[CRIU] [PATCH] Fix AUFS pathname handling when branch is not exposed

[Saied Kazemi]

The code that fixes up AUFS pathnames associated with vma entries (see
commit d8b41b6525) should handle cases where an entry does not expose
the branch pathname (e.g., pointing to a device like /dev/zero).

Signed-off-by: Saied Kazemi <saied at google.com>
---
 sysfs_parse.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sysfs_parse.c b/sysfs_parse.c
index 771a236..8e236e9 100644
--- a/sysfs_parse.c
+++ b/sysfs_parse.c
@@ -272,6 +272,7 @@ err:
  */
 int fixup_aufs_vma_fd(struct vma_area *vma)
 {
+	char *file;
 	char path[PATH_MAX];
 	int len;
 
@@ -284,7 +285,15 @@ int fixup_aufs_vma_fd(struct vma_area *vma)
 	if (len < 0)
 		return -1;
 
-	if (len > 0) {
+	if (len == 0) {
+		/*
+		 * The vma is associated with a map_files entry
+		 * that does not expose the branch pathname
+		 * (e.g., /dev/zero).  In this case, we can use
+		 * the path.
+		 */
+		file = &path[1];
+	} else {
 		vma->aufs_rpath = xmalloc(len + 2);
 		if (!vma->aufs_rpath)
 			return -1;
@@ -297,9 +306,10 @@ int fixup_aufs_vma_fd(struct vma_area *vma)
 			sprintf(vma->aufs_fpath, "%s/%s", opts.root, &path[2]);
 		}
 		pr_debug("Saved AUFS paths %s and %s\n", vma->aufs_rpath, vma->aufs_fpath);
+		file = vma->aufs_fpath;
 	}
 
-	if (stat(vma->aufs_fpath, vma->vmst) < 0) {
+	if (stat(file, vma->vmst) < 0) {
 		pr_perror("Failed stat on map %"PRIx64" (%s)",
 				vma->e->start, vma->aufs_fpath);
 		return -1;
-- 
2.2.0.rc0.207.ga3a616c