[libvirt] [PATCH 1/2] util: Introduce virFileCdromStatus

[Michal Privoznik]

On 07/03/2018 04:29 AM, Han Han wrote:
> This private API helps check cdrom drive status via ioctl().
> 
> Signed-off-by: Han Han <hhan at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virfile.c       | 52 ++++++++++++++++++++++++++++++++++++++++
>  src/util/virfile.h       | 10 ++++++++
>  3 files changed, 63 insertions(+)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 5499a368c0..e9f79ad433 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1797,6 +1797,7 @@ virFileActivateDirOverride;
>  virFileBindMountDevice;
>  virFileBuildPath;
>  virFileCanonicalizePath;
> +virFileCdromStatus;
>  virFileChownFiles;
>  virFileClose;
>  virFileComparePaths;
> diff --git a/src/util/virfile.c b/src/util/virfile.c
> index 378d03ecf0..790d9448d2 100644
> --- a/src/util/virfile.c
> +++ b/src/util/virfile.c
> @@ -2026,6 +2026,58 @@ virFileIsCDROM(const char *path)
>      return ret;
>  }
>  
> +/**
> + * virFileCdromStatus:
> + * @path: Cdrom path
> + *
> + * Returns:
> + *      -1                              error happends.
> + *      VIR_FILE_CDROM_DISC_OK          Cdrom is OK.
> + *      VIR_FILE_CDROM_NO_INFO          Information not available.
> + *      VIR_FILE_CDROM_NO_DISC          No disc in cdrom.
> + *      VIR_FILE_CDROM_TREY_OPEN        Cdrom is trey-open.
> + *      VIR_FILE_CDROM_DRIVE_NOT_READY  Cdrom is not ready.
> + * reported.
> + */
> +int
> +virFileCdromStatus(const char *path)

This is in "if defined(__linux__)" block. You need to provide non-Linux
stub for this function too otherwise we will fail to build on such systems.


> +{
> +    int ret = -1;
> +    int fd;
> +
> +    if ((fd = open(path, O_RDONLY | O_NONBLOCK)) < 0)
> +        goto cleanup;
> +
> +    /* Attempt to detect CDROM status via ioctl */
> +    if ((ret = ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT)) >= 0) {

So virFileIsCDROM calls the same ioctl(). I wonder whether we should
modify that function instead of inventing a new one. It would work like
this:

virFileISCDROM(const char *path, int *status);

if @path is a CDROM, then @status is set to one of VIR_FILE_CDROM_*.
However, caller can pass status = NULL which means they are not
interested in status rather than plain is CDROM / isn't CDROM fact.

> +        switch (ret) {
> +            case CDS_NO_INFO:
> +                ret = VIR_FILE_CDROM_NO_INFO;
> +                goto cleanup;
> +                break;

There is no reason for this goto. break is sufficient.

> +            case CDS_NO_DISC:
> +                ret = VIR_FILE_CDROM_NO_DISC;
> +                goto cleanup;
> +                break;
> +            case CDS_TRAY_OPEN:
> +                ret = VIR_FILE_CDROM_TREY_OPEN;
> +                goto cleanup;
> +                break;
> +            case CDS_DRIVE_NOT_READY:
> +                ret = VIR_FILE_CDROM_DRIVE_NOT_READY;
> +                goto cleanup;
> +                break;
> +            case CDS_DISC_OK:
> +                ret = VIR_FILE_CDROM_DISC_OK;
> +                goto cleanup;
> +                break;
> +        }
> +    }
> +
> + cleanup:
> +    VIR_FORCE_CLOSE(fd);
> +    return ret;
> +}
>  #else
>  
>  int
> diff --git a/src/util/virfile.h b/src/util/virfile.h
> index 6f1e802fde..9d4701c8d2 100644
> --- a/src/util/virfile.h
> +++ b/src/util/virfile.h
> @@ -212,6 +212,16 @@ int virFileIsSharedFS(const char *path) ATTRIBUTE_NONNULL(1);
>  int virFileIsMountPoint(const char *file) ATTRIBUTE_NONNULL(1);
>  int virFileIsCDROM(const char *path)
>      ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
> +int virFileCdromStatus(const char *path)
> +    ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
> +
> +enum {
> +    VIR_FILE_CDROM_DISC_OK = 1,
> +    VIR_FILE_CDROM_NO_INFO,
> +    VIR_FILE_CDROM_NO_DISC,
> +    VIR_FILE_CDROM_TREY_OPEN,
> +    VIR_FILE_CDROM_DRIVE_NOT_READY,
> +};

Nit pick, the enum should go before the function. The reason is that if
we decide to give the enum a name [1], we don't have to move things around.

1: which leads me to even better proposal. How about giving this enum a
name, say virFileCDRomStatus and acknowledging this in function header:

int virFileISCDROM(const char *path, virFileCDRomStatus *status);

The set of return values of the function would remain the same as is now.

Michal