1 files changed, 48 insertions, 0 deletions
diff --git a/utils.c b/utils.c
index acd27b80..8006e49b 100644
--- a/utils.c
+++ b/utils.c
@@ -2110,3 +2110,51 @@ int lookup_ino_rootid(int fd, u64 *rootid)
 
 	return 0;
 }
+
+int find_mount_root(const char *path, char **mount_root)
+{
+	FILE *mnttab;
+	int fd;
+	struct mntent *ent;
+	int len;
+	int ret;
+	int longest_matchlen = 0;
+	char *longest_match = NULL;
+
+	fd = open(path, O_RDONLY | O_NOATIME);
+	if (fd < 0)
+		return -errno;
+	close(fd);
+
+	mnttab = setmntent("/proc/self/mounts", "r");
+	if (!mnttab)
+		return -errno;
+
+	while ((ent = getmntent(mnttab))) {
+		len = strlen(ent->mnt_dir);
+		if (strncmp(ent->mnt_dir, path, len) == 0) {
+			/* match found */
+			if (longest_matchlen < len) {
+				free(longest_match);
+				longest_matchlen = len;
+				longest_match = strdup(ent->mnt_dir);
+			}
+		}
+	}
+	endmntent(mnttab);
+
+	if (!longest_match) {
+		fprintf(stderr,
+			"ERROR: Failed to find mount root for path %s.\n",
+			path);
+		return -ENOENT;
+	}
+
+	ret = 0;
+	*mount_root = realpath(longest_match, NULL);
+	if (!*mount_root)
+		ret = -errno;
+
+	free(longest_match);
+	return ret;
+}