Don't use getmntent_r from system's libc

Fix #5354

Co-authored-by: topjohnwu <topjohnwu@gmail.com>

native/jni/core/bootstages.cpp

@@ -25,6 +25,7 @@ bool zygisk_enabled = false;
  *********/
 
 #define MNT_DIR_IS(dir) (me->mnt_dir == string_view(dir))
+#define MNT_TYPE_IS(type) (me->mnt_type == string_view(type))
 #define SETMIR(b, part) snprintf(b, sizeof(b), "%s/" MIRRDIR "/" #part, MAGISKTMP.data())
 #define SETBLK(b, part) snprintf(b, sizeof(b), "%s/" BLOCKDIR "/" #part, MAGISKTMP.data())
 
@@ -39,8 +40,11 @@ bool zygisk_enabled = false;
 }
 
 #define mount_mirror(part, flag)    \
-else if (MNT_DIR_IS("/" #part) && me->mnt_type != "tmpfs"sv && me->mnt_type != "overlay"sv && lstat(me->mnt_dir, &st) == 0) \
+if (MNT_DIR_IS("/" #part) && !MNT_TYPE_IS("tmpfs") && !MNT_TYPE_IS("overlay") && \
-    do_mount_mirror(part, flag)
+    lstat(me->mnt_dir, &st) == 0) { \
+    do_mount_mirror(part, flag);    \
+    break;                          \
+}
 
 #define link_mirror(part) \
 SETMIR(buf1, part); \
@@ -50,11 +54,12 @@ if (access("/system/" #part, F_OK) == 0 && access(buf1, F_OK) != 0) { \
 }
 
 #define link_orig_dir(dir, part) \
-else if (MNT_DIR_IS(dir) && me->mnt_type != "tmpfs"sv && me->mnt_type != "overlay"sv) { \
+if (MNT_DIR_IS(dir) && !MNT_TYPE_IS("tmpfs") && !MNT_TYPE_IS("overlay")) { \
     SETMIR(buf1, part);          \
     rmdir(buf1);                 \
     xsymlink(dir, buf1);         \
     LOGI("link: %s\n", buf1);    \
+    break;                       \
 }
 
 #define link_orig(part) link_orig_dir("/" #part, part)
@@ -66,8 +71,8 @@ static void mount_mirrors() {
     LOGI("* Mounting mirrors\n");
 
     parse_mnt("/proc/mounts", [&](mntent *me) {
-        struct stat st;
+        struct stat st{};
-        if (0) {}
+        do {
             mount_mirror(system, MS_RDONLY)
             mount_mirror(vendor, MS_RDONLY)
             mount_mirror(product, MS_RDONLY)
@@ -77,9 +82,11 @@ static void mount_mirrors() {
             link_orig(metadata)
             link_orig(persist)
             link_orig_dir("/mnt/vendor/persist", persist)
-        else if (SDK_INT >= 24 && MNT_DIR_IS("/proc") && !strstr(me->mnt_opts, "hidepid=2")) {
+            if (SDK_INT >= 24 && MNT_DIR_IS("/proc") && !strstr(me->mnt_opts, "hidepid=2")) {
                 xmount(nullptr, "/proc", nullptr, MS_REMOUNT, "hidepid=2,gid=3009");
+                break;
             }
+        } while (false);
         return true;
     });
     SETMIR(buf1, system);

native/jni/utils/compat/compat.cpp

@@ -53,32 +53,6 @@ ssize_t getline(char **buf, size_t *bufsiz, FILE *fp) {
     return getdelim(buf, bufsiz, '\n', fp);
 }
 
-// Original source: https://android.googlesource.com/platform/bionic/+/master/libc/bionic/mntent.cpp
-// License: AOSP, full copyright notice please check original source
-
-struct mntent *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;
-}
-
 FILE *setmntent(const char *path, const char *mode) {
     return fopen(path, mode);
 }

native/jni/utils/files.cpp

@@ -352,12 +352,39 @@ void parse_prop_file(const char *file, const function<bool(string_view, string_v
     });
 }
 
+// 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];
-        while (getmntent_r(fp.get(), &mentry, buf, sizeof(buf))) {
+        // 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;
         }