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/* Copyright (C) 1991, 1992, 1993, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
/* Initialize STREAM as necessary.
This may change I/O functions, give a buffer, etc.
If no buffer is allocated, but the bufsize is set,
the bufsize will be used to allocate the buffer. */
void
DEFUN(__stdio_init_stream, (stream), FILE *stream)
{
register CONST int fd = (int) stream->__cookie;
struct stat statb;
if (stream->__buffer != NULL || stream->__userbuf)
/* If's unbuffered by request, we can't do anything useful. */
return;
/* Find out what sort of file this is. */
if (__fstat (fd, &statb) < 0)
return;
if (S_ISCHR (statb.st_mode))
{
/* It's a character device.
Make it line-buffered if it's a terminal. */
if (__isatty (fd))
{
stream->__linebuf = 1;
/* Unix terminal devices have the bad habit of claiming to be
seekable. On systems I have tried, seeking on a terminal
device seems to set its file position as specified, such that
a later tell says the same thing. This is in no way related
to actual seekability--the ability to seek back and read old
data. Unix terminal devices will let you "seek back", and
then read more new data from the terminal. I can think of
nothing to do about this lossage except to preemptively disable
seeking on terminal devices. */
stream->__io_funcs.__seek = NULL; /* Seeks get ESPIPE. */
}
}
#ifdef _STATBUF_ST_BLKSIZE
/* Use the block-size field to determine
the system's optimal buffering size. */
stream->__bufsize = statb.st_blksize;
#endif
}
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