Introduce _STDIO_BSD_SEMANTICS flag to switch fclose/exit file flushing

semantics from POSIX to BSD.
	* libc/stdio/fclose.c (_fclose_r): Conditionalize file flushing on
	_STDIO_BSD_SEMANTICS.  Call __sflush_r rather than _fflush_r.  Add
	comment.
	* libc/stdio/fflush.c (__sflushw_r): New function, only available
	if _STDIO_BSD_SEMANTICS is defined.
	* libc/stdio/findfp.c (_cleanup_r): Call _fwalk_reent rather than
	_fwalk.  Conditionalize cleanup function call on _STDIO_BSD_SEMANTICS.
	Add comments.  Add FIXME.
	* libc/stdio/local.h (__sflushw_r): Declare if _STDIO_BSD_SEMANTICS is
	defined.

newlib/ChangeLog

@@ -1,3 +1,18 @@
+2014-01-17  Corinna Vinschen  <vinschen@redhat.com>
+
+	Introduce _STDIO_BSD_SEMANTICS flag to switch fclose/exit file flushing
+	semantics from POSIX to BSD.
+	* libc/stdio/fclose.c (_fclose_r): Conditionalize file flushing on
+	_STDIO_BSD_SEMANTICS.  Call __sflush_r rather than _fflush_r.  Add
+	comment.
+	* libc/stdio/fflush.c (__sflushw_r): New function, only available
+	if _STDIO_BSD_SEMANTICS is defined.
+	* libc/stdio/findfp.c (_cleanup_r): Call _fwalk_reent rather than
+	_fwalk.  Conditionalize cleanup function call on _STDIO_BSD_SEMANTICS.
+	Add comments.  Add FIXME.
+	* libc/stdio/local.h (__sflushw_r): Declare if _STDIO_BSD_SEMANTICS is
+	defined.
+
 2014-01-06  Sebastian Huber  <sebastian.huber@embedded-brains.de>
 
 	* libc/include/sys/_default_fcntl.h (AT_FDCWD): Define according

newlib/libc/stdio/fclose.c

@@ -92,10 +92,15 @@ _DEFUN(_fclose_r, (rptr, fp),
 #endif
       return (0);
     }
-  /* Unconditionally flush to allow special handling for seekable read
-     files to reposition file to last byte processed as opposed to
-     last byte read ahead into the buffer.  */
-  r = _fflush_r (rptr, fp);
+#ifdef _STDIO_BSD_SEMANTICS
+  /* BSD and Glibc systems only flush streams which have been written to. */
+  r = (fp->_flags & __SWR) ? __sflush_r (rptr, fp) : 0;
+#else
+  /* Follow POSIX semantics exactly.  Unconditionally flush to allow
+     special handling for seekable read files to reposition file to last
+     byte processed as opposed to last byte read ahead into the buffer. */
+  r = __sflush_r (rptr, fp);
+#endif
   if (fp->_close != NULL && fp->_close (rptr, fp->_cookie) < 0)
     r = EOF;
   if (fp->_flags & __SMBF)

newlib/libc/stdio/fflush.c

@@ -204,6 +204,19 @@ _DEFUN(__sflush_r, (ptr, fp),
   return 0;
 }
 
+#ifdef _STDIO_BSD_SEMANTICS
+/* Called from _cleanup_r.  At exit time, we don't need file locking,
+   and we don't want to move the underlying file pointer unless we're
+   writing. */
+int
+_DEFUN(__sflushw_r, (ptr, fp),
+       struct _reent *ptr _AND
+       register FILE *fp)
+{
+  return (fp->_flags & __SWR) ?  __sflush_r (ptr, fp) : 0;
+}
+#endif
+
 int
 _DEFUN(_fflush_r, (ptr, fp),
        struct _reent *ptr _AND

newlib/libc/stdio/findfp.c

@@ -170,8 +170,17 @@ _VOID
 _DEFUN(_cleanup_r, (ptr),
        struct _reent *ptr)
 {
-  _CAST_VOID _fwalk(ptr, fclose);
-  /* _CAST_VOID _fwalk (ptr, fflush); */	/* `cheating' */
+#ifdef _STDIO_BSD_SEMANTICS
+  /* BSD and Glibc systems only flush streams which have been written to
+     at exit time.  Calling flush rather than close for speed, as on
+     the aforementioned systems. */
+  _CAST_VOID _fwalk_reent (ptr, __sflushw_r);
+#else
+  /* Otherwise close files and flush read streams, too.
+     FIXME: Do we really have to call fclose rather than fflush for
+     RTOS compatibility? */
+  _CAST_VOID _fwalk_reent (ptr, _fclose_r);
+#endif
 }
 
 #ifndef _REENT_ONLY

newlib/libc/stdio/local.h

@@ -147,6 +147,9 @@ int	      _EXFUN(_svfiwprintf_r,(struct _reent *, FILE *, const wchar_t *,
 extern FILE  *_EXFUN(__sfp,(struct _reent *));
 extern int    _EXFUN(__sflags,(struct _reent *,_CONST char*, int*));
 extern int    _EXFUN(__sflush_r,(struct _reent *,FILE *));
+#ifdef _STDIO_BSD_SEMANTICS
+extern int    _EXFUN(__sflushw_r,(struct _reent *,FILE *));
+#endif
 extern int    _EXFUN(__srefill_r,(struct _reent *,FILE *));
 extern _READ_WRITE_RETURN_TYPE _EXFUN(__sread,(struct _reent *, void *, char *,
 					       _READ_WRITE_BUFSIZE_TYPE));