[rtems] pthread_atfork(): Change to behavior from FACE Technical Standard

[Joel Sherrill]

Closes #4713.
---
 cpukit/posix/src/pthreadatfork.c            | 13 +++++--------
 testsuites/psxtests/psxenosys/init.c        | 10 ++++++++--
 testsuites/psxtests/psxenosys/psxenosys.scn |  2 +-
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/cpukit/posix/src/pthreadatfork.c b/cpukit/posix/src/pthreadatfork.c
index 1ee03a0..27e6c72 100644
--- a/cpukit/posix/src/pthreadatfork.c
+++ b/cpukit/posix/src/pthreadatfork.c
@@ -8,7 +8,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2007.
+ *  COPYRIGHT (c) 1989-2007, 2022.
  *  On-Line Applications Research Corporation (OAR).
  *
  * Redistribution and use in source and binary forms, with or without
@@ -47,12 +47,8 @@
  *
  *  3.1.3 Register Fork Handlers, P1003.1c/Draft 10, P1003.1c/Draft 10, p. 27
  *
- *  RTEMS does not support processes, so we fall under this and do not
- *  provide this routine:
- *
- *  "Either the implementation shall support the pthread_atfork() function
- *   as described above or the pthread_atfork() funciton shall not be
- *   provided."
+ *  RTEMS does not support processes and we follow the FACE Technical Standard
+ *  recommendation to return 0 when multiple processes are not supported.
  */
 int pthread_atfork(
   void (*prepare)(void),
@@ -63,5 +59,6 @@ int pthread_atfork(
   (void) prepare;
   (void) parent;
   (void) child;
-  rtems_set_errno_and_return_minus_one( ENOSYS );
+
+  return 0;
 }
diff --git a/testsuites/psxtests/psxenosys/init.c b/testsuites/psxtests/psxenosys/init.c
index 40f83aa..d9a4d83 100644
--- a/testsuites/psxtests/psxenosys/init.c
+++ b/testsuites/psxtests/psxenosys/init.c
@@ -104,9 +104,15 @@ void *POSIX_Init(
   sc = fork();
   check_enosys( sc );
 
-  puts( "pthread_atfork -- ENOSYS" );
+  /*
+   * The behavior of pthread_atfork() in single process environments was
+   * undefined by POSIX but the fACE Technical Standard required returning
+   * 0. Before ticket #4713, this did return ENOSYS. Just leaving this test
+   * case here for convenience.
+   */
+  puts( "pthread_atfork -- 0" );
   sc = pthread_atfork( NULL, NULL, NULL );
-  check_enosys( sc );
+  rtems_test_assert( !sc );
 
   puts( "pthread_getcpuclockid -- ENOSYS" );
   sc = pthread_getcpuclockid( 0, NULL );
diff --git a/testsuites/psxtests/psxenosys/psxenosys.scn b/testsuites/psxtests/psxenosys/psxenosys.scn
index 1ed64f9..9e88acd 100644
--- a/testsuites/psxtests/psxenosys/psxenosys.scn
+++ b/testsuites/psxtests/psxenosys/psxenosys.scn
@@ -9,7 +9,7 @@ execv -- ENOSYS
 execve -- ENOSYS
 execvp -- ENOSYS
 fork -- ENOSYS
-pthread_atfork -- ENOSYS
+pthread_atfork -- 0
 pthread_getcpuclockid -- ENOSYS
 sched_setparam -- ENOSYS
 sched_getparam -- ENOSYS
-- 
1.8.3.1