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 #include "libioP.h"
  46 #include <sys/types.h>
  47 #include <sys/stat.h>
  48 #ifdef __STDC__
  49 #include <stdlib.h>
  50 #include <unistd.h>
  51 #endif
  52
  53 #ifdef _LIBC
  54 # undef isatty
  55 # define isatty(Fd) __isatty (Fd)
  56 #endif
  57
  58 /*
  59  * Allocate a file buffer, or switch to unbuffered I/O.
  60  * Per the ANSI C standard, ALL tty devices default to line buffered.
  61  *
  62  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  63  * optimisation) right after the _fstat() that finds the buffer size.
  64  */
  65
  66 int
  67 _IO_file_doallocate (fp)
  68      _IO_FILE *fp;
  69 {
  70   _IO_size_t size;
  71   int couldbetty;
  72   char *p;
  73   struct stat st;
  74
  75 #if !defined(_LIBC) && !defined(__linux__)
  76   /* If _IO_cleanup_registration_needed is non-zero, we should call the
  77      function it points to.  This is to make sure _IO_cleanup gets called
  78      on exit.  We call it from _IO_file_doallocate, since that is likely
  79      to get called by any program that does buffered I/O. */
  80   if (_IO_cleanup_registration_needed)
  81     (*_IO_cleanup_registration_needed) ();
  82 #endif
  83
  84   if (fp->_fileno < 0 || _IO_SYSSTAT (fp, &st) < 0)
  85     {
  86       couldbetty = 0;
  87       size = _IO_BUFSIZ;
  88 #if 0
  89       /* do not try to optimise fseek() */
  90       fp->_flags |= __SNPT;
  91 #endif
  92     }
  93   else
  94     {
  95       couldbetty = S_ISCHR (st.st_mode);
  96 #if _IO_HAVE_ST_BLKSIZE
  97       size = st.st_blksize <= 0 ? _IO_BUFSIZ : st.st_blksize;
  98 #else
  99       size = _IO_BUFSIZ;
 100 #endif
 101     }
 102   ALLOC_BUF (p, size, EOF);
 103   _IO_setb (fp, p, p + size, 1);
 104   if (couldbetty && isatty (fp->_fileno))
 105     fp->_flags |= _IO_LINE_BUF;
 106   return 1;
 107 }