memalloc.c revision 1.15 
1/*	$NetBSD: memalloc.c,v 1.15 1995/03/21 09:09:29 cgd Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#ifndef lint
40#if 0
41static char sccsid[] = "@(#)memalloc.c	8.1 (Berkeley) 5/31/93";
42#else
43static char rcsid[] = "$NetBSD: memalloc.c,v 1.15 1995/03/21 09:09:29 cgd Exp $";
44#endif
45#endif /* not lint */
46
47#include "shell.h"
48#include "output.h"
49#include "memalloc.h"
50#include "error.h"
51#include "machdep.h"
52#include "mystring.h"
53#include <stdlib.h>
54#include <unistd.h>
55
56/*
57 * Like malloc, but returns an error when out of space.
58 */
59
60pointer
61ckmalloc(nbytes)
62	int nbytes;
63{
64	register pointer p;
65
66	if ((p = malloc(nbytes)) == NULL)
67		error("Out of space");
68	return p;
69}
70
71
72/*
73 * Same for realloc.
74 */
75
76pointer
77ckrealloc(p, nbytes)
78	register pointer p;
79	int nbytes;
80{
81
82	if ((p = realloc(p, nbytes)) == NULL)
83		error("Out of space");
84	return p;
85}
86
87
88/*
89 * Make a copy of a string in safe storage.
90 */
91
92char *
93savestr(s)
94	char *s;
95	{
96	register char *p;
97
98	p = ckmalloc(strlen(s) + 1);
99	scopy(s, p);
100	return p;
101}
102
103
104/*
105 * Parse trees for commands are allocated in lifo order, so we use a stack
106 * to make this more efficient, and also to avoid all sorts of exception
107 * handling code to handle interrupts in the middle of a parse.
108 *
109 * The size 504 was chosen because the Ultrix malloc handles that size
110 * well.
111 */
112
113#define MINSIZE 504		/* minimum size of a block */
114
115
116struct stack_block {
117	struct stack_block *prev;
118	char space[MINSIZE];
119};
120
121struct stack_block stackbase;
122struct stack_block *stackp = &stackbase;
123char *stacknxt = stackbase.space;
124int stacknleft = MINSIZE;
125int sstrnleft;
126int herefd = -1;
127
128
129
130pointer
131stalloc(nbytes)
132	int nbytes;
133{
134	register char *p;
135
136	nbytes = ALIGN(nbytes);
137	if (nbytes > stacknleft) {
138		int blocksize;
139		struct stack_block *sp;
140
141		blocksize = nbytes;
142		if (blocksize < MINSIZE)
143			blocksize = MINSIZE;
144		INTOFF;
145		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
146		sp->prev = stackp;
147		stacknxt = sp->space;
148		stacknleft = blocksize;
149		stackp = sp;
150		INTON;
151	}
152	p = stacknxt;
153	stacknxt += nbytes;
154	stacknleft -= nbytes;
155	return p;
156}
157
158
159void
160stunalloc(p)
161	pointer p;
162	{
163	if (p == NULL) {		/*DEBUG */
164		write(2, "stunalloc\n", 10);
165		abort();
166	}
167	stacknleft += stacknxt - (char *)p;
168	stacknxt = p;
169}
170
171
172
173void
174setstackmark(mark)
175	struct stackmark *mark;
176	{
177	mark->stackp = stackp;
178	mark->stacknxt = stacknxt;
179	mark->stacknleft = stacknleft;
180}
181
182
183void
184popstackmark(mark)
185	struct stackmark *mark;
186	{
187	struct stack_block *sp;
188
189	INTOFF;
190	while (stackp != mark->stackp) {
191		sp = stackp;
192		stackp = sp->prev;
193		ckfree(sp);
194	}
195	stacknxt = mark->stacknxt;
196	stacknleft = mark->stacknleft;
197	INTON;
198}
199
200
201/*
202 * When the parser reads in a string, it wants to stick the string on the
203 * stack and only adjust the stack pointer when it knows how big the
204 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
205 * of space on top of the stack and stackblocklen returns the length of
206 * this block.  Growstackblock will grow this space by at least one byte,
207 * possibly moving it (like realloc).  Grabstackblock actually allocates the
208 * part of the block that has been used.
209 */
210
211void
212growstackblock() {
213	char *p;
214	int newlen = stacknleft * 2 + 100;
215	char *oldspace = stacknxt;
216	int oldlen = stacknleft;
217	struct stack_block *sp;
218
219	if (stacknxt == stackp->space && stackp != &stackbase) {
220		INTOFF;
221		sp = stackp;
222		stackp = sp->prev;
223		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
224		sp->prev = stackp;
225		stackp = sp;
226		stacknxt = sp->space;
227		stacknleft = newlen;
228		INTON;
229	} else {
230		p = stalloc(newlen);
231		memcpy(p, oldspace, oldlen);
232		stacknxt = p;			/* free the space */
233		stacknleft += ALIGN(newlen);	/* we just allocated */
234	}
235}
236
237
238
239void
240grabstackblock(len)
241	int len;
242{
243	len = ALIGN(len);
244	stacknxt += len;
245	stacknleft -= len;
246}
247
248
249
250/*
251 * The following routines are somewhat easier to use that the above.
252 * The user declares a variable of type STACKSTR, which may be declared
253 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
254 * the user uses the macro STPUTC to add characters to the string.  In
255 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
256 * grown as necessary.  When the user is done, she can just leave the
257 * string there and refer to it using stackblock().  Or she can allocate
258 * the space for it using grabstackstr().  If it is necessary to allow
259 * someone else to use the stack temporarily and then continue to grow
260 * the string, the user should use grabstack to allocate the space, and
261 * then call ungrabstr(p) to return to the previous mode of operation.
262 *
263 * USTPUTC is like STPUTC except that it doesn't check for overflow.
264 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
265 * is space for at least one character.
266 */
267
268
269char *
270growstackstr() {
271	int len = stackblocksize();
272	if (herefd >= 0 && len >= 1024) {
273		xwrite(herefd, stackblock(), len);
274		sstrnleft = len - 1;
275		return stackblock();
276	}
277	growstackblock();
278	sstrnleft = stackblocksize() - len - 1;
279	return stackblock() + len;
280}
281
282
283/*
284 * Called from CHECKSTRSPACE.
285 */
286
287char *
288makestrspace() {
289	int len = stackblocksize() - sstrnleft;
290	growstackblock();
291	sstrnleft = stackblocksize() - len;
292	return stackblock() + len;
293}
294
295
296
297void
298ungrabstackstr(s, p)
299	char *s;
300	char *p;
301	{
302	stacknleft += stacknxt - s;
303	stacknxt = s;
304	sstrnleft = stacknleft - (p - s);
305}
306