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Updating, expanding docs. Fixes #36.

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David Humphrey (:humph) david.humphrey@senecacollege.ca 2013-12-09 11:29:13 -05:00
parent fc03bb72d3
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39
CONTRIBUTING.md Normal file
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@ -0,0 +1,39 @@
# How to Contribute
The best way to get started is to read through the `Getting Started` and `Example`
sections before having a look through the open [issues](https://github.com/js-platform/filer/issues).
Some of the issues are marked as `good first bug`, but feel free to contribute to
any of the issues there, or open a new one if the thing you want to work on isn't
there yet. If you would like to have an issue assigned to you, please send me a
message and I'll update it.
## Setup
The Filer build system is based on [grunt](http://gruntjs.com/). To get a working build system
do the following:
```
npm install
npm install -g grunt-cli
```
You can now run the following grunt tasks:
* `grunt check` will run [JSHint](http://www.jshint.com/) on your code (do this before submitting a pull request) to catch errors
* `grunt develop` will create a single file version of the library for testing in `dist/idbfs.js`
* `grunt release` like `develop` but will also create a minified version of the library in `dist/idbfs.min.js`
Once you've done some hacking and you'd like to have your work merged, you'll need to
make a pull request. If you're patch includes code, make sure to check that all the
unit tests pass, including any new tests you wrote. Finally, make sure you add yourself
to the `AUTHORS` file.
## Tests
Tests are writting using [Jasmine](http://pivotal.github.io/jasmine/). You can run the tests
in your browser by opening the `tests` directory. You can also run them
[here](http://js-platform.github.io/idbfs/tests/).
## Communication
If you'd like to talk to someone about the project, you can reach us on irc.mozilla.org in the
mofodev channel. Look for "ack" or "humph".

849
README.md
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@ -3,59 +3,47 @@
###Filer
Filer is a POSIX-like file system interface for browser-based JavaScript.
The API is as close to the node.js [fs module](http://nodejs.org/api/fs.html) as possible
with the following differences:
* No synchronous versions of methods (e.g., `mkdir()` but not `mkdirSync()`).
* No permissions (e.g., no `chown()`, `chmod()`, etc.).
* No support (yet) for `fs.watchFile()`, `fs.unwatchFile()`, `fs.watch()`.
* No support for stream-based operations (e.g., `fs.ReadStream`, `fs.WriteStream`).
### Contributing
The best way to get started is to read through the `Getting Started` and `Example` sections before having a look through the open [issues](https://github.com/js-platform/filer/issues). Some of the issues are marked as `good first bug`, but feel free to contribute to any of the issues there, or open a new one if the thing you want to work on isn't there yet. If you would like to have an issue assigned to you, please send me a message and I'll update it.
The build system is based on [grunt](http://gruntjs.com/). To get a working build system
do the following:
```
npm install
npm install -g grunt-cli
```
You can now run the following grunt tasks:
* `grunt check` will run [JSHint](http://www.jshint.com/) on your code (do this before submitting a pull request) to catch errors
* `grunt develop` will create a single file version of the library for testing in `dist/idbfs.js`
* `grunt release` like `develop` but will also create a minified version of the library in `dist/idbfs.min.js`
Once you've done some hacking and you'd like to have your work merged, you'll need to make a pull request. If you're patch includes code, make sure to check that all the unit tests pass, including any new tests you wrote. Finally, make sure you add yourself to the `AUTHORS` file.
#### Tests
You can run the tests from the project by opening the `tests` directory in your browser. You can also run them [here](http://js-platform.github.io/idbfs/tests/).
Want to join the fun? We'd love to have you! See [CONTRIBUTING](CONTRIBUTING.md).
###Downloading
Pre-built versions of the library are available in the repo:
* [idbfs.js](https://raw.github.com/js-platform/filer/develop/dist/idbfs.js)
* [idbfs.min.js](https://raw.github.com/js-platform/filer/develop/dist/idbfs.min.js)
* [filer.js](https://raw.github.com/js-platform/filer/develop/dist/filer.js)
* [filer.min.js](https://raw.github.com/js-platform/filer/develop/dist/filer.min.js)
### Getting Started
IDBFS is partly based on the `fs` module from node.js. The API is asynchronous and most methods require the caller to provide a callback function. Errors are passed to callbacks through the first parameter.
Filer is as close to the node.js [fs module](http://nodejs.org/api/fs.html) as possible,
with the following differences:
To create a new file system or open an existing one, create a new `FileSystem` instance and pass the name of the file system. A new IndexedDB database is created for each file system.
* No synchronous versions of methods (e.g., `mkdir()` but not `mkdirSync()`).
* No permissions (e.g., no `chown()`, `chmod()`, etc.).
* No support (yet) for `fs.watchFile()`, `fs.unwatchFile()`, `fs.watch()`.
* No support for stream-based operations (e.g., `fs.ReadStream`, `fs.WriteStream`).
For additional documentation, check out the `API Reference` below and have a look through the unit tests for more concrete examples of how things work.
Filer has other features lacking in node.js (e.g., swappable backend
storage providers, support for encryption and compression, extended attributes, etc).
#### Example
Like node.js, the API is asynchronous and most methods expect the caller to provide
a callback function (note: like node.js, Filer will supply one if it's missing).
Errors are passed to callbacks through the first parameter. As with node.js,
there is no guarantee that file system operations will be executed in the order
they are invoked. Ensure proper ordering by chaining operations in callbacks.
### Example
To create a new file system or open an existing one, create a new `FileSystem`
instance. By default, a new [IndexedDB](https://developer.mozilla.org/en/docs/IndexedDB)
database is created for each file system. The file system can also use other
backend storage providers, for example [WebSQL](http://en.wikipedia.org/wiki/Web_SQL_Database)
or even RAM (i.e., for temporary storage). See the section on [Storage Providers](#providers).
```javascript
var fs = new IDBFS.FileSystem();
var fs = new Filer.FileSystem();
fs.open('/myfile', 'w+', function(err, fd) {
if (err) throw err;
fs.close(fd, function(err) {
@ -68,19 +56,21 @@ fs.open('/myfile', 'w+', function(err, fd) {
});
```
As with node.js, there is no guarantee that file system operations will be executed in the order they are invoked. Ensure proper ordering by chaining operations in callbacks.
### API Reference
Like node.js, callbacks for methods that accept them are optional but suggested. The first callback parameter is reserved for passing errors. It will be `null` if no errors occurred and should always be checked.
Like node.js, callbacks for methods that accept them are optional but suggested (i.e., if
you omit the callback, errors will be thrown as exceptions). The first callback parameter is
reserved for passing errors. It will be `null` if no errors occurred and should always be checked.
#### IDBFS.FileSystem(options, callback)
#### Filer.FileSystem(options, callback) constructor
File system constructor, invoked to open an existing file system or create a new one. Accepts two arguments: an `options` object,
and an optional `callback`. The `options` object can specify a number of optional arguments, including:
* `name`: the name of the file system, defaults to "local"
* `flags`: one or more flags to use when creating/opening the file system. Use `'FORMAT'` to force IDBFS to format (i.e., erase) the file system
* `provider`: an explicit storage provider to use for the file system's database context provider. See below for details
File system constructor, invoked to open an existing file system or create a new one.
Accepts two arguments: an `options` object, and an optional `callback`. The `options`
object can specify a number of optional arguments, including:
* `name`: the name of the file system, defaults to `'"local'`
* `flags`: one or more flags to use when creating/opening the file system. Use `'FORMAT'` to force Filer to format (i.e., erase) the file system
* `provider`: an explicit storage provider to use for the file system's database context provider. See the section on [Storage Providers](#providers).
The `callback` function indicates when the file system is ready for use. Depending on the storage provider used, this might
be right away, or could take some time. The callback should expect an `error` argument, which will be null if everything worked.
@ -94,18 +84,23 @@ function fsReady(err) {
// Safe to use fs now...
}
fs = new IDBFS.FileSystem({
fs = new Filer.FileSystem({
name: "my-filesystem",
flags: 'FORMAT',
provider: new IDBFS.FileSystem.providers.Memory()
provider: new Filer.FileSystem.providers.Memory()
}, fsReady);
```
####IDBFS.FileSystem.providers - Storage Providers
NOTE: if the optional callback argument is not passed to the `FileSystem` constructor,
operations done on the resulting file system will be queued and run in sequence when
it becomes ready.
IDBFS can be configured to use a number of different storage providers. The provider object encapsulates all aspects
####Filer.FileSystem.providers - Storage Providers<a name="providers"></a>
Filer can be configured to use a number of different storage providers. The provider object encapsulates all aspects
of data access, making it possible to swap in different backend storage options. There are currently 4 different
providers to choose from:
* `FileSystem.providers.IndexedDB()` - uses IndexedDB
* `FileSystem.providers.WebSQL()` - uses WebSQL
* `FileSystem.providers.Fallback()` - attempts to use IndexedDB if possible, falling-back to WebSQL if necessary
@ -114,7 +109,7 @@ providers to choose from:
You can choose your provider when creating a `FileSystem`:
```javascript
var FileSystem = IDBFS.FileSystem;
var FileSystem = Filer.FileSystem;
var providers = FileSystem.providers;
// Example 1: Use the default provider (currently IndexedDB)
@ -130,20 +125,21 @@ var fs3 = new FileSystem({ provider: new providers.Fallback() });
Every provider has an `isSupported()` method, which returns `true` if the browser supports this provider:
```javascript
if( IDBFS.FileSystem.providers.WebSQL.isSupported() ) {
...
if( Filer.FileSystem.providers.WebSQL.isSupported() ) {
// WebSQL provider will work in current environment...
}
```
You can also write your own provider if you need a different backend. See the code in `src/providers` for details.
####IDBFS.FileSystem.adapters - Adapters for Storage Providers
####Filer.FileSystem.adapters - Adapters for Storage Providers
IDBFS based file systems can acquire new functionality by using adapters. These wrapper objects extend the abilities
Filer based file systems can acquire new functionality by using adapters. These wrapper objects extend the abilities
of storage providers without altering them in anway. An adapter can be used with any provider, and multiple
adapters can be used together in order to compose complex functionality on top of a provider.
There are currently 5 adapters available:
* `FileSystem.adapters.Compression(provider)` - a default compression adapter that uses [Zlib](https://github.com/imaya/zlib.js)
* `FileSystem.adapters.Encryption(passphrase, provider)` - a default encryption adapter that uses [AES encryption](http://code.google.com/p/crypto-js/#AES)
@ -153,7 +149,7 @@ You can also pick from other encryption cipher algorithms:
* `FileSystem.adapters.Rabbit(passphrase, provider)` - extends a provider with [Rabbit encryption](http://code.google.com/p/crypto-js/#Rabbit)
```javascript
var FileSystem = IDBFS.FileSystem;
var FileSystem = Filer.FileSystem;
var providers = FileSystem.providers;
var adapters = FileSystem.adapters;
@ -168,15 +164,15 @@ var fs = new FileSystem({ provider: compressionAdapter });
You can also write your own adapter if you need to add new capabilities to the providers. Adapters share the same
interface as providers. See the code in `src/providers` and `src/adapters` for many examples.
####IDBFS.Path
####Filer.Path
The node.js [path module](http://nodejs.org/api/path.html) is available via the `IDBFS.Path` object. It is
The node.js [path module](http://nodejs.org/api/path.html) is available via the `Filer.Path` object. It is
identical to the node.js version with the following differences:
* No support for `exits()` or `existsSync()`. Use `fs.stat()` instead.
* No notion of a current working directory in `resolve` (the root dir is used instead)
```javascript
var path = IDBFS.Path;
var path = Filer.Path;
var dir = path.dirname('/foo/bar/baz/asdf/quux');
// dir is now '/foo/bar/baz/asdf'
@ -201,9 +197,131 @@ For more info see the docs in the [path module](http://nodejs.org/api/path.html)
* `path.sep`
* `path.delimiter`
#### fs.stat(path, callback)
###FileSystem Instance Methods
Asynchronous stat(2). Callback gets `(error, stats)`, where `stats` is an object like
Once a `FileSystem` is created, it has the following methods. NOTE: code examples below assume
a `FileSystem` instance named `fs` has been created like so:
```javascript
var fs = new Filer.FileSystem();
```
* [fs.rename(oldPath, newPath, callback)](#rename)
* [fs.ftruncate(fd, len, callback)](#ftruncate)
* [fs.truncate(path, len, callback)](#truncate)
* [fs.stat(path, callback)](#stat)
* [fs.fstat(fd, callback)](#fstat)
* [fs.lstat(path, callback)](#lstat)
* [fs.link(srcpath, dstpath, callback)](#link)
* [fs.symlink(srcpath, dstpath, [type], callback)](#symlink)
* [fs.readlink(path, callback)](#readlink)
* [fs.realpath(path, [cache], callback)](#realpath)
* [fs.unlink(path, callback)](#unlink)
* [fs.rmdir(path, callback)](#rmdir)
* [fs.mkdir(path, [mode], callback)](#mkdir)
* [fs.readdir(path, callback)](#readdir)
* [fs.close(fd, callback)](#close)
* [fs.open(path, flags, [mode], callback)](#open)
* [fs.utimes(path, atime, mtime, callback)](#utimes)
* [fs.futimes(fd, atime, mtime, callback)](#fsutimes)
* [fs.fsync(fd, callback)](#fsync)
* [fs.write(fd, buffer, offset, length, position, callback)](#write)
* [fs.read(fd, buffer, offset, length, position, callback)](#read)
* [fs.readFile(filename, [options], callback)](#readFile)
* [fs.writeFile(filename, data, [options], callback)](#writeFile)
* [fs.appendFile(filename, data, [options], callback)](#appendFile)
* [fs.setxattr(path, name, value, [flag], callback)](#setxattr)
* [fs.fsetxattr(fd, name, value, [flag], callback)](#fsetxattr)
* [fs.getxattr(path, name, callback)](#getxattr)
* [fs.fgetxattr(fd, name, callback)](#fgetxattr)
* [fs.removexattr(path, name, callback)](#removexattr)
* [fs.fremovexattr(fd, name, callback)](#fremovexattr)
#### fs.rename(oldPath, newPath, callback)<a name="rename"></a>
Renames the file at `oldPath` to `newPath`. Asynchronous [rename(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/rename.html).
Callback gets no additional arguments.
Example:
```javascript
// Rename myfile.txt to myfile.bak
fs.rename("/myfile.txt", "/myfile.bak", function(err) {
if(err) throw err;
// myfile.txt is now myfile.bak
});
```
#### fs.ftruncate(fd, len, callback)<a name="ftruncate"></a>
Change the size of the file represented by the open file descriptor `fd` to be length
`len` bytes. Asynchronous [ftruncate(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/ftruncate.html).
If the file is larger than `len`, the extra bytes will be discarded; if smaller, its size will
be increased, and the extended area will appear as if it were zero-filled. See also [fs.truncate()](#truncate).
Example:
```javascript
// Create a file, shrink it, expand it.
var buffer = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw error;
fs.write(fd, buffer, 0, buffer.length, 0, function(err, result) {
if(err) throw error;
fs.ftruncate(fd, 3, function(err) {
if(err) throw error;
// /myfile is now 3 bytes in length, rest of data discarded
fs.ftruncate(fd, 50, function(err) {
if(err) throw error;
// /myfile is now 50 bytes in length, with zero padding at end
fs.close(fd);
});
});
});
});
});
```
#### fs.truncate(path, len, callback)<a name="truncate"></a>
Change the size of the file at `path` to be length `len` bytes. Asynchronous [truncate(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/truncate.html). If the file is larger than `len`, the extra bytes will be discarded; if smaller, its size will
be increased, and the extended area will appear as if it were zero-filled. See also [fs.ftruncate()](#ftruncate).
Example:
```javascript
// Create a file, shrink it, expand it.
var buffer = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw error;
fs.write(fd, buffer, 0, buffer.length, 0, function(err, result) {
if(err) throw error;
fs.close(fd, function(err) {
if(err) throw error;
fs.truncate('/myfile', 3, function(err) {
if(err) throw error;
// /myfile is now 3 bytes in length, rest of data discarded
fs.truncate('/myfile', 50, function(err) {
if(err) throw error;
// /myfile is now 50 bytes in length, with zero padding at end
});
});
});
});
});
```
#### fs.stat(path, callback)<a name="stat"></a>
Obtain file status about the file at `path`. Asynchronous [stat(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/stat.html).
Callback gets `(error, stats)`, where `stats` is an object with the following properties:
```
{
@ -214,62 +332,410 @@ Asynchronous stat(2). Callback gets `(error, stats)`, where `stats` is an object
atime: <number> // last access time
mtime: <number> // last modified time
ctime: <number> // creation time
type: <string> // file type (FILE, DIRECTORY, ...)
type: <string> // file type (FILE, DIRECTORY, SYMLINK)
}
```
#### fs.fstat(fd, callback)
If the file at `path` is a symbolik link, the file to which it links will be used instead.
To get the status of a symbolic link file, use [fs.lstat()](#lstat) instead.
Asynchronous stat(2). Callback gets `(error, stats)`. See `fs.stat`.
Examples:
#### fs.link(srcPath, dstPath, callback)
```javascript
// Check if a directory exists
function dirExists(path, callback) {
fs.stat(path, function(err, stats) {
if(err) return callback(err);
var exists = stats.type === "DIRECTORY";
callback(null, exists);
});
};
Asynchronous link(2). Callback gets no additional arguments.
// Get the size of a file in KB
function fileSize(path, callback) {
fs.stat(path, function(err, stats) {
if(err) return callback(err);
var kb = stats.size / 1000;
callback(null, kb);
});
}
```
#### fs.unlink(path, callback)
#### fs.fstat(fd, callback)<a name="fstat"></a>
Asynchronous unlink(2). Callback gets no additional arguments.
Obtain information about the open file known by the file descriptor `fd`.
Asynchronous [fstat(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/fstat.html).
Callback gets `(error, stats)`. `fstat()` is identical to `stat()`, except that the file to be stat-ed is
specified by the open file descriptor `fd` instead of a path. See also [fs.stat](#stat)
#### fs.rename(oldPath, newPath, callback)#
Example:
Asynchronous rename(2). Callback gets no additional arguments.
```javascript
fs.open("/file.txt", "r", function(err, fd) {
if(err) throw err;
fs.fstat(fd, function(err, stats) {
if(err) throw err;
// do something with stats object
// ...
fs.close(fd);
});
});
```
#### fs.rmdir(path, callback)
#### fs.lstat(path, callback)<a name="lstat"></a>
Asynchronous rmdir(2). Callback gets no additional arguments.
Obtain information about the file at `path` (i.e., the symbolic link file itself) vs.
the destination file to which it links. Asynchronous [lstat(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/lstat.html).
Callback gets `(error, stats)`. See also [fs.stat](#stat).
#### fs.mkdir(path, callback)
Example:
Asynchronous mkdir(2). Callback gets no additional arguments.
```javascript
// Create a symbolic link, /data/logs/current to /data/logs/august
// and get info about the symbolic link file, and linked file.
fs.link("/data/logs/august", "/data/logs/current", function(err) {
if(err) throw err;
#### fs.close(fd, callback)
// Get status of linked file, /data/logs/august
fs.stat("/data/logs/current", function(err, stats) {
if(err) throw err;
// Size of /data/logs/august
var size = stats.size;
});
Asynchronous close(2). Callback gets no additional arguments.
// Get status of symbolic link file itself
fs.lstat("/data/logs/current", function(err, stats) {
if(err) throw err;
// Size of /data/logs/current
var size = stats.size;
});
});
````
#### fs.open(path, flags, callback)
#### fs.link(srcPath, dstPath, callback)<a name="link"></a>
Asynchronous open(2). Flags can be
Create a (hard) link to the file at `srcPath` named `dstPath`. Asynchronous [link(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/link.html). Callback gets no additional arguments. Links are directory entries that point to the same file node.
* `'r'`: Open file for reading. An exception occurs if the file does not exist.
* `'r+'`: Open file for reading and writing. An exception occurs if the file does not exist.
* `'w'`: Open file for writing. The file is created (if it does not exist) or truncated (if it exists).
* `'w+'`: Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).
* `'a'`: Open file for appending. The file is created if it does not exist.
* `'a+'`: Open file for reading and appending. The file is created if it does not exist.
Example:
Callback gets `(error, fd)`, where `fd` is the file descriptor.
```javascript
fs.link('/logs/august.log', '/logs/current', function(err) {
if(err) throw err;
fs.readFile('/logs/current', 'utf8', function(err, data) {
// data is the contents of /logs/august.log
var currentLog = data;
});
});
```
Unlike node.js, IDBFS does not accept the optional `mode` parameter since it doesn't yet implement file permissions.
#### fs.symlink(srcPath, dstPath, [type], callback)<a name="symlink"></a>
#### fs.write(fd, buffer, offset, length, position, callback)
Create a symbolic link to the file at `dstPath` containing the path `srcPath`. Asynchronous [symlink(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/symlink.html). Callback gets no additional arguments.
Symbolic links are files that point to other paths.
Write bytes from `buffer` to the file specified by `fd`, where `offset` and `length` describe the part of the buffer to be written. The `position` refers to the offset from the beginning of the file where this data should be written. If `position` is `null`, the data will be written at the current position. See pwrite(2).
NOTE: Filer allows for, but ignores the optional `type` parameter used in node.js.
The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes written.
Example:
#### fs.writeFile(filename, data, [options], callback)
```javascript
fs.symlink('/logs/august.log', '/logs/current', function(err) {
if(err) throw err;
fs.readFile('/logs/current', 'utf8', function(err, data) {
// data is the contents of /logs/august.log
var currentLog = data;
});
});
```
Asynchronously writes data to a file. `data` can be a string or a buffer, in which case any encoding option is ignored. The `options` argument is optional, and can take the form `"utf8"` (i.e., an encoding) or be an object literal: `{ encoding: "utf8", flag: "w" }`. If no encoding is specified, and `data` is a string, the encoding defaults to `'utf8'`. The callback gets `(error)`.
#### fs.readlink(path, callback)<a name="readlink"></a>
Reads the contents of a symbolic link. Asynchronous [readlink(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/readlink.html). Callback gets `(error, linkContents)`, where `linkContents` is a string containing the symbolic link's link path.
Example:
```javascript
fs.symlink('/logs/august.log', '/logs/current', function(error) {
if(error) throw error;
fs.readlink('/logs/current', function(error, linkContents) {
// linkContents is now '/logs/august.log'
});
});
```
#### fs.realpath(path, [cache], callback)<a name="realpath"></a>
NOTE: Not yet implemented, see https://github.com/js-platform/filer/issues/85
#### fs.unlink(path, callback)<a name="unlink"></a>
Removes the directory entry located at `path`. Asynchronous [unlink(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/unlink.html).
Callback gets no additional arguments. If `path` names a symbolic link, the symbolic link will be removed
(i.e., not the linked file). Otherwise, the filed named by `path` will be removed (i.e., deleted).
Example:
```javascript
// Delete regular file /backup.old
fs.unlink('/backup.old', function(err) {
if(err) throw err;
// /backup.old is now removed
});
```
#### fs.rmdir(path, callback)<a name="rmdir"></a>
Removes the directory at `path`. Asynchronous [rmdir(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/rmdir.html).
Callback gets no additional arguments. The operation will fail if the directory at `path` is not empty.
Example:
```javascript
/**
* Given the following dir structure, remove docs/
* /docs
* a.txt
*/
// Start by deleting the files in docs/, then remove docs/
fs.unlink('/docs/a.txt', function(err) {
if(err) throw err;
fs.rmdir('/docs', function(err) {
if(err) throw err;
});
});
```
#### fs.mkdir(path, [mode], callback)<a name="mkdir"></a>
Makes a directory with name supplied in `path` argument. Asynchronous [mkdir(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/mkdir.html). Callback gets no additional arguments.
NOTE: Filer allows for, but ignores the optional `mode` argument used in node.js.
Example:
```javascript
// Create /home and then /home/carl directories
fs.mkdir('/home', function(err) {
if(err) throw err;
fs.mkdir('/home/carl', function(err) {
if(err) throw err;
// directory /home/carl now exists
});
});
```
#### fs.readdir(path, callback)<a name="readdir"></a>
Reads the contents of a directory. Asynchronous [readdir(3)](http://pubs.opengroup.org/onlinepubs/009695399/functions/readdir.html).
Callback gets `(error, files)`, where `files` is an array containing the names of each directory entry (i.e., file, directory, link) in the directory, excluding `.` and `..`.
Example:
```javascript
/**
* Given the following dir structure:
* /docs
* a.txt
* b.txt
* c/
*/
fs.readdir('/docs', function(err, files) {
if(err) throw err;
// files now contains ['a.txt', 'b.txt', 'c']
});
```
#### fs.close(fd, callback)<a name="close"></a>
Closes a file descriptor. Asynchronous [close(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/close.html).
Callback gets no additional arguments.
Example:
```javascript
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw error;
// Do something with open file descriptor `fd`
// Close file descriptor when done
fs.close(fd);
});
```
#### fs.open(path, flags, [mode], callback)<a name="open"></a>
Opens a file. Asynchronous [open(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/open.html).
Callback gets `(error, fd)`, where `fd` is the file descriptor. The `flags` argument can be:
* `'r'`: Open file for reading. An exception occurs if the file does not exist.
* `'r+'`: Open file for reading and writing. An exception occurs if the file does not exist.
* `'w'`: Open file for writing. The file is created (if it does not exist) or truncated (if it exists).
* `'w+'`: Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).
* `'a'`: Open file for appending. The file is created if it does not exist.
* `'a+'`: Open file for reading and appending. The file is created if it does not exist.
NOTE: Filer allows for, but ignores the optional `mode` argument used in node.js.
Example:
```javascript
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw error;
// Do something with open file descriptor `fd`
// Close file descriptor when done
fs.close(fd);
});
```
#### fs.utimes(path, atime, mtime, callback)<a name="utimes"></a>
Changes the file timestamps for the file given at path `path`. Asynchronous [utimes(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/utimes.html). Callback gets no additional arguments. Both `atime` (access time) and `mtime` (modified time) arguments should be a JavaScript Date.
Example:
```javascript
var now = Date.now();
fs.utimes('/myfile.txt', now, now, function(err) {
if(err) throw err;
// Access Time and Modified Time for /myfile.txt are now updated
});
```
#### fs.futimes(fd, atime, mtime, callback)<a name="futimes"></a>
Changes the file timestamps for the open file represented by the file descriptor `fd`. Asynchronous [utimes(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/utimes.html). Callback gets no additional arguments. Both `atime` (access time) and `mtime` (modified time) arguments should be a JavaScript Date.
Example:
```javascript
fs.open('/myfile.txt', function(err, fd) {
if(err) throw err;
var now = Date.now();
fs.futimes(fd, now, now, function(err) {
if(err) throw err;
// Access Time and Modified Time for /myfile.txt are now updated
fs.close(fd);
});
});
```
#### fs.fsync(fd, callback)<a name="fsync"></a>
NOTE: Not yet implemented, see https://github.com/js-platform/filer/issues/87
#### fs.write(fd, buffer, offset, length, position, callback)<a name="write"></a>
Writes bytes from `buffer` to the file specified by `fd`. Asynchronous [write(2), pwrite(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/write.html). The `offset` and `length` arguments describe the part of the buffer to be written. The `position` refers to the offset from the beginning of the file where this data should be written. If `position` is `null`, the data will be written at the current position. The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes written.
NOTE: Filer currently writes the entire buffer in a single operation. However, future versions may do it in chunks.
Example:
```javascript
// Create a file with the following bytes.
var buffer = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw error;
var expected = buffer.length, written = 0;
function writeBytes(offset, position, length) {
length = length || buffer.length - written;
fs.write(fd, buffer, offset, length, position, function(err, nbytes) {
if(err) throw error;
// nbytes is now the number of bytes written, between 0 and buffer.length.
// See if we still have more bytes to write.
written += nbytes;
if(written < expected)
writeBytes(written, null);
else
fs.close(fd);
});
}
writeBytes(0, 0);
});
```
#### fs.read(fd, buffer, offset, length, position, callback)<a name="read"></a>
Read bytes from the file specified by `fd` into `buffer`. Asynchronous [read(2), pread(2)](http://pubs.opengroup.org/onlinepubs/009695399/functions/read.html). The `offset` and `length` arguments describe the part of the buffer to be used. The `position` refers to the offset from the beginning of the file where this data should be read. If `position` is `null`, the data will be written at the current position. The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes read.
NOTE: Filer currently reads into the buffer in a single operation. However, future versions may do it in chunks.
Example:
```javascript
fs.open('/myfile', 'r', function(err, fd) {
if(err) throw error;
// Determine size of file
fs.fstat(fd, function(err, stats) {
if(err) throw error;
// Create a buffer large enough to hold the file's contents
var nbytes = expected = stats.size;
var buffer = new Uint8Array(nbytes);
var read = 0;
function readBytes(offset, position, length) {
length = length || buffer.length - read;
fs.read(fd, buffer, offset, length, position, function(err, nbytes) {
if(err) throw error;
// nbytes is now the number of bytes read, between 0 and buffer.length.
// See if we still have more bytes to read.
read += nbytes;
if(read < expected)
readBytes(read, null);
else
fs.close(fd);
});
}
readBytes(0, 0);
});
});
```
#### fs.readFile(filename, [options], callback)<a name="readFile"></a>
Reads the entire contents of a file. The `options` argument is optional, and can take the form `"utf8"` (i.e., an encoding) or be an object literal: `{ encoding: "utf8", flag: "r" }`. If no encoding is specified, the raw binary buffer is returned via the callback. The callback gets `(error, data)`, where data is the contents of the file.
Examples:
```javascript
// Read UTF8 text file
fs.readFile('/myfile.txt', 'utf8', function (err, data) {
if (err) throw err;
// data is now the contents of /myfile.txt (i.e., a String)
});
// Read binary file
fs.readFile('/myfile.txt', function (err, data) {
if (err) throw err;
// data is now the contents of /myfile.txt (i.e., an Uint8Array of bytes)
});
```
#### fs.writeFile(filename, data, [options], callback)<a name="writeFile"></a>
Writes data to a file. `data` can be a string or a buffer, in which case any encoding option is ignored. The `options` argument is optional, and can take the form `"utf8"` (i.e., an encoding) or be an object literal: `{ encoding: "utf8", flag: "w" }`. If no encoding is specified, and `data` is a string, the encoding defaults to `'utf8'`. The callback gets `(error)`.
Examples:
```javascript
// Write UTF8 text file
@ -278,93 +744,148 @@ fs.writeFile('/myfile.txt', "...data...", function (err) {
});
// Write binary file
var buffer = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);
fs.writeFile('/myfile', buffer, function (err) {
if (err) throw err;
});
```
#### fs.read(fd, buffer, offset, length, position, callback)
#### fs.appendFile(filename, data, [options], callback)<a name="appendFile"></a>
Read bytes from the file specified by `fd` into `buffer`, where `offset` and `length` describe the part of the buffer to be used. The `position` refers to the offset from the beginning of the file where this data should be read. If `position` is `null`, the data will be written at the current position. See pread(2).
NOTE: Not yet implemented, see https://github.com/js-platform/filer/issues/88
The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes read.
#### fs.setxattr(path, name, value, [flag], callback)<a name="setxattr"></a>
#### fs.readFile(filename, [options], callback)
Asynchronously reads the entire contents of a file. The `options` argument is optional, and can take the form `"utf8"` (i.e., an encoding) or be an object literal: `{ encoding: "utf8", flag: "r" }`. If no encoding is specified, the raw binary buffer is returned on the callback. The callback gets `(error, data)`, where data is the contents of the file.
```javascript
// Read UTF8 text file
fs.readFile('/myfile.txt', 'utf8', function (err, data) {
if (err) throw err;
console.log(data);
});
// Read binary file
fs.readFile('/myfile.txt', function (err, data) {
if (err) throw err;
console.log(data);
});
```
#### fs.lseek(fd, offset, whence, callback)
Asynchronous lseek(2), where `whence` can be `SET`, `CUR`, or `END`. Callback gets `(error, pos)`, where `pos` is the resulting offset, in bytes, from the beginning of the file.
#### fs.readdir(path, callback)
Asynchronous readdir(3). Reads the contents of a directory. Callback gets `(error, files)`, where `files` is an array containing the names of each file in the directory, excluding `.` and `..`.
#### fs.symlink(srcPath, dstPath, callback)
Asynchronous symlink(2). Callback gets no additional arguments.
Unlike node.js, IDBFS does not accept the optional `type` parameter.
#### fs.readlink(path, callback)
Asynchronous readlink(2). Callback gets `(error, linkContents)`, where `linkContents` is a string containing the path to which the symbolic link links to.
#### fs.lstat(path, callback)
Asynchronous lstat(2). Callback gets `(error, stats)`, See `fs.stat`.
#### fs.truncate(path, length, callback)
Asynchronous truncate(2). Callback gets no additional arguments.
#### fs.ftruncate(fd, length, callback)
Asynchronous ftruncate(2). Callback gets no additional arguments.
#### fs.utimes(path, atime, mtime, callback)
Asynchronous utimes(3). Callback gets no additional arguments.
#### fs.futimes(fd, atime, mtime, callback)
Asynchronous futimes(3). Callback gets no additional arguments.
#### fs.setxattr(path, name, value, [flag], callback)
Asynchronous setxattr(2). Sets an extended attribute of a file or directory.
The optional flag parameter can be set to the following:
XATTR_CREATE: ensures that the extended attribute with the given name will be new and not previously set. If an attribute with the given name already exists, it will return EExists error to the callback.
XATTR_REPLACE: ensures that an extended attribute with the given name already exists. If an attribute with the given name does not exist, it will return an ENoAttr error to the callback.
Sets an extended attribute of a file or directory named `path`. Asynchronous [setxattr(2)](http://man7.org/linux/man-pages/man2/setxattr.2.html).
The optional `flag` parameter can be set to the following:
* `XATTR_CREATE`: ensures that the extended attribute with the given name will be new and not previously set. If an attribute with the given name already exists, it will return an `EExists` error to the callback.
* `XATTR_REPLACE`: ensures that an extended attribute with the given name already exists. If an attribute with the given name does not exist, it will return an `ENoAttr` error to the callback.
Callback gets no additional arguments.
#### fs.getxattr(path, name, callback)
Example:
Asynchronous getxattr(2). Gets an extended attribute value for a file or directory.
```javascript
fs.writeFile('/myfile', 'data', function(err) {
if(err) throw err;
Callback gets `(error, value)`, where value is the value for the extended attribute.
// Set a simple extended attribute on /myfile
fs.setxattr('/myfile', 'extra', 'some-information', function(err) {
if(err) throw err;
#### fs.fsetxattr(fd, name, value, [flag], callback)
// /myfile now has an added attribute of extra='some-information'
});
Asynchronous fsetxattr(2). See `fs.setxattr` for flag options. Callback gets no additional arguments.
// Set a complex object attribute on /myfile
fs.setxattr('/myfile', 'extra-complex', { key1: 'value1', key2: 103 }, function(err) {
if(err) throw err;
#### fs.fgetxattr(fs, name, callback)
// /myfile now has an added attribute of extra={ key1: 'value1', key2: 103 }
});
});
```
Asynchronous fgetxattr(2). Callback gets `(error, value)`, See `fs.getxattr`.
#### fs.fsetxattr(fd, name, value, [flag], callback)<a name="fsetxattr"></a>
Sets an extended attribute of the file represented by the open file descriptor `fd`. Asynchronous [setxattr(2)](http://man7.org/linux/man-pages/man2/setxattr.2.html). See `fs.setxattr` for more details. Callback gets no additional arguments.
Example:
```javascript
fs.open('/myfile', 'w', function(err, fd) {
if(err) throw err;
// Set a simple extended attribute on fd for /myfile
fs.fsetxattr(fd, 'extra', 'some-information', function(err) {
if(err) throw err;
// /myfile now has an added attribute of extra='some-information'
});
// Set a complex object attribute on fd for /myfile
fs.fsetxattr(fd, 'extra-complex', { key1: 'value1', key2: 103 }, function(err) {
if(err) throw err;
// /myfile now has an added attribute of extra={ key1: 'value1', key2: 103 }
});
fs.close(fd);
});
```
#### fs.getxattr(path, name, callback)<a name="getxattr"></a>
Gets an extended attribute value for a file or directory. Asynchronous [getxattr(2)](http://man7.org/linux/man-pages/man2/getxattr.2.html).
Callback gets `(error, value)`, where `value` is the value for the extended attribute named `name`.
Example:
```javascript
// Get the value of the extended attribute on /myfile named `extra`
fs.getxattr('/myfile', 'extra', function(err, value) {
if(err) throw err;
// `value` is now the value of the extended attribute named `extra` for /myfile
});
```
#### fs.fgetxattr(fd, name, callback)<a name="fgetxattr"></a>
Gets an extended attribute value for the file represented by the open file descriptor `fd`.
Asynchronous [getxattr(2)](http://man7.org/linux/man-pages/man2/getxattr.2.html).
See `fs.getxattr` for more details. Callback gets `(error, value)`, where `value` is the value for the extended attribute named `name`.
Example:
```javascript
// Get the value of the extended attribute on /myfile named `extra`
fs.open('/myfile', 'r', function(err, fd) {
if(err) throw err;
fs.fgetxattr(fd, 'extra', function(err, value) {
if(err) throw err;
// `value` is now the value of the extended attribute named `extra` for /myfile
});
fs.close(fd);
});
```
#### fs.removexattr(path, name, callback)<a name="removexattr"></a>
Removes the extended attribute identified by `name` for the file given at `path`. Asynchronous [removexattr(2)](http://man7.org/linux/man-pages/man2/removexattr.2.html). Callback gets no additional arguments.
Example:
```javascript
// Remove an extended attribute on /myfile
fs.removexattr('/myfile', 'extra', function(err) {
if(err) throw err;
// The `extra` extended attribute on /myfile is now gone
});
```
#### fs.fremovexattr(fd, name, callback)<a name="fremovexattr"></a>
Removes the extended attribute identified by `name` for the file represented by the open file descriptor `fd`.
Asynchronous [removexattr(2)](http://man7.org/linux/man-pages/man2/removexattr.2.html). See `fs.removexattr` for more details.
Callback gets no additional arguments.
Example:
```javascript
// Remove an extended attribute on /myfile
fs.open('/myfile', 'r', function(err, fd) {
if(err) throw err;
fs.fremovexattr(fd, 'extra', function(err) {
if(err) throw err;
// The `extra` extended attribute on /myfile is now gone
});
fs.close(fd);
});
```