recovery: autodetect filesystem type

* Multiple fstab lines (supported in android) cause recovery to fail
  to mount partitions if the fs type is not the same as the first
  fstab entry. So when we attempt to find an fstab entry that matches
  a path for an f2fs, ext4 or vfat type, check it against blkid's
  determination of what filesystem type it is. If there is a discrepancy,
  query fs_mgr for the next possible entry that matches that path until
  either we find one that is good, or run out of fstab entries.

* Also attempt to autodetect the filesystem type for mounting from
  update.zips.

Change-Id: Ib6f4535dd88ef714ae1ca6fb0ffae1c7dac0f7ce

1 files changed, 22 insertions, 1 deletions

diff --git a/roots.cpp b/roots.cpp
index d27a2dd..3c51c35 100644
--- a/roots.cpp
+++ b/roots.cpp
@@ -37,6 +37,7 @@ extern "C" {
 }
 
 #include "voldclient.h"
+#include <blkid/blkid.h>
 
 static struct fstab *fstab = NULL;
 
@@ -143,7 +144,27 @@ bool volume_is_verity(Volume *v)
 }
 
 Volume* volume_for_path(const char* path) {
-    return fs_mgr_get_entry_for_mount_point(fstab, path);
+    Volume *rec = fs_mgr_get_entry_for_mount_point(fstab, path);
+
+    if (rec == NULL)
+        return rec;
+
+    if (strcmp(rec->fs_type, "ext4") == 0 || strcmp(rec->fs_type, "f2fs") == 0 ||
+            strcmp(rec->fs_type, "vfat") == 0) {
+        char *detected_fs_type = blkid_get_tag_value(NULL, "TYPE", rec->blk_device);
+
+        if (detected_fs_type == NULL)
+            return rec;
+
+        Volume *fetched_rec = rec;
+        while (rec != NULL && strcmp(rec->fs_type, detected_fs_type) != 0)
+            rec = fs_mgr_get_entry_for_mount_point_after(rec, fstab, path);
+
+        if (rec == NULL)
+            return fetched_rec;
+    }
+
+    return rec;
 }
 
 Volume* volume_for_label(const char* label) {