memalloc.c revision 36150 
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	"$Id$";
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 <stdlib.h>
52#include <unistd.h>
53
54/*
55 * Like malloc, but returns an error when out of space.
56 */
57
58pointer
59ckmalloc(nbytes)
60	int nbytes;
61{
62	pointer p;
63
64	if ((p = malloc(nbytes)) == NULL)
65		error("Out of space");
66	return p;
67}
68
69
70/*
71 * Same for realloc.
72 */
73
74pointer
75ckrealloc(p, nbytes)
76	pointer p;
77	int nbytes;
78{
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 + blocksize);
144		sp->prev = stackp;
145		stacknxt = sp->space;
146		stacknleft = blocksize;
147		stackp = sp;
148		INTON;
149	}
150	p = stacknxt;
151	stacknxt += nbytes;
152	stacknleft -= nbytes;
153	return p;
154}
155
156
157void
158stunalloc(p)
159	pointer p;
160	{
161	if (p == NULL) {		/*DEBUG */
162		write(2, "stunalloc\n", 10);
163		abort();
164	}
165	stacknleft += stacknxt - (char *)p;
166	stacknxt = p;
167}
168
169
170
171void
172setstackmark(mark)
173	struct stackmark *mark;
174	{
175	mark->stackp = stackp;
176	mark->stacknxt = stacknxt;
177	mark->stacknleft = stacknleft;
178}
179
180
181void
182popstackmark(mark)
183	struct stackmark *mark;
184	{
185	struct stack_block *sp;
186
187	INTOFF;
188	while (stackp != mark->stackp) {
189		sp = stackp;
190		stackp = sp->prev;
191		ckfree(sp);
192	}
193	stacknxt = mark->stacknxt;
194	stacknleft = mark->stacknleft;
195	INTON;
196}
197
198
199/*
200 * When the parser reads in a string, it wants to stick the string on the
201 * stack and only adjust the stack pointer when it knows how big the
202 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
203 * of space on top of the stack and stackblocklen returns the length of
204 * this block.  Growstackblock will grow this space by at least one byte,
205 * possibly moving it (like realloc).  Grabstackblock actually allocates the
206 * part of the block that has been used.
207 */
208
209void
210growstackblock() {
211	char *p;
212	int newlen = ALIGN(stacknleft * 2 + 100);
213	char *oldspace = stacknxt;
214	int oldlen = stacknleft;
215	struct stack_block *sp;
216
217	if (stacknxt == stackp->space && stackp != &stackbase) {
218		INTOFF;
219		sp = stackp;
220		stackp = sp->prev;
221		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
222		sp->prev = stackp;
223		stackp = sp;
224		stacknxt = sp->space;
225		stacknleft = newlen;
226		INTON;
227	} else {
228		p = stalloc(newlen);
229		memcpy(p, oldspace, oldlen);
230		stacknxt = p;			/* free the space */
231		stacknleft += newlen;		/* we just allocated */
232	}
233}
234
235
236
237void
238grabstackblock(len)
239	int len;
240{
241	len = ALIGN(len);
242	stacknxt += len;
243	stacknleft -= len;
244}
245
246
247
248/*
249 * The following routines are somewhat easier to use that the above.
250 * The user declares a variable of type STACKSTR, which may be declared
251 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
252 * the user uses the macro STPUTC to add characters to the string.  In
253 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
254 * grown as necessary.  When the user is done, she can just leave the
255 * string there and refer to it using stackblock().  Or she can allocate
256 * the space for it using grabstackstr().  If it is necessary to allow
257 * someone else to use the stack temporarily and then continue to grow
258 * the string, the user should use grabstack to allocate the space, and
259 * then call ungrabstr(p) to return to the previous mode of operation.
260 *
261 * USTPUTC is like STPUTC except that it doesn't check for overflow.
262 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
263 * is space for at least one character.
264 */
265
266
267char *
268growstackstr() {
269	int len = stackblocksize();
270	if (herefd >= 0 && len >= 1024) {
271		xwrite(herefd, stackblock(), len);
272		sstrnleft = len - 1;
273		return stackblock();
274	}
275	growstackblock();
276	sstrnleft = stackblocksize() - len - 1;
277	return stackblock() + len;
278}
279
280
281/*
282 * Called from CHECKSTRSPACE.
283 */
284
285char *
286makestrspace() {
287	int len = stackblocksize() - sstrnleft;
288	growstackblock();
289	sstrnleft = stackblocksize() - len;
290	return stackblock() + len;
291}
292
293
294
295void
296ungrabstackstr(s, p)
297	char *s;
298	char *p;
299	{
300	stacknleft += stacknxt - s;
301	stacknxt = s;
302	sstrnleft = stacknleft - (p - s);
303}
304