libio: Eliminate _IO_stdin, _IO_stdout, _IO_stderr

These variables are only used to determine if a stdio stream is
a pre-allocated stream, but it is possible to do so by comparing
a FILE * to all pre-allocated stream objects.  As a result, it is
not necessary to keep those pointers in separate variables.

Behavior with symbol interposition is unchanged because _IO_stdin_,
_IO_stdout_, _IO_stderr_ are exported, and refer to objects outside of
libc if symbol interposition or copy relocations are involved.  (The
removed variables _IO_stdin, _IO_stdout, _IO_stderr were not exported,
of course.)

1 files changed, 1 insertions, 2 deletions

diff --git a/libio/iofwide.c b/libio/iofwide.c
index 6676ad5e53..247cfde3d0 100644
--- a/libio/iofwide.c
+++ b/libio/iofwide.c
@@ -87,8 +87,7 @@ _IO_fwide (FILE *fp, int mode)
   mode = mode < 0 ? -1 : (mode == 0 ? 0 : 1);
 
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
-  if (__builtin_expect (&_IO_stdin_used == NULL, 0)
-      && (fp == _IO_stdin || fp == _IO_stdout || fp == _IO_stderr))
+  if (__glibc_unlikely (&_IO_stdin_used == NULL) && _IO_legacy_file (fp))
     /* This is for a stream in the glibc 2.0 format.  */
     return -1;
 #endif