block: add block driver read only whitelist

We may want to include a driver in the whitelist for read only tasks
such as diagnosing or exporting guest data (with libguestfs as a good
example). This patch introduces a readonly whitelist option, and for
backward compatibility, the old configure option --block-drv-whitelist
is now an alias to rw whitelist.

Drivers in readonly list is only permitted to open file readonly, and
returns -ENOTSUP for RW opening.

E.g. To include vmdk readonly, and others read+write:
    ./configure --target-list=x86_64-softmmu \
                --block-drv-rw-whitelist=qcow2,raw,file,qed \
                --block-drv-ro-whitelist=vmdk

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/blockdev.c b/blockdev.c
index d1ec99af73..b9b2d10e6b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -477,7 +477,7 @@ DriveInfo *drive_init(QemuOpts *all_opts, BlockInterfaceType block_default_type)
             error_printf("\n");
             return NULL;
         }
-        drv = bdrv_find_whitelisted_format(buf);
+        drv = bdrv_find_whitelisted_format(buf, ro);
         if (!drv) {
             error_report("'%s' invalid format", buf);
             return NULL;
@@ -1096,7 +1096,7 @@ void qmp_change_blockdev(const char *device, const char *filename,
     }
 
     if (format) {
-        drv = bdrv_find_whitelisted_format(format);
+        drv = bdrv_find_whitelisted_format(format, bs->read_only);
         if (!drv) {
             error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
             return;