From 35dcd72bbe7a9349861ff14389a38525fe9c949f Mon Sep 17 00:00:00 2001
From: Nathan Lee <utasstudent-git1271@yahoo.com>
Date: Sat, 15 Feb 2020 07:04:46 +0000
Subject: JPEG: skip bytes during incremental load

Previously only skipped bytes at the start of incremental
loads. During a incremental load, there may be bytes to skip
between reloads. Previous behavior misread metadata sometimes.

Fixes #70
---
 gdk-pixbuf/io-jpeg.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/gdk-pixbuf/io-jpeg.c b/gdk-pixbuf/io-jpeg.c
index 7628989d9..ac6adbdf1 100644
--- a/gdk-pixbuf/io-jpeg.c
+++ b/gdk-pixbuf/io-jpeg.c
@@ -970,7 +970,7 @@ gdk_pixbuf__jpeg_image_load_lines (JpegProgContext  *context,
  * buf - new image data
  * size - length of new image data
  *
- * append image data onto inrecrementally built output image
+ * append image data onto incrementally built output image
  */
 static gboolean
 gdk_pixbuf__jpeg_image_load_increment (gpointer data,
@@ -1007,22 +1007,8 @@ gdk_pixbuf__jpeg_image_load_increment (gpointer data,
 		goto out;
 	}
 
-	/* skip over data if requested, handle unsigned int sizes cleanly */
-	/* only can happen if we've already called jpeg_get_header once   */
-	if (context->src_initialized && src->skip_next) {
-		if (src->skip_next > size) {
-			src->skip_next -= size;
-			retval = TRUE;
-			goto out;
-		} else {
-			num_left = size - src->skip_next;
-			bufhd = buf + src->skip_next;
-			src->skip_next = 0;
-		}
-	} else {
-		num_left = size;
-		bufhd = buf;
-	}
+	num_left = size;
+	bufhd = buf;
 
 	if (num_left == 0) {
 		retval = TRUE;
@@ -1034,6 +1020,19 @@ gdk_pixbuf__jpeg_image_load_increment (gpointer data,
 	spinguard = 0;
 	first = TRUE;
 	while (TRUE) {
+		/* skip over data if requested, handle unsigned int sizes cleanly */
+		/* only can happen if we've already called jpeg_get_header        */
+		if (context->src_initialized && src->skip_next) {
+			if (src->skip_next >= num_left) {
+				src->skip_next -= num_left;
+				retval = TRUE;
+				goto out;
+			} else {
+				num_left -= src->skip_next;
+				bufhd += src->skip_next;
+				src->skip_next = 0;
+			}
+		}
 
 		/* handle any data from caller we haven't processed yet */
 		if (num_left > 0) {
-- 
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