POSIX_SPAWN_FILE_ACTIONS_ADPOSIX(ProgrammePOSIX_SPAWN_FILE_ACTIONS_ADDDUP2(3P)



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 associ-
       ated 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 applica-
       tion 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 descrip-
       tors 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 Electri-
       cal 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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group		     2013 POSIX_SPAWN_FILE_ACTIONS_ADDDUP2(3P)