NetBSD/gnu/lib/libg++/iostream/makebuf.C

72 lines
2.0 KiB
C

/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
// Modified for GNU iostream by Per Bothner 1991.
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "%W% (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */
#include "ioprivate.h"
#include "fstream.h"
#include <sys/types.h>
#include <sys/stat.h>
/*
* Allocate a file buffer, or switch to unbuffered I/O.
* Per the ANSI C standard, ALL tty devices default to line buffered.
*
* As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
* optimisation) right after the _fstat() that finds the buffer size.
*/
int filebuf::doallocate()
{
register size_t size, couldbetty;
register char *p;
struct stat st;
if (fd() < 0 || _fstat(fd(), &st) < 0) {
couldbetty = 0;
size = _G_BUFSIZ;
#if 0
/* do not try to optimise fseek() */
fp->_flags |= __SNPT;
#endif
} else {
couldbetty = S_ISCHR(st.st_mode);
#if _G_HAVE_ST_BLKSIZE
size = st.st_blksize <= 0 ? _G_BUFSIZ : st.st_blksize;
#else
size = _G_BUFSIZ;
#endif
}
#ifdef USE_MALLOC_BUF
if ((p = malloc(size)) == NULL) {
unbuffered(1);
// fp->_bf._base = fp->_p = fp->_nbuf;
// fp->_bf._size = 1;
return EOF;
}
#else
p = ALLOC_BUF(size);
#endif
setb(p, p+size, 1);
if (couldbetty && _isatty(fd()))
_flags |= _S_LINE_BUF;
return 1;
}