block: Ignore duplicate or NULL format_name in bdrv_iterate_format

Some block drivers have multiple BlockDriver instances with identical
format_name fields (e.g. gluster, nbd).

Both qemu-img and qemu will use bdrv_iterate_format() to list the
supported formats when a help option is invoked.  As protocols and
formats may register multiple drivers, redundant listings of formats
occur (e.g., "Supported formats: ... gluster gluster gluster gluster ...
").

Since the list of driver formats will be small, this performs a simple
linear search on format_name, and ignores any duplicates.

The end result change is that the iterator will no longer receive
duplicate string names, nor will it receive NULL pointers.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Jeff Cody 2014-04-28 18:29:54 -04:00 committed by Kevin Wolf
parent 5f6979cba9
commit e855e4fb7b
1 changed files with 16 additions and 1 deletions

17
block.c
View File

@ -3601,10 +3601,25 @@ void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
void *opaque)
{
BlockDriver *drv;
int count = 0;
const char **formats = NULL;
QLIST_FOREACH(drv, &bdrv_drivers, list) {
it(opaque, drv->format_name);
if (drv->format_name) {
bool found = false;
int i = count;
while (formats && i && !found) {
found = !strcmp(formats[--i], drv->format_name);
}
if (!found) {
formats = g_realloc(formats, (count + 1) * sizeof(char *));
formats[count++] = drv->format_name;
it(opaque, drv->format_name);
}
}
}
g_free(formats);
}
/* This function is to find block backend bs */