[libvirt] [PATCH v3 01/11] util: Introduce virHostGetDRMRenderNode helper

[Daniel P. Berrangé]

On Thu, Nov 29, 2018 at 03:20:11PM +0100, Erik Skultety wrote:
> This is the first step towards libvirt picking the first available
> render node instead of QEMU. It also makes sense for us to be able to do
> that, since we allow specifying the node directly for SPICE, so if
> there's no render node specified by the user, we should pick the first
> available one. The algorithm used for that is essentially the same as
> the one QEMU uses.
> 
> Signed-off-by: Erik Skultety <eskultet at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virutil.c       | 53 ++++++++++++++++++++++++++++++++++++++++
>  src/util/virutil.h       |  2 ++
>  3 files changed, 56 insertions(+)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 5018a13e9c..c7f08f9620 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -3151,6 +3151,7 @@ virGetUserName;
>  virGetUserRuntimeDirectory;
>  virGetUserShell;
>  virHexToBin;
> +virHostGetDRMRenderNode;
>  virHostHasIOMMU;
>  virIndexToDiskName;
>  virIsDevMapperDevice;
> diff --git a/src/util/virutil.c b/src/util/virutil.c
> index 974cffc2ee..da12a11e04 100644
> --- a/src/util/virutil.c
> +++ b/src/util/virutil.c
> @@ -2145,3 +2145,56 @@ virHostHasIOMMU(void)
>      VIR_DIR_CLOSE(iommuDir);
>      return ret;
>  }
> +
> +
> +/**
> + * virHostGetDRMRenderNode:
> + *
> + * Picks the first DRM render node available. Missing DRI or missing DRM render
> + * nodes in the system results in an error.
> + *
> + * Returns an absolute path to the first render node available or NULL in case
> + * of an error with the error being reported.
> + * Caller is responsible for freeing the result string.
> + *
> + */
> +char *
> +virHostGetDRMRenderNode(void)
> +{
> +    char *ret = NULL;
> +    DIR *driDir = NULL;
> +    const char *driPath = "/dev/dri";
> +    struct dirent *ent = NULL;
> +    int dirErr = 0;
> +    bool have_rendernode = false;
> +
> +    if (virDirOpen(&driDir, driPath) < 0)
> +        return NULL;
> +
> +    while ((dirErr = virDirRead(driDir, &ent, driPath)) > 0) {
> +        if (ent->d_type != DT_CHR)
> +            continue;

The 'd_type' field is a Linux-ism, so this has broken the build

Is it even needed ? ie are then any files in /dev/dri that have
a prefix of "renderD" but which are not character devices ?

> +
> +        if (STRPREFIX(ent->d_name, "renderD")) {
> +            have_rendernode = true;
> +            break;
> +        }
> +    }

Regards,
Daniel
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