libio/filedoalloc.c

   1 /* Copyright (C) 1993-2014 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, see
  16    <http://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 /*
  28    Copyright (C) 1990 The Regents of the University of California.
  29    All rights reserved.
  30
  31    Redistribution and use in source and binary forms, with or without
  32    modification, are permitted provided that the following conditions
  33    are met:
  34
  35    1. Redistributions of source code must retain the above copyright
  36       notice, this list of conditions and the following disclaimer.
  37    2. Redistributions in binary form must reproduce the above copyright
  38       notice, this list of conditions and the following disclaimer in the
  39       documentation and/or other materials provided with the distribution.
  40    4. Neither the name of the University nor the names of its contributors
  41       may be used to endorse or promote products derived from this software
  42       without specific prior written permission.
  43
  44    THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47    ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50    OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54    SUCH DAMAGE.*/
  55
  56 /* Modified for GNU iostream by Per Bothner 1991, 1992. */
  57
  58 #ifndef _POSIX_SOURCE
  59 # define _POSIX_SOURCE
  60 #endif
  61 #include "libioP.h"
  62 #include <sys/types.h>
  63 #include <sys/stat.h>
  64 #include <stdlib.h>
  65 #include <unistd.h>
  66
  67 #ifdef _LIBC
  68 # undef isatty
  69 # define isatty(Fd) __isatty (Fd)
  70
  71 # include <device-nrs.h>
  72 #endif
  73
  74
  75 static int
  76 local_isatty (int fd)
  77 {
  78   int save_errno = errno;
  79   int res = isatty (fd);
  80   __set_errno (save_errno);
  81   return res;
  82 }
  83
  84
  85 /*
  86  * Allocate a file buffer, or switch to unbuffered I/O.
  87  * Per the ANSI C standard, ALL tty devices default to line buffered.
  88  *
  89  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  90  * optimisation) right after the _fstat() that finds the buffer size.
  91  */
  92
  93 int
  94 _IO_file_doallocate (fp)
  95      _IO_FILE *fp;
  96 {
  97   _IO_size_t size;
  98   char *p;
  99   struct stat64 st;
 100
 101 #ifndef _LIBC
 102   /* If _IO_cleanup_registration_needed is non-zero, we should call the
 103      function it points to.  This is to make sure _IO_cleanup gets called
 104      on exit.  We call it from _IO_file_doallocate, since that is likely
 105      to get called by any program that does buffered I/O. */
 106   if (__glibc_unlikely (_IO_cleanup_registration_needed != NULL))
 107     (*_IO_cleanup_registration_needed) ();
 108 #endif
 109
 110   size = _IO_BUFSIZ;
 111   if (fp->_fileno >= 0 && __builtin_expect (_IO_SYSSTAT (fp, &st), 0) >= 0)
 112     {
 113       if (S_ISCHR (st.st_mode))
 114         {
 115           /* Possibly a tty.  */
 116           if (
 117 #ifdef DEV_TTY_P
 118               DEV_TTY_P (&st) ||
 119 #endif
 120               local_isatty (fp->_fileno))
 121             fp->_flags |= _IO_LINE_BUF;
 122         }
 123 #if _IO_HAVE_ST_BLKSIZE
 124       if (st.st_blksize > 0)
 125         size = st.st_blksize;
 126 #endif
 127     }
 128   ALLOC_BUF (p, size, EOF);
 129   _IO_setb (fp, p, p + size, 1);
 130   return 1;
 131 }
 132 libc_hidden_def (_IO_file_doallocate)