/* 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 }