From 06bdebe39003f18e3dc157c64d47b9f7e719a4df Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Wed, 26 Sep 2018 15:19:17 -0400
Subject: [PATCH] gif: Don't get into infinite loops on truncated files.

---
 IMG_gif.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/IMG_gif.c b/IMG_gif.c
index 0fd88f28..32618a0b 100644
--- a/IMG_gif.c
+++ b/IMG_gif.c
@@ -317,7 +317,7 @@ DoExtension(SDL_RWops *src, int label)
     break;
     case 0xfe:          /* Comment Extension */
     str = "Comment Extension";
-    while (GetDataBlock(src, (unsigned char *) buf) != 0)
+    while (GetDataBlock(src, (unsigned char *) buf) > 0)
         ;
     return FALSE;
     case 0xf9:          /* Graphic Control Extension */
@@ -329,7 +329,7 @@ DoExtension(SDL_RWops *src, int label)
     if ((buf[0] & 0x1) != 0)
         Gif89.transparent = buf[3];
 
-    while (GetDataBlock(src, (unsigned char *) buf) != 0)
+    while (GetDataBlock(src, (unsigned char *) buf) > 0)
         ;
     return FALSE;
     default:
@@ -338,7 +338,7 @@ DoExtension(SDL_RWops *src, int label)
     break;
     }
 
-    while (GetDataBlock(src, (unsigned char *) buf) != 0)
+    while (GetDataBlock(src, (unsigned char *) buf) > 0)
     ;
 
     return FALSE;
@@ -387,7 +387,7 @@ GetCode(SDL_RWops *src, int code_size, int flag)
     buf[0] = buf[last_byte - 2];
     buf[1] = buf[last_byte - 1];
 
-    if ((count = GetDataBlock(src, &buf[2])) == 0)
+    if ((count = GetDataBlock(src, &buf[2])) <= 0)
         done = TRUE;
 
     last_byte = 2 + count;