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.TH POSIX_SPAWN_FILE_ACTIONS_ADDDUP2 "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH 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.

.SH NAME

posix_spawn_file_actions_adddup2

\(em add dup2 action to spawn file actions object

(\fBADVANCED REALTIME\fP)

.SH SYNOPSIS

.LP

.nf

#include <spawn.h>

.P

int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t

    *\fIfile_actions\fP, int \fIfildes\fP, int \fInewfildes\fP);

.fi

.SH DESCRIPTION

The

\fIposix_spawn_file_actions_adddup2\fR()

function shall add a

\fIdup2\fR()

action to the object referenced by

.IR file_actions

that shall cause the file descriptor

.IR fildes

to be duplicated as

.IR newfildes

(as if

.IR dup2 (\c

.IR fildes ,

.IR newfildes )

had been called) when a new process is spawned using this file actions

object.

.P

A spawn file actions object is as defined in

.IR "\fIposix_spawn_file_actions_addclose\fR\^(\|)".

.SH "RETURN VALUE"

Upon successful completion, the

\fIposix_spawn_file_actions_adddup2\fR()

function shall return zero; otherwise, an error number shall be

returned to indicate the error.

.SH ERRORS

The

\fIposix_spawn_file_actions_adddup2\fR()

function shall fail if:

.TP

.BR EBADF

The value specified by

.IR fildes

or

.IR newfildes

is negative or greater than or equal to

{OPEN_MAX}.

.TP

.BR ENOMEM

Insufficient memory exists to add to the spawn file actions object.

.P

The

\fIposix_spawn_file_actions_adddup2\fR()

function may fail if:

.TP

.BR EINVAL

The value specified by

.IR file_actions

is invalid.

.P

It shall not be considered an error for the

.IR fildes

argument passed to the

\fIposix_spawn_file_actions_adddup2\fR()

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

\fIposix_spawn\fR()

or

\fIposix_spawnp\fR()

operation.

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

The

\fIposix_spawn_file_actions_adddup2\fR()

function is part of the Spawn option and need not be

provided on all implementations.

.P

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

\fIposix_spawn_file_actions_adddup2\fR()

with an arbitrary integer for

.IR 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

.IR exec .

.SH RATIONALE

Refer to the RATIONALE section in

.IR "\fIposix_spawn_file_actions_addclose\fR\^(\|)".

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIdup\fR\^(\|)",

.IR "\fIposix_spawn\fR\^(\|)",

.IR "\fIposix_spawn_file_actions_addclose\fR\^(\|)",

.IR "\fIposix_spawn_file_actions_destroy\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "\fB<spawn.h>\fP"

.SH 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 .