POSIX_SPAWN_FILE_ACTIONS_ADDDUP2
Section: POSIX Programmer's Manual (3P)
Updated: 2013
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PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
posix_spawn_file_actions_adddup2
--- add dup2 action to spawn file actions object
(
ADVANCED REALTIME)
SYNOPSIS
#include <spawn.h>
int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t
*file_actions, int fildes, int newfildes);
DESCRIPTION
The
posix_spawn_file_actions_adddup2()
function shall add a
dup2()
action to the object referenced by
file_actions
that shall cause 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.
A spawn file actions object is as defined in
posix_spawn_file_actions_addclose().
RETURN VALUE
Upon successful completion, the
posix_spawn_file_actions_adddup2()
function shall return zero; otherwise, an error number shall be
returned to indicate the error.
ERRORS
The
posix_spawn_file_actions_adddup2()
function shall fail if:
- EBADF
-
The value specified by
fildes
or
newfildes
is negative or greater than or equal to
{OPEN_MAX}.
- ENOMEM
-
Insufficient memory exists to add to the spawn file actions object.
The
posix_spawn_file_actions_adddup2()
function may fail if:
- EINVAL
-
The value specified by
file_actions
is invalid.
It shall not be considered an error for the
fildes
argument passed to the
posix_spawn_file_actions_adddup2()
function 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 later used during a
posix_spawn()
or
posix_spawnp()
operation.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The
posix_spawn_file_actions_adddup2()
function is part of the Spawn option and need not be
provided on all implementations.
Implementations may use file descriptors that must be inherited into
child processes for the child process to remain conforming, such as for
message catalog or tracing purposes. Therefore, an application that calls
posix_spawn_file_actions_adddup2()
with an arbitrary integer for
newfildes
risks non-conforming behavior, and this function can only portably be
used to overwrite file descriptor values that the application has obtained
through explicit actions, or for the three file descriptors corresponding
to the standard file streams. In order to avoid a race condition of
leaking an unintended file descriptor into a child process, an application
should consider opening all file descriptors with the FD_CLOEXEC bit
set unless the file descriptor is intended to be inherited across
exec.
RATIONALE
Refer to the RATIONALE section in
posix_spawn_file_actions_addclose().
FUTURE DIRECTIONS
None.
SEE ALSO
dup(),
posix_spawn(),
posix_spawn_file_actions_addclose(),
posix_spawn_file_actions_destroy()
The Base Definitions volume of POSIX.1-2008,
<spawn.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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