qemu-img: Reject broken -o ""
qemu-img create, convert, amend, and measure use accumulate_options()
to merge multiple -o options. This is broken for -o "":
$ qemu-img create -f qcow2 -o backing_file=a -o "" -o backing_fmt=raw,size=1M new.qcow2
qemu-img: warning: Could not verify backing image. This may become an error in future versions.
Could not open 'a,backing_fmt=raw': No such file or directory
Formatting 'new.qcow2', fmt=qcow2 size=1048576 backing_file=a,,backing_fmt=raw cluster_size=65536 lazy_refcounts=off refcount_bits=16
$ qemu-img info new.qcow2
image: new.qcow2
file format: qcow2
virtual size: 1 MiB (1048576 bytes)
disk size: 196 KiB
cluster_size: 65536
--> backing file: a,backing_fmt=raw
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
Merging these three -o the obvious way is wrong, because it results in
an unwanted ',' escape:
backing_file=a,,backing_fmt=raw,size=1M
~~
We could silently drop -o "", but Kevin asked me to reject it instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200415074927.19897-10-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c
index cc51db7..a236976 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -229,14 +229,16 @@
* To make that work, @optarg must not start with ',' (or else a
* separating ',' preceding it gets escaped), and it must not end with
* an odd number of ',' (or else a separating ',' following it gets
- * escaped).
+ * escaped), or be empty (or else a separating ',' preceding it can
+ * escape a separating ',' following it).
+ *
*/
static bool is_valid_option_list(const char *optarg)
{
size_t len = strlen(optarg);
size_t i;
- if (optarg[0] == ',') {
+ if (!optarg[0] || optarg[0] == ',') {
return false;
}
