POSIX_SPAWN_FILE_ACTIONS_ADDOPEN(3) FreeBSD Library Functions Manual
NAME
posix_spawn_file_actions_addopen, posix_spawn_file_actions_adddup2,
posix_spawn_file_actions_addclose,
posix_spawn_file_actions_addclosefrom_np,
posix_spawn_file_actions_addchdir, posix_spawn_file_actions_addfchdir -
add open, dup2, close, closefrom, or chdir/fchdir actions to spawn file
actions object
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <spawn.h>
int
posix_spawn_file_actions_addopen(posix_spawn_file_actions_t * file_actions,
int fildes, const char *restrict path, int oflag, mode_t mode);
int
posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t * file_actions,
int fildes, int newfildes);
int
posix_spawn_file_actions_addclose(posix_spawn_file_actions_t * file_actions,
int fildes);
int
posix_spawn_file_actions_addclosefrom_np(posix_spawn_file_actions_t * file_actions,
int from);
int
posix_spawn_file_actions_addchdir(posix_spawn_file_actions_t *restrict file_actions,
const char *restrict path);
int
posix_spawn_file_actions_addfchdir(posix_spawn_file_actions_t * file_actions,
int fildes);
DESCRIPTION
These functions add an open, dup2 or close action to a spawn file actions
object.
A spawn file actions object is of type posix_spawn_file_actions_t
(defined in <spawn.h>) and is used to specify a series of actions to be
performed by a posix_spawn() or posix_spawnp() operation in order to
arrive at the set of open file descriptors for the child process given
the set of open file descriptors of the parent.
A spawn file actions object, when passed to posix_spawn() or
posix_spawnp(), specify how the set of open file descriptors in the
calling process is transformed into a set of potentially open file
descriptors for the spawned process. This transformation is as if the
specified sequence of actions was performed exactly once, in the context
of the spawned process (prior to execution of the new process image), in
the order in which the actions were added to the object; additionally,
when the new process image is executed, any file descriptor (from this
new set) which has its FD_CLOEXEC flag set is closed (see posix_spawn()).
The posix_spawn_file_actions_addopen() function adds an open action to
the object referenced by file_actions that causes the file named by path
to be opened (as if
open(path, oflag, mode)
had been called, and the returned file descriptor, if not fildes, had
been changed to fildes) when a new process is spawned using this file
actions object. If fildes was already an open file descriptor, it is
closed before the new file is opened.
The string described by path is copied by the
posix_spawn_file_actions_addopen() function.
The posix_spawn_file_actions_adddup2() function adds a dup2 action to the
object referenced by file_actions that causes the file descriptor fildes
to be duplicated as newfildes (as if
dup2(fildes, newfildes)
had been called) when a new process is spawned using this file actions
object, except that the FD_CLOEXEC flag for newfildes is cleared even if
fildes is equal to newfildes. The difference from dup2() is useful for
passing a particular file descriptor to a particular child process.
The posix_spawn_file_actions_addclose() function adds a close action to
the object referenced by file_actions that causes the file descriptor
fildes to be closed (as if
close(fildes)
had been called) when a new process is spawned using this file actions
object.
The posix_spawn_file_actions_addclosefrom_np() function adds a close
action to close all file descriptors numerically equal or greater then
the argument from. For each open file descriptor, logically the close
action is performed, and any possible errors encountered are ignored.
The posix_spawn_file_actions_addchdir() and
posix_spawn_file_actions_addfchdir() functions add a change current
directory action to the object referenced by file_actions that affects
actions (opens with relative path) performed after the operation, in the
order of insertion into the file_actions object. It also sets the
working directory for the spawned program. The
posix_spawn_file_actions_addchdir() function takes the path to set as the
working directory, while posix_spawn_file_actions_addfchdir() takes the
directory file descriptor.
RETURN VALUES
Upon successful completion, these functions return zero; otherwise, an
error number is returned to indicate the error.
ERRORS
These functions fail if:
[EBADF] The value specified by fildes or newfildes is
negative.
[ENOMEM] Insufficient memory exists to add to the spawn file
actions object.
SEE ALSO
close(2), dup2(2), open(2), posix_spawn(3),
posix_spawn_file_actions_destroy(3), posix_spawn_file_actions_init(3),
posix_spawnp(3)
STANDARDS
The posix_spawn_file_actions_addopen(),
posix_spawn_file_actions_adddup2() and
posix_spawn_file_actions_addclose() functions conform to IEEE Std
1003.1-2001 ("POSIX.1"), with the exception of the behavior of
posix_spawn_file_actions_adddup2() if fildes is equal to newfildes
(clearing FD_CLOEXEC). A future update of the Standard is expected to
require this behavior.
The posix_spawn_file_actions_addclosefrom_np() function is non-standard
and implemented after the similar functionality provided by glibc.
HISTORY
The posix_spawn_file_actions_addopen(),
posix_spawn_file_actions_adddup2() and
posix_spawn_file_actions_addclose() functions first appeared in
FreeBSD 8.0. The posix_spawn_file_actions_addchdir_np(),
posix_spawn_file_actions_addfchdir_np(), and
posix_spawn_file_actions_addclosefrom_np() functions first appeared in
FreeBSD 13.1. In FreeBSD 16.0, the posix_spawn_file_actions_addchdir(),
posix_spawn_file_actions_addfchdir() aliases where added to the
corresponding functions with the `_np' suffix.
AUTHORS
Ed Schouten <ed@FreeBSD.org>
FreeBSD 15.1-STABLE-HBSD May 9, 2013
POSIX_SPAWN_FILE_ACTIONS_ADDOPEN(3)