On 05/20/2015 03:57 AM, Dimitris Aragiorgis wrote: > Until now, an SG device was identified only by checking if its path > started with "/dev/sg". Then, hdev_open() set bs->sg accordingly. > This is very fragile, e.g. it fails with symlinks or relative paths. > We should rely on the actual properties of the device instead of the > specified file path. > > Test for an SG device (e.g. /dev/sg0) by ensuring that all of the > following holds: > > - The device supports the SG_GET_VERSION_NUM ioctl > - The device supports the SG_GET_SCSI_ID ioctl > - The specified file name corresponds to a character device
I'd check stat first. ioctl's on the wrong device type might have
unexpected side effects.
> +static int hdev_is_sg(BlockDriverState *bs)
> +{
> +
> +#if defined(__linux__)
> +
> + struct stat st;
> + struct sg_scsi_id scsiid;
> + int sg_version;
> +
> + if (!bdrv_ioctl(bs, SG_GET_VERSION_NUM, &sg_version) &&
> + !bdrv_ioctl(bs, SG_GET_SCSI_ID, &scsiid) &&
> + stat(bs->filename, &st) >= 0 && S_ISCHR(st.st_mode)) {
> + DPRINTF("SG device found: type=%d, version=%d\n",
> + scsiid.scsi_type, sg_version);
> + return 1;
> + }
> +
> +#endif
> +
> + return 0;
Make this return 'bool', using 'true' and 'false'. We require a C99
compiler, after all.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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