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[COMMITTED PATCH 3/3] Clean up NPTL system to be compat-only.
- From: Roland McGrath <roland at hack dot frob dot com>
- To: "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Fri, 6 Feb 2015 12:19:59 -0800 (PST)
- Subject: [COMMITTED PATCH 3/3] Clean up NPTL system to be compat-only.
- Authentication-results: sourceware.org; auth=none
- References: <20150206201843 dot AD5922C3A9B at topped-with-meat dot com>
I don't know if there was a historical reason for libpthread to have a
system wrapper, but there is certainly none in the current code. This
change makes it compat-only.
Tested x86_64-linux-gnu.
Thanks,
Roland
* nptl/pt-system.c: Rewritten. Put everything under
[SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)].
Use IFUNC to redirect when possible.
--- a/nptl/pt-system.c
+++ b/nptl/pt-system.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2002-2015 Free Software Foundation, Inc.
+/* ABI compatibility for 'system' symbol in libpthread ABI.
+ Copyright (C) 2002-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -16,17 +17,48 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <errno.h>
#include <stdlib.h>
-#include <sysdep.h>
-#include "pthreadP.h"
+#include <shlib-compat.h>
+/* libpthread once had its own 'system', though there was no apparent
+ reason for it. There is no use in having a separate symbol in
+ libpthread, but the historical ABI requires it. For static linking,
+ there is no need to provide anything here--the libc version will be
+ linked in. For shared library ABI compatibility, there must be a
+ 'system' symbol in libpthread.so; so we define it using IFUNC to
+ redirect to the libc function. */
-int
-system (const char *line)
+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
+
+# if HAVE_IFUNC
+
+static __typeof (system) *
+__attribute__ ((used))
+system_resolve (void)
+{
+ return &__libc_system;
+}
+
+asm (".globl system_ifunc\n"
+ ".type system_ifunc, %gnu_indirect_function");
+
+# ifdef HAVE_ASM_SET_DIRECTIVE
+asm (".set system_ifunc, system_resolve");
+# else
+asm ("system_ifunc = system_resolve");
+# endif
+
+# else /* !HAVE_IFUNC */
+
+static int __attribute__ ((used))
+system_compat (const char *line)
{
return __libc_system (line);
}
+strong_alias (system_compat, system_ifunc)
+
+# endif /* HAVE_IFUNC */
+
+compat_symbol (libpthread, system_ifunc, system, GLIBC_2_0);
-/* __libc_system in libc.so handles cancellation. */
-LIBC_CANCEL_HANDLED ();
+#endif