659 lines
		
	
	
		
			30 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
			
		
		
	
	
			659 lines
		
	
	
		
			30 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
| # yauzl
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| 
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| [](https://travis-ci.org/thejoshwolfe/yauzl)
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| [](https://coveralls.io/r/thejoshwolfe/yauzl)
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| 
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| yet another unzip library for node. For zipping, see
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| [yazl](https://github.com/thejoshwolfe/yazl).
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| 
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| Design principles:
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| 
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|  * Follow the spec.
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|    Don't scan for local file headers.
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|    Read the central directory for file metadata.
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|    (see [No Streaming Unzip API](#no-streaming-unzip-api)).
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|  * Don't block the JavaScript thread.
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|    Use and provide async APIs.
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|  * Keep memory usage under control.
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|    Don't attempt to buffer entire files in RAM at once.
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|  * Never crash (if used properly).
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|    Don't let malformed zip files bring down client applications who are trying to catch errors.
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|  * Catch unsafe file names.
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|    See `validateFileName()`.
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| 
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| ## Usage
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| 
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| ```js
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| var yauzl = require("yauzl");
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| 
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| yauzl.open("path/to/file.zip", {lazyEntries: true}, function(err, zipfile) {
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|   if (err) throw err;
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|   zipfile.readEntry();
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|   zipfile.on("entry", function(entry) {
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|     if (/\/$/.test(entry.fileName)) {
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|       // Directory file names end with '/'.
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|       // Note that entires for directories themselves are optional.
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|       // An entry's fileName implicitly requires its parent directories to exist.
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|       zipfile.readEntry();
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|     } else {
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|       // file entry
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|       zipfile.openReadStream(entry, function(err, readStream) {
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|         if (err) throw err;
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|         readStream.on("end", function() {
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|           zipfile.readEntry();
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|         });
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|         readStream.pipe(somewhere);
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|       });
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|     }
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|   });
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| });
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| ```
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| 
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| See also `examples/` for more usage examples.
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| 
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| ## API
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| 
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| The default for every optional `callback` parameter is:
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| 
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| ```js
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| function defaultCallback(err) {
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|   if (err) throw err;
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| }
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| ```
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| 
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| ### open(path, [options], [callback])
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| 
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| Calls `fs.open(path, "r")` and reads the `fd` effectively the same as `fromFd()` would.
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| 
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| `options` may be omitted or `null`. The defaults are `{autoClose: true, lazyEntries: false, decodeStrings: true, validateEntrySizes: true, strictFileNames: false}`.
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| 
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| `autoClose` is effectively equivalent to:
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| 
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| ```js
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| zipfile.once("end", function() {
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|   zipfile.close();
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| });
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| ```
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| 
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| `lazyEntries` indicates that entries should be read only when `readEntry()` is called.
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| If `lazyEntries` is `false`, `entry` events will be emitted as fast as possible to allow `pipe()`ing
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| file data from all entries in parallel.
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| This is not recommended, as it can lead to out of control memory usage for zip files with many entries.
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| See [issue #22](https://github.com/thejoshwolfe/yauzl/issues/22).
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| If `lazyEntries` is `true`, an `entry` or `end` event will be emitted in response to each call to `readEntry()`.
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| This allows processing of one entry at a time, and will keep memory usage under control for zip files with many entries.
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| 
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| `decodeStrings` is the default and causes yauzl to decode strings with `CP437` or `UTF-8` as required by the spec.
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| The exact effects of turning this option off are:
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| 
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| * `zipfile.comment`, `entry.fileName`, and `entry.fileComment` will be `Buffer` objects instead of `String`s.
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| * Any Info-ZIP Unicode Path Extra Field will be ignored. See `extraFields`.
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| * Automatic file name validation will not be performed. See `validateFileName()`.
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| 
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| `validateEntrySizes` is the default and ensures that an entry's reported uncompressed size matches its actual uncompressed size.
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| This check happens as early as possible, which is either before emitting each `"entry"` event (for entries with no compression),
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| or during the `readStream` piping after calling `openReadStream()`.
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| See `openReadStream()` for more information on defending against zip bomb attacks.
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| 
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| When `strictFileNames` is `false` (the default) and `decodeStrings` is `true`,
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| all backslash (`\`) characters in each `entry.fileName` are replaced with forward slashes (`/`).
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| The spec forbids file names with backslashes,
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| but Microsoft's `System.IO.Compression.ZipFile` class in .NET versions 4.5.0 until 4.6.1
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| creates non-conformant zipfiles with backslashes in file names.
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| `strictFileNames` is `false` by default so that clients can read these
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| non-conformant zipfiles without knowing about this Microsoft-specific bug.
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| When `strictFileNames` is `true` and `decodeStrings` is `true`,
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| entries with backslashes in their file names will result in an error. See `validateFileName()`.
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| When `decodeStrings` is `false`, `strictFileNames` has no effect.
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| 
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| The `callback` is given the arguments `(err, zipfile)`.
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| An `err` is provided if the End of Central Directory Record cannot be found, or if its metadata appears malformed.
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| This kind of error usually indicates that this is not a zip file.
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| Otherwise, `zipfile` is an instance of `ZipFile`.
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| 
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| ### fromFd(fd, [options], [callback])
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| 
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| Reads from the fd, which is presumed to be an open .zip file.
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| Note that random access is required by the zip file specification,
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| so the fd cannot be an open socket or any other fd that does not support random access.
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| 
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| `options` may be omitted or `null`. The defaults are `{autoClose: false, lazyEntries: false, decodeStrings: true, validateEntrySizes: true, strictFileNames: false}`.
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| 
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| See `open()` for the meaning of the options and callback.
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| 
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| ### fromBuffer(buffer, [options], [callback])
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| 
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| Like `fromFd()`, but reads from a RAM buffer instead of an open file.
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| `buffer` is a `Buffer`.
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| 
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| If a `ZipFile` is acquired from this method,
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| it will never emit the `close` event,
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| and calling `close()` is not necessary.
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| 
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| `options` may be omitted or `null`. The defaults are `{lazyEntries: false, decodeStrings: true, validateEntrySizes: true, strictFileNames: false}`.
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| 
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| See `open()` for the meaning of the options and callback.
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| The `autoClose` option is ignored for this method.
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| 
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| ### fromRandomAccessReader(reader, totalSize, [options], [callback])
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| 
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| This method of reading a zip file allows clients to implement their own back-end file system.
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| For example, a client might translate read calls into network requests.
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| 
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| The `reader` parameter must be of a type that is a subclass of
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| [RandomAccessReader](#class-randomaccessreader) that implements the required methods.
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| The `totalSize` is a Number and indicates the total file size of the zip file.
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| 
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| `options` may be omitted or `null`. The defaults are `{autoClose: true, lazyEntries: false, decodeStrings: true, validateEntrySizes: true, strictFileNames: false}`.
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| 
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| See `open()` for the meaning of the options and callback.
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| 
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| ### dosDateTimeToDate(date, time)
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| 
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| Converts MS-DOS `date` and `time` data into a JavaScript `Date` object.
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| Each parameter is a `Number` treated as an unsigned 16-bit integer.
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| Note that this format does not support timezones,
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| so the returned object will use the local timezone.
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| 
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| ### validateFileName(fileName)
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| 
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| Returns `null` or a `String` error message depending on the validity of `fileName`.
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| If `fileName` starts with `"/"` or `/[A-Za-z]:\//` or if it contains `".."` path segments or `"\\"`,
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| this function returns an error message appropriate for use like this:
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| 
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| ```js
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| var errorMessage = yauzl.validateFileName(fileName);
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| if (errorMessage != null) throw new Error(errorMessage);
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| ```
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| 
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| This function is automatically run for each entry, as long as `decodeStrings` is `true`.
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| See `open()`, `strictFileNames`, and `Event: "entry"` for more information.
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| 
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| ### Class: ZipFile
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| 
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| The constructor for the class is not part of the public API.
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| Use `open()`, `fromFd()`, `fromBuffer()`, or `fromRandomAccessReader()` instead.
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| 
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| #### Event: "entry"
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| 
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| Callback gets `(entry)`, which is an `Entry`.
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| See `open()` and `readEntry()` for when this event is emitted.
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| 
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| If `decodeStrings` is `true`, entries emitted via this event have already passed file name validation.
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| See `validateFileName()` and `open()` for more information.
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| 
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| If `validateEntrySizes` is `true` and this entry's `compressionMethod` is `0` (stored without compression),
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| this entry has already passed entry size validation.
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| See `open()` for more information.
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| 
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| #### Event: "end"
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| 
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| Emitted after the last `entry` event has been emitted.
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| See `open()` and `readEntry()` for more info on when this event is emitted.
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| 
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| #### Event: "close"
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| 
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| Emitted after the fd is actually closed.
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| This is after calling `close()` (or after the `end` event when `autoClose` is `true`),
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| and after all stream pipelines created from `openReadStream()` have finished reading data from the fd.
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| 
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| If this `ZipFile` was acquired from `fromRandomAccessReader()`,
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| the "fd" in the previous paragraph refers to the `RandomAccessReader` implemented by the client.
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| 
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| If this `ZipFile` was acquired from `fromBuffer()`, this event is never emitted.
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| 
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| #### Event: "error"
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| 
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| Emitted in the case of errors with reading the zip file.
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| (Note that other errors can be emitted from the streams created from `openReadStream()` as well.)
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| After this event has been emitted, no further `entry`, `end`, or `error` events will be emitted,
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| but the `close` event may still be emitted.
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| 
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| #### readEntry()
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| 
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| Causes this `ZipFile` to emit an `entry` or `end` event (or an `error` event).
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| This method must only be called when this `ZipFile` was created with the `lazyEntries` option set to `true` (see `open()`).
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| When this `ZipFile` was created with the `lazyEntries` option set to `true`,
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| `entry` and `end` events are only ever emitted in response to this method call.
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| 
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| The event that is emitted in response to this method will not be emitted until after this method has returned,
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| so it is safe to call this method before attaching event listeners.
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| 
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| After calling this method, calling this method again before the response event has been emitted will cause undefined behavior.
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| Calling this method after the `end` event has been emitted will cause undefined behavior.
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| Calling this method after calling `close()` will cause undefined behavior.
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| 
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| #### openReadStream(entry, [options], callback)
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| 
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| `entry` must be an `Entry` object from this `ZipFile`.
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| `callback` gets `(err, readStream)`, where `readStream` is a `Readable Stream` that provides the file data for this entry.
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| If this zipfile is already closed (see `close()`), the `callback` will receive an `err`.
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| 
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| `options` may be omitted or `null`, and has the following defaults:
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| 
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| ```js
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| {
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|   decompress: entry.isCompressed() ? true : null,
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|   decrypt: null,
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|   start: 0,                  // actually the default is null, see below
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|   end: entry.compressedSize, // actually the default is null, see below
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| }
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| ```
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| 
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| If the entry is compressed (with a supported compression method),
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| and the `decompress` option is `true` (or omitted),
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| the read stream provides the decompressed data.
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| Omitting the `decompress` option is what most clients should do.
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| 
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| The `decompress` option must be `null` (or omitted) when the entry is not compressed (see `isCompressed()`),
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| and either `true` (or omitted) or `false` when the entry is compressed.
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| Specifying `decompress: false` for a compressed entry causes the read stream
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| to provide the raw compressed file data without going through a zlib inflate transform.
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| 
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| If the entry is encrypted (see `isEncrypted()`), clients may want to avoid calling `openReadStream()` on the entry entirely.
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| Alternatively, clients may call `openReadStream()` for encrypted entries and specify `decrypt: false`.
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| If the entry is also compressed, clients must *also* specify `decompress: false`.
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| Specifying `decrypt: false` for an encrypted entry causes the read stream to provide the raw, still-encrypted file data.
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| (This data includes the 12-byte header described in the spec.)
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| 
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| The `decrypt` option must be `null` (or omitted) for non-encrypted entries, and `false` for encrypted entries.
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| Omitting the `decrypt` option (or specifying it as `null`) for an encrypted entry
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| will result in the `callback` receiving an `err`.
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| This default behavior is so that clients not accounting for encrypted files aren't surprised by bogus file data.
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| 
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| The `start` (inclusive) and `end` (exclusive) options are byte offsets into this entry's file data,
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| and can be used to obtain part of an entry's file data rather than the whole thing.
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| If either of these options are specified and non-`null`,
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| then the above options must be used to obain the file's raw data.
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| Speficying `{start: 0, end: entry.compressedSize}` will result in the complete file,
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| which is effectively the default values for these options,
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| but note that unlike omitting the options, when you specify `start` or `end` as any non-`null` value,
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| the above requirement is still enforced that you must also pass the appropriate options to get the file's raw data.
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| 
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| It's possible for the `readStream` provided to the `callback` to emit errors for several reasons.
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| For example, if zlib cannot decompress the data, the zlib error will be emitted from the `readStream`.
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| Two more error cases (when `validateEntrySizes` is `true`) are if the decompressed data has too many
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| or too few actual bytes compared to the reported byte count from the entry's `uncompressedSize` field.
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| yauzl notices this false information and emits an error from the `readStream`
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| after some number of bytes have already been piped through the stream.
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| 
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| This check allows clients to trust the `uncompressedSize` field in `Entry` objects.
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| Guarding against [zip bomb](http://en.wikipedia.org/wiki/Zip_bomb) attacks can be accomplished by
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| doing some heuristic checks on the size metadata and then watching out for the above errors.
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| Such heuristics are outside the scope of this library,
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| but enforcing the `uncompressedSize` is implemented here as a security feature.
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| 
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| It is possible to destroy the `readStream` before it has piped all of its data.
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| To do this, call `readStream.destroy()`.
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| You must `unpipe()` the `readStream` from any destination before calling `readStream.destroy()`.
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| If this zipfile was created using `fromRandomAccessReader()`, the `RandomAccessReader` implementation
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| must provide readable streams that implement a `.destroy()` method (see `randomAccessReader._readStreamForRange()`)
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| in order for calls to `readStream.destroy()` to work in this context.
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| 
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| #### close()
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| 
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| Causes all future calls to `openReadStream()` to fail,
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| and closes the fd, if any, after all streams created by `openReadStream()` have emitted their `end` events.
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| 
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| If the `autoClose` option is set to `true` (see `open()`),
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| this function will be called automatically effectively in response to this object's `end` event.
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| 
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| If the `lazyEntries` option is set to `false` (see `open()`) and this object's `end` event has not been emitted yet,
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| this function causes undefined behavior.
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| If the `lazyEntries` option is set to `true`,
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| you can call this function instead of calling `readEntry()` to abort reading the entries of a zipfile.
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| 
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| It is safe to call this function multiple times; after the first call, successive calls have no effect.
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| This includes situations where the `autoClose` option effectively calls this function for you.
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| 
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| If `close()` is never called, then the zipfile is "kept open".
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| For zipfiles created with `fromFd()`, this will leave the `fd` open, which may be desirable.
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| For zipfiles created with `open()`, this will leave the underlying `fd` open, thereby "leaking" it, which is probably undesirable.
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| For zipfiles created with `fromRandomAccessReader()`, the reader's `close()` method will never be called.
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| For zipfiles created with `fromBuffer()`, the `close()` function has no effect whether called or not.
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| 
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| Regardless of how this `ZipFile` was created, there are no resources other than those listed above that require cleanup from this function.
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| This means it may be desirable to never call `close()` in some usecases.
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| 
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| #### isOpen
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| 
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| `Boolean`. `true` until `close()` is called; then it's `false`.
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| 
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| #### entryCount
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| 
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| `Number`. Total number of central directory records.
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| 
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| #### comment
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| 
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| `String`. Always decoded with `CP437` per the spec.
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| 
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| If `decodeStrings` is `false` (see `open()`), this field is the undecoded `Buffer` instead of a decoded `String`.
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| 
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| ### Class: Entry
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| 
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| Objects of this class represent Central Directory Records.
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| Refer to the zipfile specification for more details about these fields.
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| 
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| These fields are of type `Number`:
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| 
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|  * `versionMadeBy`
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|  * `versionNeededToExtract`
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|  * `generalPurposeBitFlag`
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|  * `compressionMethod`
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|  * `lastModFileTime` (MS-DOS format, see `getLastModDateTime`)
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|  * `lastModFileDate` (MS-DOS format, see `getLastModDateTime`)
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|  * `crc32`
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|  * `compressedSize`
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|  * `uncompressedSize`
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|  * `fileNameLength` (bytes)
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|  * `extraFieldLength` (bytes)
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|  * `fileCommentLength` (bytes)
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|  * `internalFileAttributes`
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|  * `externalFileAttributes`
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|  * `relativeOffsetOfLocalHeader`
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| 
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| #### fileName
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| 
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| `String`.
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| Following the spec, the bytes for the file name are decoded with
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| `UTF-8` if `generalPurposeBitFlag & 0x800`, otherwise with `CP437`.
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| Alternatively, this field may be populated from the Info-ZIP Unicode Path Extra Field
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| (see `extraFields`).
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| 
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| This field is automatically validated by `validateFileName()` before yauzl emits an "entry" event.
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| If this field would contain unsafe characters, yauzl emits an error instead of an entry.
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| 
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| If `decodeStrings` is `false` (see `open()`), this field is the undecoded `Buffer` instead of a decoded `String`.
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| Therefore, `generalPurposeBitFlag` and any Info-ZIP Unicode Path Extra Field are ignored.
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| Furthermore, no automatic file name validation is performed for this file name.
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| 
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| #### extraFields
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| 
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| `Array` with each entry in the form `{id: id, data: data}`,
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| where `id` is a `Number` and `data` is a `Buffer`.
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| 
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| This library looks for and reads the ZIP64 Extended Information Extra Field (0x0001)
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| in order to support ZIP64 format zip files.
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| 
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| This library also looks for and reads the Info-ZIP Unicode Path Extra Field (0x7075)
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| in order to support some zipfiles that use it instead of General Purpose Bit 11
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| to convey `UTF-8` file names.
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| When the field is identified and verified to be reliable (see the zipfile spec),
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| the the file name in this field is stored in the `fileName` property,
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| and the file name in the central directory record for this entry is ignored.
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| Note that when `decodeStrings` is false, all Info-ZIP Unicode Path Extra Fields are ignored.
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| 
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| None of the other fields are considered significant by this library.
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| Fields that this library reads are left unalterned in the `extraFields` array.
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| 
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| #### fileComment
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| 
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| `String` decoded with the charset indicated by `generalPurposeBitFlag & 0x800` as with the `fileName`.
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| (The Info-ZIP Unicode Path Extra Field has no effect on the charset used for this field.)
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| 
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| If `decodeStrings` is `false` (see `open()`), this field is the undecoded `Buffer` instead of a decoded `String`.
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| 
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| Prior to yauzl version 2.7.0, this field was erroneously documented as `comment` instead of `fileComment`.
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| For compatibility with any code that uses the field name `comment`,
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| yauzl creates an alias field named `comment` which is identical to `fileComment`.
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| 
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| #### getLastModDate()
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| 
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| Effectively implemented as:
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| 
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| ```js
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| return dosDateTimeToDate(this.lastModFileDate, this.lastModFileTime);
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| ```
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| 
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| #### isEncrypted()
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| 
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| Returns is this entry encrypted with "Traditional Encryption".
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| Effectively implemented as:
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| 
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| ```js
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| return (this.generalPurposeBitFlag & 0x1) !== 0;
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| ```
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| 
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| See `openReadStream()` for the implications of this value.
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| 
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| Note that "Strong Encryption" is not supported, and will result in an `"error"` event emitted from the `ZipFile`.
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| 
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| #### isCompressed()
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| 
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| Effectively implemented as:
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| 
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| ```js
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| return this.compressionMethod === 8;
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| ```
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| 
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| See `openReadStream()` for the implications of this value.
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| 
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| ### Class: RandomAccessReader
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| 
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| This class is meant to be subclassed by clients and instantiated for the `fromRandomAccessReader()` function.
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| 
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| An example implementation can be found in `test/test.js`.
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| 
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| #### randomAccessReader._readStreamForRange(start, end)
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| 
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| Subclasses *must* implement this method.
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| 
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| `start` and `end` are Numbers and indicate byte offsets from the start of the file.
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| `end` is exclusive, so `_readStreamForRange(0x1000, 0x2000)` would indicate to read `0x1000` bytes.
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| `end - start` will always be at least `1`.
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| 
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| This method should return a readable stream which will be `pipe()`ed into another stream.
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| It is expected that the readable stream will provide data in several chunks if necessary.
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| If the readable stream provides too many or too few bytes, an error will be emitted.
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| (Note that `validateEntrySizes` has no effect on this check,
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| because this is a low-level API that should behave correctly regardless of the contents of the file.)
 | |
| Any errors emitted on the readable stream will be handled and re-emitted on the client-visible stream
 | |
| (returned from `zipfile.openReadStream()`) or provided as the `err` argument to the appropriate callback
 | |
| (for example, for `fromRandomAccessReader()`).
 | |
| 
 | |
| The returned stream *must* implement a method `.destroy()`
 | |
| if you call `readStream.destroy()` on streams you get from `openReadStream()`.
 | |
| If you never call `readStream.destroy()`, then streams returned from this method do not need to implement a method `.destroy()`.
 | |
| `.destroy()` should abort any streaming that is in progress and clean up any associated resources.
 | |
| `.destroy()` will only be called after the stream has been `unpipe()`d from its destination.
 | |
| 
 | |
| Note that the stream returned from this method might not be the same object that is provided by `openReadStream()`.
 | |
| The stream returned from this method might be `pipe()`d through one or more filter streams (for example, a zlib inflate stream).
 | |
| 
 | |
| #### randomAccessReader.read(buffer, offset, length, position, callback)
 | |
| 
 | |
| Subclasses may implement this method.
 | |
| The default implementation uses `createReadStream()` to fill the `buffer`.
 | |
| 
 | |
| This method should behave like `fs.read()`.
 | |
| 
 | |
| #### randomAccessReader.close(callback)
 | |
| 
 | |
| Subclasses may implement this method.
 | |
| The default implementation is effectively `setImmediate(callback);`.
 | |
| 
 | |
| `callback` takes parameters `(err)`.
 | |
| 
 | |
| This method is called once the all streams returned from `_readStreamForRange()` have ended,
 | |
| and no more `_readStreamForRange()` or `read()` requests will be issued to this object.
 | |
| 
 | |
| ## How to Avoid Crashing
 | |
| 
 | |
| When a malformed zipfile is encountered, the default behavior is to crash (throw an exception).
 | |
| If you want to handle errors more gracefully than this,
 | |
| be sure to do the following:
 | |
| 
 | |
|  * Provide `callback` parameters where they are allowed, and check the `err` parameter.
 | |
|  * Attach a listener for the `error` event on any `ZipFile` object you get from `open()`, `fromFd()`, `fromBuffer()`, or `fromRandomAccessReader()`.
 | |
|  * Attach a listener for the `error` event on any stream you get from `openReadStream()`.
 | |
| 
 | |
| Minor version updates to yauzl will not add any additional requirements to this list.
 | |
| 
 | |
| ## Limitations
 | |
| 
 | |
| ### No Streaming Unzip API
 | |
| 
 | |
| Due to the design of the .zip file format, it's impossible to interpret a .zip file from start to finish
 | |
| (such as from a readable stream) without sacrificing correctness.
 | |
| The Central Directory, which is the authority on the contents of the .zip file, is at the end of a .zip file, not the beginning.
 | |
| A streaming API would need to either buffer the entire .zip file to get to the Central Directory before interpreting anything
 | |
| (defeating the purpose of a streaming interface), or rely on the Local File Headers which are interspersed through the .zip file.
 | |
| However, the Local File Headers are explicitly denounced in the spec as being unreliable copies of the Central Directory,
 | |
| so trusting them would be a violation of the spec.
 | |
| 
 | |
| Any library that offers a streaming unzip API must make one of the above two compromises,
 | |
| which makes the library either dishonest or nonconformant (usually the latter).
 | |
| This library insists on correctness and adherence to the spec, and so does not offer a streaming API.
 | |
| 
 | |
| Here is a way to create a spec-conformant .zip file using the `zip` command line program (Info-ZIP)
 | |
| available in most unix-like environments, that is (nearly) impossible to parse correctly with a streaming parser:
 | |
| 
 | |
| ```
 | |
| $ echo -ne '\x50\x4b\x07\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' > file.txt
 | |
| $ zip -q0 - file.txt | cat > out.zip
 | |
| ```
 | |
| 
 | |
| This .zip file contains a single file entry that uses General Purpose Bit 3,
 | |
| which means the Local File Header doesn't know the size of the file.
 | |
| Any streaming parser that encounters this situation will either immediately fail,
 | |
| or attempt to search for the Data Descriptor after the file's contents.
 | |
| The file's contents is a sequence of 16-bytes crafted to exactly mimic a valid Data Descriptor for an empty file,
 | |
| which will fool any parser that gets this far into thinking that the file is empty rather than containing 16-bytes.
 | |
| What follows the file's real contents is the file's real Data Descriptor,
 | |
| which will likely cause some kind of signature mismatch error for a streaming parser (if one hasn't occurred already).
 | |
| 
 | |
| By using General Purpose Bit 3 (and compression method 0),
 | |
| it's possible to create arbitrarily ambiguous .zip files that
 | |
| distract parsers with file contents that contain apparently valid .zip file metadata.
 | |
| 
 | |
| ### Limitted ZIP64 Support
 | |
| 
 | |
| For ZIP64, only zip files smaller than `8PiB` are supported,
 | |
| not the full `16EiB` range that a 64-bit integer should be able to index.
 | |
| This is due to the JavaScript Number type being an IEEE 754 double precision float.
 | |
| 
 | |
| The Node.js `fs` module probably has this same limitation.
 | |
| 
 | |
| ### ZIP64 Extensible Data Sector Is Ignored
 | |
| 
 | |
| The spec does not allow zip file creators to put arbitrary data here,
 | |
| but rather reserves its use for PKWARE and mentions something about Z390.
 | |
| This doesn't seem useful to expose in this library, so it is ignored.
 | |
| 
 | |
| ### No Multi-Disk Archive Support
 | |
| 
 | |
| This library does not support multi-disk zip files.
 | |
| The multi-disk fields in the zipfile spec were intended for a zip file to span multiple floppy disks,
 | |
| which probably never happens now.
 | |
| If the "number of this disk" field in the End of Central Directory Record is not `0`,
 | |
| the `open()`, `fromFd()`, `fromBuffer()`, or `fromRandomAccessReader()` `callback` will receive an `err`.
 | |
| By extension the following zip file fields are ignored by this library and not provided to clients:
 | |
| 
 | |
|  * Disk where central directory starts
 | |
|  * Number of central directory records on this disk
 | |
|  * Disk number where file starts
 | |
| 
 | |
| ### Limited Encryption Handling
 | |
| 
 | |
| You can detect when a file entry is encrypted with "Traditional Encryption" via `isEncrypted()`,
 | |
| but yauzl will not help you decrypt it.
 | |
| See `openReadStream()`.
 | |
| 
 | |
| If a zip file contains file entries encrypted with "Strong Encryption", yauzl emits an error.
 | |
| 
 | |
| If the central directory is encrypted or compressed, yauzl emits an error.
 | |
| 
 | |
| ### Local File Headers Are Ignored
 | |
| 
 | |
| Many unzip libraries mistakenly read the Local File Header data in zip files.
 | |
| This data is officially defined to be redundant with the Central Directory information,
 | |
| and is not to be trusted.
 | |
| Aside from checking the signature, yauzl ignores the content of the Local File Header.
 | |
| 
 | |
| ### No CRC-32 Checking
 | |
| 
 | |
| This library provides the `crc32` field of `Entry` objects read from the Central Directory.
 | |
| However, this field is not used for anything in this library.
 | |
| 
 | |
| ### versionNeededToExtract Is Ignored
 | |
| 
 | |
| The field `versionNeededToExtract` is ignored,
 | |
| because this library doesn't support the complete zip file spec at any version,
 | |
| 
 | |
| ### No Support For Obscure Compression Methods
 | |
| 
 | |
| Regarding the `compressionMethod` field of `Entry` objects,
 | |
| only method `0` (stored with no compression)
 | |
| and method `8` (deflated) are supported.
 | |
| Any of the other 15 official methods will cause the `openReadStream()` `callback` to receive an `err`.
 | |
| 
 | |
| ### Data Descriptors Are Ignored
 | |
| 
 | |
| There may or may not be Data Descriptor sections in a zip file.
 | |
| This library provides no support for finding or interpreting them.
 | |
| 
 | |
| ### Archive Extra Data Record Is Ignored
 | |
| 
 | |
| There may or may not be an Archive Extra Data Record section in a zip file.
 | |
| This library provides no support for finding or interpreting it.
 | |
| 
 | |
| ### No Language Encoding Flag Support
 | |
| 
 | |
| Zip files officially support charset encodings other than CP437 and UTF-8,
 | |
| but the zip file spec does not specify how it works.
 | |
| This library makes no attempt to interpret the Language Encoding Flag.
 | |
| 
 | |
| ## Change History
 | |
| 
 | |
|  * 2.10.0
 | |
|    * Added support for non-conformant zipfiles created by Microsoft, and added option `strictFileNames` to disable the workaround. [issue #66](https://github.com/thejoshwolfe/yauzl/issues/66), [issue #88](https://github.com/thejoshwolfe/yauzl/issues/88)
 | |
|  * 2.9.2
 | |
|    * Removed `tools/hexdump-zip.js` and `tools/hex2bin.js`. Those tools are now located here: [thejoshwolfe/hexdump-zip](https://github.com/thejoshwolfe/hexdump-zip) and [thejoshwolfe/hex2bin](https://github.com/thejoshwolfe/hex2bin)
 | |
|    * Worked around performance problem with zlib when using `fromBuffer()` and `readStream.destroy()` for large compressed files. [issue #87](https://github.com/thejoshwolfe/yauzl/issues/87)
 | |
|  * 2.9.1
 | |
|    * Removed `console.log()` accidentally introduced in 2.9.0. [issue #64](https://github.com/thejoshwolfe/yauzl/issues/64)
 | |
|  * 2.9.0
 | |
|    * Throw an exception if `readEntry()` is called without `lazyEntries:true`. Previously this caused undefined behavior. [issue #63](https://github.com/thejoshwolfe/yauzl/issues/63)
 | |
|  * 2.8.0
 | |
|    * Added option `validateEntrySizes`. [issue #53](https://github.com/thejoshwolfe/yauzl/issues/53)
 | |
|    * Added `examples/promises.js`
 | |
|    * Added ability to read raw file data via `decompress` and `decrypt` options. [issue #11](https://github.com/thejoshwolfe/yauzl/issues/11), [issue #38](https://github.com/thejoshwolfe/yauzl/issues/38), [pull #39](https://github.com/thejoshwolfe/yauzl/pull/39)
 | |
|    * Added `start` and `end` options to `openReadStream()`. [issue #38](https://github.com/thejoshwolfe/yauzl/issues/38)
 | |
|  * 2.7.0
 | |
|    * Added option `decodeStrings`. [issue #42](https://github.com/thejoshwolfe/yauzl/issues/42)
 | |
|    * Fixed documentation for `entry.fileComment` and added compatibility alias. [issue #47](https://github.com/thejoshwolfe/yauzl/issues/47)
 | |
|  * 2.6.0
 | |
|    * Support Info-ZIP Unicode Path Extra Field, used by WinRAR for Chinese file names. [issue #33](https://github.com/thejoshwolfe/yauzl/issues/33)
 | |
|  * 2.5.0
 | |
|    * Ignore malformed Extra Field that is common in Android .apk files. [issue #31](https://github.com/thejoshwolfe/yauzl/issues/31)
 | |
|  * 2.4.3
 | |
|    * Fix crash when parsing malformed Extra Field buffers. [issue #31](https://github.com/thejoshwolfe/yauzl/issues/31)
 | |
|  * 2.4.2
 | |
|    * Remove .npmignore and .travis.yml from npm package.
 | |
|  * 2.4.1
 | |
|    * Fix error handling.
 | |
|  * 2.4.0
 | |
|    * Add ZIP64 support. [issue #6](https://github.com/thejoshwolfe/yauzl/issues/6)
 | |
|    * Add `lazyEntries` option. [issue #22](https://github.com/thejoshwolfe/yauzl/issues/22)
 | |
|    * Add `readStream.destroy()` method. [issue #26](https://github.com/thejoshwolfe/yauzl/issues/26)
 | |
|    * Add `fromRandomAccessReader()`. [issue #14](https://github.com/thejoshwolfe/yauzl/issues/14)
 | |
|    * Add `examples/unzip.js`.
 | |
|  * 2.3.1
 | |
|    * Documentation updates.
 | |
|  * 2.3.0
 | |
|    * Check that `uncompressedSize` is correct, or else emit an error. [issue #13](https://github.com/thejoshwolfe/yauzl/issues/13)
 | |
|  * 2.2.1
 | |
|    * Update dependencies.
 | |
|  * 2.2.0
 | |
|    * Update dependencies.
 | |
|  * 2.1.0
 | |
|    * Remove dependency on `iconv`.
 | |
|  * 2.0.3
 | |
|    * Fix crash when trying to read a 0-byte file.
 | |
|  * 2.0.2
 | |
|    * Fix event behavior after errors.
 | |
|  * 2.0.1
 | |
|    * Fix bug with using `iconv`.
 | |
|  * 2.0.0
 | |
|    * Initial release.
 |