Eric Blake <ebl...@redhat.com> writes:
> On 01/14/2013 12:09 AM, Wenchao Xia wrote:
>> This patch move it from savevm.c to block.c and export it.
>>
>> Signed-off-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
>> ---
>> block.c | 23 +++++++++++++++++++++++
>> include/block/block.h | 2 ++
>> savevm.c | 22 ----------------------
>> 3 files changed, 25 insertions(+), 22 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index 8192d8e..b7d2f03 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -3351,6 +3351,29 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
>> return -ENOTSUP;
>> }
>>
>> +int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
>> + const char *name)
>> +{
>> + QEMUSnapshotInfo *sn_tab, *sn;
>> + int nb_sns, i, ret;
>> +
>> + ret = -ENOENT;
>> + nb_sns = bdrv_snapshot_list(bs, &sn_tab);
>> + if (nb_sns < 0) {
>> + return ret;
>> + }
>> + for (i = 0; i < nb_sns; i++) {
>> + sn = &sn_tab[i];
>> + if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
>
> It is possible (albeit probably stupid) to create a qcow2 file where
> snapshot names are merely numeric strings. In fact, just to see what
> would happen, I once[1] created a file where:
>
> snapshot id '1' was named '2'
> snapshot id '2' was named 'foo'
>
> This code comparison favors ids over names; so if I request to delvm 2,
> I end up removing the second snapshot, not the first. This is okay, but
> probably worth documenting, and probably worth making sure that all code
> that looks up a snapshot by name or id goes through this function so
> that we get the same behavior everywhere. My experiment was done
> several months ago, but my recollection was that at the time, there was
> an inconsistency where 'qemu-img snapshot' picked a different snapshot
> for the request of '2' than the online 'delvm' monitor command of qemu;
> making it unsafe to rely on either behavior in that version of qemu
> source code.
>
> [1]https://bugzilla.redhat.com/show_bug.cgi?id=733143
In QemuOpts, we restricted IDs to [[:alpha:]][[:alnum:]-._]*, see
id_wellformed(). I'd recommend the same for new interfaces. But this
is an old one, and we shouldn't make existing snapshots inaccessible
just because their names were chosen unwisely.
