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