framebuffer.c: fb_count

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/src/framebuffer.c b/src/framebuffer.c
new file mode 100644
index 0000000..91a9b2a
--- /dev/null
+++ b/src/framebuffer.c
@@ -0,0 +1,49 @@
+/**
+ * crt-calibrator – Calibration utility for CRT monitors
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "framebuffer.h"
+
+#include <unistd.h>
+#include <stdio.h>
+
+
+/**
+ * The psuedodevice pathname pattern used to access a framebuffer
+ */
+#ifndef FB_DEVICE_PATTERN
+# define FB_DEVICE_PATTERN  "/dev/fb%lu"
+#endif
+
+
+/**
+ * Figure out how many framebuffers there are on the system
+ * 
+ * @return  The number of framebuffers on the system
+ */
+size_t fb_count(void)
+{
+  char buf[sizeof(FB_DEVICE_PATTERN) / sizeof(char) + 3 * sizeof(size_t)];
+  size_t count = 0;
+  
+  for (;; count++)
+    {
+      sprintf(buf, FB_DEVICE_PATTERN, count);
+      if (access(buf, F_OK) < 0)
+	return count;
+    }
+}
+