Add drmGetDeviceNameFromFd function

Determines the /dev filename of the drm fd argument.

tests/Makefile.am

@@ -40,6 +40,7 @@ TESTS =						\
 	getstats				\
 	setversion				\
 	updatedraw				\
+	name_from_fd				\
 	$(NULL)
 
 if HAVE_INTEL

tests/name_from_fd.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright © 2009 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Kristian Høgsberg <krh@bitplanet.net>
+ *
+ */
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <limits.h>
+#include "drmtest.h"
+
+/**
+ * Checks drmGetDeviceNameFromFd
+ *
+ * This tests that we can get the actual version out, and that setting invalid
+ * major/minor numbers fails appropriately.  It does not check the actual
+ * behavior differenses resulting from an increased DI version.
+ */
+int main(int argc, char **argv)
+{
+	int fd, ret;
+	drm_set_version_t sv, version;
+	const char *name = "/dev/dri/card0";
+	char *v;
+
+	fd = open("/dev/dri/card0", O_RDWR);
+	if (fd == -1)
+		return 0;
+
+	v = drmGetDeviceNameFromFd(fd);
+	close(fd);
+
+	assert(strcmp(name, v) == 0);
+	drmFree(v);
+
+	return 0;
+}

xf86drm.c

@@ -2510,3 +2510,29 @@ int drmDropMaster(int fd)
 	ret = ioctl(fd, DRM_IOCTL_DROP_MASTER, 0);
 	return ret;
 }
+
+char *drmGetDeviceNameFromFd(int fd)
+{
+	char name[128];
+	struct stat sbuf;
+	dev_t d;
+	int i;
+
+	/* The whole drmOpen thing is a fiasco and we need to find a way
+	 * back to just using open(2).  For now, however, lets just make
+	 * things worse with even more ad hoc directory walking code to
+	 * discover the device file name. */
+
+	fstat(fd, &sbuf);
+	d = sbuf.st_rdev;
+
+	for (i = 0; i < DRM_MAX_MINOR; i++) {
+		snprintf(name, sizeof name, DRM_DEV_NAME, DRM_DIR_NAME, i);
+		if (stat(name, &sbuf) == 0 && sbuf.st_rdev == d)
+			break;
+	}
+	if (i == DRM_MAX_MINOR)
+		return NULL;
+
+	return drmStrdup(name);
+}

xf86drm.h

@@ -708,4 +708,6 @@ typedef struct _drmEventContext {
 
 extern int drmHandleEvent(int fd, drmEventContextPtr evctx);
 
+extern char *drmGetDeviceNameFromFd(int fd);
+
 #endif