Add pthread_atfork() function

For now, Unikraft does not support fork(), so we will just print an
warning saying that.

Signed-off-by: Costin Lupu <[email protected]>
Reviewed-by: Felipe Huici <[email protected]>

Makefile.uk

@@ -66,6 +66,7 @@ LIBPTHREAD-EMBEDDED_EXPORTS = $(LIBPTHREAD-EMBEDDED_BASE)/exportsyms.uk
 ################################################################################
 LIBPTHREAD-EMBEDDED_SRCS-y += $(LIBPTHREAD-EMBEDDED_BASE)/pte_osal.c|glue
 LIBPTHREAD-EMBEDDED_SRCS-y += $(LIBPTHREAD-EMBEDDED_BASE)/attributes.c|glue
+LIBPTHREAD-EMBEDDED_SRCS-y += $(LIBPTHREAD-EMBEDDED_BASE)/pthread_atfork.c|glue
 
 ################################################################################
 # pthread-embedded code

exportsyms.uk

@@ -83,6 +83,7 @@ pthread_rwlockattr_destroy
 pthread_rwlockattr_getpshared
 pthread_rwlockattr_setpshared
 pthread_kill
+pthread_atfork
 sched_yield
 sched_get_priority_min
 sched_get_priority_max

include/pthread.h

@@ -29,6 +29,9 @@ extern "C" {
 /* The C code in pthread.h is not guarded for C++ */
 #include_next <pthread.h>
 
+int pthread_atfork(void (*prepare)(void),
+	void (*parent)(void), void (*child)(void));
+
 /* C functions not implemented in pthread-embedded */
 int pthread_attr_setguardsize(pthread_attr_t *attr, size_t guardsize);
 int pthread_attr_getguardsize(const pthread_attr_t *attr, size_t *guardsize);

pthread_atfork.c

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.0-or-later */
+/*
+ *      Unikraft port of POSIX Threads Library for embedded systems
+ *      Copyright(C) 2019 Costin Lupu, University Politehnica of Bucharest
+ *
+ *      This 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 of the License, or (at your option) any later version.
+ *
+ *      This 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 this library in the file COPYING.LIB;
+ *      if not, write to the Free Software Foundation, Inc.,
+ *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <pthread.h>
+#include <uk/print.h>
+
+
+int pthread_atfork(void (*prepare)(void),
+	void (*parent)(void), void (*child)(void))
+{
+	uk_pr_warn("Unikraft does not support fork yet!");
+	return 0;
+}