libstdc++-v3/libio/filedoalloc.c

   1 /* Copyright (C) 1993, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU IO Library.
   3
   4    This library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License as
   6    published by the Free Software Foundation; either version 2, or (at
   7    your option) any later version.
   8
   9    This library is distributed in the hope that it will be useful, but
  10    WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this library; see the file COPYING.  If not, write to
  16    the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
  17    MA 02111-1307, USA.
  18
  19    As a special exception, if you link this library with files
  20    compiled with a GNU compiler to produce an executable, this does
  21    not cause the resulting executable to be covered by the GNU General
  22    Public License.  This exception does not however invalidate any
  23    other reasons why the executable file might be covered by the GNU
  24    General Public License.  */
  25
  26 /*
  27  * Copyright (c) 1990 The Regents of the University of California.
  28  * All rights reserved.
  29  *
  30  * Redistribution and use in source and binary forms are permitted
  31  * provided that the above copyright notice and this paragraph are
  32  * duplicated in all such forms and that any documentation,
  33  * advertising materials, and other materials related to such
  34  * distribution and use acknowledge that the software was developed
  35  * by the University of California, Berkeley.  The name of the
  36  * University may not be used to endorse or promote products derived
  37  * from this software without specific prior written permission.
  38  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  39  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  40  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  41  */
  42
  43 /* Modified for GNU iostream by Per Bothner 1991, 1992. */
  44
  45 #ifndef _POSIX_SOURCE
  46 # define _POSIX_SOURCE
  47 #endif
  48 #include "libioP.h"
  49 #include <sys/types.h>
  50 #include <sys/stat.h>
  51 #ifdef __STDC__
  52 #include <stdlib.h>
  53 #include <unistd.h>
  54 #endif
  55
  56 #ifdef _LIBC
  57 # undef isatty
  58 # define isatty(Fd) __isatty (Fd)
  59 #endif
  60
  61 /*
  62  * Allocate a file buffer, or switch to unbuffered I/O.
  63  * Per the ANSI C standard, ALL tty devices default to line buffered.
  64  *
  65  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  66  * optimisation) right after the _fstat() that finds the buffer size.
  67  */
  68
  69 int
  70 _IO_file_doallocate (fp)
  71      _IO_FILE *fp;
  72 {
  73   _IO_size_t size;
  74   int couldbetty;
  75   char *p;
  76   struct _G_stat64 st;
  77
  78   if (fp->_fileno < 0 || _IO_SYSSTAT (fp, &st) < 0)
  79     {
  80       couldbetty = 0;
  81       size = _IO_BUFSIZ;
  82 #if 0
  83       /* do not try to optimise fseek() */
  84       fp->_flags |= __SNPT;
  85 #endif
  86     }
  87   else
  88     {
  89       couldbetty = S_ISCHR (st.st_mode);
  90 #if _IO_HAVE_ST_BLKSIZE
  91       size = st.st_blksize <= 0 ? _IO_BUFSIZ : st.st_blksize;
  92 #else
  93       size = _IO_BUFSIZ;
  94 #endif
  95     }
  96   ALLOC_BUF (p, size, EOF);
  97   _IO_setb (fp, p, p + size, 1);
  98   if (couldbetty && isatty (fp->_fileno))
  99     fp->_flags |= _IO_LINE_BUF;
 100   return 1;
 101 }