return XZ_STREAM_END;
+				}
+
+				if (b->in[b->in_pos] != 0x00) {
+					if (s->pos != 0)
+						return XZ_DATA_ERROR;
+
+					break;
+				}
+
+				++b->in_pos;
+				s->pos = (s->pos + 1) & 3;
+			}
+
+			/*
+			 * More input remains. It should be a new Stream.
+			 *
+			 * In single-call mode xz_dec_run() will always call
+			 * xz_dec_reset(). Thus, we need to do it here only
+			 * in multi-call mode.
+			 */
+			if (DEC_IS_MULTI(s->mode))
+				xz_dec_reset(s);
+		}
+
+		ret = xz_dec_run(s, b);
+
+		if (ret != XZ_STREAM_END)
+			break;
+
+		s->sequence = SEQ_STREAM_PADDING;
+	}
+
+	return ret;
+}
+#endif
+
+XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
+{
+	struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (s == NULL)
+		return NULL;
+
+	s->mode = mode;
+
+#ifdef XZ_DEC_BCJ
+	s->bcj = xz_dec_bcj_create(DEC_IS_SINGLE(mode));
+	if (s->bcj == NULL)
+		goto error_bcj;
+#endif
+
+	s->lzma2 = xz_dec_lzma2_create(mode, dict_max);
+	if (s->lzma2 == NULL)
+		goto error_lzma2;
+
+	xz_dec_reset(s);
+	return s;
+
+error_lzma2:
+#ifdef XZ_DEC_BCJ
+	xz_dec_bcj_end(s->bcj);
+error_bcj:
+#endif
+	kfree(s);
+	return NULL;
+}
+
+XZ_EXTERN void xz_dec_reset(struct xz_dec *s)
+{
+	s->sequence = SEQ_STREAM_HEADER;
+	s->allow_buf_error = false;
+	s->pos = 0;
+	s->crc = 0;
+	memzero(&s->block, sizeof(s->block));
+	memzero(&s->index, sizeof(s->index));
+	s->temp.pos = 0;
+	s->temp.size = STREAM_HEADER_SIZE;
+}
+
+XZ_EXTERN void xz_dec_end(struct xz_dec *s)
+{
+	if (s != NULL) {
+		xz_dec_lzma2_end(s->lzma2);
+#ifdef XZ_DEC_BCJ
+		xz_dec_bcj_end(s->bcj);
+#endif
+		kfree(s);
+	}
+}

android/app/src/xposed/cpp/xz/xz_lzma2.h

@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: 0BSD */
+
+/*
+ * LZMA2 definitions
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <https://7-zip.org/>
+ */
+
+#ifndef XZ_LZMA2_H
+#define XZ_LZMA2_H
+
+/* Range coder constants */
+#define RC_SHIFT_BITS 8
+#define RC_TOP_BITS 24
+#define RC_TOP_VALUE (1 << RC_TOP_BITS)
+#define RC_BIT_MODEL_TOTAL_BITS 11
+#define RC_BIT_MODEL_TOTAL (1 << RC_BIT_MODEL_TOTAL_BITS)
+#define RC_MOVE_BITS 5
+
+/*
+ * Maximum number of position states. A position state is the lowest pb
+ * number of bits of the current uncompressed offset. In some places there
+ * are different sets of probabilities for different position states.
+ */
+#define POS_STATES_MAX (1 << 4)
+
+/*
+ * This enum is used to track which LZMA symbols have occurred most recently
+ * and in which order. This information is used to predict the next symbol.
+ *
+ * Symbols:
+ *  - Literal: One 8-bit byte
+ *  - Match: Repeat a chunk of data at some distance
+ *  - Long repeat: Multi-byte match at a recently seen distance
+ *  - Short repeat: One-byte repeat at a recently seen distance
+ *
+ * The symbol names are in from STATE_oldest_older_previous. REP means
+ * either short or long repeated match, and NONLIT means any non-literal.
+ */
+enum lzma_state {
+	STATE_LIT_LIT,
+	STATE_MATCH_LIT_LIT,
+	STATE_REP_LIT_LIT,
+	STATE_SHORTREP_LIT_LIT,
+	STATE_MATCH_LIT,
+	STATE_REP_LIT,
+	STATE_SHORTREP_LIT,
+	STATE_LIT_MATCH,
+	STATE_LIT_LONGREP,
+	STATE_LIT_SHORTREP,
+	STATE_NONLIT_MATCH,
+	STATE_NONLIT_REP
+};
+
+/* Total number of states */
+#define STATES 12
+
+/* The lowest 7 states indicate that the previous state was a literal. */
+#define LIT_STATES 7
+
+/* Indicate that the latest symbol was a literal. */
+static inline void lzma_state_literal(enum lzma_state *state)
+{
+	if (*state <= STATE_SHORTREP_LIT_LIT)
+		*state = STATE_LIT_LIT;
+	else if (*state <= STATE_LIT_SHORTREP)
+		*state -= 3;
+	else
+		*state -= 6;
+}
+
+/* Indicate that the latest symbol was a match. */
+static inline void lzma_state_match(enum lzma_state *state)
+{
+	*state = *state < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH;
+}
+
+/* Indicate that the latest state was a long repeated match. */
+static inline void lzma_state_long_rep(enum lzma_state *state)
+{
+	*state = *state < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP;
+}
+
+/* Indicate that the latest symbol was a short match. */
+static inline void lzma_state_short_rep(enum lzma_state *state)
+{
+	*state = *state < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP;
+}
+
+/* Test if the previous symbol was a literal. */
+static inline bool lzma_state_is_literal(enum lzma_state state)
+{
+	return state < LIT_STATES;
+}
+
+/* Each literal coder is divided in three sections:
+ *   - 0x001-0x0FF: Without match byte
+ *   - 0x101-0x1FF: With match byte; match bit is 0
+ *   - 0x201-0x2FF: With match byte; match bit is 1
+ *
+ * Match byte is used when the previous LZMA symbol was something else than
+ * a literal (that is, it was some kind of match).
+ */
+#define LITERAL_CODER_SIZE 0x300
+
+/* Maximum number of literal coders */
+#define LITERAL_CODERS_MAX (1 << 4)
+
+/* Minimum length of a match is two bytes. */
+#define MATCH_LEN_MIN 2
+
+/* Match length is encoded with 4, 5, or 10 bits.
+ *
+ * Length   Bits
+ *  2-9      4 = Choice=0 + 3 bits
+ * 10-17     5 = Choice=1 + Choice2=0 + 3 bits
+ * 18-273   10 = Choice=1 + Choice2=1 + 8 bits
+ */
+#define LEN_LOW_BITS 3
+#define LEN_LOW_SYMBOLS (1 << LEN_LOW_BITS)
+#define LEN_MID_BITS 3
+#define LEN_MID_SYMBOLS (1 << LEN_MID_BITS)
+#define LEN_HIGH_BITS 8
+#define LEN_HIGH_SYMBOLS (1 << LEN_HIGH_BITS)
+#define LEN_SYMBOLS (LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS + LEN_HIGH_SYMBOLS)
+
+/*
+ * Maximum length of a match is 273 which is a result of the encoding
+ * described above.
+ */
+#define MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1)
+
+/*
+ * Different sets of probabilities are used for match distances that have
+ * very short match length: Lengths of 2, 3, and 4 bytes have a separate
+ * set of probabilities for each length. The matches with longer length
+ * use a shared set of probabilities.
+ */
+#define DIST_STATES 4
+
+/*
+ * Get the index of the appropriate probability array for decoding
+ * the distance slot.
+ */
+static inline uint32_t lzma_get_dist_state(uint32_t len)
+{
+	return len < DIST_STATES + MATCH_LEN_MIN
+			? len - MATCH_LEN_MIN : DIST_STATES - 1;
+}
+
+/*
+ * The highest two bits of a 32-bit match distance are encoded using six bits.
+ * This six-bit value is called a distance slot. This way encoding a 32-bit
+ * value takes 6-36 bits, larger values taking more bits.
+ */
+#define DIST_SLOT_BITS 6
+#define DIST_SLOTS (1 << DIST_SLOT_BITS)
+
+/* Match distances up to 127 are fully encoded using probabilities. Since
+ * the highest two bits (distance slot) are always encoded using six bits,
+ * the distances 0-3 don't need any additional bits to encode, since the
+ * distance slot itself is the same as the actual distance. DIST_MODEL_START
+ * indicates the first distance slot where at least one additional bit is
+ * needed.
+ */
+#define DIST_MODEL_START 4
+
+/*
+ * Match distances greater than 127 are encoded in three pieces:
+ *   - distance slot: the highest two bits
+ *   - direct bits: 2-26 bits below the highest two bits
+ *   - alignment bits: four lowest bits
+ *
+ * Direct bits don't use any probabilities.
+ *
+ * The distance slot value of 14 is for distances 128-191.
+ */
+#define DIST_MODEL_END 14
+
+/* Distance slots that indicate a distance <= 127. */
+#define FULL_DISTANCES_BITS (DIST_MODEL_END / 2)
+#define FULL_DISTANCES (1 << FULL_DISTANCES_BITS)
+
+/*
+ * For match distances greater than 127, only the highest two bits and the
+ * lowest four bits (alignment) is encoded using probabilities.
+ */
+#define ALIGN_BITS 4
+#define ALIGN_SIZE (1 << ALIGN_BITS)
+#define ALIGN_MASK (ALIGN_SIZE - 1)
+
+/* Total number of all probability variables */
+#define PROBS_TOTAL (1846 + LITERAL_CODERS_MAX * LITERAL_CODER_SIZE)
+
+/*
+ * LZMA remembers the four most recent match distances. Reusing these
+ * distances tends to take less space than re-encoding the actual
+ * distance value.
+ */
+#define REPS 4
+
+#endif

android/app/src/xposed/cpp/xz/xz_private.h

@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: 0BSD */
+
+/*
+ * Private includes and definitions
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ */
+
+#ifndef XZ_PRIVATE_H
+#define XZ_PRIVATE_H
+
+#ifdef __KERNEL__
+#	include <linux/xz.h>
+#	include <linux/kernel.h>
+#	include <linux/unaligned.h>
+	/* XZ_PREBOOT may be defined only via decompress_unxz.c. */
+#	ifndef XZ_PREBOOT
+#		include <linux/slab.h>
+#		include <linux/vmalloc.h>
+#		include <linux/string.h>
+#		ifdef CONFIG_XZ_DEC_X86
+#			define XZ_DEC_X86
+#		endif
+#		ifdef CONFIG_XZ_DEC_POWERPC
+#			define XZ_DEC_POWERPC
+#		endif
+#		ifdef CONFIG_XZ_DEC_IA64
+#			define XZ_DEC_IA64
+#		endif
+#		ifdef CONFIG_XZ_DEC_ARM
+#			define XZ_DEC_ARM
+#		endif
+#		ifdef CONFIG_XZ_DEC_ARMTHUMB
+#			define XZ_DEC_ARMTHUMB
+#		endif
+#		ifdef CONFIG_XZ_DEC_SPARC
+#			define XZ_DEC_SPARC
+#		endif
+#		ifdef CONFIG_XZ_DEC_ARM64
+#			define XZ_DEC_ARM64
+#		endif
+#		ifdef CONFIG_XZ_DEC_RISCV
+#			define XZ_DEC_RISCV
+#		endif
+#		ifdef CONFIG_XZ_DEC_MICROLZMA
+#			define XZ_DEC_MICROLZMA
+#		endif
+#		define memeq(a, b, size) (memcmp(a, b, size) == 0)
+#		define memzero(buf, size) memset(buf, 0, size)
+#	endif
+#	define get_le32(p) le32_to_cpup((const uint32_t *)(p))
+#else
+	/*
+	 * For userspace builds, use a separate header to define the required
+	 * macros and functions. This makes it easier to adapt the code into
+	 * different environments and avoids clutter in the Linux kernel tree.
+	 */
+#	include "xz_config.h"
+#endif
+
+/* If no specific decoding mode is requested, enable support for all modes. */
+#if !defined(XZ_DEC_SINGLE) && !defined(XZ_DEC_PREALLOC) \
+		&& !defined(XZ_DEC_DYNALLOC)
+#	define XZ_DEC_SINGLE
+#	define XZ_DEC_PREALLOC
+#	define XZ_DEC_DYNALLOC
+#endif
+
+/*
+ * The DEC_IS_foo(mode) macros are used in "if" statements. If only some
+ * of the supported modes are enabled, these macros will evaluate to true or
+ * false at compile time and thus allow the compiler to omit unneeded code.
+ */
+#ifdef XZ_DEC_SINGLE
+#	define DEC_IS_SINGLE(mode) ((mode) == XZ_SINGLE)
+#else
+#	define DEC_IS_SINGLE(mode) (false)
+#endif
+
+#ifdef XZ_DEC_PREALLOC
+#	define DEC_IS_PREALLOC(mode) ((mode) == XZ_PREALLOC)
+#else
+#	define DEC_IS_PREALLOC(mode) (false)
+#endif
+
+#ifdef XZ_DEC_DYNALLOC
+#	define DEC_IS_DYNALLOC(mode) ((mode) == XZ_DYNALLOC)
+#else
+#	define DEC_IS_DYNALLOC(mode) (false)
+#endif
+
+#if !defined(XZ_DEC_SINGLE)
+#	define DEC_IS_MULTI(mode) (true)
+#elif defined(XZ_DEC_PREALLOC) || defined(XZ_DEC_DYNALLOC)
+#	define DEC_IS_MULTI(mode) ((mode) != XZ_SINGLE)
+#else
+#	define DEC_IS_MULTI(mode) (false)
+#endif
+
+/*
+ * If any of the BCJ filter decoders are wanted, define XZ_DEC_BCJ.
+ * XZ_DEC_BCJ is used to enable generic support for BCJ decoders.
+ */
+#ifndef XZ_DEC_BCJ
+#	if defined(XZ_DEC_X86) || defined(XZ_DEC_POWERPC) \
+			|| defined(XZ_DEC_IA64) \
+			|| defined(XZ_DEC_ARM) || defined(XZ_DEC_ARMTHUMB) \
+			|| defined(XZ_DEC_SPARC) || defined(XZ_DEC_ARM64) \
+			|| defined(XZ_DEC_RISCV)
+#		define XZ_DEC_BCJ
+#	endif
+#endif
+
+struct xz_sha256 {
+	/* Buffered input data */
+	uint8_t data[64];
+
+	/* Internal state and the final hash value */
+	uint32_t state[8];
+
+	/* Size of the input data */
+	uint64_t size;
+};
+
+/* Reset the SHA-256 state to prepare for a new calculation. */
+XZ_EXTERN void xz_sha256_reset(struct xz_sha256 *s);
+
+/* Update the SHA-256 state with new data. */
+XZ_EXTERN void xz_sha256_update(const uint8_t *buf, size_t size,
+				struct xz_sha256 *s);
+
+/*
+ * Finish the SHA-256 calculation. Compare the result with the first 32 bytes
+ * from buf. Return true if the values are equal and false if they aren't.
+ */
+XZ_EXTERN bool xz_sha256_validate(const uint8_t *buf, struct xz_sha256 *s);
+
+/*
+ * Allocate memory for LZMA2 decoder. xz_dec_lzma2_reset() must be used
+ * before calling xz_dec_lzma2_run().
+ */
+XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
+						   uint32_t dict_max);
+
+/*
+ * Decode the LZMA2 properties (one byte) and reset the decoder. Return
+ * XZ_OK on success, XZ_MEMLIMIT_ERROR if the preallocated dictionary is not
+ * big enough, and XZ_OPTIONS_ERROR if props indicates something that this
+ * decoder doesn't support.
+ */
+XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s,
+					 uint8_t props);
+
+/* Decode raw LZMA2 stream from b->in to b->out. */
+XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
+				       struct xz_buf *b);
+
+/* Free the memory allocated for the LZMA2 decoder. */
+XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s);
+
+#ifdef XZ_DEC_BCJ
+/*
+ * Allocate memory for BCJ decoders. xz_dec_bcj_reset() must be used before
+ * calling xz_dec_bcj_run().
+ */
+XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call);
+
+/*
+ * Decode the Filter ID of a BCJ filter. This implementation doesn't
+ * support custom start offsets, so no decoding of Filter Properties
+ * is needed. Returns XZ_OK if the given Filter ID is supported.
+ * Otherwise XZ_OPTIONS_ERROR is returned.
+ */
+XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id);
+
+/*
+ * Decode raw BCJ + LZMA2 stream. This must be used only if there actually is
+ * a BCJ filter in the chain. If the chain has only LZMA2, xz_dec_lzma2_run()
+ * must be called directly.
+ */
+XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
+				     struct xz_dec_lzma2 *lzma2,
+				     struct xz_buf *b);
+
+/* Free the memory allocated for the BCJ filters. */
+#define xz_dec_bcj_end(s) kfree(s)
+#endif
+
+#endif

android/app/src/xposed/cpp/xz/xz_sha256.c

@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: 0BSD
+
+/*
+ * SHA-256
+ *
+ * This is based on the XZ Utils version which is based public domain code
+ * from Crypto++ Library 5.5.1 released in 2007: https://www.cryptopp.com/
+ *
+ * Authors: Wei Dai
+ *          Lasse Collin <lasse.collin@tukaani.org>
+ */
+
+#include "xz_private.h"
+
+static inline uint32_t
+rotr_32(uint32_t num, unsigned amount)
+{
+	return (num >> amount) | (num << (32 - amount));
+}
+
+#define blk0(i) (W[i] = get_be32(&data[4 * i]))
+#define blk2(i) (W[i & 15] += s1(W[(i - 2) & 15]) + W[(i - 7) & 15] \
+		+ s0(W[(i - 15) & 15]))
+
+#define Ch(x, y, z) (z ^ (x & (y ^ z)))
+#define Maj(x, y, z) ((x & (y ^ z)) + (y & z))
+
+#define a(i) T[(0 - i) & 7]
+#define b(i) T[(1 - i) & 7]
+#define c(i) T[(2 - i) & 7]
+#define d(i) T[(3 - i) & 7]
+#define e(i) T[(4 - i) & 7]
+#define f(i) T[(5 - i) & 7]
+#define g(i) T[(6 - i) & 7]
+#define h(i) T[(7 - i) & 7]
+
+#define R(i, j, blk) \
+	h(i) += S1(e(i)) + Ch(e(i), f(i), g(i)) + SHA256_K[i + j] + blk; \
+	d(i) += h(i); \
+	h(i) += S0(a(i)) + Maj(a(i), b(i), c(i))
+#define R0(i) R(i, 0, blk0(i))
+#define R2(i) R(i, j, blk2(i))
+
+#define S0(x) rotr_32(x ^ rotr_32(x ^ rotr_32(x, 9), 11), 2)
+#define S1(x) rotr_32(x ^ rotr_32(x ^ rotr_32(x, 14), 5), 6)
+#define s0(x) (rotr_32(x ^ rotr_32(x, 11), 7) ^ (x >> 3))
+#define s1(x) (rotr_32(x ^ rotr_32(x, 2), 17) ^ (x >> 10))
+
+static const uint32_t SHA256_K[64] = {
+	0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5,
+	0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
+	0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3,
+	0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
+	0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC,
+	0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
+	0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7,
+	0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
+	0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13,
+	0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
+	0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3,
+	0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
+	0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5,
+	0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
+	0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208,
+	0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2
+};
+
+static void
+transform(uint32_t state[8], const uint8_t data[64])
+{
+	uint32_t W[16];
+	uint32_t T[8];
+	unsigned int j;
+
+	/* Copy state[] to working vars. */
+	memcpy(T, state, sizeof(T));
+
+	/* The first 16 operations unrolled */
+	R0( 0); R0( 1); R0( 2); R0( 3);
+	R0( 4); R0( 5); R0( 6); R0( 7);
+	R0( 8); R0( 9); R0(10); R0(11);
+	R0(12); R0(13); R0(14); R0(15);
+
+	/* The remaining 48 operations partially unrolled */
+	for (j = 16; j < 64; j += 16) {
+		R2( 0); R2( 1); R2( 2); R2( 3);
+		R2( 4); R2( 5); R2( 6); R2( 7);
+		R2( 8); R2( 9); R2(10); R2(11);
+		R2(12); R2(13); R2(14); R2(15);
+	}
+
+	/* Add the working vars back into state[]. */
+	state[0] += a(0);
+	state[1] += b(0);
+	state[2] += c(0);
+	state[3] += d(0);
+	state[4] += e(0);
+	state[5] += f(0);
+	state[6] += g(0);
+	state[7] += h(0);
+}
+
+XZ_EXTERN void xz_sha256_reset(struct xz_sha256 *s)
+{
+	static const uint32_t initial_state[8] = {
+		0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
+		0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19
+	};
+
+	memcpy(s->state, initial_state, sizeof(initial_state));
+	s->size = 0;
+}
+
+XZ_EXTERN void xz_sha256_update(const uint8_t *buf, size_t size,
+				struct xz_sha256 *s)
+{
+	size_t copy_start;
+	size_t copy_size;
+
+	/*
+	 * Copy the input data into a properly aligned temporary buffer.
+	 * This way we can be called with arbitrarily sized buffers
+	 * (no need to be a multiple of 64 bytes).
+	 *
+	 * Full 64-byte chunks could be processed directly from buf with
+	 * unaligned access. It seemed to make very little difference in
+	 * speed on x86-64 though. Thus it was omitted.
+	 */
+	while (size > 0) {
+		copy_start = s->size & 0x3F;
+		copy_size = 64 - copy_start;
+		if (copy_size > size)
+			copy_size = size;
+
+		memcpy(s->data + copy_start, buf, copy_size);
+
+		buf += copy_size;
+		size -= copy_size;
+		s->size += copy_size;
+
+		if ((s->size & 0x3F) == 0)
+			transform(s->state, s->data);
+	}
+}
+
+XZ_EXTERN bool xz_sha256_validate(const uint8_t *buf, struct xz_sha256 *s)
+{
+	/*
+	 * Add padding as described in RFC 3174 (it describes SHA-1 but
+	 * the same padding style is used for SHA-256 too).
+	 */
+	size_t i = s->size & 0x3F;
+	s->data[i++] = 0x80;
+
+	while (i != 64 - 8) {
+		if (i == 64) {
+			transform(s->state, s->data);
+			i = 0;
+		}
+
+		s->data[i++] = 0x00;
+	}
+
+	/* Convert the message size from bytes to bits. */
+	s->size *= 8;
+
+	/*
+	 * Store the message size in big endian byte order and
+	 * calculate the final hash value.
+	 */
+	for (i = 0; i < 8; ++i)
+		s->data[64 - 8 + i] = (uint8_t)(s->size >> ((7 - i) * 8));
+
+	transform(s->state, s->data);
+
+	/* Compare if the hash value matches the first 32 bytes in buf. */
+	for (i = 0; i < 8; ++i)
+		if (get_unaligned_be32(buf + 4 * i) != s->state[i])
+			return false;
+
+	return true;
+}

android/app/src/xposed/cpp/xz/xz_stream.h

@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: 0BSD */
+
+/*
+ * Definitions for handling the .xz file format
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ */
+
+#ifndef XZ_STREAM_H
+#define XZ_STREAM_H
+
+#if defined(__KERNEL__) && !XZ_INTERNAL_CRC32
+#	include <linux/crc32.h>
+#	undef crc32
+#	define xz_crc32(buf, size, crc) \
+		(~crc32_le(~(uint32_t)(crc), buf, size))
+#endif
+
+/*
+ * See the .xz file format specification at
+ * https://tukaani.org/xz/xz-file-format.txt
+ * to understand the container format.
+ */
+
+#define STREAM_HEADER_SIZE 12
+
+#define HEADER_MAGIC "\3757zXZ"
+#define HEADER_MAGIC_SIZE 6
+
+#define FOOTER_MAGIC "YZ"
+#define FOOTER_MAGIC_SIZE 2
+
+/*
+ * Variable-length integer can hold a 63-bit unsigned integer or a special
+ * value indicating that the value is unknown.
+ *
+ * Experimental: vli_type can be defined to uint32_t to save a few bytes
+ * in code size (no effect on speed). Doing so limits the uncompressed and
+ * compressed size of the file to less than 256 MiB and may also weaken
+ * error detection slightly.
+ */
+typedef uint64_t vli_type;
+
+#define VLI_MAX ((vli_type)-1 / 2)
+#define VLI_UNKNOWN ((vli_type)-1)
+
+/* Maximum encoded size of a VLI */
+#define VLI_BYTES_MAX (sizeof(vli_type) * 8 / 7)
+
+/* Integrity Check types */
+enum xz_check {
+	XZ_CHECK_NONE = 0,
+	XZ_CHECK_CRC32 = 1,
+	XZ_CHECK_CRC64 = 4,
+	XZ_CHECK_SHA256 = 10
+};
+
+/* Maximum possible Check ID */
+#define XZ_CHECK_MAX 15
+
+#endif

android/app/src/xposed/java/me/kavishdevar/librepods/LibrePodsApplication.kt

@@ -0,0 +1,21 @@
+package me.kavishdevar.librepods
+
+import android.app.Application
+import io.github.libxposed.service.XposedService
+import io.github.libxposed.service.XposedServiceHelper
+import me.kavishdevar.librepods.utils.XposedServiceHolder
+
+class LibrePodsApplication: Application(), XposedServiceHelper.OnServiceListener {
+    override fun onCreate() {
+        super.onCreate()
+        XposedServiceHelper.registerListener(this)
+    }
+
+    override fun onServiceBind(p0: XposedService) {
+        XposedServiceHolder.service = p0
+    }
+
+    override fun onServiceDied(p0: XposedService) {
+        XposedServiceHolder.service = null
+    }
+}

android/app/src/xposed/java/me/kavishdevar/librepods/data/XposedRemotePrefImpl.kt

@@ -0,0 +1,21 @@
+package me.kavishdevar.librepods.data
+
+import androidx.core.content.edit
+import me.kavishdevar.librepods.utils.XposedServiceHolder
+
+class XposedRemotePrefImpl: XposedRemotePref {
+    override fun isAvailable(): Boolean {
+        return XposedServiceHolder.service != null
+    }
+
+    override fun getBoolean(key: String, def: Boolean): Boolean {
+        val s = XposedServiceHolder.service ?: return def
+        return s.getRemotePreferences("me.kavishdevar.librepods").getBoolean(key, def)
+    }
+
+    override fun putBoolean(key: String, value: Boolean) {
+        val s = XposedServiceHolder.service ?: return
+        s.getRemotePreferences("me.kavishdevar.librepods")
+            .edit { putBoolean(key, value) }
+    }
+}

android/app/src/xposed/java/me/kavishdevar/librepods/utils/KotlinModule.kt

@@ -0,0 +1,126 @@
+package me.kavishdevar.librepods.utils
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.os.Handler
+import android.os.Looper
+import android.util.Log
+import android.widget.ImageView
+import androidx.core.net.toUri
+import io.github.libxposed.api.XposedModule
+import io.github.libxposed.api.XposedModuleInterface.ModuleLoadedParam
+import io.github.libxposed.api.XposedModuleInterface.PackageLoadedParam
+
+private const val TAG = "LibrePodsHook"
+
+@SuppressLint("DiscouragedApi", "PrivateApi")
+class KotlinModule: XposedModule() {
+    override fun onModuleLoaded(param: ModuleLoadedParam) {
+        log(Log.INFO, TAG, "module initialized at :: ${param.processName}")
+        log(Log.INFO, TAG, "framework: $frameworkName($frameworkVersionCode) API $apiVersion")
+    }
+
+    override fun onPackageLoaded(param: PackageLoadedParam) {
+        log(Log.INFO, TAG, "onPackageLoaded :: ${param.packageName}")
+
+        if (param.packageName == "com.google.android.bluetooth" || param.packageName == "com.android.bluetooth") {
+            log(Log.INFO, TAG, "Bluetooth app detected, hooking l2c_fcr_chk_chan_modes")
+            try {
+                if (param.isFirstPackage) {
+                    log(Log.INFO, TAG, "Loading native library for Bluetooth hook")
+                    System.loadLibrary("l2c_fcr_hook")
+                    val remotePrefValue = getRemotePreferences("me.kavishdevar.librepods").getBoolean("vendor_id_hook", false)
+                    log(Log.INFO, TAG, "sdp hook enabled (remote pref): $remotePrefValue")
+                    NativeBridge.setSdpHook(remotePrefValue)
+                    log(Log.INFO, TAG, "Native library loaded successfully")
+                }
+            } catch (e: Exception) {
+                log(Log.ERROR, TAG, "Failed to load native library: ${e.message}")
+            }
+        }
+
+        if (param.packageName == "com.google.android.settings") {
+            hookSettingsController(param, "com.google.android.settings.bluetooth.AdvancedBluetoothDetailsHeaderController")
+        }
+
+        if (param.packageName == "com.android.settings") {
+            hookSettingsController(param, "com.android.settings.bluetooth.AdvancedBluetoothDetailsHeaderController")
+        }
+    }
+
+    private fun hookSettingsController(param: PackageLoadedParam, className: String) {
+        log(Log.INFO, TAG, "Settings app detected, hooking Bluetooth icon handling")
+        try {
+            val headerControllerClass = Class.forName(className, false, param.defaultClassLoader)
+            val updateIconMethod = headerControllerClass.getDeclaredMethod(
+                "updateIcon",
+                ImageView::class.java,
+                String::class.java
+            )
+
+            hook(updateIconMethod).intercept { chain ->
+                try {
+                    log(Log.INFO, TAG, "Bluetooth icon hook called with args: ${chain.args.joinToString(", ")}")
+                    val imageView = chain.args[0] as? ImageView
+                    val iconUri = chain.args[1] as? String
+
+                    if (imageView == null || iconUri == null) {
+                        return@intercept chain.proceed()
+                    }
+
+                    val uri = iconUri.toUri()
+                    if (!uri.toString().startsWith("android.resource://me.kavishdevar.librepods")) {
+                        return@intercept chain.proceed()
+                    }
+
+                    log(Log.INFO, TAG, "Handling AirPods icon URI: $uri")
+
+                    Handler(Looper.getMainLooper()).post {
+                        try {
+                            val context = imageView.context
+                            val packageName = uri.authority ?: return@post
+                            val packageContext = context.createPackageContext(
+                                packageName,
+                                Context.CONTEXT_IGNORE_SECURITY
+                            )
+
+                            val resPath = uri.pathSegments
+                            if (resPath.size >= 2 && resPath[0] == "drawable") {
+                                val resourceName = resPath[1]
+                                val resourceId = packageContext.resources.getIdentifier(
+                                    resourceName, "drawable", packageName
+                                )
+
+                                if (resourceId != 0) {
+                                    val drawable = packageContext.resources.getDrawable(
+                                        resourceId, packageContext.theme
+                                    )
+                                    imageView.setImageDrawable(drawable)
+                                    imageView.alpha = 1.0f
+                                    log(Log.INFO, TAG, "Successfully loaded icon from resource: $resourceName")
+                                } else {
+                                    log(Log.ERROR, TAG, "Resource not found: $resourceName")
+                                }
+                            }
+                        } catch (e: Exception) {
+                            log(Log.ERROR, TAG, "Error loading resource from URI $uri: ${e.message}")
+                        }
+                    }
+                    null
+                } catch (e: Exception) {
+                    log(Log.ERROR, TAG, "Error in Bluetooth icon hook: ${e.message}")
+                    chain.proceed()
+                }
+            }
+
+            log(Log.INFO, TAG, "Successfully hooked updateIcon method in Bluetooth settings")
+        } catch (e: Exception) {
+            log(Log.ERROR, TAG, "Failed to hook Bluetooth icon handler: ${e.message}")
+        }
+    }
+}
+
+
+object NativeBridge {
+    external fun setSdpHook(enabled: Boolean)
+}

android/app/src/xposed/resources/META-INF/xposed/java_init.list

@@ -0,0 +1 @@
+me.kavishdevar.librepods.utils.KotlinModule

android/app/src/xposed/resources/META-INF/xposed/module.prop

@@ -0,0 +1,3 @@
+minApiVersion=101
+targetApiVersion=101
+staticScope=true

android/app/src/xposed/resources/META-INF/xposed/native_init.list

@@ -0,0 +1 @@
+libl2c_fcr_hook.so

android/app/src/xposed/resources/META-INF/xposed/scope.list

@@ -0,0 +1,4 @@
+com.android.bluetooth
+com.google.android.settings
+com.android.settings
+com.google.android.bluetooth