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#2098: scanning for stream length when it's incorrect

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This commit is contained in:
Yury Delendik 2013-06-22 13:21:19 -05:00
parent c3096d98d4
commit 4d9ee7b530
3 changed files with 55 additions and 2 deletions
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6
src/chunked_stream.js
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@ -141,6 +141,12 @@ var ChunkedStream = (function ChunkedStreamClosure() {
return bytes.subarray(pos, end);
},
peekBytes: function ChunkedStream_peekBytes(length) {
var bytes = this.getBytes(length);
this.pos -= bytes.length;
return bytes;
},
getByteRange: function ChunkedStream_getBytes(begin, end) {
this.ensureRange(begin, end);
return this.bytes.subarray(begin, end);

39
src/parser.js
View File

@ -209,9 +209,46 @@ var Parser = (function ParserClosure() {
this.shift(); // '>>'
this.shift(); // 'stream'
if (!isCmd(this.buf1, 'endstream')) {
warn('Missing endstream');
// bad stream length, scanning for endstream
stream.pos = pos;
var SCAN_BLOCK_SIZE = 2048;
var ENDSTREAM_SIGNATURE_LENGTH = 9;
var ENDSTREAM_SIGNATURE = [0x65, 0x6E, 0x64, 0x73, 0x74, 0x72, 0x65,
0x61, 0x6D];
var skipped = 0, found = false;
while (stream.pos < stream.end) {
var scanBytes = stream.peekBytes(SCAN_BLOCK_SIZE);
var scanLength = scanBytes.length - ENDSTREAM_SIGNATURE_LENGTH;
var found = false, i, ii, j;
for (i = 0, j = 0; i < scanLength; i++) {
var b = scanBytes[i];
if (b !== ENDSTREAM_SIGNATURE[j]) {
i -= j;
j = 0;
} else {
j++;
if (j >= ENDSTREAM_SIGNATURE_LENGTH) {
found = true;
break;
}
}
}
if (found) {
skipped += i - ENDSTREAM_SIGNATURE_LENGTH;
stream.pos += i - ENDSTREAM_SIGNATURE_LENGTH;
break;
}
skipped += scanLength;
stream.pos += scanLength;
}
if (!found) {
error('Missing endstream');
}
length = skipped;
this.shift();
this.shift();
}
this.shift(); // 'endstream'
stream = stream.makeSubStream(pos, length, dict);
if (cipherTransform)

10
src/stream.js
View File

@ -57,6 +57,11 @@ var Stream = (function StreamClosure() {
this.pos = end;
return bytes.subarray(pos, end);
},
peekBytes: function Stream_peekBytes(length) {
var bytes = this.getBytes(length);
this.pos -= bytes.length;
return bytes;
},
lookChar: function Stream_lookChar() {
if (this.pos >= this.end)
return null;
@ -161,6 +166,11 @@ var DecodeStream = (function DecodeStreamClosure() {
this.pos = end;
return this.buffer.subarray(pos, end);
},
peekBytes: function DecodeStream_peekBytes(length) {
var bytes = this.getBytes(length);
this.pos -= bytes.length;
return bytes;
},
lookChar: function DecodeStream_lookChar() {
var pos = this.pos;
while (this.bufferLength <= pos) {