Attachment 5200 Details for Bug 6500 – patch for this bug

[patch] patch for this bug

jbig2-extraneous-data-after-segment-end.patch (text/plain), 1.81 KB, created by paul walmsley on 2006-04-05 08:51:19 UTC

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Creator: paul walmsley

Created: 2006-04-05 08:51:19 UTC

Size: 1.81 KB

patch

obsolete

>--- poppler/JBIG2Stream.orig.cc	2006-04-04 15:38:23.000000000 -0700
>+++ poppler/JBIG2Stream.cc	2006-04-04 15:37:22.000000000 -0700
>@@ -1229,6 +1229,7 @@
>   Guint segNum, segFlags, segType, page, segLength;
>   Guint refFlags, nRefSegs;
>   Guint *refSegs;
>+  int segDataPos;
>   int c1, c2, c3;
>   Guint i;
> 
>@@ -1296,6 +1297,9 @@
>       goto eofError2;
>     }
> 
>+    // keep track of the start of the segment data 
>+    segDataPos = getPos();
>+
>     // read the segment data
>     switch (segType) {
>     case 0:
>@@ -1373,6 +1377,45 @@
>       break;
>     }
> 
>+    // Make sure the segment handler read all of the bytes in the 
>+    // segment data, unless this segment is marked as having an
>+    // unknown length (section 7.2.7 of the JBIG2 Final Committee Draft)
>+
>+    if (segLength != 0xffffffff) {
>+
>+      int segExtraBytes = segDataPos + segLength - getPos();
>+      if (segExtraBytes > 0) {
>+
>+	// If we didn't read all of the bytes in the segment data,
>+	// indicate an error, and throw away the rest of the data.
>+	
>+	// v.3.1.01.13 of the LuraTech PDF Compressor Server will
>+	// sometimes generate an extraneous NULL byte at the end of
>+	// arithmetic-coded symbol dictionary segments when numNewSyms
>+	// == 0.  Segments like this often occur for blank pages.
>+	
>+	error(getPos(), "%d extraneous byte%s after segment",
>+	      segExtraBytes, (segExtraBytes > 1) ? "s" : "");
>+	
>+	// Burn through the remaining bytes -- inefficient, but
>+	// hopefully we're not doing this much
>+	
>+	int trash;
>+	for (int i = segExtraBytes; i > 0; i--) {
>+	  readByte(&trash);
>+	}
>+	
>+      } else if (segExtraBytes < 0) {
>+	
>+	// If we read more bytes than we should have, according to the 
>+	// segment length field, note an error.
>+	
>+	error(getPos(), "Previous segment handler read too many bytes");
>+	
>+      }
>+
>+    }
>+    
>     gfree(refSegs);
>   }
>

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