Replace parse_mnt with parse_mount_info

native/src/base/files.cpp

@@ -345,45 +345,6 @@ void parse_prop_file(const char *file, const function<bool(string_view, string_v
         parse_prop_file(fp.get(), fn);
 }
 
-// Original source: https://android.googlesource.com/platform/bionic/+/master/libc/bionic/mntent.cpp
-// License: AOSP, full copyright notice please check original source
-static struct mntent *compat_getmntent_r(FILE *fp, struct mntent *e, char *buf, int buf_len) {
-    memset(e, 0, sizeof(*e));
-    while (fgets(buf, buf_len, fp) != nullptr) {
-        // Entries look like "proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0".
-        // That is: mnt_fsname mnt_dir mnt_type mnt_opts 0 0.
-        int fsname0, fsname1, dir0, dir1, type0, type1, opts0, opts1;
-        if (sscanf(buf, " %n%*s%n %n%*s%n %n%*s%n %n%*s%n %d %d",
-                   &fsname0, &fsname1, &dir0, &dir1, &type0, &type1, &opts0, &opts1,
-                   &e->mnt_freq, &e->mnt_passno) == 2) {
-            e->mnt_fsname = &buf[fsname0];
-            buf[fsname1] = '\0';
-            e->mnt_dir = &buf[dir0];
-            buf[dir1] = '\0';
-            e->mnt_type = &buf[type0];
-            buf[type1] = '\0';
-            e->mnt_opts = &buf[opts0];
-            buf[opts1] = '\0';
-            return e;
-        }
-    }
-    return nullptr;
-}
-
-void parse_mnt(const char *file, const function<bool(mntent*)> &fn) {
-    auto fp = sFILE(setmntent(file, "re"), endmntent);
-    if (fp) {
-        mntent mentry{};
-        char buf[4096];
-        // getmntent_r from system's libc.so is broken on old platform
-        // use the compat one instead
-        while (compat_getmntent_r(fp.get(), &mentry, buf, sizeof(buf))) {
-            if (!fn(&mentry))
-                break;
-        }
-    }
-}
-
 std::vector<mount_info> parse_mount_info(const char *pid) {
     char buf[PATH_MAX] = {};
     ssprintf(buf, sizeof(buf), "/proc/%s/mountinfo", pid);

native/src/base/files.hpp

@@ -106,7 +106,6 @@ void parse_prop_file(const char *file,
 void frm_rf(int dirfd);
 void clone_dir(int src, int dest);
 std::vector<mount_info> parse_mount_info(const char *pid);
-void parse_mnt(const char *file, const std::function<bool(mntent*)> &fn);
 std::string find_apk_path(const char *pkg);
 
 using sFILE = std::unique_ptr<FILE, decltype(&fclose)>;

native/src/init/mount.cpp

@@ -1,3 +1,4 @@
+#include <set>
 #include <sys/mount.h>
 #include <sys/sysmacros.h>
 #include <libgen.h>
@@ -91,23 +92,17 @@ static int64_t setup_block() {
 static void switch_root(const string &path) {
     LOGD("Switch root to %s\n", path.data());
     int root = xopen("/", O_RDONLY);
-    vector<string> mounts;
+    for (set<string, greater<>> mounts; auto &info : parse_mount_info("self")) {
-    parse_mnt("/proc/mounts", [&](mntent *me) {
+        if (info.target == "/" || info.target == path)
-        // Skip root and self
+            continue;
-        if (me->mnt_dir == "/"sv || me->mnt_dir == path)
+        if (auto last_mount = mounts.upper_bound(info.target);
-            return true;
+                last_mount != mounts.end() && info.target.starts_with(*last_mount + '/')) {
-        // Do not include subtrees
+            continue;
-        for (const auto &m : mounts) {
-            if (strncmp(me->mnt_dir, m.data(), m.length()) == 0 && me->mnt_dir[m.length()] == '/')
-                return true;
         }
-        mounts.emplace_back(me->mnt_dir);
+        mounts.emplace(info.target);
-        return true;
+        auto new_path = path + info.target;
-    });
-    for (auto &dir : mounts) {
-        auto new_path = path + dir;
         xmkdir(new_path.data(), 0755);
-        xmount(dir.data(), new_path.data(), nullptr, MS_MOVE, nullptr);
+        xmount(info.target.data(), new_path.data(), nullptr, MS_MOVE, nullptr);
     }
     chdir(path.data());
     xmount(path.data(), "/", nullptr, MS_MOVE, nullptr);