JBIG2: finds end of segment when length is not specified

src/jbig2.js

@@ -710,9 +710,42 @@ var Jbig2Image = (function Jbig2ImageClosure() {
       position += 4;
     }
     segmentHeader.length = readUint32(data, position);
-    if (segmentHeader.length == 0xFFFFFFFF)
-      error('JBIG2 error: unknown segment length is not supported');
     position += 4;
+    if (segmentHeader.length == 0xFFFFFFFF) {
+      // 7.2.7 Segment data length, unknown segment length
+      if (segmentType === 38) { // ImmediateGenericRegion
+        var genericRegionInfo = readRegionSegmentInformation(data, position);
+        var genericRegionSegmentFlags = data[position +
+          RegionSegmentInformationFieldLength];
+        var genericRegionMmr = !!(genericRegionSegmentFlags & 1);
+        // searching for the segment end
+        var searchPatternLength = 6;
+        var searchPattern = new Uint8Array(searchPatternLength);
+        if (!genericRegionMmr) {
+          searchPattern[0] = 0xFF;
+          searchPattern[1] = 0xAC;
+        }
+        searchPattern[2] = (genericRegionInfo.height >>> 24) & 0xFF;
+        searchPattern[3] = (genericRegionInfo.height >> 16) & 0xFF;
+        searchPattern[4] = (genericRegionInfo.height >> 8) & 0xFF;
+        searchPattern[5] = genericRegionInfo.height & 0xFF;
+        for (var i = position, ii = data.length; i < ii; i++) {
+          var j = 0;
+          while (j < searchPatternLength && searchPattern[j] === data[i + j]) {
+            j++;
+          }
+          if (j == searchPatternLength) {
+            segmentHeader.length = i + searchPatternLength;
+            break;
+          }
+        }
+        if (segmentHeader.length == 0xFFFFFFFF) {
+          error('JBIG2 error: segment end was not found');
+        }
+      } else {
+        error('JBIG2 error: invalid unknown segment length');
+      }
+    }
     segmentHeader.headerEnd = position;
     return segmentHeader;
   }

test/pdfs/issue2139.pdf.link

@@ -0,0 +1 @@
+http://www.cs.wustl.edu/~cytron/cse547/PDFs/p1.pdf

test/test_manifest.json

@@ -474,6 +474,13 @@
       "link": true,
       "type": "load"
     },
+    {  "id": "issue2139",
+      "file": "pdfs/issue2139.pdf",
+      "md5": "ee4072992e7c5ffd5063181916a2fcae",
+      "rounds": 1,
+      "link": true,
+      "type": "eq"
+    },
     {  "id": "issue1010",
       "file": "pdfs/issue1010.pdf",
       "md5": "f991ef093484a107fe9f59dff18fc155",