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Manual Reference Pages  -  POSIX_SPAWN_FILE_ACTIONS_ADDOPEN (3)

NAME

posix_spawn_file_actions_addopen, posix_spawn_file_actions_adddup2, posix_spawn_file_actions_addclose - add open, dup2 or close action to spawn file actions object

CONTENTS

Library
Synopsis
Description
Return Values
Errors
See Also
Standards
History
Authors

LIBRARY


.Lb libc

SYNOPSIS


.In 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

DESCRIPTION

These functions add an open, dup2 or close action to a spawn file actions object.

A spawn file actions object is of type
.Vt posix_spawn_file_actions_t (defined in
.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.

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 -p1003.1-2001, 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.

HISTORY

The posix_spawn_file_actions_addopen, posix_spawn_file_actions_adddup2 and posix_spawn_file_actions_addclose functions first appeared in
.Fx 8.0 .

AUTHORS


.An Ed Schouten Aq ed@FreeBSD.org
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