Fix stpcpy / mempcpy namespace (bug 17573)

Fix stpcpy / mempcpy namespace (bug 17573)

[Joseph Myers]

Various glibc functions call __stpcpy and __mempcpy for namespace
reasons instead of plain stpcpy and mempcpy.  But __stpcpy and
__mempcpy are macros that call __builtin_stpcpy and __builtin_mempcpy,
and unless GCC optimizes the calls, they end up calling the C
functions stpcpy and mempcpy.

For calls from within shared libc, libc_hidden_builtin_proto ensures
that calls to those C functions are in turn mapped to call __GI_stpcpy
and __GI_mempcpy.  However, for static libc, and for calls from shared
libraries other than libc, the ELF symbols stpcpy and mempcpy end up
getting called, breaking the ISO C namespace (in the case of stpcpy)
or glibc conventions about not relying on the "future library
directions" reservations (in the case of mempcpy).

This patch fixes this by adding declarations of these functions to
include/string.h, under an appropriate condition, with __asm__ used to
change the assembler name used for calls; this fixes one of the bugs
shown in the sample output of my proposed tests for such namespace
issues <https://sourceware.org/ml/libc-alpha/2014-11/msg00157.html>
(the mempcpy case was previously discussed, and the approach for the
fix is as I suggested in
<https://sourceware.org/ml/libc-alpha/2013-02/msg00063.html>).
(Siddhesh, the new NOT_IN_libc conditional will I expect need updating
as part of your overhaul of such conditionals.)

Tested for x86_64 with the testsuite; also checked that dcigettext.o
(an example previously noted of undesired calls to stpcpy and mempcpy)
now calls __stpcpy and __mempcpy instead, as do non-libc shared
libraries (__stpcpy and __mempcpy were already exported from shared
libc).  Disassembly of installed shared libraries isn't easy to
compare because of reordered PLT entries resulting from the change in
functions called (libnsl, libnss_compat, libnss_dns, libnss_files,
libnss_hesiod, libnss_nis, libnss_nisplus, libpthread, librt all have
such changes).

2014-11-10  Joseph Myers  <joseph@codesourcery.com>

	[BZ #17573]
	* include/string.h [NOT_IN_libc || !SHARED] (mempcpy): Declare
	with asm name __mempcpy.
	[NOT_IN_libc || !SHARED] (stpcpy): Declare with asm name __stpcpy.

diff --git a/include/string.h b/include/string.h
index 8323412..2603e9c 100644
--- a/include/string.h
+++ b/include/string.h
@@ -113,6 +113,13 @@ libc_hidden_builtin_proto (strspn)
 libc_hidden_builtin_proto (strstr)
 libc_hidden_builtin_proto (ffs)
 
+#if defined NOT_IN_libc || !defined SHARED
+/* Redirect calls to __builtin_mempcpy and __builtin_stpcpy to call
+   __mempcpy and __stpcpy if not inlined.  */
+extern __typeof (mempcpy) mempcpy __asm__ ("__mempcpy");
+extern __typeof (stpcpy) stpcpy __asm__ ("__stpcpy");
+#endif
+
 # ifndef _ISOMAC
 #  ifndef index
 #   define index(s, c)	(strchr ((s), (c)))

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Roland McGrath]

Looks OK.

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Andreas Schwab]

Joseph Myers <joseph@codesourcery.com> writes:

> 	[BZ #17573]
> 	* include/string.h [NOT_IN_libc || !SHARED] (mempcpy): Declare
> 	with asm name __mempcpy.
> 	[NOT_IN_libc || !SHARED] (stpcpy): Declare with asm name __stpcpy.

gcc mempcpy.c -c -std=gnu99 -fgnu89-inline  -D_FORTIFY_SOURCE=2 -O2 -U_FORTIFY_SOURCE -Wall -Winline -Wundef -Wwrite-strings -fasynchronous-unwind-tables -fmerge-all-constants -fmessage-length=0 -frounding-math -funwind-tables -g -grecord-gcc-switches -mtune=power3 -mhard-float -Wstrict-prototypes -Werror=implicit-function-declaration -mlong-double-128         -I../include -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string  -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32  -I../sysdeps/unix/sysv/linux/powerpc  -I../sysdeps/powerpc/nptl  -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread  -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv  -I../sysdeps/unix/powerpc  -I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/powerpc/powerpc32/fpu  -I../sysdeps/powerpc/powerpc32  -I../sysdeps/wordsize-32  -I../sysdeps/powerpc/fpu  -I../sysdeps/powerpc  -I../sysdeps/ieee754/ldbl-128ibm  -I../sysdeps/ieee754/ldbl-opt  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32  -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I.   -D_LIBC_REENTRANT -include ../include/libc-symbols.h       -o /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o -MD -MP -MF /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o.dt -MT /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o
/tmp/ccXDS5DL.s: Assembler messages:
/tmp/ccXDS5DL.s:40: Error: symbol `__mempcpy' is already defined

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Adhemerval Zanella]

On 13-11-2014 08:22, Andreas Schwab wrote:
> Joseph Myers <joseph@codesourcery.com> writes:
>
>> 	[BZ #17573]
>> 	* include/string.h [NOT_IN_libc || !SHARED] (mempcpy): Declare
>> 	with asm name __mempcpy.
>> 	[NOT_IN_libc || !SHARED] (stpcpy): Declare with asm name __stpcpy.
> gcc mempcpy.c -c -std=gnu99 -fgnu89-inline  -D_FORTIFY_SOURCE=2 -O2 -U_FORTIFY_SOURCE -Wall -Winline -Wundef -Wwrite-strings -fasynchronous-unwind-tables -fmerge-all-constants -fmessage-length=0 -frounding-math -funwind-tables -g -grecord-gcc-switches -mtune=power3 -mhard-float -Wstrict-prototypes -Werror=implicit-function-declaration -mlong-double-128         -I../include -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string  -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32  -I../sysdeps/unix/sysv/linux/powerpc  -I../sysdeps/powerpc/nptl  -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread  -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv  -I../sysdeps/unix/powerpc  -I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/powerpc/powerpc32/fpu  -I../sysdeps/powerpc/powerpc32  -I../sysdeps/wordsize-32  -I../sysdeps/powerpc/fpu  -I../sysdeps/powerpc  -I../sysdeps/ieee754/ldbl-128ibm  -I../sysdeps/ieee754/ldbl-opt  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32  -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I.   -D_LIBC_REENTRANT -include ../include/libc-symbols.h       -o /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o -MD -MP -MF /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o.dt -MT /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o
> /tmp/ccXDS5DL.s: Assembler messages:
> /tmp/ccXDS5DL.s:40: Error: symbol `__mempcpy' is already defined
>
> Andreas.
>
This also breaks powerpc64 build with a similar issue.  I have tried to disable
multiarch for statics builds, as x86_64 custom implementation does, but it also
breaks. 

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Stefan Liebler]

On 11/13/2014 11:22 AM, Andreas Schwab wrote:
> Joseph Myers <joseph@codesourcery.com> writes:
>
>> 	[BZ #17573]
>> 	* include/string.h [NOT_IN_libc || !SHARED] (mempcpy): Declare
>> 	with asm name __mempcpy.
>> 	[NOT_IN_libc || !SHARED] (stpcpy): Declare with asm name __stpcpy.
>
> gcc mempcpy.c -c -std=gnu99 -fgnu89-inline  -D_FORTIFY_SOURCE=2 -O2 -U_FORTIFY_SOURCE -Wall -Winline -Wundef -Wwrite-strings -fasynchronous-unwind-tables -fmerge-all-constants -fmessage-length=0 -frounding-math -funwind-tables -g -grecord-gcc-switches -mtune=power3 -mhard-float -Wstrict-prototypes -Werror=implicit-function-declaration -mlong-double-128         -I../include -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string  -I/home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu  -I../sysdeps/unix/sysv/linux/powerpc/powerpc32  -I../sysdeps/unix/sysv/linux/powerpc  -I../sysdeps/powerpc/nptl  -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread  -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv  -I../sysdeps/unix/powerpc  -I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/powerpc/powerpc32/fpu  -I../sysdeps/powerpc/powerpc32  -I../sysdeps/wordsize-32  -I../sysd
eps/powerpc/fpu  -I../sysdeps/powerpc  -I../sysdeps/ieee754/ldbl-128ibm  -I../sysdeps/ieee754/ldbl-opt  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32  -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I.   -D_LIBC_REENTRANT -include ../include/libc-symbols.h       -o /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o -MD -MP -MF /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o.dt -MT /home/abuild/rpmbuild/BUILD/glibc-2.20.90/cc-base/string/mempcpy.o
> /tmp/ccXDS5DL.s: Assembler messages:
> /tmp/ccXDS5DL.s:40: Error: symbol `__mempcpy' is already defined
>
> Andreas.
>

Hi,

I get the same error message on s390.
When building with multiple jobs, i get the following error in addition:
/tmp/ccRwSbmU.s:23: Error: symbol `__stpcpy' is already defined

Bye
Stefan.

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Jiong Wang]

On 13/11/14 11:37, Stefan Liebler wrote:
>
> Hi,
>
> I get the same error message on s390.
> When building with multiple jobs, i get the following error in addition:
> /tmp/ccRwSbmU.s:23: Error: symbol `__stpcpy' is already defined

  + aarch64

>
> Bye
> Stefan.
>
>
>
>

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Joseph Myers]

On Thu, 13 Nov 2014, Andreas Schwab wrote:

> /tmp/ccXDS5DL.s: Assembler messages:
> /tmp/ccXDS5DL.s:40: Error: symbol `__mempcpy' is already defined

This patch fixes the build of C mempcpy and stpcpy by disabling the
redirection to __mempcpy and __stpcpy asm names if
NO_MEMPCPY_STPCPY_REDIRECT is defined, and defining that macro in the
relevant source files.

Tested for powerpc32 that the build is fixed.

2014-11-13  Joseph Myers  <joseph@codesourcery.com>

	* include/string.h [NO_MEMPCPY_STPCPY_REDIRECT] (mempcpy): Do not
	redeclare with asm name.
	[NO_MEMPCPY_STPCPY_REDIRECT] (stpcpy): Likewise.
	* string/mempcpy.c (NO_MEMPCPY_STPCPY_REDIRECT): Define before
	including <string.h>.
	* string/stpcpy.c (NO_MEMPCPY_STPCPY_REDIRECT): Likewise.
	* sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c
	[!NOT_IN_libc] (NO_MEMPCPY_STPCPY_REDIRECT): Likewise.
	* sysdeps/powerpc/powerpc64/multiarch/mempcpy.c
	[!NOT_IN_libc] (NO_MEMPCPY_STPCPY_REDIRECT): Likewise.
	* sysdeps/powerpc/powerpc64/multiarch/stpcpy.c
	[SHARED && !NOT_IN_libc] (NO_MEMPCPY_STPCPY_REDIRECT): Likewise.

diff --git a/include/string.h b/include/string.h
index 99cc2d3..172940b 100644
--- a/include/string.h
+++ b/include/string.h
@@ -115,7 +115,8 @@ libc_hidden_builtin_proto (strspn)
 libc_hidden_builtin_proto (strstr)
 libc_hidden_builtin_proto (ffs)
 
-#if defined NOT_IN_libc || !defined SHARED
+#if (defined NOT_IN_libc || !defined SHARED) \
+  && !defined NO_MEMPCPY_STPCPY_REDIRECT
 /* Redirect calls to __builtin_mempcpy and __builtin_stpcpy to call
    __mempcpy and __stpcpy if not inlined.  */
 extern __typeof (mempcpy) mempcpy __asm__ ("__mempcpy");
diff --git a/string/mempcpy.c b/string/mempcpy.c
index 9749863..aab1bed 100644
--- a/string/mempcpy.c
+++ b/string/mempcpy.c
@@ -19,6 +19,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#define NO_MEMPCPY_STPCPY_REDIRECT
 #include <string.h>
 
 #undef mempcpy
diff --git a/string/stpcpy.c b/string/stpcpy.c
index fc5ae55..9185acc 100644
--- a/string/stpcpy.c
+++ b/string/stpcpy.c
@@ -19,6 +19,7 @@
 # include <config.h>
 #endif
 
+#define NO_MEMPCPY_STPCPY_REDIRECT
 #include <string.h>
 
 #undef __stpcpy
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c b/sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c
index 38fbcc3..89f4912 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #ifndef NOT_IN_libc
+# define NO_MEMPCPY_STPCPY_REDIRECT
 # include <string.h>
 # include <shlib-compat.h>
 # include "init-arch.h"
diff --git a/sysdeps/powerpc/powerpc64/multiarch/mempcpy.c b/sysdeps/powerpc/powerpc64/multiarch/mempcpy.c
index 38fbcc3..89f4912 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/mempcpy.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/mempcpy.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #ifndef NOT_IN_libc
+# define NO_MEMPCPY_STPCPY_REDIRECT
 # include <string.h>
 # include <shlib-compat.h>
 # include "init-arch.h"
diff --git a/sysdeps/powerpc/powerpc64/multiarch/stpcpy.c b/sysdeps/powerpc/powerpc64/multiarch/stpcpy.c
index c7118d5..28153b7 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/stpcpy.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/stpcpy.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #if defined SHARED && !defined NOT_IN_libc
+# define NO_MEMPCPY_STPCPY_REDIRECT
 # include <string.h>
 # include <shlib-compat.h>
 # include "init-arch.h"

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Joseph Myers]

Note that I haven't yet committed this build fix patch for architectures 
using C stpcpy / mempcpy 
<https://sourceware.org/ml/libc-alpha/2014-11/msg00305.html>, pending 
confirmation from somebody that it seems sane.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Maciej W. Rozycki]

On Thu, 13 Nov 2014, Joseph Myers wrote:

> > /tmp/ccXDS5DL.s: Assembler messages:
> > /tmp/ccXDS5DL.s:40: Error: symbol `__mempcpy' is already defined
> 
> This patch fixes the build of C mempcpy and stpcpy by disabling the
> redirection to __mempcpy and __stpcpy asm names if
> NO_MEMPCPY_STPCPY_REDIRECT is defined, and defining that macro in the
> relevant source files.
> 
> Tested for powerpc32 that the build is fixed.

 Likewise with the `mips64-linux-gnu' target (spanning the three usual 
MIPS ABIs).  Thanks!

  Maciej

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Vidya Praveen]

On Thu, Nov 13, 2014 at 08:18:49PM +0000, Joseph Myers wrote:
> Note that I haven't yet committed this build fix patch for architectures 
> using C stpcpy / mempcpy 
> <https://sourceware.org/ml/libc-alpha/2014-11/msg00305.html>, pending 
> confirmation from somebody that it seems sane.

This fixes aarch64-none-linux-gnu build.

VP.

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Adhemerval Zanella]

On 13-11-2014 18:18, Joseph Myers wrote:
> Note that I haven't yet committed this build fix patch for architectures 
> using C stpcpy / mempcpy 
> <https://sourceware.org/ml/libc-alpha/2014-11/msg00305.html>, pending 
> confirmation from somebody that it seems sane.
>
It fixes the powerpc64 build issues I was seeing.

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Stefan Liebler]

On 11/13/2014 09:18 PM, Joseph Myers wrote:
> Note that I haven't yet committed this build fix patch for architectures
> using C stpcpy / mempcpy
> <https://sourceware.org/ml/libc-alpha/2014-11/msg00305.html>, pending
> confirmation from somebody that it seems sane.
>
This fixes build issues on s390. Thanks.

Re: Fix stpcpy / mempcpy namespace (bug 17573)

[Vidya Praveen]

On Fri, Nov 14, 2014 at 10:20:48AM +0000, Vidya Praveen wrote:
> On Thu, Nov 13, 2014 at 08:18:49PM +0000, Joseph Myers wrote:
> > Note that I haven't yet committed this build fix patch for architectures 
> > using C stpcpy / mempcpy 
> > <https://sourceware.org/ml/libc-alpha/2014-11/msg00305.html>, pending 
> > confirmation from somebody that it seems sane.
> 
> This fixes aarch64-none-linux-gnu build.

And arm-none-linux-gnueabi/gnueabihf.

VP.