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Merged
merged 3 commits into from
Feb 8, 2013
Merged

Use the central dir instead of the local file header (+ other patches) #31

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c4da116
folder() shouldn't throw an exception
dduponchel Feb 6, 2013
821d25e
Fix : the folders wasn't marked as folder.
dduponchel Feb 6, 2013
1a3cd72
Load zip : a new way to read them.
dduponchel Feb 6, 2013
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17 changes: 14 additions & 3 deletions index.html
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Expand Up @@ -538,12 +538,23 @@ <h4 id="jszip_support">JSZip.support</h4>

<h3 id="zip_load_limits">Loading zip files, limitations</h3>
<p>
The first limitation comes from the limited subset of supported zip features.
All the features of zip files are not supported.
Classic zip files will work but encrypted zip, multi-volume, etc are not supported
and the load() method will throw an <code>Error</code>.
</p>
<p>
The second limitation comes from the browser (and the machine running the browser).
ZIP64 files can be loaded, but only if the zip file is not "too big". ZIP64 uses 64bits integers
but Javascript represents all numbers as
<a href="http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf">
64-bit double precision IEEE 754 floating point numbers</a> (see section 8.5).
So, we have 53bits for integers and
<a href="https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/Bitwise_Operators">
bitwise operations treat everything as 32bits</a>.
So if all the 64bits integers can fit into 32 bits integers, everything will be fine. If
it's not the case, you will have other problems anyway (see next limitation).
</p>
<p>
An other limitation comes from the browser (and the machine running the browser).
A compressed zip file of 10M is common and easily opened by desktop application,
but not in a browser. The processing of such a beast is likely to be painful :
the browser will eat hundreds of megabytes while using CPU like never.<br/>
Expand All @@ -553,7 +564,7 @@ <h3 id="zip_load_limits">Loading zip files, limitations</h3>
Conclusion : reading small files is OK, reading others is not.
</p>
<p>
Third limitation : reading and generating a zip file won't give you back the same file.
Reading and generating a zip file won't give you back the same file.
Some data are discarded (file metadata) and other are added (subfolders).
</p>
</div>
Expand Down
228 changes: 120 additions & 108 deletions jszip-load.js
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Expand Up @@ -10,6 +10,9 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
/*global JSZip,JSZipBase64 */
(function () {

var MAX_VALUE_16BITS = 65535;
var MAX_VALUE_32BITS = -1; // well, "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF" is parsed as -1

/**
* Prettify a string read as binary.
* @param {string} str the string to prettify.
Expand Down Expand Up @@ -42,6 +45,8 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
// class StreamReader {{{
/**
* Read bytes from a stream.
* Developer tip : when debugging, a watch on pretty(this.reader.stream.slice(this.reader.index))
* is very useful :)
* @constructor
* @param {String|ArrayBuffer|Uint8Array} stream the stream to read.
*/
Expand Down Expand Up @@ -88,11 +93,12 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
this.index = newIndex;
},
/**
* Check if the end of the file has been reached.
* @return {boolean} true if it is the case, false otherwise.
* Skip the next n bytes.
* @param {number} n the number of bytes to skip.
* @throws {Error} if the new index is out of the stream.
*/
eof : function () {
return this.index >= this.stream.length;
skip : function (n) {
this.setIndex(this.index + n);
},
/**
* Get the byte at the specified index.
Expand Down Expand Up @@ -165,14 +171,6 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
// bit 1 is set
return (this.bitFlag & 0x0001) === 0x0001;
},
/**
* say if the file has a data decriptor.
* @return {boolean} true if the file has a data descriptor, false otherwise.
*/
hasDataDescriptor : function () {
// bit 3 is set
return (this.bitFlag & 0x0008) === 0x0008;
},
/**
* say if the file has utf-8 filename/comment.
* @return {boolean} true if the filename/comment is in utf-8, false otherwise.
Expand All @@ -181,60 +179,40 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
// bit 11 is set
return (this.bitFlag & 0x0800) === 0x0800;
},
/**
* say if the file is a zip64 file.
* @return {boolean} true if the file is zip64, false otherwise.
*/
isZIP64 : function () {
return this.options.zip64;
},
/**
* Read the local part header of a zip file and add the info in this object.
* @param {StreamReader} reader the reader to use.
*/
readLocalPartHeader : function(reader) {
// the signature has already been consumed
this.versionNeeded = reader.readInt(2);
this.bitFlag = reader.readInt(2);
this.compressionMethod = reader.readString(2);
this.date = reader.readDate();
this.crc32 = reader.readInt(4);
this.compressedSize = reader.readInt(4);
this.uncompressedSize = reader.readInt(4);
this.fileNameLength = reader.readInt(2);
this.extraFieldsLength = reader.readInt(2);

if (this.isEncrypted()) {
throw new Error("Encrypted zip are not supported");
}
},
/**
* Read the local part of a zip file and add the info in this object.
* @param {StreamReader} reader the reader to use.
*/
readLocalPart : function(reader) {
var compression;

this.readLocalPartHeader(reader);

var compression, localExtraFieldsLength;

// we already know everything from the central dir !
// If the central dir data are false, we are doomed.
// On the bright side, the local part is scary : zip64, data descriptors, both, etc.
// The less data we get here, the more reliable this should be.
// Let's skip the whole header and dash to the data !
reader.skip(22);
// in some zip created on windows, the filename stored in the central dir contains \ instead of /.
// Strangely, the filename here is OK.
// I would love to treat these zip files as corrupted (see http://www.info-zip.org/FAQ.html#backslashes
// or APPNOTE#4.4.17.1, "All slashes MUST be forward slashes '/'") but there are a lot of bad zip generators...
// Search "unzip mismatching "local" filename continuing with "central" filename version" on
// the internet.
//
// I think I see the logic here : the central directory is used to display
// content and the local directory is used to extract the files. Mixing / and \
// may be used to display \ to windows users and use / when extracting the files.
// Unfortunately, this lead also to some issues : http://seclists.org/fulldisclosure/2009/Sep/394
this.fileNameLength = reader.readInt(2);
localExtraFieldsLength = reader.readInt(2); // can't be sure this will be the same as the central dir
this.fileName = reader.readString(this.fileNameLength);
this.readExtraFields(reader);
reader.skip(localExtraFieldsLength);

if (!this.hasDataDescriptor()) {
// easy : we know the file length
this.compressedFileData = reader.readString(this.compressedSize);
} else {
// hard way : find the data descriptor manually
this.compressedFileData = this.findDataUntilDataDescriptor(reader);
this.crc32 = reader.readInt(4);
this.compressedSize = reader.readInt(this.isZIP64() ? 8 : 4);
this.uncompressedSize = reader.readInt(this.isZIP64() ? 8 : 4);

if (this.compressedFileData.length !== this.compressedSize) {
throw new Error("Bug : data descriptor incorrectly read (size mismatch)");
}
if (this.compressedSize == -1 || this.uncompressedSize == -1) {
throw new Error("Bug or corrupted zip : didn't get enough informations from the central directory " +
"(compressedSize == -1 || uncompressedSize == -1)");
}
this.uncompressedFileData = null;
this.compressedFileData = reader.readString(this.compressedSize);

compression = findCompression(this.compressionMethod);
if (compression === null) { // no compression found
Expand All @@ -243,53 +221,44 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
}
this.uncompressedFileData = compression.uncompress(this.compressedFileData);

if (this.loadOptions.checkCRC32 && JSZip.prototype.crc32(this.uncompressedFileData) !== this.crc32) {
throw new Error("Corrupted zip : CRC32 mismatch");
if (this.uncompressedFileData.length !== this.uncompressedSize) {
throw new Error("Bug : uncompressed data size mismatch");
}

if (this.useUTF8()) {
this.fileName = JSZip.prototype.utf8decode(this.fileName);
if (this.loadOptions.checkCRC32 && JSZip.prototype.crc32(this.uncompressedFileData) !== this.crc32) {
throw new Error("Corrupted zip : CRC32 mismatch");
}
},

/**
* Read data until a data descriptor signature is found.
* @param {StreamReader} reader the reader to use.
*/
findDataUntilDataDescriptor : function(reader) {
var data = "",
buffer = reader.readString(4),
aByte;

while(buffer !== JSZip.signature.DATA_DESCRIPTOR) {
aByte = reader.readString(1);
data += buffer.slice(0, 1);
buffer = (buffer + aByte).slice(-4);
}
return data;
},
/**
* Read the central part of a zip file and add the info in this object.
* @param {StreamReader} reader the reader to use.
*/
readCentralPart : function(reader) {
this.versionMadeBy = reader.readString(2);

this.readLocalPartHeader(reader);

this.versionMadeBy = reader.readString(2);
this.versionNeeded = reader.readInt(2);
this.bitFlag = reader.readInt(2);
this.compressionMethod = reader.readString(2);
this.date = reader.readDate();
this.crc32 = reader.readInt(4);
this.compressedSize = reader.readInt(4);
this.uncompressedSize = reader.readInt(4);
this.fileNameLength = reader.readInt(2);
this.extraFieldsLength = reader.readInt(2);
this.fileCommentLength = reader.readInt(2);
this.diskNumberStart = reader.readInt(2);
this.internalFileAttributes = reader.readInt(2);
this.externalFileAttributes = reader.readInt(4);
this.localHeaderOffset = reader.readInt(4);

if (this.isEncrypted()) {
throw new Error("Encrypted zip are not supported");
}

this.fileName = reader.readString(this.fileNameLength);
this.readExtraFields(reader);
this.parseZIP64ExtraField(reader);
this.fileComment = reader.readString(this.fileCommentLength);
if (this.useUTF8()) {
this.fileName = JSZip.prototype.utf8decode(this.fileName);
this.fileComment = JSZip.prototype.utf8decode(this.fileComment);
}

// warning, this is true only for zip with madeBy == DOS (plateform dependent feature)
this.dir = this.externalFileAttributes & 0x00000010 ? true : false;
Expand All @@ -299,18 +268,26 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
* @param {StreamReader} reader the reader to use.
*/
parseZIP64ExtraField : function(reader) {

if(!this.extraFields[0x0001]) {
return;
}

// should be something, preparing the extra reader
var extraReader = new StreamReader(this.extraFields[0x0001].value);
if(this.uncompressedSize === -1) {

// I really hope that these 64bits integer can fit in 32 bits integer, because js
// won't let us have more.
if(this.uncompressedSize === MAX_VALUE_32BITS) {
this.uncompressedSize = extraReader.readInt(8);
}
if(this.compressedSize === -1) {
if(this.compressedSize === MAX_VALUE_32BITS) {
this.compressedSize = extraReader.readInt(8);
}
if(this.localHeaderOffset === -1) {
if(this.localHeaderOffset === MAX_VALUE_32BITS) {
this.localHeaderOffset = extraReader.readInt(8);
}
if(this.diskNumberStart === -1) {
if(this.diskNumberStart === MAX_VALUE_32BITS) {
this.diskNumberStart = extraReader.readInt(4);
}
},
Expand All @@ -337,9 +314,14 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
value: extraFieldValue
};
}

if(this.isZIP64() && this.extraFields[0x0001]) {
this.parseZIP64ExtraField(reader);
},
/**
* Apply an UTF8 transformation if needed.
*/
handleUTF8 : function() {
if (this.useUTF8()) {
this.fileName = JSZip.prototype.utf8decode(this.fileName);
this.fileComment = JSZip.prototype.utf8decode(this.fileComment);
}
}
};
Expand Down Expand Up @@ -441,6 +423,7 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
this.reader.setIndex(file.localHeaderOffset);
this.checkSignature(JSZip.signature.LOCAL_FILE_HEADER);
file.readLocalPart(this.reader);
file.handleUTF8();
}
},
/**
Expand All @@ -462,28 +445,57 @@ Dual licenced under the MIT license or GPLv3. See LICENSE.markdown.
* Read the end of central directory.
*/
readEndOfCentral : function() {
// zip 64 ?
var offset = this.reader.stream.lastIndexOf(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_LOCATOR);
if (offset === -1) { // nope
this.zip64 = false;
offset = this.reader.stream.lastIndexOf(JSZip.signature.CENTRAL_DIRECTORY_END);
var offset = this.reader.stream.lastIndexOf(JSZip.signature.CENTRAL_DIRECTORY_END);
if (offset === -1) {
throw new Error("Corrupted zip : can't find end of central directory");
}

this.reader.setIndex(offset);
this.checkSignature(JSZip.signature.CENTRAL_DIRECTORY_END);
this.readBlockEndOfCentral();
} else { // zip 64 !
this.zip64 = true;
this.reader.setIndex(offset);
this.checkSignature(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_LOCATOR);
this.readBlockZip64EndOfCentralLocator();

this.reader.setIndex(this.relativeOffsetEndOfZip64CentralDir);
this.checkSignature(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_END);
this.readBlockZip64EndOfCentral();
}

/* extract from the zip spec :
4) If one of the fields in the end of central directory
record is too small to hold required data, the field
should be set to -1 (0xFFFF or 0xFFFFFFFF) and the
ZIP64 format record should be created.
5) The end of central directory record and the
Zip64 end of central directory locator record must
reside on the same disk when splitting or spanning
an archive.
*/
if ( this.diskNumber === MAX_VALUE_16BITS
|| this.diskWithCentralDirStart === MAX_VALUE_16BITS
|| this.centralDirRecordsOnThisDisk === MAX_VALUE_16BITS
|| this.centralDirRecords === MAX_VALUE_16BITS
|| this.centralDirSize === MAX_VALUE_32BITS
|| this.centralDirOffset === MAX_VALUE_32BITS
) {
this.zip64 = true;

/*
Warning : the zip64 extension is supported, but ONLY if the 64bits integer read from
the zip file can fit into a 32bits integer. This cannot be solved : Javascript represents
all numbers as 64-bit double precision IEEE 754 floating point numbers.
So, we have 53bits for integers and bitwise operations treat everything as 32bits.
see https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/Bitwise_Operators
and http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf section 8.5
*/

// should look for a zip64 EOCD locator
offset = this.reader.stream.lastIndexOf(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_LOCATOR);
if (offset === -1) {
throw new Error("Corrupted zip : can't find the ZIP64 end of central directory locator");
}
this.reader.setIndex(offset);
this.checkSignature(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_LOCATOR);
this.readBlockZip64EndOfCentralLocator();

// now the zip64 EOCD record
this.reader.setIndex(this.relativeOffsetEndOfZip64CentralDir);
this.checkSignature(JSZip.signature.ZIP64_CENTRAL_DIRECTORY_END);
this.readBlockZip64EndOfCentral();
}
},
/**
* Read a zip file and create ZipEntries.
Expand Down
4 changes: 2 additions & 2 deletions jszip.js
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Expand Up @@ -387,7 +387,7 @@ JSZip.prototype = (function () {
*/
folder : function(arg) {
if (!arg) {
throw new Error("folder : wrong argument");
return this;
}

if (arg instanceof RegExp) {
Expand Down Expand Up @@ -487,7 +487,7 @@ JSZip.prototype = (function () {
// internal file attributes TODO
"\x00\x00" +
// external file attributes
(this.files[name].dir===true?"\x10\x00\x00\x00":"\x00\x00\x00\x00")+
(this.files[name].options.dir===true?"\x10\x00\x00\x00":"\x00\x00\x00\x00")+
// relative offset of local header
decToHex(fileOffset, 4) +
// file name
Expand Down
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