Signed-off-by: Xu Wang <cngesa...@gmail.com>
---
block.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/block/block.h | 4 ++
qemu-img.c | 30 +++++----------
3 files changed, 114 insertions(+), 21 deletions(-)
diff --git a/block.c b/block.c
index b88ad2f..53b1a01 100644
--- a/block.c
+++ b/block.c
@@ -4431,6 +4431,107 @@ bdrv_acct_done(BlockDriverState *bs, BlockAcctCookie
*cookie)
bs->total_time_ns[cookie->type] += get_clock() - cookie->start_time_ns;
}
+static gboolean str_equal_func(gconstpointer a, gconstpointer b)
+{
+ return strcmp(a, b) == 0;
+}
+
+/**
+ * Check backing file chain if there is a loop in it and build list of
+ * ImageInfo if needed.
+ *
+ * @filename: topmost image filename, absolute or relative path is OK.
+ * @fmt: topmost image format (may be NULL to autodetect)
+ * @head: head of ImageInfo list. If not need please set head to null.
+ * @chain: true - enumerate entire backing file chain
+ * false - only topmost image file
+ * @backing_file: if this value is set, @filename inode (-1 if it doesn't
+ * exist) will insert into hash table directly. Loop check
+ * starts from it. Absolute or relative path is OK for it.
+ * @backing_format: format of backing file
+ *
+ * If return true, stands for a backing file loop exists or some error
+ * happened. If return false, everything is ok.
+ */
+bool bdrv_backing_file_loop_check(const char *filename, const char *fmt,
+ bool chain, const char *backing_file,
+ const char *backing_format) {
+ GHashTable *inodes;
+ BlockDriverState *bs;
+ BlockDriver *drv;
+ struct stat sbuf;
+ long inode = 0;
+ int ret;
+ char fbuf[1024];
+
+ inodes = g_hash_table_new_full(g_str_hash, str_equal_func, NULL, NULL);
+
+ if (backing_file) {
+ /* Check if file exists. */
+ if (access(filename, F_OK)) {
+ inode = -1;
+ } else {
+ if (stat(filename, &sbuf) == -1) {
+ error_report("Get file %s stat failed.", filename);
+ goto err;
+ }
+ inode = (long)sbuf.st_ino;
+ }
+
+ filename = backing_file;
+ fmt = backing_format;
+ g_hash_table_insert(inodes, (gpointer)&inode, NULL);
+ }
+
+ while (filename && (filename[0] != '\0')) {
+ if (stat(filename, &sbuf) == -1) {
+ error_report("Get file %s stat failed.", filename);
+ goto err;
+ }
+ inode = (long)sbuf.st_ino;
+
+ if (g_hash_table_lookup_extended(inodes, &inode, NULL, NULL)) {
+ error_report("Backing file '%s' creates an infinite loop.",
+ filename);
+ goto err;
+ }
+ g_hash_table_insert(inodes, (gpointer)&inode, NULL);
+
+ bs = bdrv_new("image");
+
+ if (fmt) {
+ drv = bdrv_find_format(fmt);
+ if (!drv) {
+ error_report("Unknown file format '%s'", fmt);
+ goto err;
+ }
+ } else {
+ drv = NULL;
+ }
+
+ ret = bdrv_open(bs, filename, NULL,
+ BDRV_O_CACHE_WB | BDRV_O_NO_BACKING, drv);
+ if (ret < 0) {
+ error_report("Could not open '%s': %s", filename, strerror(-ret));
+ goto err;
+ }
+
+ filename = fmt = NULL;
+ if (chain) {
+ bdrv_get_backing_filename(bs, fbuf, sizeof(fbuf));
+ filename = fbuf;
+ }
+
+ bdrv_delete(bs);
+ }
+ g_hash_table_destroy(inodes);
+ return false;
+
+err:
+ g_hash_table_destroy(inodes);
+ return true;
+}
+
void bdrv_img_create(const char *filename, const char *fmt,
const char *base_filename, const char *base_fmt,
char *options, uint64_t img_size, int flags,
diff --git a/include/block/block.h b/include/block/block.h
index 2307f67..6c631f2 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -332,6 +332,10 @@ int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t
*buf,
int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size);
+bool bdrv_backing_file_loop_check(const char *filename, const char *fmt,
+ bool chain, const char *backing_file,
+ const char *backing_format);
+
void bdrv_img_create(const char *filename, const char *fmt,
const char *base_filename, const char *base_fmt,
char *options, uint64_t img_size, int flags,
diff --git a/qemu-img.c b/qemu-img.c
index 809b4f1..48284c5 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1620,11 +1620,6 @@ static void dump_human_image_info_list(ImageInfoList
*list)
}
}
-static gboolean str_equal_func(gconstpointer a, gconstpointer b)
-{
- return strcmp(a, b) == 0;
-}
-
/**
* Open an image file chain and return an ImageInfoList
*
@@ -1642,24 +1637,18 @@ static ImageInfoList *collect_image_info_list(const
char *filename,
bool chain)
{
ImageInfoList *head = NULL;
+ BlockDriverState *bs;
+ ImageInfoList *elem;
ImageInfoList **last = &head;
- GHashTable *filenames;
+ ImageInfo *info;
Error *err = NULL;
-
- filenames = g_hash_table_new_full(g_str_hash, str_equal_func, NULL, NULL);
+
+ /* check if loop exists and build ImageInfoList */
+ if (bdrv_backing_file_loop_check(filename, fmt, chain, NULL, NULL)) {
+ goto err;
+ }
while (filename) {
- BlockDriverState *bs;
- ImageInfo *info;
- ImageInfoList *elem;
-
- if (g_hash_table_lookup_extended(filenames, filename, NULL, NULL)) {
- error_report("Backing file '%s' creates an infinite loop.",
- filename);
- goto err;
- }
- g_hash_table_insert(filenames, (gpointer)filename, NULL);
-
bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING,
false, false);
if (!bs) {
@@ -1692,12 +1681,11 @@ static ImageInfoList *collect_image_info_list(const
char *filename,
}
}
}
- g_hash_table_destroy(filenames);
+
return head;
err:
qapi_free_ImageInfoList(head);
- g_hash_table_destroy(filenames);
return NULL;
}
--
1.8.1.4
