newlib-2.4.0

git-svn-id: svn://kolibrios.org@6536 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/newlib/libc/stdio/fpurge.c

@@ -0,0 +1,113 @@
+/* Copyright (C) 2009 Eric Blake
+ * Permission to use, copy, modify, and distribute this software
+ * is freely granted, provided that this notice is preserved.
+ */
+
+/*
+FUNCTION
+<<fpurge>>---discard pending file I/O
+
+INDEX
+	fpurge
+INDEX
+	_fpurge_r
+INDEX
+	__fpurge
+
+ANSI_SYNOPSIS
+	#include <stdio.h>
+	int fpurge(FILE *<[fp]>);
+
+	int _fpurge_r(struct _reent *<[reent]>, FILE *<[fp]>);
+
+	#include <stdio.h>
+	#include <stdio_ext.h>
+	void  __fpurge(FILE *<[fp]>);
+
+
+DESCRIPTION
+Use <<fpurge>> to clear all buffers of the given stream.  For output
+streams, this discards data not yet written to disk.  For input streams,
+this discards any data from <<ungetc>> and any data retrieved from disk
+but not yet read via <<getc>>.  This is more severe than <<fflush>>,
+and generally is only needed when manually altering the underlying file
+descriptor of a stream.
+
+<<__fpurge>> behaves exactly like <<fpurge>> but does not return a value.
+
+The alternate function <<_fpurge_r>> is a reentrant version, where the
+extra argument <[reent]> is a pointer to a reentrancy structure, and
+<[fp]> must not be NULL.
+
+RETURNS
+<<fpurge>> returns <<0>> unless <[fp]> is not valid, in which case it
+returns <<EOF>> and sets <<errno>>.
+
+PORTABILITY
+These functions are not portable to any standard.
+
+No supporting OS subroutines are required.
+*/
+
+#include <_ansi.h>
+#include <stdio.h>
+#ifndef __rtems__
+#include <stdio_ext.h>
+#endif
+#include <errno.h>
+#include "local.h"
+
+/* Discard I/O from a single file.  */
+
+int
+_DEFUN(_fpurge_r, (ptr, fp),
+       struct _reent *ptr _AND
+       register FILE * fp)
+{
+  int t;
+
+  CHECK_INIT (ptr, fp);
+
+  _newlib_flockfile_start (fp);
+
+  t = fp->_flags;
+  if (!t)
+    {
+      ptr->_errno = EBADF;
+      _newlib_flockfile_exit (fp);
+      return EOF;
+    }
+  fp->_p = fp->_bf._base;
+  if ((t & __SWR) == 0)
+    {
+      fp->_r = 0;
+      if (HASUB (fp))
+	FREEUB (ptr, fp);
+    }
+  else
+    fp->_w = t & (__SLBF | __SNBF) ? 0 : fp->_bf._size;
+  _newlib_flockfile_end (fp);
+  return 0;
+}
+
+#ifndef _REENT_ONLY
+
+int
+_DEFUN(fpurge, (fp),
+       register FILE * fp)
+{
+  return _fpurge_r (_REENT, fp);
+}
+
+#ifndef __rtems__
+
+void
+_DEFUN(__fpurge, (fp),
+       register FILE * fp)
+{
+  _fpurge_r (_REENT, fp);
+}
+
+#endif
+
+#endif /* _REENT_ONLY */