oracular (3) posix_spawn_file_actions_adddup2.3posix.gz

Provided by: manpages-posix-dev_2017a-2_all bug

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.1‐2017, <spawn.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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 .