Hi Emil,
On 23/02/15 12:22, Emil Velikov wrote:
> Currently most places assume reliable master <> render node mapping.
> Although this may work in some cases, it is not correct.
>
> Add a couple of helpers that hide the details and provide the name of
> the master/render device name, given an render/master FD.
>
> v2:
> - Rename Device and Primary to Master (aka the /dev/dri/cardX device).
> - Check for the file via readdir_r() rather than stat().
> - Wrap the check into a single function.
> - Return NULL for non-linux platforms.
>
> Cc: Frank Binns <frank.binns@xxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: David Herrmann <dh.herrmann@xxxxxxxxxxxxxx>
> Signed-off-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
> ---
> xf86drm.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> xf86drm.h | 3 +++
> 2 files changed, 85 insertions(+)
>
> diff --git a/xf86drm.c b/xf86drm.c
> index e117bc6..d4a4dc6 100644
> --- a/xf86drm.c
> +++ b/xf86drm.c
> @@ -40,6 +40,8 @@
> #include <string.h>
> #include <strings.h>
> #include <ctype.h>
> +#include <dirent.h>
> +#include <stddef.h>
> #include <fcntl.h>
> #include <errno.h>
> #include <signal.h>
> @@ -522,6 +524,20 @@ static int drmGetMinorType(int minor)
> }
> }
>
> +static const char *drmGetMinorName(int type)
> +{
> + switch (type) {
> + case DRM_NODE_PRIMARY:
> + return "card";
> + case DRM_NODE_CONTROL:
> + return "controlD";
> + case DRM_NODE_RENDER:
> + return "renderD";
> + default:
> + return NULL;
> + }
> +}
> +
> /**
> * Open the device by bus ID.
> *
> @@ -2736,3 +2752,69 @@ int drmPrimeFDToHandle(int fd, int prime_fd, uint32_t *handle)
> return 0;
> }
>
> +static char *drmGetMinorNameForFD(int fd, int type)
> +{
> +#ifdef __linux__
> + DIR *sysdir;
> + struct dirent *pent, *ent;
> + struct stat sbuf;
> + const char *name = drmGetMinorName(type);
> + const int len = strlen(name);
This will cause a segfault if 'name' is NULL.
> + char dev_name[64], buf[64];
> + long name_max;
> + int maj, min;
> +
> + if (!name)
> + return NULL;
> +
> + if (fstat(fd, &sbuf))
> + return NULL;
> +
> + maj = major(sbuf.st_rdev);
> + min = minor(sbuf.st_rdev);
> +
> + if (maj != DRM_MAJOR || !S_ISCHR(sbuf.st_mode))
> + return NULL;
> +
> + snprintf(buf, sizeof(buf), "/sys/dev/char/%d:%d/device/drm", maj, min);
> +
> + sysdir = opendir(buf);
> + if (!sysdir)
> + return NULL;
> +
> + name_max = fpathconf(dirfd(sysdir), _PC_NAME_MAX);
> + if (name_max == -1)
> + goto out_close_dir;
> +
> + pent = malloc(offsetof(struct dirent, d_name) + name_max + 1);
> + if (pent == NULL)
> + goto out_close_dir;
> +
> + while (readdir_r(sysdir, pent, &ent) == 0 && ent != NULL) {
> + if (strncmp(ent->d_name, name, len) == 0) {
> + free(pent);
> + closedir(sysdir);
> +
> + snprintf(dev_name, sizeof(dev_name), DRM_DIR_NAME "/%s",
> + ent->d_name);
> + return strdup(dev_name);
> + }
> + }
> +
> + free(pent);
> +
> +out_close_dir:
> + closedir(sysdir);
> +#endif
> + return NULL;
> +}
> +
> +char *drmGetMasterNameFromRenderFD(int fd)
I think drmGetPrimaryDeviceNameFromFd would be more appropriate given
the node type is 'primary', the type of the fd doesn't matter afaics and
for consistency with other drmGet* functions. However, given that's a
bit of a mouthful I guess the 'Device' part could be dropped.
> +{
> + return drmGetMinorNameForFD(fd, DRM_NODE_PRIMARY);
> +}
> +
> +char *drmGetRenderNameFromMasterFD(int fd)
As above, maybe drmGetRenderDeviceNameFromFd?
With those things changed/fixed you can have a:
Reviewed-by: Frank Binns <frank.binns@xxxxxxxxxx>
Thanks
Frank
> +{
> + return drmGetMinorNameForFD(fd, DRM_NODE_RENDER);
> +}
> diff --git a/xf86drm.h b/xf86drm.h
> index afd38a1..5fdf27b 100644
> --- a/xf86drm.h
> +++ b/xf86drm.h
> @@ -749,6 +749,9 @@ extern int drmGetNodeTypeFromFd(int fd);
> extern int drmPrimeHandleToFD(int fd, uint32_t handle, uint32_t flags, int *prime_fd);
> extern int drmPrimeFDToHandle(int fd, int prime_fd, uint32_t *handle);
>
> +extern char *drmGetRenderNameFromMasterFD(int fd);
> +extern char *drmGetMasterNameFromRenderFD(int fd);
> +
> #if defined(__cplusplus) || defined(c_plusplus)
> }
> #endif
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