WebSVN - shark - Blame - Rev 2 - /shark/branches/pj/libc/stdio/ungetc.c

Rev	Author	Line No.	Line
2	pj	1	/*-
		2	* Copyright (c) 1990, 1993
		3	* The Regents of the University of California. All rights reserved.
		4	*
		5	* This code is derived from software contributed to Berkeley by
		6	* Chris Torek.
		7	*
		8	* Redistribution and use in source and binary forms, with or without
		9	* modification, are permitted provided that the following conditions
		10	* are met:
		11	* 1. Redistributions of source code must retain the above copyright
		12	* notice, this list of conditions and the following disclaimer.
		13	* 2. Redistributions in binary form must reproduce the above copyright
		14	* notice, this list of conditions and the following disclaimer in the
		15	* documentation and/or other materials provided with the distribution.
		16	* 3. All advertising materials mentioning features or use of this software
		17	* must display the following acknowledgement:
		18	* This product includes software developed by the University of
		19	* California, Berkeley and its contributors.
		20	* 4. Neither the name of the University nor the names of its contributors
		21	* may be used to endorse or promote products derived from this software
		22	* without specific prior written permission.
		23	*
		24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
		25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
		26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
		27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
		28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
		29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
		30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
		31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
		32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
		33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
		34	* SUCH DAMAGE.
		35	*/
		36
		37	#if defined(LIBC_SCCS) && !defined(lint)
		38	#if 0
		39	static char sccsid[] = "@(#)ungetc.c 8.2 (Berkeley) 11/3/93";
		40	#endif
		41	static const char rcsid[] =
		42	"$\Id: ungetc.c,v 1.3 1996/06/22 10:33:59 jraynard Exp $";
		43	#endif /* LIBC_SCCS and not lint */
		44
		45	#include <stdio.h>
		46	#include <stdlib.h>
		47	#include <string.h>
		48	#include "local.h"
		49	#ifdef _THREAD_SAFE
		50	#include <pthread.h>
		51	#include "pthread_private.h"
		52	#endif
		53
		54	static int __submore __P((FILE *));
		55
		56	/*
		57	* Expand the ungetc buffer `in place'. That is, adjust fp->_p when
		58	* the buffer moves, so that it points the same distance from the end,
		59	* and move the bytes in the buffer around as necessary so that they
		60	* are all at the end (stack-style).
		61	*/
		62	static int
		63	__submore(fp)
		64	register FILE *fp;
		65	{
		66	register int i;
		67	register unsigned char *p;
		68
		69	if (fp->_ub._base == fp->_ubuf) {
		70	/*
		71	* Get a new buffer (rather than expanding the old one).
		72	*/
		73	if ((p = malloc((size_t)BUFSIZ)) == NULL)
		74	return (EOF);
		75	fp->_ub._base = p;
		76	fp->_ub._size = BUFSIZ;
		77	p += BUFSIZ - sizeof(fp->_ubuf);
		78	for (i = sizeof(fp->_ubuf); --i >= 0;)
		79	p[i] = fp->_ubuf[i];
		80	fp->_p = p;
		81	return (0);
		82	}
		83	i = fp->_ub._size;
		84	p = realloc(fp->_ub._base, (size_t)(i << 1));
		85	if (p == NULL)
		86	return (EOF);
		87	/* no overlap (hence can use memcpy) because we doubled the size */
		88	(void)memcpy((void )(p + i), (void )p, (size_t)i);
		89	fp->_p = p + i;
		90	fp->_ub._base = p;
		91	fp->_ub._size = i << 1;
		92	return (0);
		93	}
		94
		95	int
		96	ungetc(c, fp)
		97	int c;
		98	register FILE *fp;
		99	{
		100	if (c == EOF)
		101	return (EOF);
		102	if (!__sdidinit)
		103	__sinit();
		104	#ifdef _THREAD_SAFE
		105	_thread_flockfile(fp,__FILE__,__LINE__);
		106	#endif
		107	if ((fp->_flags & __SRD) == 0) {
		108	/*
		109	* Not already reading: no good unless reading-and-writing.
		110	* Otherwise, flush any current write stuff.
		111	*/
		112	if ((fp->_flags & __SRW) == 0) {
		113	#ifdef _THREAD_SAFE
		114	_thread_funlockfile(fp);
		115	#endif
		116	return (EOF);
		117	}
		118	if (fp->_flags & __SWR) {
		119	if (__sflush(fp)) {
		120	#ifdef _THREAD_SAFE
		121	_thread_funlockfile(fp);
		122	#endif
		123	return (EOF);
		124	}
		125	fp->_flags &= ~__SWR;
		126	fp->_w = 0;
		127	fp->_lbfsize = 0;
		128	}
		129	fp->_flags \|= __SRD;
		130	}
		131	c = (unsigned char)c;
		132
		133	/*
		134	* If we are in the middle of ungetc'ing, just continue.
		135	* This may require expanding the current ungetc buffer.
		136	*/
		137	if (HASUB(fp)) {
		138	if (fp->_r >= fp->_ub._size && __submore(fp)) {
		139	#ifdef _THREAD_SAFE
		140	_thread_funlockfile(fp);
		141	#endif
		142	return (EOF);
		143	}
		144	*--fp->_p = c;
		145	fp->_r++;
		146	#ifdef _THREAD_SAFE
		147	_thread_funlockfile(fp);
		148	#endif
		149	return (c);
		150	}
		151	fp->_flags &= ~__SEOF;
		152
		153	/*
		154	* If we can handle this by simply backing up, do so,
		155	* but never replace the original character.
		156	* (This makes sscanf() work when scanning `const' data.)
		157	*/
		158	if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
		159	fp->_p[-1] == c) {
		160	fp->_p--;
		161	fp->_r++;
		162	#ifdef _THREAD_SAFE
		163	_thread_funlockfile(fp);
		164	#endif
		165	return (c);
		166	}
		167
		168	/*
		169	* Create an ungetc buffer.
		170	* Initially, we will use the `reserve' buffer.
		171	*/
		172	fp->_ur = fp->_r;
		173	fp->_up = fp->_p;
		174	fp->_ub._base = fp->_ubuf;
		175	fp->_ub._size = sizeof(fp->_ubuf);
		176	fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
		177	fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
		178	fp->_r = 1;
		179	#ifdef _THREAD_SAFE
		180	_thread_funlockfile(fp);
		181	#endif
		182	return (c);
		183	}

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