[unix-history] / lib / libpthread / stdio / ungetc.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)ungetc.c	5.6 (Berkeley) 5/4/91";*/
static char *rcsid = "$Id: ungetc.c,v 1.15 1994/01/27 06:12:34 proven Exp $";
#endif /* LIBC_SCCS and not lint */

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "local.h"

/*
 * Expand the ungetc buffer `in place'.  That is, adjust fp->_p when
 * the buffer moves, so that it points the same distance from the end,
 * and move the bytes in the buffer around as necessary so that they
 * are all at the end (stack-style).
 */
static
__submore(fp)
	register FILE *fp;
{
	register int i;
	register unsigned char *p;

	if (fp->_ub._base == fp->_ubuf) {
		/*
		 * Get a new buffer (rather than expanding the old one).
		 */
		if ((p = malloc((size_t)BUFSIZ)) == NULL)
			return (EOF);
		fp->_ub._base = p;
		fp->_ub._size = BUFSIZ;
		p += BUFSIZ - sizeof(fp->_ubuf);
		for (i = sizeof(fp->_ubuf); --i >= 0;)
			p[i] = fp->_ubuf[i];
		fp->_p = p;
		return (0);
	}
	i = fp->_ub._size;
	p = realloc(fp->_ub._base, i << 1);
	if (p == NULL)
		return (EOF);
	(void) bcopy((void *)p, (void *)(p + i), (size_t)i);
	fp->_p = p + i;
	fp->_ub._base = p;
	fp->_ub._size = i << 1;
	return (0);
}

ungetc(c, fp)
	int c;
	register FILE *fp;
{
	if (c == EOF)
		return (EOF);
	pthread_once(&__sdidinit, __sinit);

	flockfile(fp);
	if ((fp->_flags & __SRD) == 0) {
		/*
		 * Not already reading: no good unless reading-and-writing.
		 * Otherwise, flush any current write stuff.
		 */
		if ((fp->_flags & __SRW) == 0)
			c = EOF;
			goto ungetc_end;
		if (fp->_flags & __SWR) {
			if (__sflush(fp))
				c = EOF;
				goto ungetc_end;
			fp->_flags &= ~__SWR;
			fp->_w = 0;
			fp->_lbfsize = 0;
		}
		fp->_flags |= __SRD;
	}
	c = (unsigned char)c;

	/*
	 * If we are in the middle of ungetc'ing, just continue.
	 * This may require expanding the current ungetc buffer.
	 */
	if (HASUB(fp)) {
		if (fp->_r >= fp->_ub._size && __submore(fp))
			return (EOF);
		*--fp->_p = c;
		fp->_r++;
		goto ungetc_end;
	}

	/*
	 * If we can handle this by simply backing up, do so,
	 * but never replace the original character.
	 * (This makes sscanf() work when scanning `const' data.)
	 */
	if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
	    fp->_p[-1] == c) {
		fp->_p--;
		fp->_r++;
		goto ungetc_end;
	}

	/*
	 * Create an ungetc buffer.
	 * Initially, we will use the `reserve' buffer.
	 */
	fp->_ur = fp->_r;
	fp->_up = fp->_p;
	fp->_ub._base = fp->_ubuf;
	fp->_ub._size = sizeof(fp->_ubuf);
	fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
	fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
	fp->_r = 1;

ungetc_end:;
	funlockfile(fp);
	return (c);
}
Commit	Line	Data
8f953e65 CP	1	/*-
	2	* Copyright (c) 1990 The Regents of the University of California.
	3	* 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	/static char sccsid = "from: @(#)ungetc.c 5.6 (Berkeley) 5/4/91";*/
	39	static char *rcsid = "$Id: ungetc.c,v 1.15 1994/01/27 06:12:34 proven Exp $";
	40	#endif /* LIBC_SCCS and not lint */
	41
	42	#include <pthread.h>
	43	#include <stdio.h>
	44	#include <stdlib.h>
	45	#include <string.h>
	46	#include "local.h"
	47
	48	/*
	49	* Expand the ungetc buffer `in place'. That is, adjust fp->_p when
	50	* the buffer moves, so that it points the same distance from the end,
	51	* and move the bytes in the buffer around as necessary so that they
	52	* are all at the end (stack-style).
	53	*/
	54	static
	55	__submore(fp)
	56	register FILE *fp;
	57	{
	58	register int i;
	59	register unsigned char *p;
	60
	61	if (fp->_ub._base == fp->_ubuf) {
	62	/*
	63	* Get a new buffer (rather than expanding the old one).
	64	*/
65	if ((p = malloc((size_t)BUFSIZ)) == NULL)
66	return (EOF);
67	fp->_ub._base = p;
68	fp->_ub._size = BUFSIZ;
69	p += BUFSIZ - sizeof(fp->_ubuf);
70	for (i = sizeof(fp->_ubuf); --i >= 0;)
71	p[i] = fp->_ubuf[i];
72	fp->_p = p;
73	return (0);
74	}
75	i = fp->_ub._size;
76	p = realloc(fp->_ub._base, i << 1);
77	if (p == NULL)
78	return (EOF);
79	(void) bcopy((void )p, (void )(p + i), (size_t)i);
80	fp->_p = p + i;
81	fp->_ub._base = p;
82	fp->_ub._size = i << 1;
83	return (0);
84	}
85
86	ungetc(c, fp)
87	int c;
88	register FILE *fp;
89	{
90	if (c == EOF)
91	return (EOF);
92	pthread_once(&__sdidinit, __sinit);
93
94	flockfile(fp);
95	if ((fp->_flags & __SRD) == 0) {
96	/*
97	* Not already reading: no good unless reading-and-writing.
98	* Otherwise, flush any current write stuff.
99	*/
100	if ((fp->_flags & __SRW) == 0)
101	c = EOF;
102	goto ungetc_end;
103	if (fp->_flags & __SWR) {
104	if (__sflush(fp))
105	c = EOF;
106	goto ungetc_end;
107	fp->_flags &= ~__SWR;
108	fp->_w = 0;
109	fp->_lbfsize = 0;
110	}
111	fp->_flags \|= __SRD;
112	}
113	c = (unsigned char)c;
114
115	/*
116	* If we are in the middle of ungetc'ing, just continue.
117	* This may require expanding the current ungetc buffer.
118	*/
119	if (HASUB(fp)) {
120	if (fp->_r >= fp->_ub._size && __submore(fp))
121	return (EOF);
122	*--fp->_p = c;
123	fp->_r++;
124	goto ungetc_end;
125	}
126
127	/*
128	* If we can handle this by simply backing up, do so,
129	* but never replace the original character.
130	* (This makes sscanf() work when scanning `const' data.)
131	*/
132	if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
133	fp->_p[-1] == c) {
134	fp->_p--;
135	fp->_r++;
136	goto ungetc_end;
137	}
138
139	/*
140	* Create an ungetc buffer.
141	* Initially, we will use the `reserve' buffer.
142	*/
143	fp->_ur = fp->_r;
144	fp->_up = fp->_p;
145	fp->_ub._base = fp->_ubuf;
146	fp->_ub._size = sizeof(fp->_ubuf);
147	fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
148	fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
149	fp->_r = 1;
150
151	ungetc_end:;
152	funlockfile(fp);
153	return (c);
154	}