From: Dirk Lemstra <dirk@lemstra.org>
Date: Thu, 18 Jul 2019 19:50:46 +0000 (+0200)
Subject: Handle negative count.
X-Git-Tag: 7.0.8-55~7
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1f70b13ac169b522b0b8df59cb82e23fb52801a1;p=imagemagick

Handle negative count.
---

diff --git a/coders/bytebuffer-private.h b/coders/bytebuffer-private.h
index 94eb6ab7e..c70219bc9 100644
--- a/coders/bytebuffer-private.h
+++ b/coders/bytebuffer-private.h
@@ -52,13 +52,16 @@ static inline int ReadMagickByteBuffer(MagickByteBuffer *buffer)
 static inline char *GetMagickByteBufferDatum(MagickByteBuffer *buffer)
 {
   ssize_t
+    count,
     i;
 
   i=0;
   while (buffer->offset < buffer->count)
     buffer->data[i++]=buffer->data[buffer->offset++];
-  buffer->count=ReadBlob(buffer->image,sizeof(buffer->data)-i,buffer->data+i);
-  buffer->count+=i;
+  count=ReadBlob(buffer->image,sizeof(buffer->data)-i,buffer->data+i);
+  buffer->count=i;
+  if (count > 0)
+    buffer->count+=count;
   buffer->offset=0;
   return((char *) buffer->data);
 }