From 611aa4a16e1fd8976dd853d1b2f2192a20b2c067 Mon Sep 17 00:00:00 2001
From: metamuffin <metamuffin@disroot.org>
Date: Fri, 27 Jun 2025 16:17:16 +0200
Subject: get fbdev size

---
 piboot.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/piboot.c b/piboot.c
index 0aa6326..8a36739 100644
--- a/piboot.c
+++ b/piboot.c
@@ -16,10 +16,12 @@
 */
 #include <errno.h>
 #include <fcntl.h>
+#include <linux/fb.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
 
 int main(int argc, char **argv) {
@@ -28,11 +30,18 @@ int main(int argc, char **argv) {
     fbpath = argv[1];
   int fd = open(fbpath, O_CLOEXEC | O_WRONLY);
   if (fd < 0) {
-    fprintf(stderr, "cannot open fb0: %s\n", strerror(errno));
+    fprintf(stderr, "cannot open fbdev %s: %s\n", fbpath, strerror(errno));
     return 1;
   }
 
-  int w = 1920, h = 1080;
+  struct fb_var_screeninfo sinfo;
+  int res = ioctl(fd, FBIOGET_VSCREENINFO, &sinfo);
+  if (res < 0) {
+    fprintf(stderr, "cannot get fbdev info: %s\n", strerror(errno));
+    return 1;
+  }
+
+  int w = sinfo.xres_virtual, h = sinfo.yres_virtual;
   int sidepad = (w - h) / 2;
   uint8_t *frame = malloc(w * h * 4);
   memset(frame, 0, w * h * 4);
@@ -48,7 +57,7 @@ int main(int argc, char **argv) {
       frame[base + 2] = 255 - v;
     }
 
-  int res = write(fd, frame, w * h * 4);
+  res = write(fd, frame, w * h * 4);
   if (res < 0) {
     fprintf(stderr, "cannot write to fb0: %s\n", strerror(errno));
     return 1;
-- 
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