POSIX_SPAWN_FILE_ACTIONS_ADDPDOUSPI2X(3P)rogrammer'PsOSMIaXn_uSaPlAWN_FILE_ACTIONS_ADDDUP2(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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>

COPYRIGHT
       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 .



IEEE/The Open Group                  2017  POSIX_SPAWN_FILE_ACTIONS_ADDDUP2(3)
