JavaScript OS.Constants

JavaScript module OS.Constants contains Operating System-specific constants. This module is largely a companion to js-ctypes.

Using OS.Constants

From the main thread

To initialize OS.Constants for use in the main thread, add the following snippet to your code:

 Components.classes["@mozilla.org/net/osfileconstantsservice;1"].
    getService(Components.interfaces.nsIOSFileConstantsService).
    init();

From a chrome worker

No initialization is required. Module OS.Constants is always available for chrome workers.

OS.Constants.Sys

Constants related to system configuration.

`Name`	The name of the operating system (e.g. "Darwin").
DEBUG	Set to true on debug build configurations, non-existent otherwise.

OS.Constants.Path

Paths of well-known files and directories.

`libxul`	The path to the file containing libxul. Useful, for instance, to access the platform code from JavaScript in conjunction with js-ctypes.
`profileDir`	The path to the current profile.
`homeDir`	The path to the user's home directory.
`desktopDir`	The path to the user's desktop directory (or, if it doesn't exist, the path to the user's home directory).
`winAppDataDir`	The path to the user's application data directory.
`winStartMenuProgsDir`	The path to the programs subdirectory in the user's start menu.
`macUserLibDir`	The path to the user's Library directory.
`macLocalApplicationsDir`	The path to the local Applications directory.

OS.Constants.libc

Constants for interacting with libc. Useful mostly for using js-ctypes to interact with the following platforms:

MacOS X;
Android;
Linux;
other variants of Unix.

OS.Constants.libc is available on all platforms, although some constants are not defined everywhere. Before using a constant, you should check that it is defined.

Error values

EACCES	Permission denied
EAGAIN	Resource temporarily unavailable
EBADF	Bad file descriptor
EEXIST	File exists
EFAULT	Bad address
EFBIG	File too large
EINVAL	Invalid argument
EIO	Input/output error
EISDIR	Is a directory
ELOOP	(Not always available under Windows) Too many levels of symbolic links.
EMFILE	Too many open files in the process
ENAMETOOLONG	Name too long
ENFILE	Too many open files on the system
ENOENT	No such file or directory
ENOMEM	Cannot allocate memory
ENOSPC	No space on device
ENOTDIR	Is not a directory
ENXIO	Device no configured or does not support operation
EOPNOTSUPP	(Not always available under Windows) Operation not supported.
EOVERFLOW	(Not always available under Windows) Value too large to be stored in datatype.
EPERM	Operation not permitted
ERANGE	Result too large
ETIMEDOUT	(Not always available under Windows) Operation timed out.
EWOULDBLOCK	(Not always available under Windows) Operation would block.
EXDEV	Cross-device link

Opening files

Unix access rights

Defined on all platforms but meaningful only on Unix.

S_IRWXU	Current User can Read, Write, eXecute the file. Equivalent to `S_IRUSR \| S_IWUSR \| S_IXUSR`.
S_IRUSR	Current User can Read the file.
S_IWUSR	Current User can Write (modify) the file.
S_IXUSR	Current User can eXecute the file.
S_IRWXG	Current GRouP of the current user can Read, Write, eXecute the file. Equivalent to `S_IRGRP \| S_IWGRP \| S_IXGRP`.
S_IRGRP	Current GRouP of the current user can Read the file.
S_IWGRP	Current GRouP of the current user can Write (modify) the file.
S_IXGRP	Current GRouP of the current user can eXecute the file.
S_IRWXO	All Other users can Read, Write, eXecute the file. Equivalent to `S_IROTH \| S_IWOTH \| S_IXOTH`.
S_IROTH	All Other users can Read the file.
S_IWOTH	All Other users can Write (modify) the file.
S_IXOTH	All Other users can eXecute the file.

Unix opening mode

O_APPEND	Open the file for appending.
O_CREAT	Create the file if it does not exist yet.
O_DIRECTORY	(Linux only) Succeed only of the file is a directory.
O_EVTONLY	Descriptor requested for event notifications only.
O_EXCL	Raise an error if O_CREAT is set and the file exists.
O_EXLOCK	Atomically obtain an exclusive lock.
O_LARGEFILE
O_NOFOLLOW	Do not follow symbolic links.
O_NONBLOCK	Do not block on open or for data to become available.
O_RDONLY	Open the file for read only.
O_RDWR	Open the file for read and write.
O_RSYNC
O_SHLOCK	Atomically obtain a shared lock.
O_SYMLINK	Allow opening of symbolic links.
O_SYNC	(Linux only) Open for purely synchronous access.
O_TRUNC	Truncate the file.
O_WRONLY	Open the file for write only.

OS.Constants.Win

Constants for interacting with the Windows API. OS.Constants.Win is undefined on non-Windows platforms. Useful mostly in conjunction with js-ctypes.

(tbd)