On 23 February 2015 at 14:35, Frank Binns <frank.binns@xxxxxxxxxx> wrote:
> 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',
Most places that I've seen call "/dev/dri/cardX" master node, although
with the introduction of DRM_NODE_PRIMARY I believe your suggestion
may be better.
> 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.
>
I was thinking about this initially then decided to keep the
Render/MasterFD explicit. Mainly because I'm don't know how cumbersome
the *BSD implementation will be.
But with that said it none of the BSD guys objects within 1-2 weeks
I'll go with your suggestion.
Thanks
Emil
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