Remove redundant MapInfo::Scan function

With inline hook, we no longer need to scan process virtual maps.

Moreover, I can no longer justify the point 3 stated in commit
156c6ae855 by experiments, which is
mysterious given my previous experiments done for the commit
3c020a9cd7.

Currently, only one thing is sure: reading `/proc/self/map` can be
detected by Holmes. Hence, it is always a good practice to not inject
unnecessary codes during the preAppSpecialize API.

magisk-loader/src/main/jni/src/magisk_loader.cpp

@@ -50,45 +50,6 @@ constexpr int PER_USER_RANGE = 100000;
 static constexpr uid_t kAidInjected = INJECTED_AID;
 static constexpr uid_t kAidInet = 3003;
 
-std::vector<MapInfo> MapInfo::Scan(std::string_view pid) {
-    constexpr static auto kPermLength = 5;
-    constexpr static auto kMapEntry = 7;
-    std::vector<MapInfo> info;
-    auto path = "/proc/" + std::string{pid} + "/maps";
-    auto maps = fopen(path.c_str(), "r");
-    if (maps) {
-        char *line = nullptr;
-        size_t len = 0;
-        ssize_t read;
-        while ((read = getline(&line, &len, maps)) > 0) {
-            line[read - 1] = '\0';
-            uintptr_t start = 0;
-            uintptr_t end = 0;
-            uintptr_t off = 0;
-            ino_t inode = 0;
-            unsigned int dev_major = 0;
-            unsigned int dev_minor = 0;
-            std::array<char, kPermLength> perm{'\0'};
-            int path_off;
-            if (sscanf(line, "%" PRIxPTR "-%" PRIxPTR " %4s %" PRIxPTR " %x:%x %lu %n%*s", &start,
-                       &end, perm.data(), &off, &dev_major, &dev_minor, &inode,
-                       &path_off) != kMapEntry) {
-                continue;
-            }
-            while (path_off < read && isspace(line[path_off])) path_off++;
-            auto &ref = info.emplace_back(MapInfo{start, end, 0, perm[3] == 'p', off,
-                                                  static_cast<dev_t>(makedev(dev_major, dev_minor)),
-                                                  inode, line + path_off});
-            if (perm[0] == 'r') ref.perms |= PROT_READ;
-            if (perm[1] == 'w') ref.perms |= PROT_WRITE;
-            if (perm[2] == 'x') ref.perms |= PROT_EXEC;
-        }
-        free(line);
-    }
-    fclose(maps);
-    return info;
-}
-
 void MagiskLoader::LoadDex(JNIEnv *env, PreloadedDex &&dex) {
     auto classloader = JNI_FindClass(env, "java/lang/ClassLoader");
     auto getsyscl_mid = JNI_GetStaticMethodID(env, classloader, "getSystemClassLoader",

magisk-loader/src/main/jni/src/magisk_loader.h

@@ -67,34 +67,4 @@ private:
 
     static void setAllowUnload(bool unload);
 };
-
-struct MapInfo {
-    /// \brief The start address of the memory region.
-    uintptr_t start;
-    /// \brief The end address of the memory region.
-    uintptr_t end;
-    /// \brief The permissions of the memory region. This is a bit mask of the following values:
-    /// - PROT_READ
-    /// - PROT_WRITE
-    /// - PROT_EXEC
-    uint8_t perms;
-    /// \brief Whether the memory region is private.
-    bool is_private;
-    /// \brief The offset of the memory region.
-    uintptr_t offset;
-    /// \brief The device number of the memory region.
-    /// Major can be obtained by #major()
-    /// Minor can be obtained by #minor()
-    dev_t dev;
-    /// \brief The inode number of the memory region.
-    ino_t inode;
-    /// \brief The path of the memory region.
-    std::string path;
-
-    /// \brief Scans /proc/self/maps and returns a list of \ref MapInfo entries.
-    /// This is useful to find out the inode of the library to hook.
-    /// \param[in] pid The process id to scan. This is "self" by default.
-    /// \return A list of \ref MapInfo entries.
-    static std::vector<MapInfo> Scan(std::string_view pid = "self");
-};
 }  // namespace lspd