The missing POSIX system calls
npm install santosh-posixThe missing POSIX system calls for Node.
* Q: Why?
* A: Because the Node core has a limited set of POSIX system calls.
* Q: How mature/stable is this?
* A: Each version released in NPM has decent automated test coverage. The
module is still new and not battle-hardened.
* Q: I have a feature request/bug report...
* A: Please submit a pull request or an issue ticket at
https://github.com/melor/node-posix
Other extension modules that provide POSIX/Unix/Linux/BSD functionality:
* glob() http://search.npmjs.org/#/glob
* getrusage() http://search.npmjs.org/#/getrusage
* chroot(), daemonization http://search.npmjs.org/#/daemon-tools
* iconv() http://search.npmjs.org/#/iconv
* mmap() http://search.npmjs.org/#/mmap
* PAM authentication, flock() and mkstemp() http://search.npmjs.org/#/unixlib
getgid() in Node core as process.getgidgetuid() in Node core as process.getuidsetgid() in Node core as process.setgidsetuid() in Node core as process.setuid, NOTE: should be used carefullyulimit() is obsolete, use posix.setrlimit() instead* Installation: npm install posix
* In your code: var posix = require('posix');
Changes the root directory of the calling process to that specified in path.
This directory will be used for pathnames beginning with /. The root
directory is inherited by all children of the calling process.
The working directory is also automatically set to the new root directory.
NOTE: Please be aware of the limitations of chroot jails:
* "Best Practices for UNIX chroot() Operations":
http://www.unixwiz.net/techtips/chroot-practices.html
* "How to break out of a chroot() jail":
http://www.bpfh.net/simes/computing/chroot-break.html
Example:
posix.chroot('/somewhere/safe');
Returns the current process's effective group ID.
console.log('Effective GID: ' + posix.getegid());
Returns the current process's effective user ID.
console.log('Effective UID: ' + posix.geteuid());
Get the group database entry for the given group. group can be specified
either as a numeric GID or a group name (string).
var util = require('util');
util.inspect(posix.getgrnam('wheel'));
Example output of above:
{ name: 'wheel', passwd: '*', gid: 0, members: [ 'root' ] }
Return the process group ID of the current process (posix.getpgid(0)) or of
a process of a given PID (posix.getpgid(PID)).
console.log('My PGID: ' + posix.getpgid(0));
console.log('init's PGID: ' + posix.getpgid(1));
Returns the parent process's PID.
console.log('Parent PID: ' + posix.getppid());
Get the user database entry for the given user. user can be specified either
as a numeric UID or a username (string).
var util = require('util');
util.inspect(posix.getpwnam('root'));
Example output of above:
{ name: 'root',
passwd: '*',
uid: 0,
gid: 0,
gecos: 'System Administrator',
shell: '/bin/sh',
dir: '/var/root' }
Get resource limits. (See getrlimit(2).)
The soft limit is the value that the kernel enforces for the
corresponding resource. The hard limit acts as a ceiling for the soft
limit: an unprivileged process may only set its soft limit to a value in the
range from 0 up to the hard limit, and (irreversibly) lower its hard limit.
Supported resources:
'core' (RLIMIT_CORE) Maximum size of core file. When 0 no core dump files
are created.
'cpu' (RLIMIT_CPU) CPU time limit in seconds. When the process reaches the
soft limit, it is sent a SIGXCPU signal. The default action for this signal is
to terminate the process.
'data' (RLIMIT_DATA) The maximum size of the process's data segment
(initialized data, uninitialized data, and heap).
'fsize' (RLIMIT_FSIZE) The maximum size of files that the process may create.
Attempts to extend a file beyond this limit result in delivery of a SIGXFSZ
signal.
'nofile' (RLIMIT_NOFILE) Specifies a value one greater than the maximum file
descriptor number that can be opened by this process.
'stack' (RLIMIT_STACK) The maximum size of the process stack, in bytes. Upon
reaching this limit, a SIGSEGV signal is generated.
'as' (RLIMIT_AS) The maximum size of the process's virtual memory (address
space) in bytes.
var limits = posix.getrlimit('nofile');
console.log('Current limits: soft=' + limits.soft + ', max=' + limits.hard);
Sets the Effective group ID of the current process. gid can be either a
numeric GID or a group name (string).
posix.setegid(0); // set effective group UID to "wheel"
posix.setegid('nobody');
Sets the Effective user ID of the current process. uid can be either a
numeric UID or a username (string).
posix.seteuid(0); // set effective UID to "root"
posix.seteuid('nobody');
Sets the Real and Effective group IDs of the current process. rgid and egid
can be either a numeric UIDs or group names (strings). A value of -1 means
that the corresponding GID is left unchanged.
posix.setregid(-1, 1000); // just set the EGID to 1000
posix.setregid('www-data', 'www-data'); // change both RGID and EGID to "www-data"
Sets the Real and Effective user IDs of the current process. ruid and euid
can be either a numeric UIDs or usernames (strings). A value of -1 means
that the corresponding UID is left unchanged.
IMPORTANT NOTE: what happens to the Saved UID when setreuid() is called is
operating system dependent. For example on OSX the Saved UID seems to be set
to the previous EUID. This means that the process can escape back to EUID=0
simply by calling setreuid(0, 0). A workaround for this is to callposix.setreuid(ruid, euid) twice with the same arguments.
posix.setreuid(-1, 1000); // just set the EUID to 1000
posix.setreuid('nobody', 'nobody'); // change both RUID and EUID to "nobody"
Set resource limits. (See setrlimit(2).) Supported resource types are listed
under posix.getrlimit.
The limits argument is an object in the form{ soft: SOFT_LIMIT, hard: HARD_LIMIT }. Current limit values are used if
either soft or hard key is not specifing in the limits object. A limit
value of null indicates "unlimited" (RLIM_INFINITY).
// raise maximum number of open file descriptors to 10k, hard limit is left unchanged
posix.setrlimit('nofile', { soft: 10000 });
// enable core dumps of unlimited size
posix.setrlimit('core', { soft: null, hard: null });
Creates a session and sets the process group ID. Returns the process group ID.
console.log('Session ID: ' + posix.setsid());
Open a connection to the logger.
Arguments:
* identity - defines the name of the process visible in the logged entries.
* options - set of option flags (see below).
* facility - facility code for the logged messages (see below).
Options:
* 'cons' - Log to the system console on error.
* 'ndelay' - Connect to syslog daemon immediately.
* 'nowait' - Do not wait for child processes.
* 'odelay' - Delay open until syslog() is called.
* 'pid' - Log the process ID with each message.
Facilities:
NOTE: only 'user' and 'local0' .. 'local7' are defined in the POSIX
standard. However, the other codes should be pretty well supported on most
platforms.
* 'kern'
* 'user'
* 'mail'
* 'news'
* 'uucp'
* 'daemon'
* 'auth'
* 'cron'
* 'lpr'
* 'local0' .. 'local7'
Example:
posix.openlog('myprog', {odelay: true, pid: true}, 'local7');
Close connection to the logger.
Sets a priority mask for log messages. Further posix.syslog() messages are
only sent out if their priority is included in the mask. Priorities are listed
under posix.syslog().
// only send the most critical messages
posix.setlogmask({emerg:true, alert: true, crit: true});
Send a message to the syslog logger using the given priority.
Priorities:
* 'emerg'
* 'alert'
* 'crit'
* 'err'
* 'warning'
* 'notice'
* 'info'
* 'debug'
Example:
posix.syslog('info', 'hello, world!');
* Some of the documentation strings stolen from Linux man pages.
* posix.seteuid etc. implementation is based on Node core project SetUid
* Fixes: Dan Bornstein
Copyright (c) 2011-2012 Mika Eloranta
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