Fixed Bug #65171 imagescale() fails

Third param (height) is set as optional,
but default value = -1 is incorrect

Compute correct height to preserve ratio.

1 files changed, 14 insertions, 2 deletions

diff --git a/ext/gd/gd.c b/ext/gd/gd.c
index cbc7219e37..f86dad58dc 100644
--- a/ext/gd/gd.c
+++ b/ext/gd/gd.c
@@ -5110,11 +5110,23 @@ PHP_FUNCTION(imagescale)
 		return;
 	}
 	method = tmp_m;
-	new_width = tmp_w;
-	new_height = tmp_h;
 
 	ZEND_FETCH_RESOURCE(im, gdImagePtr, &IM, -1, "Image", le_gd);
 
+	if (tmp_h < 0) {
+		/* preserve ratio */
+		long src_x, src_y;
+
+		src_x = gdImageSX(im);
+		src_y = gdImageSY(im);
+		if (src_x) {
+			tmp_h = tmp_w * src_y / src_x;
+		}
+	}
+
+	new_width = tmp_w;
+	new_height = tmp_h;
+
 	if (gdImageSetInterpolationMethod(im, method)) {
 		im_scaled = gdImageScale(im, new_width, new_height);
 	}