memalloc.c revision 1.20 
1/*	$NetBSD: memalloc.c,v 1.20 1997/07/04 21:02:08 christos 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#include <sys/cdefs.h>
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)memalloc.c	8.3 (Berkeley) 5/4/95";
43#else
44__RCSID("$NetBSD: memalloc.c,v 1.20 1997/07/04 21:02:08 christos Exp $");
45#endif
46#endif /* not lint */
47
48#include "shell.h"
49#include "output.h"
50#include "memalloc.h"
51#include "error.h"
52#include "machdep.h"
53#include "mystring.h"
54#include <stdlib.h>
55#include <unistd.h>
56
57/*
58 * Like malloc, but returns an error when out of space.
59 */
60
61pointer
62ckmalloc(nbytes)
63	int nbytes;
64{
65	pointer p;
66
67	if ((p = malloc(nbytes)) == NULL)
68		error("Out of space");
69	return p;
70}
71
72
73/*
74 * Same for realloc.
75 */
76
77pointer
78ckrealloc(p, nbytes)
79	pointer p;
80	int nbytes;
81{
82
83	if ((p = realloc(p, nbytes)) == NULL)
84		error("Out of space");
85	return p;
86}
87
88
89/*
90 * Make a copy of a string in safe storage.
91 */
92
93char *
94savestr(s)
95	char *s;
96	{
97	char *p;
98
99	p = ckmalloc(strlen(s) + 1);
100	scopy(s, p);
101	return p;
102}
103
104
105/*
106 * Parse trees for commands are allocated in lifo order, so we use a stack
107 * to make this more efficient, and also to avoid all sorts of exception
108 * handling code to handle interrupts in the middle of a parse.
109 *
110 * The size 504 was chosen because the Ultrix malloc handles that size
111 * well.
112 */
113
114#define MINSIZE 504		/* minimum size of a block */
115
116
117struct stack_block {
118	struct stack_block *prev;
119	char space[MINSIZE];
120};
121
122struct stack_block stackbase;
123struct stack_block *stackp = &stackbase;
124char *stacknxt = stackbase.space;
125int stacknleft = MINSIZE;
126int sstrnleft;
127int herefd = -1;
128
129
130
131pointer
132stalloc(nbytes)
133	int nbytes;
134{
135	char *p;
136
137	nbytes = ALIGN(nbytes);
138	if (nbytes > stacknleft) {
139		int blocksize;
140		struct stack_block *sp;
141
142		blocksize = nbytes;
143		if (blocksize < MINSIZE)
144			blocksize = MINSIZE;
145		INTOFF;
146		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
147		sp->prev = stackp;
148		stacknxt = sp->space;
149		stacknleft = blocksize;
150		stackp = sp;
151		INTON;
152	}
153	p = stacknxt;
154	stacknxt += nbytes;
155	stacknleft -= nbytes;
156	return p;
157}
158
159
160void
161stunalloc(p)
162	pointer p;
163	{
164	if (p == NULL) {		/*DEBUG */
165		write(2, "stunalloc\n", 10);
166		abort();
167	}
168	stacknleft += stacknxt - (char *)p;
169	stacknxt = p;
170}
171
172
173
174void
175setstackmark(mark)
176	struct stackmark *mark;
177	{
178	mark->stackp = stackp;
179	mark->stacknxt = stacknxt;
180	mark->stacknleft = stacknleft;
181}
182
183
184void
185popstackmark(mark)
186	struct stackmark *mark;
187	{
188	struct stack_block *sp;
189
190	INTOFF;
191	while (stackp != mark->stackp) {
192		sp = stackp;
193		stackp = sp->prev;
194		ckfree(sp);
195	}
196	stacknxt = mark->stacknxt;
197	stacknleft = mark->stacknleft;
198	INTON;
199}
200
201
202/*
203 * When the parser reads in a string, it wants to stick the string on the
204 * stack and only adjust the stack pointer when it knows how big the
205 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
206 * of space on top of the stack and stackblocklen returns the length of
207 * this block.  Growstackblock will grow this space by at least one byte,
208 * possibly moving it (like realloc).  Grabstackblock actually allocates the
209 * part of the block that has been used.
210 */
211
212void
213growstackblock() {
214	char *p;
215	int newlen = ALIGN(stacknleft * 2 + 100);
216	char *oldspace = stacknxt;
217	int oldlen = stacknleft;
218	struct stack_block *sp;
219
220	if (stacknxt == stackp->space && stackp != &stackbase) {
221		INTOFF;
222		sp = stackp;
223		stackp = sp->prev;
224		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
225		sp->prev = stackp;
226		stackp = sp;
227		stacknxt = sp->space;
228		stacknleft = newlen;
229		INTON;
230	} else {
231		p = stalloc(newlen);
232		memcpy(p, oldspace, oldlen);
233		stacknxt = p;			/* free the space */
234		stacknleft += newlen;		/* we just allocated */
235	}
236}
237
238
239
240void
241grabstackblock(len)
242	int len;
243{
244	len = ALIGN(len);
245	stacknxt += len;
246	stacknleft -= len;
247}
248
249
250
251/*
252 * The following routines are somewhat easier to use that the above.
253 * The user declares a variable of type STACKSTR, which may be declared
254 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
255 * the user uses the macro STPUTC to add characters to the string.  In
256 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
257 * grown as necessary.  When the user is done, she can just leave the
258 * string there and refer to it using stackblock().  Or she can allocate
259 * the space for it using grabstackstr().  If it is necessary to allow
260 * someone else to use the stack temporarily and then continue to grow
261 * the string, the user should use grabstack to allocate the space, and
262 * then call ungrabstr(p) to return to the previous mode of operation.
263 *
264 * USTPUTC is like STPUTC except that it doesn't check for overflow.
265 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
266 * is space for at least one character.
267 */
268
269
270char *
271growstackstr() {
272	int len = stackblocksize();
273	if (herefd >= 0 && len >= 1024) {
274		xwrite(herefd, stackblock(), len);
275		sstrnleft = len - 1;
276		return stackblock();
277	}
278	growstackblock();
279	sstrnleft = stackblocksize() - len - 1;
280	return stackblock() + len;
281}
282
283
284/*
285 * Called from CHECKSTRSPACE.
286 */
287
288char *
289makestrspace() {
290	int len = stackblocksize() - sstrnleft;
291	growstackblock();
292	sstrnleft = stackblocksize() - len;
293	return stackblock() + len;
294}
295
296
297
298void
299ungrabstackstr(s, p)
300	char *s;
301	char *p;
302	{
303	stacknleft += stacknxt - s;
304	stacknxt = s;
305	sstrnleft = stacknleft - (p - s);
306}
307