[glibc/google/grte/v5-2.27/master] Fix -Os putc_unlocked, fputc_unlocked linknamespace, localplt issues (bug 15105, bug 19463).

[Fangrui Song <maskray@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2641081f12b77defb12ecf65f528610aad6318fd

commit 2641081f12b77defb12ecf65f528610aad6318fd
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Feb 21 18:02:24 2018 +0000

    Fix -Os putc_unlocked, fputc_unlocked linknamespace, localplt issues (bug 15105, bug 19463).
    
    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.
    
    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.
    
    (cherry picked from commit 039c721a30392790be50dba53b4c72dbcd65be67)

Diff:
---
 include/stdio.h | 9 +++++++++
 libio/fputc_u.c | 1 +
 libio/putc_u.c  | 4 +++-
 misc/syslog.c   | 4 ++--
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/stdio.h b/include/stdio.h
index 6ad5794baa..c0cb776690 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -183,6 +183,9 @@ 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.  */
@@ -221,6 +224,12 @@ __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 abe07f33d3..25e2035cf4 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 61ca95beda..2d122a6d23 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 2b6bd373bc..644dbe80ec 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.  */