Consolidate pthread_atfork

The pthread_atfork is similar between Linux and Hurd, only the compat
version bits differs.  The generic version is place at sysdeps/pthread
with a common name.

It also fixes an issue with Hurd license, where the static-only object
did not use LGPL + exception.

Checked on x86_64-linux-gnu, i686-linux-gnu, and with a build for
i686-gnu.

3 files changed, 89 insertions, 1 deletions

diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
index 9e6ed3c6f7..fedb785d38 100644
--- a/sysdeps/pthread/Makefile
+++ b/sysdeps/pthread/Makefile
@@ -29,7 +29,7 @@ endif
 ifneq (,$(filter $(subdir),htl nptl))
 headers += threads.h
 
-routines += thrd_current thrd_equal thrd_sleep thrd_yield
+routines += thrd_current thrd_equal thrd_sleep thrd_yield pthread_atfork
 
 $(libpthread-routines-var) += \
   call_once \
@@ -45,6 +45,7 @@ $(libpthread-routines-var) += \
   mtx_timedlock \
   mtx_trylock \
   mtx_unlock \
+  pthread_atfork_compat \
   thrd_create \
   thrd_detach \
   thrd_exit \
@@ -134,6 +135,7 @@ tests-time64 := \
   tst-sem5-time64 \
   tst-thrd-sleep-time64 \
 
+static-only-routines = pthread_atfork
 
 # Files which must not be linked with libpthread.
 tests-nolibpthread += tst-unload
diff --git a/sysdeps/pthread/pthread_atfork.c b/sysdeps/pthread/pthread_atfork.c
new file mode 100644
index 0000000000..7646fe7efc
--- /dev/null
+++ b/sysdeps/pthread/pthread_atfork.c
@@ -0,0 +1,58 @@
+/* Copyright (C) 2002-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "pthreadP.h"
+#include <register-atfork.h>
+#include <dso_handle.h>
+#include <register-atfork.h>
+
+
+/* Hide the symbol so that no definition but the one locally in the
+   executable or DSO is used.  */
+int
+#ifndef __pthread_atfork
+/* Don't mark the compatibility function as hidden.  */
+attribute_hidden
+#endif
+__pthread_atfork (void (*prepare) (void), void (*parent) (void),
+		  void (*child) (void))
+{
+  return __register_atfork (prepare, parent, child, __dso_handle);
+}
+#ifndef __pthread_atfork
+extern int pthread_atfork (void (*prepare) (void), void (*parent) (void),
+			   void (*child) (void)) attribute_hidden;
+weak_alias (__pthread_atfork, pthread_atfork)
+#endif
diff --git a/sysdeps/pthread/pthread_atfork_compat.c b/sysdeps/pthread/pthread_atfork_compat.c
new file mode 100644
index 0000000000..4533f765d1
--- /dev/null
+++ b/sysdeps/pthread/pthread_atfork_compat.c
@@ -0,0 +1,28 @@
+/* Compat pthread_atfork implementation.
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <pthread_atfork_compat.h>
+#include <shlib-compat.h>
+
+#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_3)
+# define __pthread_atfork __dyn_pthread_atfork
+# include "pthread_atfork.c"
+# undef __pthread_atfork
+compat_symbol (libpthread, __dyn_pthread_atfork, pthread_atfork,
+	       PTHREAD_ATFORK_COMPAT_INTRODUCED);
+#endif