posix_spawn_file_actions_addclose or posix_spawn_file_actions_addopen Subroutine

Purpose

Adds close or open action to the spawn file actions object.

Syntax

#include <spawn.h>

int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *
       file_actions, int fildes);
int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *
       restrict file_actions, int fildes,
       const char *restrict path, int oflag, mode_t mode); 

Description

The posix_spawn_file_actions_addclose and posix_spawn_file_actions_addopen subroutines close or open action to a spawn file actions object.

A spawn file actions object is of type posix_spawn_file_actions_t (defined in the spawn.h header file) 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. Comparison or assignment operators for the type posix_spawn_file_actions_t are not defined.

A spawn file actions object, when passed to posix_spawn or posix_spawnp, specifies 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 running the new process image), in the order in which the actions were added to the object. Additionally, when the new process image is run, any file descriptor (from this new set) that has its FD_CLOEXEC flag set is closed (see posix_spawn or posix_spawnp Subroutine).

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_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 closes before the new file is opened.

The string described by path is copied by the posix_spawn_file_actions_addopen function.

Return Values

Upon successful completion, the posix_spawn_file_actions_addclose and posix_spawn_file_actions_addopen subroutines return 0; otherwise, an error number is returned to indicate the error.

Error Codes

It is not an error for the fildes argument passed to these functions to specify a file descriptor for which the specified operation could not be performed at the time of the call. Any such error will be detected when the associated file actions object is used later during a posix_spawn or posix_spawnp operation.