11 KiB
yazl
yet another zip library for node. For unzipping, see yauzl.
Design principles:
- Don't block the JavaScript thread. Use and provide async APIs.
- Keep memory usage under control. Don't attempt to buffer entire files in RAM at once.
- Prefer to open input files one at a time than all at once. This is slightly suboptimal for time performance, but avoids OS-imposed limits on the number of simultaneously open file handles.
Usage
var yazl = require("yazl");
var zipfile = new yazl.ZipFile();
zipfile.addFile("file1.txt", "file1.txt");
// (add only files, not directories)
zipfile.addFile("path/to/file.txt", "path/in/zipfile.txt");
// pipe() can be called any time after the constructor
zipfile.outputStream.pipe(fs.createWriteStream("output.zip")).on("close", function() {
console.log("done");
});
// alternate apis for adding files:
zipfile.addReadStream(process.stdin, "stdin.txt", {
mtime: new Date(),
mode: 0100664, // -rw-rw-r--
});
zipfile.addBuffer(new Buffer("hello"), "hello.txt", {
mtime: new Date(),
mode: 0100664, // -rw-rw-r--
});
// call end() after all the files have been added
zipfile.end();
API
Class: ZipFile
new ZipFile()
No parameters. Nothing can go wrong.
addFile(realPath, metadataPath, [options])
Adds a file from the file system at realPath into the zipfile as metadataPath.
Typically metadataPath would be calculated as path.relative(root, realPath).
Unzip programs would extract the file from the zipfile as metadataPath.
realPath is not stored in the zipfile.
A valid metadataPath must not be blank.
If a metadataPath contains "\\" characters, they will be replaced by "/" characters.
After this substitution, a valid metadataPath must not start with "/" or /[A-Za-z]:\//,
and must not contain ".." path segments.
File paths must not end with "/".
options may be omitted or null and has the following structure and default values:
{
mtime: stats.mtime,
mode: stats.mode,
compress: true,
}
Use options.mtime and/or options.mode to override the values
that would normally be obtained by the fs.Stats for the realPath.
The mode is the unix permission bits and file type.
The mtime and mode are stored in the zip file in the fields "last mod file time",
"last mod file date", and "external file attributes".
yazl does not store group and user ids in the zip file.
Internally, fs.stat() is called immediately in the addFile function,
and fs.createReadStream() is used later when the file data is actually required.
Throughout adding and encoding n files with addFile(),
the number of simultaneous open files is O(1), probably just 1 at a time.
addReadStream(readStream, metadataPath, [options])
Adds a file to the zip file whose content is read from readStream.
See addFile() for info about the metadataPath parameter.
options may be omitted or null and has the following structure and default values:
{
mtime: new Date(),
mode: 0100664,
compress: true,
size: 12345, // example value
}
See addFile() for the meaning of mtime and mode.
If size is given, it will be checked against the actual number of bytes in the readStream,
and an error will be emitted if there is a mismatch.
Note that yazl will .pipe() data from readStream, so be careful using .on('data').
In certain versions of node, .on('data') makes .pipe() behave incorrectly.
addBuffer(buffer, metadataPath, [options])
Adds a file to the zip file whose content is buffer.
See addFile() for info about the metadataPath parameter.
options may be omitted or null and has the following structure and default values:
{
mtime: new Date(),
mode: 0100664,
compress: true,
}
See addFile() for the meaning of mtime and mode.
This method has the unique property that General Purpose Bit 3 will not be used in the Local File Header.
This doesn't matter for unzip implementations that conform to the Zip File Spec.
However, 7-Zip 9.20 has a known bug where General Purpose Bit 3 is declared an unsupported compression method
(note that it really has nothing to do with the compression method.).
See issue #11.
If you would like to create zip files that 7-Zip 9.20 can understand,
you must use addBuffer() instead of addFile() or addReadStream() for all entries in the zip file
(and addEmptyDirectory() is fine too).
addEmptyDirectory(metadataPath, [options])
Adds an entry to the zip file that indicates a directory should be created, even if no other items in the zip file are contained in the directory. This method is only required if the zip file is intended to contain an empty directory.
See addFile() for info about the metadataPath parameter.
If metadataPath does not end with a "/", a "/" will be appended.
options may be omitted or null and has the following structure and default values:
{
mtime: new Date(),
mode: 040775,
}
See addFile() for the meaning of mtime and mode.
end([finalSizeCallback])
Indicates that no more files will be added via addFile(), addReadStream(), or addBuffer().
Some time after calling this function, outputStream will be ended.
If specified and non-null, finalSizeCallback is given the parameters (finalSize)
sometime during or after the call to end().
finalSize is of type Number and can either be -1
or the guaranteed eventual size in bytes of the output data that can be read from outputStream.
If finalSize is -1, it means means the final size is too hard to guess before processing the input file data.
This will happen if and only if the compress option is true on any call to addFile(), addReadStream(), or addBuffer(),
or if addReadStream() is called and the optional size option is not given.
In other words, clients should know whether they're going to get a -1 or a real value
by looking at how they are calling this function.
The call to finalSizeCallback might be delayed if yazl is still waiting for fs.Stats for an addFile() entry.
If addFile() was never called, finalSizeCallback will be called during the call to end().
It is not required to start piping data from outputStream before finalSizeCallback is called.
finalSizeCallback will be called only once, and only if this is the first call to end().
outputStream
A readable stream that will produce the contents of the zip file.
It is typical to pipe this stream to a writable stream created from fs.createWriteStream().
Internally, large amounts of file data are piped to outputStream using pipe(),
which means throttling happens appropriately when this stream is piped to a slow destination.
Data becomes available in this stream soon after calling one of addFile(), addReadStream(), or addBuffer().
Clients can call pipe() on this stream at any time,
such as immediately after getting a new ZipFile instance, or long after calling end().
As a reminder, be careful using both .on('data') and .pipe() with this stream.
In certain versions of node, you cannot use both .on('data') and .pipe() successfully.
dateToDosDateTime(jsDate)
jsDate is a Date instance.
Returns {date: date, time: time}, where date and time are unsigned 16-bit integers.
Output Structure
The Zip File Spec leaves a lot of flexibility up to the zip file creator. This section explains and justifies yazl's interpretation and decisions regarding this flexibility.
This section is probably not useful to yazl clients, but may be interesting to unzip implementors and zip file enthusiasts.
Disk Numbers
All values related to disk numbers are 0,
because yazl has no multi-disk archive support.
Version Made By
Always 0x031e.
This is the value reported by a Linux build of Info-Zip.
Instead of experimenting with different values of this field
to see how different unzip clients would behave,
yazl mimics Info-Zip, which should work everywhere.
Note that the top byte means "UNIX" and has implications in the External File Attributes.
Version Needed to Extract
Always 0x0014.
Without this value, Info-Zip, and possibly other unzip implementations,
refuse to acknowledge General Purpose Bit 8, which enables utf8 filename encoding.
General Purpose Bit Flag
Bit 8 is always set.
Filenames are always encoded in utf8, even if the result is indistinguishable from ascii.
Bit 3 is usually set in the Local File Header.
To support both a streaming input and streaming output api,
it is impossible to know the crc32 before processing the file data.
When bit 3 is set, file Descriptors are given after each file data with this information, as per the spec.
But remember a complete metadata listing is still always available in the central directory record,
so if unzip implementations are relying on that, like they should,
none of this paragraph will matter anyway.
Even so, some popular unzip implementations do not follow the spec.
Mac's Archive Utility requires File Descriptors to include the optional signature,
so yazl includes the optional file descriptor signature.
When bit 3 is not used, Mac's Archive Utility requires there to be no file descriptor, so yazl skips it in that case.
Additionally, 7-Zip 9.20 does not seem to support bit 3 at all
(see issue #11).
All other bits are unset.
Internal File Attributes
Always 0.
The "apparently an ASCII or text file" bit is always unset meaning "apparently binary".
This kind of determination is outside the scope of yazl,
and is probably not significant in any modern unzip implementation.
External File Attributes
Always stats.mode << 16.
This is apparently the convention for "version made by" = 0x03xx (UNIX).
Note that for directory entries (see addEmptyDirectory()),
it is conventional to use the lower 8 bits for the MS-DOS directory attribute byte.
However, the spec says this is only required if the Version Made By is DOS,
so this library does not do that.
Directory Entries
When adding a metadataPath such as "parent/file.txt", yazl does not add a directory entry for "parent/",
because file entries imply the need for their parent directories.
Unzip clients seem to respect this style of pathing,
and the zip file spec does not specify what is standard in this regard.
In order to create empty directories, use addEmptyDirectory().
Change History
- 2.3.0
metadataPathcan have\characters now; they will be replaced with/. issue #18
- 2.2.2
- Fix 7-Zip compatibility issue. pull request #17
- 2.2.1
- Fix Mac Archive Utility compatibility issue. issue #14
- 2.2.0
- Avoid using general purpose bit 3 for
addBuffer()calls. issue #13
- Avoid using general purpose bit 3 for
- 2.1.3
- Fix bug when only addBuffer() and end() are called. issue #12
- 2.1.2
- Fixed typo in parameter validation. pull request #10
- 2.1.1
- Fixed stack overflow when using addBuffer() in certain ways. issue #9
- 2.1.0
- Added
addEmptyDirectory(). optionsis now optional foraddReadStream()andaddBuffer().
- Added
- 2.0.0
- Initial release.