memalloc.c revision 50471 
1/*-
2 * Copyright (c) 1991, 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 * Kenneth Almquist.
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#ifndef lint
38#if 0
39static char sccsid[] = "@(#)memalloc.c	8.3 (Berkeley) 5/4/95";
40#endif
41static const char rcsid[] =
42  "$FreeBSD: head/bin/sh/memalloc.c 50471 1999-08-27 23:15:48Z peter $";
43#endif /* not lint */
44
45#include "shell.h"
46#include "output.h"
47#include "memalloc.h"
48#include "error.h"
49#include "machdep.h"
50#include "mystring.h"
51#include "expand.h"
52#include <stdlib.h>
53#include <unistd.h>
54
55/*
56 * Like malloc, but returns an error when out of space.
57 */
58
59pointer
60ckmalloc(nbytes)
61	int nbytes;
62{
63	pointer p;
64
65	if ((p = malloc(nbytes)) == NULL)
66		error("Out of space");
67	return p;
68}
69
70
71/*
72 * Same for realloc.
73 */
74
75pointer
76ckrealloc(p, nbytes)
77	pointer p;
78	int nbytes;
79{
80	if ((p = realloc(p, nbytes)) == NULL)
81		error("Out of space");
82	return p;
83}
84
85
86/*
87 * Make a copy of a string in safe storage.
88 */
89
90char *
91savestr(s)
92	char *s;
93{
94	char *p;
95
96	p = ckmalloc(strlen(s) + 1);
97	scopy(s, p);
98	return p;
99}
100
101
102/*
103 * Parse trees for commands are allocated in lifo order, so we use a stack
104 * to make this more efficient, and also to avoid all sorts of exception
105 * handling code to handle interrupts in the middle of a parse.
106 *
107 * The size 504 was chosen because the Ultrix malloc handles that size
108 * well.
109 */
110
111#define MINSIZE 504		/* minimum size of a block */
112
113
114struct stack_block {
115	struct stack_block *prev;
116	char space[MINSIZE];
117};
118
119struct stack_block stackbase;
120struct stack_block *stackp = &stackbase;
121char *stacknxt = stackbase.space;
122int stacknleft = MINSIZE;
123int sstrnleft;
124int herefd = -1;
125
126
127
128pointer
129stalloc(nbytes)
130	int nbytes;
131{
132	char *p;
133
134	nbytes = ALIGN(nbytes);
135	if (nbytes > stacknleft) {
136		int blocksize;
137		struct stack_block *sp;
138
139		blocksize = nbytes;
140		if (blocksize < MINSIZE)
141			blocksize = MINSIZE;
142		INTOFF;
143		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE +
144		    blocksize);
145		sp->prev = stackp;
146		stacknxt = sp->space;
147		stacknleft = blocksize;
148		stackp = sp;
149		INTON;
150	}
151	p = stacknxt;
152	stacknxt += nbytes;
153	stacknleft -= nbytes;
154	return p;
155}
156
157
158void
159stunalloc(p)
160	pointer p;
161{
162	if (p == NULL) {		/*DEBUG */
163		write(2, "stunalloc\n", 10);
164		abort();
165	}
166	stacknleft += stacknxt - (char *)p;
167	stacknxt = p;
168}
169
170
171
172void
173setstackmark(mark)
174	struct stackmark *mark;
175{
176	mark->stackp = stackp;
177	mark->stacknxt = stacknxt;
178	mark->stacknleft = stacknleft;
179}
180
181
182void
183popstackmark(mark)
184	struct stackmark *mark;
185{
186	struct stack_block *sp;
187
188	INTOFF;
189	while (stackp != mark->stackp) {
190		sp = stackp;
191		stackp = sp->prev;
192		ckfree(sp);
193	}
194	stacknxt = mark->stacknxt;
195	stacknleft = mark->stacknleft;
196	INTON;
197}
198
199
200/*
201 * When the parser reads in a string, it wants to stick the string on the
202 * stack and only adjust the stack pointer when it knows how big the
203 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
204 * of space on top of the stack and stackblocklen returns the length of
205 * this block.  Growstackblock will grow this space by at least one byte,
206 * possibly moving it (like realloc).  Grabstackblock actually allocates the
207 * part of the block that has been used.
208 */
209
210void
211growstackblock()
212{
213	char *p;
214	int newlen;
215	char *oldspace;
216	int oldlen;
217	struct stack_block *sp;
218
219	newlen = ALIGN(stacknleft * 2 + 100);
220	oldspace = stacknxt;
221	oldlen = stacknleft;
222
223	if (stacknxt == stackp->space && stackp != &stackbase) {
224		INTOFF;
225		sp = stackp;
226		stackp = sp->prev;
227		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) -
228		    MINSIZE + newlen);
229		sp->prev = stackp;
230		stackp = sp;
231		stacknxt = sp->space;
232		stacknleft = newlen;
233		INTON;
234	} else {
235		p = stalloc(newlen);
236		memcpy(p, oldspace, oldlen);
237		stacknxt = p;			/* free the space */
238		stacknleft += newlen;		/* we just allocated */
239	}
240}
241
242
243
244void
245grabstackblock(len)
246	int len;
247{
248	len = ALIGN(len);
249	stacknxt += len;
250	stacknleft -= len;
251}
252
253
254
255/*
256 * The following routines are somewhat easier to use that the above.
257 * The user declares a variable of type STACKSTR, which may be declared
258 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
259 * the user uses the macro STPUTC to add characters to the string.  In
260 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
261 * grown as necessary.  When the user is done, she can just leave the
262 * string there and refer to it using stackblock().  Or she can allocate
263 * the space for it using grabstackstr().  If it is necessary to allow
264 * someone else to use the stack temporarily and then continue to grow
265 * the string, the user should use grabstack to allocate the space, and
266 * then call ungrabstr(p) to return to the previous mode of operation.
267 *
268 * USTPUTC is like STPUTC except that it doesn't check for overflow.
269 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
270 * is space for at least one character.
271 */
272
273
274char *
275growstackstr()
276{
277	int len;
278
279	len = stackblocksize();
280	if (herefd >= 0 && len >= 1024) {
281		xwrite(herefd, stackblock(), len);
282		sstrnleft = len - 1;
283		return stackblock();
284	}
285	growstackblock();
286	sstrnleft = stackblocksize() - len - 1;
287	return stackblock() + len;
288}
289
290
291/*
292 * Called from CHECKSTRSPACE.
293 */
294
295char *
296makestrspace()
297{
298	int len;
299
300	len = stackblocksize() - sstrnleft;
301	growstackblock();
302	sstrnleft = stackblocksize() - len;
303	return stackblock() + len;
304}
305
306
307
308void
309ungrabstackstr(s, p)
310	char *s;
311	char *p;
312{
313	stacknleft += stacknxt - s;
314	stacknxt = s;
315	sstrnleft = stacknleft - (p - s);
316}
317