nixpkgs/pkgs/development/libraries/libepoxy/libgl-path.patch

diff --git a/src/dispatch_common.c b/src/dispatch_common.c
index b3e4f5f..303e8f5 100644
--- a/src/dispatch_common.c
+++ b/src/dispatch_common.c
@@ -310,6 +310,19 @@ get_dlopen_handle(void **handle, const char *lib_name, bool exit_on_fail, bool l
             flags |= RTLD_NOLOAD;
 
         *handle = dlopen(lib_name, flags);
+#ifdef LIBGL_PATH
+        if (!*handle) {
+          char pathbuf[sizeof(LIBGL_PATH) + 1 + 1024 + 1];
+          int l = snprintf(pathbuf, sizeof(pathbuf), "%s/%s", LIBGL_PATH, lib_name);
+          if (l < 0 || l >= sizeof(pathbuf)) {
+            // This really shouldn't happen
+            fprintf(stderr, "Error prefixing library pathname\n");
+            exit(1);
+          }
+          *handle = dlopen(pathbuf, flags);
+        }
+#endif
+
         if (!*handle) {
             if (exit_on_fail) {
                 fprintf(stderr, "Couldn't open %s: %s\n", lib_name, dlerror());