libio/filedoalloc.c

   1 /* Copyright (C) 1993-2023 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    <https://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 #include "libioP.h"
  59 #include <device-nrs.h>
  60 #include <sys/stat.h>
  61 #include <stdlib.h>
  62 #include <unistd.h>
  63
  64 /* Return the result of isatty, without changing errno.  */
  65 static int
  66 local_isatty (int fd)
  67 {
  68   int save_errno = errno;
  69   int res = __isatty (fd);
  70   __set_errno (save_errno);
  71   return res;
  72 }
  73
  74 /* Allocate a file buffer, or switch to unbuffered I/O.  Streams for
  75    TTY devices default to line buffered.  */
  76 int
  77 _IO_file_doallocate (FILE *fp)
  78 {
  79   size_t size;
  80   char *p;
  81   struct __stat64_t64 st;
  82
  83   size = BUFSIZ;
  84   if (fp->_fileno >= 0 && __builtin_expect (_IO_SYSSTAT (fp, &st), 0) >= 0)
  85     {
  86       if (S_ISCHR (st.st_mode))
  87         {
  88           /* Possibly a tty.  */
  89           if (
  90 #ifdef DEV_TTY_P
  91               DEV_TTY_P (&st) ||
  92 #endif
  93               local_isatty (fp->_fileno))
  94             fp->_flags |= _IO_LINE_BUF;
  95         }
  96 #if defined _STATBUF_ST_BLKSIZE
  97       if (st.st_blksize > 0 && st.st_blksize < BUFSIZ)
  98         size = st.st_blksize;
  99 #endif
 100     }
 101   p = malloc (size);
 102   if (__glibc_unlikely (p == NULL))
 103     return EOF;
 104   _IO_setb (fp, p, p + size, 1);
 105   return 1;
 106 }
 107 libc_hidden_def (_IO_file_doallocate)