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authorJeff Cody <jcody@redhat.com>2012-10-16 15:49:09 -0400
committerKevin Wolf <kwolf@redhat.com>2012-10-24 10:26:18 +0200
commitb1b1d783eabdb6ac4e4578b2c04b0c24483dce77 (patch)
tree93934cecb2a119298e7346ce8a34fd761936806b /block.c
parenta616673dd1c2e00db5e3458d2ba4b6619b78876a (diff)
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block: make bdrv_find_backing_image compare canonical filenames
Currently, bdrv_find_backing_image compares bs->backing_file with what is passed in as a backing_file name. Mismatches may occur, however, when bs->backing_file and backing_file are not both absolute or relative. Use path_combine() to make sure any relative backing filenames are relative to the current image filename being searched, and then use realpath() to make all comparisons based on absolute filenames. If either backing_file or bs->backing_file is determine to be a protocol, then no filename normalization is performed. This also changes bdrv_find_backing_image to no longer be recursive, but iterative. Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c60
1 files changed, 54 insertions, 6 deletions
diff --git a/block.c b/block.c
index e95f613..5e7fc9e 100644
--- a/block.c
+++ b/block.c
@@ -3123,22 +3123,70 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
return -ENOTSUP;
}
+/* backing_file can either be relative, or absolute, or a protocol. If it is
+ * relative, it must be relative to the chain. So, passing in bs->filename
+ * from a BDS as backing_file should not be done, as that may be relative to
+ * the CWD rather than the chain. */
BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
const char *backing_file)
{
- if (!bs->drv) {
+ char *filename_full = NULL;
+ char *backing_file_full = NULL;
+ char *filename_tmp = NULL;
+ int is_protocol = 0;
+ BlockDriverState *curr_bs = NULL;
+ BlockDriverState *retval = NULL;
+
+ if (!bs || !bs->drv || !backing_file) {
return NULL;
}
- if (bs->backing_hd) {
- if (strcmp(bs->backing_file, backing_file) == 0) {
- return bs->backing_hd;
+ filename_full = g_malloc(PATH_MAX);
+ backing_file_full = g_malloc(PATH_MAX);
+ filename_tmp = g_malloc(PATH_MAX);
+
+ is_protocol = path_has_protocol(backing_file);
+
+ for (curr_bs = bs; curr_bs->backing_hd; curr_bs = curr_bs->backing_hd) {
+
+ /* If either of the filename paths is actually a protocol, then
+ * compare unmodified paths; otherwise make paths relative */
+ if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
+ if (strcmp(backing_file, curr_bs->backing_file) == 0) {
+ retval = curr_bs->backing_hd;
+ break;
+ }
} else {
- return bdrv_find_backing_image(bs->backing_hd, backing_file);
+ /* If not an absolute filename path, make it relative to the current
+ * image's filename path */
+ path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
+ backing_file);
+
+ /* We are going to compare absolute pathnames */
+ if (!realpath(filename_tmp, filename_full)) {
+ continue;
+ }
+
+ /* We need to make sure the backing filename we are comparing against
+ * is relative to the current image filename (or absolute) */
+ path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
+ curr_bs->backing_file);
+
+ if (!realpath(filename_tmp, backing_file_full)) {
+ continue;
+ }
+
+ if (strcmp(backing_file_full, filename_full) == 0) {
+ retval = curr_bs->backing_hd;
+ break;
+ }
}
}
- return NULL;
+ g_free(filename_full);
+ g_free(backing_file_full);
+ g_free(filename_tmp);
+ return retval;
}
int bdrv_get_backing_file_depth(BlockDriverState *bs)