diff --git a/README.md b/README.md index 913bcda..7b8b385 100644 --- a/README.md +++ b/README.md @@ -15,3 +15,269 @@ NOTES: - On ARM64 linux, at least, 3 of the tests fail. - Upstream seems abandoned. - On ARM64 linux upstream doesn't install, due to the shared library binary that they ship, which is wrong. + +## API + +In order to create a FUSE mountpoint, you first need to create a `Fuse` object that wraps a set of implemented FUSE syscall handlers: + +#### `const fuse = new Fuse(mnt, handlers, opts = {})` + +Create a new `Fuse` object. + +`mnt` is the string path of your desired mountpoint. + +`handlers` is an object mapping syscall names to implementations. The complete list of available syscalls is described below. As an example, if you wanted to implement a filesystem that only supports `getattr`, your handle object would look like: + +```js +{ + getattr: function (path, cb) { + if (path === '/') return process.nextTick(cb, null, stat({ mode: 'dir', size: 4096 })) + if (path === '/test') return process.nextTick(cb, null, stat({ mode: 'file', size: 11 })) + return process.nextTick(cb, Fuse.ENOENT) + } +} +``` + +`opts` can be include: + +``` + displayFolder: 'Folder Name', // Add a name/icon to the mount volume on OSX, + debug: false, // Enable detailed tracing of operations. + force: false, // Attempt to unmount a the mountpoint before remounting. + mkdir: false // Create the mountpoint before mounting. +``` + +### FUSE API + +Most of the [FUSE api](http://fuse.sourceforge.net/doxygen/structfuse__operations.html) is supported. In general the callback for each op should be called with `cb(returnCode, [value])` where the return code is a number (`0` for OK and `< 0` for errors). See below for a list of POSIX error codes. + +#### `ops.init(cb)` + +Called on filesystem init. + +#### `ops.access(path, mode, cb)` + +Called before the filesystem accessed a file + +#### `ops.statfs(path, cb)` + +Called when the filesystem is being stat'ed. Accepts a fs stat object after the return code in the callback. + +``` js +ops.statfs = function (path, cb) { + cb(0, { + bsize: 1000000, + frsize: 1000000, + blocks: 1000000, + bfree: 1000000, + bavail: 1000000, + files: 1000000, + ffree: 1000000, + favail: 1000000, + fsid: 1000000, + flag: 1000000, + namemax: 1000000 + }) +} +``` + +#### `ops.getattr(path, cb)` + +Called when a path is being stat'ed. Accepts a stat object (similar to the one returned in `fs.stat(path, cb)`) after the return code in the callback. + +``` js +ops.getattr = function (path, cb) { + cb(0, { + mtime: new Date(), + atime: new Date(), + ctime: new Date(), + size: 100, + mode: 16877, + uid: process.getuid(), + gid: process.getgid() + }) +} +``` + +#### `ops.fgetattr(path, fd, cb)` + +Same as above but is called when someone stats a file descriptor + +#### `ops.flush(path, fd, cb)` + +Called when a file descriptor is being flushed + +#### `ops.fsync(path, fd, datasync, cb)` + +Called when a file descriptor is being fsync'ed. + +#### `ops.fsyncdir(path, fd, datasync, cb)` + +Same as above but on a directory + +#### `ops.readdir(path, cb)` + +Called when a directory is being listed. Accepts an array of file/directory names after the return code in the callback + +``` js +ops.readdir = function (path, cb) { + cb(0, ['file-1.txt', 'dir']) +} +``` + +#### `ops.truncate(path, size, cb)` + +Called when a path is being truncated to a specific size + +#### `ops.ftruncate(path, fd, size, cb)` + +Same as above but on a file descriptor + +#### `ops.readlink(path, cb)` + +Called when a symlink is being resolved. Accepts a pathname (that the link should resolve to) after the return code in the callback + +``` js +ops.readlink = function (path, cb) { + cb(null, 'file.txt') // make link point to file.txt +} +``` + +#### `ops.chown(path, uid, gid, cb)` + +Called when ownership of a path is being changed + +#### `ops.chmod(path:string, mode:number, cb)` + +Called when the mode of a path is being changed. Always called +with mode a number (not a string). + +#### `ops.mknod(path, mode, dev, cb)` + +Called when a new device file is being made. + +#### `ops.setxattr(path, name, value, position, flags, cb)` + +Called when extended attributes is being set (see the extended docs for your platform). + +Copy the `value` buffer somewhere to store it. + +The position argument is mostly a legacy argument only used on MacOS but see the getxattr docs +on Mac for more on that (you probably don't need to use that). + +#### `ops.getxattr(path, name, position, cb)` + +Called when extended attributes is being read. + +Return the extended attribute as the second argument to the callback (needs to be a buffer). +If no attribute is stored return `null` as the second argument. + +The position argument is mostly a legacy argument only used on MacOS but see the getxattr docs +on Mac for more on that (you probably don't need to use that). + +#### `ops.listxattr(path, cb)` + +Called when extended attributes of a path are being listed. + +Return a list of strings of the names of the attributes you have stored as the second argument to the callback. + +#### `ops.removexattr(path, name, cb)` + +Called when an extended attribute is being removed. + +#### `ops.open(path, flags, cb)` + +Called when a path is being opened. `flags` in a number containing the permissions being requested. Accepts a file descriptor after the return code in the callback. + +``` js +var toFlag = function(flags) { + flags = flags & 3 + if (flags === 0) return 'r' + if (flags === 1) return 'w' + return 'r+' +} + +ops.open = function (path, flags, cb) { + var flag = toFlag(flags) // convert flags to a node style string + ... + cb(0, 42) // 42 is a file descriptor +} +``` + +#### `ops.opendir(path, flags, cb)` + +Same as above but for directories + +#### `ops.read(path, fd, buffer, length, position, cb)` + +Called when contents of a file is being read. You should write the result of the read to the `buffer` and return the number of bytes written as the first argument in the callback. +If no bytes were written (read is complete) return 0 in the callback. + +``` js +var data = new Buffer('hello world') + +ops.read = function (path, fd, buffer, length, position, cb) { + if (position >= data.length) return cb(0) // done + var part = data.slice(position, position + length) + part.copy(buffer) // write the result of the read to the result buffer + cb(part.length) // return the number of bytes read +} +``` + +#### `ops.write(path, fd, buffer, length, position, cb)` + +Called when a file is being written to. You can get the data being written in `buffer` and you should return the number of bytes written in the callback as the first argument. + +``` js +ops.write = function (path, fd, buffer, length, position, cb) { + console.log('writing', buffer.slice(0, length)) + cb(length) // we handled all the data +} +``` + +#### `ops.release(path, fd, cb)` + +Called when a file descriptor is being released. Happens when a read/write is done etc. + +#### `ops.releasedir(path, fd, cb)` + +Same as above but for directories + +#### `ops.create(path, mode, cb)` + +Called when a new file is being opened. + +#### `ops.utimens(path, atime, mtime, cb)` + +Called when the atime/mtime of a file is being changed. + +#### `ops.unlink(path, cb)` + +Called when a file is being unlinked. + +#### `ops.rename(src, dest, cb)` + +Called when a file is being renamed. + +#### `ops.link(src, dest, cb)` + +Called when a new link is created. + +#### `ops.symlink(src, dest, cb)` + +Called when a new symlink is created + +#### `ops.mkdir(path, mode, cb)` + +Called when a new directory is being created + +#### `ops.rmdir(path, cb)` + +Called when a directory is being removed + +## License + +MIT for these bindings. + +See the [libfuse](https://github.com/libfuse/libfuse) license for Linux/BSD +for the FUSE shared library license, which is LGPL