Merge branch 'PHP-8.4'

* PHP-8.4:
  Add support for reading GIFs without colormap

Author: cmb69

ext/gd/libgd/gd_gif_in.c

@@ -244,8 +244,10 @@ gdImagePtr gdImageCreateFromGifCtx(gdIOCtxPtr fd) /* {{{ */
 					BitSet(buf[8], INTERLACE), &ZeroDataBlock);
 		} else {
 			if (!haveGlobalColormap) {
-				gdImageDestroy(im);
-				return 0;
+				// Still a valid gif, apply simple default palette as per spec
+				ColorMap[CM_RED][1] = 0xff;
+				ColorMap[CM_GREEN][1] = 0xff;
+				ColorMap[CM_BLUE][1] = 0xff;
 			}
 			ReadImage(im, fd, width, height,
 						ColorMap,

ext/gd/tests/gif_nocolormaps.gif

@@ -0,0 +1,11 @@
+--TEST--
+A GIF without any Global or Local color tables is still decoded
+--EXTENSIONS--
+gd
+--FILE--
+<?php
+$im = imagecreatefromgif(__DIR__ . "/gif_nocolormaps.gif");
+var_dump($im instanceof GdImage);
+?>
+--EXPECT--
+bool(true)