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Made GIF extractor more robust. #879

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merged 2 commits into from
Nov 8, 2019
Merged

Made GIF extractor more robust. #879

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51cc94b
Made GIF extractor more robust
n1073645 Nov 8, 2019
f3864b0
Made GIF extractor more robust
n1073645 Nov 8, 2019
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38 changes: 20 additions & 18 deletions src/core/lib/FileSignatures.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -2455,10 +2455,11 @@ export function extractGIF(bytes, offset) {

//Move to Graphic Control Extension for frame #1.
stream.continueUntil([0x21, 0xf9]);
stream.moveForwardsBy(2);
while (stream.hasMore()) {

//Move to Image descriptor.
stream.continueUntil(0x2c);
stream.moveForwardsBy(stream.getBytes(1)[0]+1);

//Move past Image descriptor to the image data.
stream.moveForwardsBy(11);
Expand All @@ -2474,7 +2475,7 @@ export function extractGIF(bytes, offset) {
//When the end of the file is [0x00, 0x3b], end.
if (stream.getBytes(1)[0] === 0x3b)
break;
stream.moveBackwardsBy(1);
stream.moveForwardsBy(1);
}
return stream.carve();
}
Expand Down Expand Up @@ -2818,37 +2819,38 @@ export function extractGZIP(bytes, offset) {


/**
* BZIP2 extractor.
*
* @param {Uint8Array} bytes
* @param {Number} offset
* @returns {Uint8Array}
*/
export function extractBZIP2(bytes, offset){
export function extractBZIP2(bytes, offset) {
const stream = new Stream(bytes.slice(offset));

//The EOFs shifted between all possible combinations.
var lookingfor = [
[0x77, 0x24, 0x53, 0x85, 0x09],
[0xee, 0x48, 0xa7, 0x0a, 0x12],
[0xdc, 0x91, 0x4e, 0x14, 0x24],
[0xb9, 0x22, 0x9c, 0x28, 0x48],
[0x72, 0x45, 0x38, 0x50, 0x90],
[0xbb, 0x92, 0x29, 0xc2, 0x84],
[0x5d, 0xc9, 0x14, 0xe1, 0x42],
[0x2e, 0xe4, 0x8a, 0x70, 0xa1],
[0x17, 0x72, 0x45, 0x38, 0x50]];
for(let i = 0; i < 9; i++){
const lookingfor = [
[0x77, 0x24, 0x53, 0x85, 0x09],
[0xee, 0x48, 0xa7, 0x0a, 0x12],
[0xdc, 0x91, 0x4e, 0x14, 0x24],
[0xb9, 0x22, 0x9c, 0x28, 0x48],
[0x72, 0x45, 0x38, 0x50, 0x90],
[0xbb, 0x92, 0x29, 0xc2, 0x84],
[0x5d, 0xc9, 0x14, 0xe1, 0x42],
[0x2e, 0xe4, 0x8a, 0x70, 0xa1],
[0x17, 0x72, 0x45, 0x38, 0x50]];

for (let i = 0; i < lookingfor.length; i++) {

//Continue until an EOF.
stream.continueUntil(lookingfor[i]);
if(stream.getBytes(5).join("") == lookingfor[i].join(""))
if (stream.getBytes(5).join("") === lookingfor[i].join(""))
break;

//Jump back to the start if invalid EOF.
stream.moveTo(0);
}
stream.moveForwardsBy(4);

return stream.carve();
}

Expand Down