Fix -Os putc_unlocked, fputc_unlocked linknamespace, localplt issues (bug 15105, bug 19463)

[Joseph Myers <joseph at codesourcery dot com>]

Continuing the fixes for linknamespace and localplt test failures with
-Os that arise from functions not being inlined in that case, this
patch fixes such failures for putc_unlocked and fputc_unlocked.  This
is relative to a tree with
<https://sourceware.org/ml/libc-alpha/2018-02/msg00475.html> (pending
review) applied, but has only trivial textual dependence on that
patch.

libc_hidden_* are used for both functions, while namespace issues are
addressed by making putc_unlocked a weak alias of hidden
__putc_unlocked, which is called in the one place where namespace
issues arise (and defined as an inline function in include/stdio.h).

Tested for x86_64 (both without -Os to make sure that case continues
to work, and with -Os to make sure all the relevant linknamespace and
localplt test failures are resolved).  This completes fixing the -Os
linknamespace failures (at least for x86_64); localplt failures remain
after this patch.

2018-02-19  Joseph Myers  <joseph@codesourcery.com>

	[BZ #15105]
	[BZ #19463]
	* libio/fputc_u.c (fputc_unlocked): Use libc_hidden_def.
	* libio/putc_u.c (putc_unlocked): Rename to __putc_unlocked and
	define as weak alias of __putc_unlocked.  Use libc_hidden_weak.
	* include/stdio.h [!_ISOMAC] (fputc_unlocked): Use
	libc_hidden_proto.
	[!_ISOMAC] (putc_unlocked): Likewise.
	[!_ISOMAC] (__putc_unlocked): Declare as hidden function, and
	define inline if [__USE_EXTERN_INLINES].
	* misc/syslog.c (__vsyslog_chk): Call __putc_unlocked instead of
	putc_unlocked.

diff --git a/include/stdio.h b/include/stdio.h
index 937235f..aac5acd 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -188,6 +188,9 @@ extern __typeof (feof_unlocked) __feof_unlocked attribute_hidden;
 libc_hidden_proto (ferror_unlocked)
 extern __typeof (ferror_unlocked) __ferror_unlocked attribute_hidden;
 libc_hidden_proto (getc_unlocked)
+libc_hidden_proto (fputc_unlocked)
+libc_hidden_proto (putc_unlocked)
+extern __typeof (putc_unlocked) __putc_unlocked attribute_hidden;
 libc_hidden_proto (fmemopen)
 /* The prototype needs repeating instead of using __typeof to use
    __THROW in C++ tests.  */
@@ -226,6 +229,12 @@ __getc_unlocked (FILE *__fp)
 {
   return __getc_unlocked_body (__fp);
 }
+
+__extern_inline int
+__putc_unlocked (int __c, FILE *__stream)
+{
+  return __putc_unlocked_body (__c, __stream);
+}
 #  endif
 
 # endif /* not _ISOMAC */
diff --git a/libio/fputc_u.c b/libio/fputc_u.c
index abe07f3..25e2035 100644
--- a/libio/fputc_u.c
+++ b/libio/fputc_u.c
@@ -35,3 +35,4 @@ fputc_unlocked (int c, _IO_FILE *fp)
   CHECK_FILE (fp, EOF);
   return _IO_putc_unlocked (c, fp);
 }
+libc_hidden_def (fputc_unlocked)
diff --git a/libio/putc_u.c b/libio/putc_u.c
index 61ca95b..2d122a6 100644
--- a/libio/putc_u.c
+++ b/libio/putc_u.c
@@ -21,8 +21,10 @@
 #undef putc_unlocked
 
 int
-putc_unlocked (int c, _IO_FILE *fp)
+__putc_unlocked (int c, _IO_FILE *fp)
 {
   CHECK_FILE (fp, EOF);
   return _IO_putc_unlocked (c, fp);
 }
+weak_alias (__putc_unlocked, putc_unlocked)
+libc_hidden_weak (putc_unlocked)
diff --git a/misc/syslog.c b/misc/syslog.c
index 2b6bd37..644dbe8 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -207,8 +207,8 @@ __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
 	      fprintf (f, "[%d]", (int) __getpid ());
 	    if (LogTag != NULL)
 	      {
-		putc_unlocked (':', f);
-		putc_unlocked (' ', f);
+		__putc_unlocked (':', f);
+		__putc_unlocked (' ', f);
 	      }
 
 	    /* Restore errno for %m format.  */

-- 
Joseph S. Myers
joseph@codesourcery.com