Use libc_hidden_proto / libc_hidden_def with __strnlen

[Joseph Myers <joseph at codesourcery dot com>]

Various code in glibc uses __strnlen instead of strnlen for namespace
reasons.  However, __strnlen does not use libc_hidden_proto /
libc_hidden_def (as is normally done for any function defined and
called within the same library, whether or not exported from the
library and whatever namespace it is in), so the compiler does not
know that those calls are to a function within libc.

This patch uses libc_hidden_proto / libc_hidden_def with __strnlen.
On x86_64, it makes no difference to the installed stripped shared
libraries.  On 32-bit x86, it causes __strnlen calls to go to the same
place as strnlen calls (the fallback strnlen implementation), rather
than through a PLT entry for the strnlen IFUNC; I'm not sure of the
logic behind when calls from within libc should use IFUNCs versus when
they should go direct to a particular function implementation, but
clearly it doesn't make sense for strnlen and __strnlen to be handled
differently in this regard.

Tested for x86_64 and x86 (testsuite, and comparison of installed
shared libraries as described above).

2015-06-02  Joseph Myers  <joseph@codesourcery.com>

	* string/strnlen.c [!STRNLEN] (__strnlen): Use libc_hidden_def.
	* include/string.h (__strnlen): Use libc_hidden_proto.
	* sysdeps/aarch64/strnlen.S (__strnlen): Use libc_hidden_def.
	* sysdeps/i386/i686/multiarch/strnlen-c.c [SHARED]
	(libc_hidden_def): Define __GI___strnlen as well as __GI_strnlen.
	* sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S
	(libc_hidden_def): Undefine and redefine.
	* sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c
	[SHARED] (libc_hidden_def): Define __GI___strnlen as well as
	__GI_strnlen.
	* sysdeps/powerpc/powerpc32/power7/strnlen.S (__strnlen): Use
	libc_hidden_def.
	* sysdeps/tile/tilegx/strnlen.c (__strnlen): Likewise.

diff --git a/include/string.h b/include/string.h
index 89f00fd..c57671e 100644
--- a/include/string.h
+++ b/include/string.h
@@ -91,6 +91,7 @@ libc_hidden_proto (__strtok_r)
 extern char *__strsep_g (char **__stringp, const char *__delim);
 libc_hidden_proto (__strsep_g)
 libc_hidden_proto (strnlen)
+libc_hidden_proto (__strnlen)
 libc_hidden_proto (memmem)
 extern __typeof (memmem) __memmem;
 libc_hidden_proto (__memmem)
diff --git a/string/strnlen.c b/string/strnlen.c
index 803d78b..d2bb843 100644
--- a/string/strnlen.c
+++ b/string/strnlen.c
@@ -160,6 +160,7 @@ __strnlen (const char *str, size_t maxlen)
   return char_ptr - str;
 }
 #ifndef STRNLEN
+libc_hidden_def (__strnlen)
 weak_alias (__strnlen, strnlen)
 #endif
 libc_hidden_def (strnlen)
diff --git a/sysdeps/aarch64/strnlen.S b/sysdeps/aarch64/strnlen.S
index 743172c..9d6b19f 100644
--- a/sysdeps/aarch64/strnlen.S
+++ b/sysdeps/aarch64/strnlen.S
@@ -157,5 +157,6 @@ L(hit_limit):
 	mov	len, limit
 	RET
 END (__strnlen)
+libc_hidden_def (__strnlen)
 weak_alias (__strnlen, strnlen)
 libc_hidden_def (strnlen)
diff --git a/sysdeps/i386/i686/multiarch/strnlen-c.c b/sysdeps/i386/i686/multiarch/strnlen-c.c
index f02465d..351e939 100644
--- a/sysdeps/i386/i686/multiarch/strnlen-c.c
+++ b/sysdeps/i386/i686/multiarch/strnlen-c.c
@@ -2,7 +2,9 @@
 #ifdef SHARED
 # undef libc_hidden_def
 # define libc_hidden_def(name)  \
-    __hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32);
+    __hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32); \
+    strong_alias (__strnlen_ia32, __strnlen_ia32_1); \
+    __hidden_ver1 (__strnlen_ia32_1, __GI___strnlen, __strnlen_ia32_1);
 #endif
 
 #include "string/strnlen.c"
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S
index 32fba1b..e857754 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S
@@ -31,6 +31,9 @@
  cfi_endproc;							\
  ASM_SIZE_DIRECTIVE(__strnlen_power7)
 
+#undef libc_hidden_def
+#define libc_hidden_def(name)
+
 #undef libc_hidden_builtin_def
 #define libc_hidden_builtin_def(name)
 
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c
index 6eaed60..a5f7516 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c
@@ -20,7 +20,9 @@
 #ifdef SHARED
 # undef libc_hidden_def
 # define libc_hidden_def(name)  \
-    __hidden_ver1 (__strnlen_ppc, __GI_strnlen, __strnlen_ppc);
+    __hidden_ver1 (__strnlen_ppc, __GI_strnlen, __strnlen_ppc); \
+    strong_alias (__strnlen_ppc, __strnlen_ppc_1); \
+    __hidden_ver1 (__strnlen_ppc_1, __GI___strnlen, __strnlen_ppc_1);
 #endif
 
 #include <string/strnlen.c>
diff --git a/sysdeps/powerpc/powerpc32/power7/strnlen.S b/sysdeps/powerpc/powerpc32/power7/strnlen.S
index be169c6..de1001c 100644
--- a/sysdeps/powerpc/powerpc32/power7/strnlen.S
+++ b/sysdeps/powerpc/powerpc32/power7/strnlen.S
@@ -171,5 +171,6 @@ L(loop_small):
 	blr
 
 END (__strnlen)
+libc_hidden_def (__strnlen)
 weak_alias (__strnlen, strnlen)
 libc_hidden_builtin_def (strnlen)
diff --git a/sysdeps/tile/tilegx/strnlen.c b/sysdeps/tile/tilegx/strnlen.c
index 575f8f5..d1f212b 100644
--- a/sysdeps/tile/tilegx/strnlen.c
+++ b/sysdeps/tile/tilegx/strnlen.c
@@ -52,5 +52,6 @@ __strnlen (const char *s, size_t maxlen)
   size_t len = ((const char *) p) + (CFZ (bits) >> 3) - s;
   return (len < maxlen ? len : maxlen);
 }
+libc_hidden_def (__strnlen)
 weak_alias (__strnlen, strnlen)
 libc_hidden_def (strnlen)

-- 
Joseph S. Myers
joseph@codesourcery.com