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decompress-zip.js
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decompress-zip.js
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'use strict';
// The zip file spec is at http://www.pkware.com/documents/casestudies/APPNOTE.TXT
// TODO: There is fair chunk of the spec that I have ignored. Need to add
// assertions everywhere to make sure that we are not dealing with a ZIP type
// that I haven't designed for. Things like spanning archives, non-DEFLATE
// compression, encryption, etc.
var fs = require('graceful-fs');
var Q = require('q');
var path = require('path');
var util = require('util');
var events = require('events');
var structures = require('./structures');
var signatures = require('./signatures');
var extractors = require('./extractors');
var FileDetails = require('./file-details');
var fstat = Q.denodeify(fs.fstat);
var read = Q.denodeify(fs.read);
var fopen = Q.denodeify(fs.open);
function DecompressZip(filename) {
events.EventEmitter.call(this);
this.filename = filename;
this.stats = null;
this.fd = null;
this.chunkSize = 1024 * 1024; // Buffer up to 1Mb at a time
this.dirCache = {};
// When we need a resource, we should check if there is a promise for it
// already and use that. If the promise is already fulfilled we don't do the
// async work again and we get to queue up dependant tasks.
this._p = {}; // _p instead of _promises because it is a lot easier to read
}
util.inherits(DecompressZip, events.EventEmitter);
DecompressZip.prototype.openFile = function () {
return fopen(this.filename, 'r');
};
DecompressZip.prototype.closeFile = function () {
if (this.fd) {
fs.closeSync(this.fd);
this.fd = null;
}
};
DecompressZip.prototype.statFile = function (fd) {
this.fd = fd;
return fstat(fd);
};
DecompressZip.prototype.list = function () {
var self = this;
this.getFiles()
.then(function (files) {
var result = [];
files.forEach(function (file) {
result.push(file.path);
});
self.emit('list', result);
})
.fail(function (error) {
self.emit('error', error);
})
.fin(self.closeFile.bind(self));
return this;
};
DecompressZip.prototype.extract = function (options) {
var self = this;
options = options || {};
options.path = options.path || '.';
options.filter = options.filter || null;
options.follow = !!options.follow;
options.strip = +options.strip || 0;
this.getFiles()
.then(function (files) {
var copies = [];
if (options.filter) {
files = files.filter(options.filter);
}
if (options.follow) {
copies = files.filter(function (file) {
return file.type === 'SymbolicLink';
});
files = files.filter(function (file) {
return file.type !== 'SymbolicLink';
});
}
if (options.strip) {
files = files.map(function (file) {
if (file.type !== 'Directory') {
// we don't use `path.sep` as we're using `/` in Windows too
var dir = file.parent.split('/');
var filename = file.filename;
if (options.strip > dir.length) {
throw new Error('You cannot strip more levels than there are directories');
} else {
dir = dir.slice(options.strip);
}
file.path = path.join(dir.join(path.sep), filename);
return file;
}
});
}
return self.extractFiles(files, options)
.then(self.extractFiles.bind(self, copies, options));
})
.then(function (results) {
self.emit('extract', results);
})
.fail(function (error) {
self.emit('error', error);
})
.fin(self.closeFile.bind(self));
return this;
};
// Utility methods
DecompressZip.prototype.getSearchBuffer = function (stats) {
var size = Math.min(stats.size, this.chunkSize);
this.stats = stats;
return this.getBuffer(stats.size - size, stats.size);
};
DecompressZip.prototype.getBuffer = function (start, end) {
var size = end - start;
return read(this.fd, new Buffer(size), 0, size, start)
.then(function (result) {
return result[1];
});
};
DecompressZip.prototype.findEndOfDirectory = function (buffer) {
var index = buffer.length - 3;
var chunk = '';
// Apparently the ZIP spec is not very good and it is impossible to
// guarantee that you have read a zip file correctly, or to determine
// the location of the CD without hunting.
// Search backwards through the buffer, as it is very likely to be near the
// end of the file.
while (index > Math.max(buffer.length - this.chunkSize, 0) && chunk !== signatures.END_OF_CENTRAL_DIRECTORY) {
index--;
chunk = buffer.readUInt32LE(index);
}
if (chunk !== signatures.END_OF_CENTRAL_DIRECTORY) {
throw new Error('Could not find the End of Central Directory Record');
}
return buffer.slice(index);
};
// Directory here means the ZIP Central Directory, not a folder
DecompressZip.prototype.readDirectory = function (recordBuffer) {
var record = structures.readEndRecord(recordBuffer);
return this.getBuffer(record.directoryOffset, record.directoryOffset + record.directorySize)
.then(structures.readDirectory.bind(null));
};
DecompressZip.prototype.getFiles = function () {
if (!this._p.getFiles) {
this._p.getFiles = this.openFile()
.then(this.statFile.bind(this))
.then(this.getSearchBuffer.bind(this))
.then(this.findEndOfDirectory.bind(this))
.then(this.readDirectory.bind(this))
.then(this.readFileEntries.bind(this));
}
return this._p.getFiles;
};
DecompressZip.prototype.readFileEntries = function (directory) {
var promises = [];
var files = [];
var self = this;
directory.forEach(function (directoryEntry, index) {
var start = directoryEntry.relativeOffsetOfLocalHeader;
var end = Math.min(self.stats.size, start + structures.maxFileEntrySize);
var fileDetails = new FileDetails(directoryEntry);
var promise = self.getBuffer(start, end)
.then(structures.readFileEntry.bind(null))
.then(function (fileEntry) {
var maxSize;
if (fileDetails.compressedSize > 0) {
maxSize = fileDetails.compressedSize;
} else {
maxSize = self.stats.size;
if (index < directory.length - 1) {
maxSize = directory[index + 1].relativeOffsetOfLocalHeader;
}
maxSize -= start + fileEntry.entryLength;
}
fileDetails._offset = start + fileEntry.entryLength;
fileDetails._maxSize = maxSize;
self.emit('file', fileDetails);
files[index] = fileDetails;
});
promises.push(promise);
});
return Q.all(promises)
.then(function () {
return files;
});
};
DecompressZip.prototype.extractFiles = function (files, options, results) {
var promises = [];
var self = this;
results = results || [];
var fileIndex = 0;
files.forEach(function (file) {
var promise = self.extractFile(file, options)
.then(function (result) {
self.emit('progress', fileIndex++, files.length);
results.push(result);
});
promises.push(promise);
});
return Q.all(promises)
.then(function () {
return results;
});
};
DecompressZip.prototype.extractFile = function (file, options) {
var destination = path.join(options.path, file.path);
// Possible compression methods:
// 0 - The file is stored (no compression)
// 1 - The file is Shrunk
// 2 - The file is Reduced with compression factor 1
// 3 - The file is Reduced with compression factor 2
// 4 - The file is Reduced with compression factor 3
// 5 - The file is Reduced with compression factor 4
// 6 - The file is Imploded
// 7 - Reserved for Tokenizing compression algorithm
// 8 - The file is Deflated
// 9 - Enhanced Deflating using Deflate64(tm)
// 10 - PKWARE Data Compression Library Imploding (old IBM TERSE)
// 11 - Reserved by PKWARE
// 12 - File is compressed using BZIP2 algorithm
// 13 - Reserved by PKWARE
// 14 - LZMA (EFS)
// 15 - Reserved by PKWARE
// 16 - Reserved by PKWARE
// 17 - Reserved by PKWARE
// 18 - File is compressed using IBM TERSE (new)
// 19 - IBM LZ77 z Architecture (PFS)
// 97 - WavPack compressed data
// 98 - PPMd version I, Rev 1
if (file.type === 'Directory') {
return extractors.folder(file, destination, this);
}
if (file.type === 'File') {
switch (file.compressionMethod) {
case 0:
return extractors.store(file, destination, this);
case 8:
return extractors.deflate(file, destination, this);
default:
throw new Error('Unsupported compression type');
}
}
if (file.type === 'SymbolicLink') {
if (options.follow) {
return extractors.copy(file, destination, this, options.path);
} else {
return extractors.symlink(file, destination, this, options.path);
}
}
throw new Error('Unsupported file type "' + file.type + '"');
};
module.exports = DecompressZip;