Better bytes support in C++

native/src/base/files.cpp

@@ -1,3 +1,4 @@
+#include <sys/mman.h>
 #include <sys/sendfile.h>
 #include <sys/sysmacros.h>
 #include <linux/fs.h>
@@ -433,55 +434,25 @@ sFILE make_file(FILE *fp) {
     return sFILE(fp, [](FILE *fp){ return fp ? fclose(fp) : 1; });
 }
 
-int byte_data::patch(str_pairs list) {
+byte_view::byte_view(string_view s, bool with_nul)
-    if (_buf == nullptr)
+: byte_view(static_cast<const void *>(s.data()), s.length()) {
-        return 0;
+    if (with_nul && s[s.length()] == '\0') {
-    int count = 0;
+        ++_sz;
-    for (uint8_t *p = _buf, *eof = _buf + _sz; p < eof; ++p) {
-        for (auto &[from, to] : list) {
-            if (memcmp(p, from.data(), from.length() + 1) == 0) {
-                LOGD("Patch @ %08X [%s] -> [%s]\n", (unsigned)(p - _buf), from.data(), to.data());
-                memset(p, 0, from.length());
-                memcpy(p, to.data(), to.length());
-                ++count;
-                p += from.length();
-            }
-        }
     }
-    return count;
 }
 
-int byte_data::patch(byte_pairs list) {
+bool byte_view::contains(byte_view pattern) const {
-    if (_buf == nullptr)
-        return 0;
-    int count = 0;
-    for (uint8_t *p = _buf, *eof = _buf + _sz; p < eof; ++p) {
-        for (auto &[from, to] : list) {
-            if (memcmp(p, from.buf(), from.sz()) == 0) {
-                LOGD("Patch @ %08X\n", (unsigned)(p - _buf));
-                memset(p, 0, from.sz());
-                memcpy(p, to.buf(), to.sz());
-                ++count;
-                p += from.sz();
-            }
-        }
-    }
-    return count;
-}
-
-bool byte_view::contains(string_view pattern) const {
     if (_buf == nullptr)
         return false;
     for (uint8_t *p = _buf, *eof = _buf + _sz; p < eof; ++p) {
-        if (memcmp(p, pattern.data(), pattern.length() + 1) == 0) {
+        if (memcmp(p, pattern.buf(), pattern.sz()) == 0) {
-            LOGD("Found pattern [%s]\n", pattern.data());
             return true;
         }
     }
     return false;
 }
 
-bool byte_view::equals(const byte_view &o) const {
+bool byte_view::equals(byte_view o) const {
     return _sz == o._sz && memcmp(_buf, o._buf, _sz) == 0;
 }
 
@@ -496,6 +467,24 @@ heap_data byte_view::clone() const {
     return copy;
 }
 
+vector<size_t> byte_data::patch(byte_view from, byte_view to) {
+    vector<size_t> v;
+    if (_buf == nullptr)
+        return v;
+    auto p = _buf;
+    auto eof = _buf + _sz;
+    while (p < eof) {
+        p = static_cast<uint8_t *>(memmem(p, eof - p, from.buf(), from.sz()));
+        if (p == nullptr)
+            return v;
+        memset(p, 0, from.sz());
+        memcpy(p, to.buf(), to.sz());
+        v.push_back(p - _buf);
+        p += from.sz();
+    }
+    return v;
+}
+
 void heap_data::realloc(size_t sz) {
     _buf = static_cast<uint8_t *>(::realloc(_buf, sz));
 }
@@ -504,23 +493,33 @@ mmap_data::mmap_data(const char *name, bool rw) {
     int fd = xopen(name, (rw ? O_RDWR : O_RDONLY) | O_CLOEXEC);
     if (fd < 0)
         return;
-    struct stat st;
+
+    run_finally g([=] { close(fd); });
+    struct stat st{};
     if (fstat(fd, &st))
         return;
     if (S_ISBLK(st.st_mode)) {
         uint64_t size;
         ioctl(fd, BLKGETSIZE64, &size);
-        _sz = size;
+        init(fd, size, rw);
     } else {
-        _sz = st.st_size;
+        init(fd, st.st_size, rw);
     }
-    void *b = _sz > 0
+}
-            ? xmmap(nullptr, _sz, PROT_READ | PROT_WRITE, rw ? MAP_SHARED : MAP_PRIVATE, fd, 0)
+
+void mmap_data::init(int fd, size_t sz, bool rw) {
+    _sz = sz;
+    void *b = sz > 0
+            ? xmmap(nullptr, sz, PROT_READ | PROT_WRITE, rw ? MAP_SHARED : MAP_PRIVATE, fd, 0)
             : nullptr;
-    close(fd);
     _buf = static_cast<uint8_t *>(b);
 }
 
+mmap_data::~mmap_data() {
+    if (_buf)
+        munmap(_buf, _sz);
+}
+
 string find_apk_path(const char *pkg) {
     char buf[PATH_MAX];
     size_t len = strlen(pkg);

native/src/base/files.hpp

@@ -1,8 +1,6 @@
 #pragma once
 
-#include <sys/mman.h>
 #include <sys/stat.h>
-#include <mntent.h>
 #include <functional>
 #include <string_view>
 #include <string>
@@ -48,38 +46,44 @@ struct heap_data;
 struct byte_view {
     byte_view() : _buf(nullptr), _sz(0) {}
     byte_view(const void *buf, size_t sz) : _buf((uint8_t *) buf), _sz(sz) {}
-    byte_view(std::string_view str) : byte_view(str.data(), str.length()) {}
+
+    // byte_view, or any of its sub-type, can be copied as byte_view
+    byte_view(const byte_view &o) : _buf(o._buf), _sz(o._sz) {}
+
+    // String as bytes
+    byte_view(std::string_view s, bool with_nul = true);
+    byte_view(const char *s, bool with_nul = true)
+    : byte_view(std::string_view(s), with_nul) {}
+    byte_view(const std::string &s, bool with_nul = true)
+    : byte_view(std::string_view(s), with_nul) {}
+
+    // Vector as bytes
     byte_view(const std::vector<uint8_t> &v) : byte_view(v.data(), v.size()) {}
 
     const uint8_t *buf() const { return _buf; }
-    const size_t &sz() const { return _sz; }
+    size_t sz() const { return _sz; }
 
-    bool contains(std::string_view pattern) const;
+    bool contains(byte_view pattern) const;
-    bool equals(const byte_view &o) const;
+    bool equals(byte_view o) const;
     heap_data clone() const;
 
 protected:
     uint8_t *_buf;
     size_t _sz;
 
-    byte_view(uint8_t *buf, size_t sz) : _buf(buf), _sz(sz) {}
     void swap(byte_view &o);
 };
 
 struct byte_data : public byte_view {
-    using str_pairs = std::initializer_list<std::pair<std::string_view, std::string_view>>;
-    using byte_pairs = std::initializer_list<std::pair<byte_view, byte_view>>;
-
     byte_data() = default;
-    byte_data(void *buf, size_t sz) : byte_view(static_cast<uint8_t *>(buf), sz) {}
+    byte_data(void *buf, size_t sz) : byte_view(buf, sz) {}
 
     using byte_view::buf;
     using byte_view::sz;
     uint8_t *buf() { return _buf; }
     size_t &sz() { return _sz; }
 
-    int patch(str_pairs list);
+    std::vector<size_t> patch(byte_view from, byte_view to);
-    int patch(byte_pairs list);
 };
 
 #define MOVE_ONLY(clazz) \
@@ -92,7 +96,6 @@ struct heap_data : public byte_data {
     MOVE_ONLY(heap_data)
 
     explicit heap_data(size_t sz) : byte_data(malloc(sz), sz) {}
-    heap_data(const void *buf, size_t sz) : heap_data(sz) { memcpy(_buf, buf, sz); }
     ~heap_data() { free(_buf); }
 
     void realloc(size_t sz);
@@ -101,8 +104,11 @@ struct heap_data : public byte_data {
 struct mmap_data : public byte_data {
     MOVE_ONLY(mmap_data)
 
-    mmap_data(const char *name, bool rw = false);
+    explicit mmap_data(const char *name, bool rw = false);
-    ~mmap_data() { if (_buf) munmap(_buf, _sz); }
+    mmap_data(int fd, size_t sz, bool rw = false) { init(fd, sz, rw); }
+    ~mmap_data();
+private:
+    void init(int fd, size_t sz, bool rw);
 };
 
 extern "C" {

native/src/boot/cpio.cpp

@@ -45,7 +45,7 @@ static uint32_t x8u(const char *hex) {
 
 cpio_entry::cpio_entry(uint32_t mode) : mode(mode), uid(0), gid(0), data(0) {}
 
-cpio_entry::cpio_entry(uint32_t mode, const byte_view &data) :
+cpio_entry::cpio_entry(uint32_t mode, byte_view data) :
 mode(mode), uid(0), gid(0), data(data.clone()) {}
 
 cpio_entry::cpio_entry(const cpio_newc_header *h) :
@@ -187,8 +187,7 @@ void cpio::mkdir(mode_t mode, const char *name) {
 }
 
 void cpio::ln(const char *target, const char *name) {
-    byte_view link(target);
+    auto e = new cpio_entry(S_IFLNK, {target, false});
-    auto e = new cpio_entry(S_IFLNK, link);
     insert(name, e);
     fprintf(stderr, "Create symlink [%s] -> [%s]\n", name, target);
 }

native/src/boot/cpio.hpp

@@ -17,7 +17,7 @@ struct cpio_entry {
     heap_data data;
 
     explicit cpio_entry(uint32_t mode);
-    explicit cpio_entry(uint32_t mode, const byte_view &data);
+    explicit cpio_entry(uint32_t mode, byte_view data);
     explicit cpio_entry(const cpio_newc_header *h);
 };
 

native/src/boot/dtb.cpp

@@ -223,7 +223,7 @@ static bool fdt_patch(void *fdt) {
         // Force remove AVB for 2SI since it may bootloop some devices
         int len;
         const void *value = fdt_getprop(fdt, node, "fsmgr_flags", &len);
-        heap_data copy(value, len);
+        heap_data copy = byte_view(value, len).clone();
         if (patch_verity(copy)) {
             modified = true;
             fdt_setprop(fdt, node, "fsmgr_flags", copy.buf(), copy.sz());
@@ -291,8 +291,7 @@ static bool dt_table_patch(const Header *hdr, const char *out) {
     total_size += xwrite(fd, buf, dtb_map.begin()->first);
 
     // mmap rw to patch table values retroactively
-    auto mmap_sz = lseek(fd, 0, SEEK_CUR);
+    mmap_data m(fd, lseek(fd, 0, SEEK_CUR), true);
-    auto addr = (uint8_t *) xmmap(nullptr, mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 
     // Guess alignment using gcd
     uint32_t align = 1;
@@ -319,17 +318,16 @@ static bool dt_table_patch(const Header *hdr, const char *out) {
 
     // Patch headers
     if constexpr (is_aosp) {
-        auto hdr_rw = reinterpret_cast<Header *>(addr);
+        auto hdr_rw = reinterpret_cast<Header *>(m.buf());
         hdr_rw->total_size = le_to_be(total_size);
     }
-    auto tables_rw = reinterpret_cast<Table *>(addr + sizeof(Header));
+    auto tables_rw = reinterpret_cast<Table *>(m.buf() + sizeof(Header));
     for (int i = 0; i < num_dtb; ++i) {
         auto &blob = dtb_map[be_to_le(tables_rw[i].offset)];
         tables_rw[i].offset = le_to_be(blob.offset);
         tables_rw[i].len = le_to_be(blob.len);
     }
 
-    munmap(addr, mmap_sz);
     close(fd);
 
     return true;

native/src/boot/hexpatch.cpp

@@ -20,5 +20,9 @@ int hexpatch(const char *file, string_view from, string_view to) {
     hex2byte(from, pattern.data());
     hex2byte(to, patch.data());
 
-    return m.patch({ make_pair(pattern, patch) }) > 0 ? 0 : 1;
+    auto v = m.patch(pattern, patch);
+    for (size_t off : v) {
+        fprintf(stderr, "Patch @ %08zX [%s] -> [%s]\n", off, from.data(), to.data());
+    }
+    return v.empty() ? 1 : 0;
 }

native/src/boot/ramdisk.cpp

@@ -186,8 +186,7 @@ void magisk_cpio::backup(const char *orig) {
     }
 
     if (!rm_list.empty()) {
-        byte_view rm(rm_list);
+        auto rm_list_file = new cpio_entry(S_IFREG, {rm_list, false});
-        auto rm_list_file = new cpio_entry(S_IFREG, rm);
         backups.emplace(".backup/.rmlist", rm_list_file);
     }
 

native/src/core/module.cpp

@@ -1,3 +1,4 @@
+#include <sys/mman.h>
 #include <sys/mount.h>
 #include <map>
 #include <utility>

native/src/init/rootdir.cpp

@@ -244,7 +244,9 @@ void MagiskInit::patch_ro_root() {
         int src = xopen("/init", O_RDONLY | O_CLOEXEC);
         mmap_data init("/init");
         // Force disable early mount on original init
-        init.patch({ make_pair("android,fstab", "xxx") });
+        for (size_t off : init.patch("android,fstab", "xxx")) {
+            LOGD("Patch @ %08zX [android,fstab] -> [xxx]\n", off);
+        }
         int dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC, 0);
         xwrite(dest, init.buf(), init.sz());
         fclone_attr(src, dest);

native/src/init/twostage.cpp

@@ -13,7 +13,9 @@ void FirstStageInit::prepare() {
     restore_ramdisk_init();
     auto init = mmap_data("/init", true);
     // Redirect original init to magiskinit
-    init.patch({ make_pair(INIT_PATH, REDIR_PATH) });
+    for (size_t off : init.patch(INIT_PATH, REDIR_PATH)) {
+        LOGD("Patch @ %08zX [" INIT_PATH "] -> [" REDIR_PATH "]\n", off);
+    }
 }
 
 void LegacySARInit::first_stage_prep() {
@@ -22,7 +24,9 @@ void LegacySARInit::first_stage_prep() {
     int dest = xopen("/data/init", O_CREAT | O_WRONLY, 0);
     {
         mmap_data init("/init");
-        init.patch({ make_pair(INIT_PATH, REDIR_PATH) });
+        for (size_t off : init.patch(INIT_PATH, REDIR_PATH)) {
+            LOGD("Patch @ %08zX [" INIT_PATH "] -> [" REDIR_PATH "]\n", off);
+        }
         write(dest, init.buf(), init.sz());
         fclone_attr(src, dest);
         close(dest);

native/src/zygisk/memory.cpp

@@ -1,3 +1,4 @@
+#include <sys/mman.h>
 #include "memory.hpp"
 
 namespace jni_hook {

native/src/zygisk/zygisk.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <sys/mman.h>
 #include <stdint.h>
 #include <jni.h>
 #include <vector>