Add a C wrapper for prctl [BZ #25896]

Add a C wrapper to pass arguments in

/* Control process execution.  */
extern int prctl (int __option, ...) __THROW;

to prctl syscall:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);

1 files changed, 42 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
new file mode 100644
index 0000000000..d5725f14cf
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/prctl.c
@@ -0,0 +1,42 @@
+/* prctl - Linux specific syscall.
+   Copyright (C) 2020 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 <sysdep.h>
+#include <stdarg.h>
+#include <sys/prctl.h>
+
+/* Unconditionally read all potential arguments.  This may pass
+   garbage values to the kernel, but avoids the need for teaching
+   glibc the argument counts of individual options (including ones
+   that are added to the kernel in the future).  */
+
+int
+__prctl (int option, ...)
+{
+  va_list arg;
+  va_start (arg, option);
+  unsigned long int arg2 = va_arg (arg, unsigned long int);
+  unsigned long int arg3 = va_arg (arg, unsigned long int);
+  unsigned long int arg4 = va_arg (arg, unsigned long int);
+  unsigned long int arg5 = va_arg (arg, unsigned long int);
+  va_end (arg);
+  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
+}
+
+libc_hidden_def (__prctl)
+weak_alias (__prctl, prctl)