libio/filedoalloc.c

   1 /* Copyright (C) 1993, 1997, 2001, 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.
  18
  19    As a special exception, if you link the code in this file with
  20    files compiled with a GNU compiler to produce an executable,
  21    that does not cause the resulting executable to be covered by
  22    the GNU Lesser General Public License.  This exception does not
  23    however invalidate any other reasons why the executable file
  24    might be covered by the GNU Lesser General Public License.
  25    This exception applies to code released by its copyright holders
  26    in files containing the exception.  */
  27
  28 /*
  29  * Copyright (c) 1990 The Regents of the University of California.
  30  * All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms are permitted
  33  * provided that the above copyright notice and this paragraph are
  34  * duplicated in all such forms and that any documentation,
  35  * advertising materials, and other materials related to such
  36  * distribution and use acknowledge that the software was developed
  37  * by the University of California, Berkeley.  The name of the
  38  * University may not be used to endorse or promote products derived
  39  * from this software without specific prior written permission.
  40  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  41  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  42  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  43  */
  44
  45 /* Modified for GNU iostream by Per Bothner 1991, 1992. */
  46
  47 #ifndef _POSIX_SOURCE
  48 # define _POSIX_SOURCE
  49 #endif
  50 #include "libioP.h"
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53 #ifdef __STDC__
  54 #include <stdlib.h>
  55 #include <unistd.h>
  56 #endif
  57
  58 #ifdef _LIBC
  59 # undef isatty
  60 # define isatty(Fd) __isatty (Fd)
  61
  62 # include <device-nrs.h>
  63 #endif
  64
  65 /*
  66  * Allocate a file buffer, or switch to unbuffered I/O.
  67  * Per the ANSI C standard, ALL tty devices default to line buffered.
  68  *
  69  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  70  * optimisation) right after the _fstat() that finds the buffer size.
  71  */
  72
  73 int
  74 _IO_file_doallocate (fp)
  75      _IO_FILE *fp;
  76 {
  77   _IO_size_t size;
  78   char *p;
  79   struct _G_stat64 st;
  80
  81 #ifndef _LIBC
  82   /* If _IO_cleanup_registration_needed is non-zero, we should call the
  83      function it points to.  This is to make sure _IO_cleanup gets called
  84      on exit.  We call it from _IO_file_doallocate, since that is likely
  85      to get called by any program that does buffered I/O. */
  86   if (__builtin_expect (_IO_cleanup_registration_needed != NULL, 0))
  87     (*_IO_cleanup_registration_needed) ();
  88 #endif
  89
  90   size = _IO_BUFSIZ;
  91   if (fp->_fileno >= 0 && __builtin_expect (_IO_SYSSTAT (fp, &st), 0) >= 0)
  92     {
  93       if (S_ISCHR (st.st_mode))
  94         {
  95           /* Possibly a tty.  */
  96           if (
  97 #ifdef DEV_TTY_P
  98               DEV_TTY_P (&st) ||
  99 #endif
 100               isatty (fp->_fileno))
 101             fp->_flags |= _IO_LINE_BUF;
 102         }
 103 #if _IO_HAVE_ST_BLKSIZE
 104       if (st.st_blksize > 0)
 105         size = st.st_blksize;
 106 #endif
 107     }
 108   ALLOC_BUF (p, size, EOF);
 109   INTUSE(_IO_setb) (fp, p, p + size, 1);
 110   return 1;
 111 }
 112 INTDEF(_IO_file_doallocate)