70 lines
2.4 KiB
C
70 lines
2.4 KiB
C
/* Copyright (C) 1991, 1992, 1993, 1995, 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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/* Initialize STREAM as necessary.
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This may change I/O functions, give a buffer, etc.
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If no buffer is allocated, but the bufsize is set,
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the bufsize will be used to allocate the buffer. */
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void
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__stdio_init_stream (FILE *stream)
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{
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const int fd = (int) stream->__cookie;
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struct stat statb;
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if (stream->__buffer != NULL || stream->__userbuf)
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/* If's unbuffered by request, we can't do anything useful. */
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return;
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/* Find out what sort of file this is. */
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if (__fstat (fd, &statb) < 0)
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return;
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if (S_ISCHR (statb.st_mode))
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{
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/* It's a character device.
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Make it line-buffered if it's a terminal. */
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if (__isatty (fd))
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{
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stream->__linebuf = 1;
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/* Unix terminal devices have the bad habit of claiming to be
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seekable. On systems I have tried, seeking on a terminal
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device seems to set its file position as specified, such that
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a later tell says the same thing. This is in no way related
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to actual seekability--the ability to seek back and read old
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data. Unix terminal devices will let you "seek back", and
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then read more new data from the terminal. I can think of
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nothing to do about this lossage except to preemptively disable
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seeking on terminal devices. */
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stream->__io_funcs.__seek = NULL; /* Seeks get ESPIPE. */
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}
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}
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#ifdef _STATBUF_ST_BLKSIZE
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/* Use the block-size field to determine
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the system's optimal buffering size. */
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stream->__bufsize = statb.st_blksize;
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#endif
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}
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