Re: [Qemu-devel] [PATCH] Add an error_report when failing to open due to block-drv-whitelist

[Kevin Wolf <kwolf@redhat.com>]

Am 09.06.2010 21:28, schrieb Ryan Harper:
> When configure qemu with --block-drv-whitelist we don't report when we are
> blocked by the white list and the resulting error message is misleading:
> 
> ./configure --target-list=x86_64-softmmu \
>             --block-drv-whitelist=qcow2,raw,host_device,host_cdrom
> 
> x86_64-softmmu/qemu-system-x86_64 -L pc-bios -m 512 -drive \
>         file=fedora9_32_20G.qcow2,if=ide -monitor stdio
> qemu: could not open disk image fedora9_32_20G.qcow2: Inappropriate ioctl for device
> 
> Which might lead one to look at the bdrv probe functions for floppy/cdrom
> because we indeed will get an ioctl failure stored in errno and we report this
> in vl.c when we get a non-zero return value from bdrv_open().
> 
> This patch adds an error report when we fail the whitelist and changes the errno
> value to ENOPROTOOPT which was the closest thing I could think of that matched
> the actual error.
> 
> Now we get the following output on whitelist failure:
> 
> x86_64-softmmu/qemu-system-x86_64 -L pc-bios -m 512 -drive \
>         file=fedora9_32_20G.qcow2,if=ide -monitor stdio
> qemu-system-x86_64: -drive file=fedora9_32_20G.qcow2,if=ide: block-drv-whitelist prevents using format 'file'
> qemu: could not open disk image fedora9_32_20G.qcow2: Protocol not supported
> 
> Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
> ---
>  block.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 39724c1..ffcf7f2 100644
> --- a/block.c
> +++ b/block.c
> @@ -403,6 +403,9 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
>      pstrcpy(bs->filename, sizeof(bs->filename), filename);
>  
>      if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
> +        error_report("block-drv-whitelist prevents using format '%s'", drv->format_name);
> +        /* reset errno since we're failing because of whitelist restrictions */
> +        errno = EPROTONOSUPPORT;

Any code that relies on this errno is broken. errno isn't part of the
bdrv_open interface. In fact, last week I have sent a patch to fix the
error message to use the return value instead, Anthony just needs to pull.

The error_report may be a good idea, though.

Kevin