Make bdrv_get_full_backing_filename_from_filename() return an allocated
string instead of placing the result in a caller-provided buffer.
Signed-off-by: Max Reitz <mre...@redhat.com>
Reviewed-by: Alberto Garcia <be...@igalia.com>
---
include/block/block.h | 7 +++---
block.c | 53 ++++++++++++++++++++++++++++++-------------
block/vmdk.c | 9 ++++----
qemu-img.c | 12 ++++------
4 files changed, 48 insertions(+), 33 deletions(-)
diff --git a/include/block/block.h b/include/block/block.h
index e5f01ebed0..bb238488c4 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -484,10 +484,9 @@ void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size);
void bdrv_get_full_backing_filename(BlockDriverState *bs,
char *dest, size_t sz, Error **errp);
-void bdrv_get_full_backing_filename_from_filename(const char *backed,
- const char *backing,
- char *dest, size_t sz,
- Error **errp);
+char *bdrv_get_full_backing_filename_from_filename(const char *backed,
+ const char *backing,
+ Error **errp);
int path_has_protocol(const char *path);
int path_is_absolute(const char *path);
diff --git a/block.c b/block.c
index d083b02b58..d31c759091 100644
--- a/block.c
+++ b/block.c
@@ -293,20 +293,29 @@ int bdrv_set_read_only(BlockDriverState *bs, bool
read_only, Error **errp)
return 0;
}
-void bdrv_get_full_backing_filename_from_filename(const char *backed,
- const char *backing,
- char *dest, size_t sz,
- Error **errp)
+/*
+ * If @backing is empty, this function returns NULL without setting
+ * @errp. In all other cases, NULL will only be returned with @errp
+ * set.
+ *
+ * Therefore, a return value of NULL without @errp set means that
+ * there is no backing file; if @errp is set, there is one but its
+ * absolute filename cannot be generated.
+ */
+char *bdrv_get_full_backing_filename_from_filename(const char *backed,
+ const char *backing,
+ Error **errp)
{
- if (backing[0] == '\0' || path_has_protocol(backing) ||
- path_is_absolute(backing))
- {
- pstrcpy(dest, sz, backing);
+ if (backing[0] == '\0') {
+ return NULL;
+ } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
+ return g_strdup(backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
+ return NULL;
} else {
- path_combine_deprecated(dest, sz, backed, backing);
+ return path_combine(backed, backing);
}
}
@@ -314,12 +323,24 @@ void bdrv_get_full_backing_filename(BlockDriverState *bs,
char *dest, size_t sz,
Error **errp)
{
char *backed;
+ char *full_name;
+ Error *local_error = NULL;
bdrv_refresh_filename(bs);
backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
- bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
- dest, sz, errp);
+
+ full_name = bdrv_get_full_backing_filename_from_filename(backed,
+ bs->backing_file,
+ &local_error);
+ if (full_name) {
+ pstrcpy(dest, sz, full_name);
+ g_free(full_name);
+ } else if (local_error) {
+ error_propagate(errp, local_error);
+ } else if (sz > 0) {
+ *dest = '\0';
+ }
}
void bdrv_register(BlockDriver *bdrv)
@@ -4871,17 +4892,17 @@ void bdrv_img_create(const char *filename, const char
*fmt,
size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
BlockDriverState *bs;
- char *full_backing = g_new0(char, PATH_MAX);
+ char *full_backing;
int back_flags;
QDict *backing_options = NULL;
- bdrv_get_full_backing_filename_from_filename(filename, backing_file,
- full_backing, PATH_MAX,
- &local_err);
+ full_backing =
+ bdrv_get_full_backing_filename_from_filename(filename,
backing_file,
+ &local_err);
if (local_err) {
- g_free(full_backing);
goto out;
}
+ assert(full_backing);
/* backing files always opened read-only */
back_flags = flags;
diff --git a/block/vmdk.c b/block/vmdk.c
index 3d3273e65b..b3fc3b9e12 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2049,16 +2049,15 @@ static int coroutine_fn vmdk_co_create_opts(const char
*filename, QemuOpts *opts
}
if (backing_file) {
BlockBackend *blk;
- char *full_backing = g_new0(char, PATH_MAX);
- bdrv_get_full_backing_filename_from_filename(filename, backing_file,
- full_backing, PATH_MAX,
- &local_err);
+ char *full_backing =
+ bdrv_get_full_backing_filename_from_filename(filename,
backing_file,
+ &local_err);
if (local_err) {
- g_free(full_backing);
error_propagate(errp, local_err);
ret = -ENOENT;
goto exit;
}
+ assert(full_backing);
blk = blk_new_open(full_backing, NULL, NULL,
BDRV_O_NO_BACKING, errp);
diff --git a/qemu-img.c b/qemu-img.c
index b12f4cd19b..22c9abe411 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3327,18 +3327,14 @@ static int img_rebase(int argc, char **argv)
overlay_filename = bs->exact_filename[0] ? bs->exact_filename
: bs->filename;
- out_real_path = g_malloc(PATH_MAX);
-
- bdrv_get_full_backing_filename_from_filename(overlay_filename,
- out_baseimg,
- out_real_path,
- PATH_MAX,
- &local_err);
+ out_real_path =
+ bdrv_get_full_backing_filename_from_filename(overlay_filename,
+ out_baseimg,
+ &local_err);
if (local_err) {
error_reportf_err(local_err,
"Could not resolve backing filename: ");
ret = -1;
- g_free(out_real_path);
goto out;
}
--
2.17.1
