libmount: use fstatat(AT_NO_AUTOMOUNT) for mountpoints

Signed-off-by: Karel Zak <kzak@redhat.com>

5 files changed, 20 insertions, 6 deletions

diff --git a/Documentation/TODO b/Documentation/TODO
index 22fa0e06f..6b4ee3020 100644
--- a/Documentation/TODO
+++ b/Documentation/TODO
@@ -1,6 +1,10 @@
 
  Note that items with (!) have high priority.
 
+canonicalize
+------------
+  - reimplement realpath(3) (for lib/canonicalize()) to use fstatat(AT_NO_AUTOMOUNT)
+
 lsblk
 -----
   - currently it does not show mountpoint for all devices in btrfs RAID. It's because
diff --git a/libmount/src/context.c b/libmount/src/context.c
index 5ab0b794e..7b965a07f 100644
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -1069,7 +1069,7 @@ int mnt_context_get_mtab_for_target(struct libmnt_context *cxt,
 	char *cn_tgt = NULL;
 	int rc;
 
-	if (stat(tgt, &st) == 0 && S_ISDIR(st.st_mode)) {
+	if (mnt_stat_mountpoint(tgt, &st) == 0 && S_ISDIR(st.st_mode)) {
 		cache = mnt_context_get_cache(cxt);
 		cn_tgt = mnt_resolve_path(tgt, cache);
 		if (cn_tgt)
@@ -1540,7 +1540,7 @@ static int mkdir_target(const char *tgt, struct libmnt_fs *fs)
 
 	if (mnt_optstr_get_option(fs->user_optstr, "x-mount.mkdir", &mstr, &mstr_sz) != 0)
 		return 0;
-	if (stat(tgt, &st) == 0)
+	if (mnt_stat_mountpoint(tgt, &st) == 0)
 		return 0;
 
 	if (mstr && mstr_sz) {
diff --git a/libmount/src/context_umount.c b/libmount/src/context_umount.c
index c4e9ebbee..b67f48b91 100644
--- a/libmount/src/context_umount.c
+++ b/libmount/src/context_umount.c
@@ -129,7 +129,7 @@ try_loopdev:
 		 */
 		struct stat st;
 
-		if (stat(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
+		if (mnt_stat_mountpoint(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
 			int count;
 			struct libmnt_cache *cache = mnt_context_get_cache(cxt);
 			const char *bf = cache ? mnt_resolve_path(tgt, cache) : tgt;
@@ -242,7 +242,7 @@ static int lookup_umount_fs(struct libmnt_context *cxt)
 	    && !mnt_context_is_force(cxt)
 	    && !mnt_context_is_lazy(cxt)
 	    && !mnt_context_is_loopdel(cxt)
-	    && stat(tgt, &st) == 0 && S_ISDIR(st.st_mode)
+	    && mnt_stat_mountpoint(tgt, &st) == 0 && S_ISDIR(st.st_mode)
 	    && !has_utab_entry(cxt, tgt)) {
 
 		const char *type = mnt_fs_get_fstype(cxt->fs);
diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index 660e0ad08..25418a2e4 100644
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -99,6 +99,7 @@ extern int mnt_get_filesystems(char ***filesystems, const char *pattern);
 extern void mnt_free_filesystems(char **filesystems);
 
 extern char *mnt_get_kernel_cmdline_option(const char *name);
+extern int mnt_stat_mountpoint(const char *target, struct stat *st);
 
 /* tab.c */
 extern int is_mountinfo(struct libmnt_table *tb);
diff --git a/libmount/src/utils.c b/libmount/src/utils.c
index 6c9217ee9..e57eb33ba 100644
--- a/libmount/src/utils.c
+++ b/libmount/src/utils.c
@@ -117,6 +117,15 @@ static int fstype_cmp(const void *v1, const void *v2)
 	return strcmp(s1, s2);
 }
 
+int mnt_stat_mountpoint(const char *target, struct stat *st)
+{
+#ifdef AT_NO_AUTOMOUNT
+	return fstatat(-1, target, st, AT_NO_AUTOMOUNT);
+#else
+	return stat(target, st);
+#endif
+}
+
 /*
  * Note that the @target has to be an absolute path (so at least "/").  The
  * @filename returns an allocated buffer with the last path component, for example:
@@ -983,7 +992,7 @@ char *mnt_get_mountpoint(const char *path)
 	if (*mnt == '/' && *(mnt + 1) == '\0')
 		goto done;
 
-	if (stat(mnt, &st))
+	if (mnt_stat_mountpoint(mnt, &st))
 		goto err;
 	base = st.st_dev;
 
@@ -992,7 +1001,7 @@ char *mnt_get_mountpoint(const char *path)
 
 		if (!p)
 			break;
-		if (stat(*mnt ? mnt : "/", &st))
+		if (mnt_stat_mountpoint(*mnt ? mnt : "/", &st))
 			goto err;
 		dir = st.st_dev;
 		if (dir != base) {