Change check for /dev/kfd permissions

On newer kernels, it seems the group was changed from "video" to
"render". The check for video group misled me for quite some time, so
relax this check. Rather than specifically checking for video group
ownership, first see if /dev/kfd can be open as read-write. Then
diagnose whether the user belongs to the group that owns it, rather
than hardcoding the video group.

Change-Id: I9e65427363e9a5cdba802e09cee2f40fb80520ed


[ROCm/rocminfo commit: cd4b7cea85]

projects/rocminfo/rocminfo.cc

@@ -44,7 +44,9 @@
  */
 #include <stdio.h>
 #include <string.h>
+#include <sys/stat.h>
 #include <sys/types.h>
+#include <fcntl.h>
 #include <grp.h>
 #include <unistd.h>
 #include <pwd.h>
@@ -1042,7 +1044,8 @@ void CheckInitialState(void) {
     printf("%sROCk module is loaded%s\n", COL_WHT, COL_RESET);
   }
 
-  // Check if user belongs to group "video"
+  // Check if user belongs to the group for /dev/kfd (e.g. "video" or
+  // "render")
   // @note: User who are not members of "video"
   // group cannot access DRM services
   char u_name[32];
@@ -1051,16 +1054,44 @@ void CheckInitialState(void) {
   int num_groups = 0;
   gid_t *groups;
 
-  struct group *gr_s = getgrnam("video");  // NOLINT
+  // Check if we can open /dev/kfd as read-write. If not, try to
+  // diagnose common reasons why you can't.
+  int open_kfd = open("/dev/kfd", O_RDWR);
+  if (open_kfd >= 0) {
+      close(open_kfd);
+      printf("%sAble to open /dev/kfd read-write%s\n",
+             COL_WHT, COL_RESET);
+      return;
+  }
+
+  printf("%sUnable to open /dev/kfd read-write: %s%s\n",
+         COL_RED, strerror(errno), COL_RESET);
+
+  const char *kfd_gr_name = NULL;
+
+  struct stat sb;
+  if (stat("/dev/kfd", &sb) == 0) {
+      // The owner of kfd was renamed, so avoid hard-coding the
+      // name. Check whatever group owns it.
+      if (struct group *kfd_gr = getgrgid(sb.st_gid))
+          kfd_gr_name = kfd_gr->gr_name;
+  }
+
+  if (!kfd_gr_name)
+      kfd_gr_name = "video";
+
+  struct group *gr_s = getgrnam(kfd_gr_name);  // NOLINT
   if (gr_s == nullptr) {
     printf("%sFailed to get group info to check"
-                       " for video group membership%s\n", COL_RED, COL_RESET);
+           " for %s group membership%s\n", COL_RED, kfd_gr_name,
+           COL_RESET);
     return;
   }
 
   if (getlogin_r(u_name, 32)) {
     printf("%sFailed to get user name to check for"
-                           " video group membership%s\n", COL_RED, COL_RESET);
+           " %s group membership%s\n", COL_RED, kfd_gr_name,
+           COL_RESET);
     return;
   }
 
@@ -1081,16 +1112,16 @@ void CheckInitialState(void) {
 
   for (int i = 0; i < num_groups; ++i) {
     if (gr_s->gr_gid == groups[i]) {
-      printf("%s%s is member of video group%s\n", COL_WHT, u_name, COL_RESET);
+      printf("%s%s is member of %s group%s\n", COL_WHT, u_name, kfd_gr_name, COL_RESET);
       member = true;
       break;
     }
   }
   if (member == false) {
-    printf("%s%s is not member of \"video\" group, the default DRM access "
-     "group. Users must be a member of the \"video\" group or another"
+    printf("%s%s is not member of \"%s\" group, the default DRM access "
+     "group. Users must be a member of the \"%s\" group or another"
         " DRM access group in order for ROCm applications to run "
-                             "successfully%s.\n", COL_RED, u_name, COL_RESET);
+           "successfully%s.\n", COL_RED, u_name, kfd_gr_name, kfd_gr_name, COL_RESET);
   }
 
   delete []groups;