memalloc.c revision 1.6 
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
38static char sccsid[] = "@(#)memalloc.c	8.1 (Berkeley) 5/31/93";
39#endif /* not lint */
40
41#include "shell.h"
42#include "output.h"
43#include "memalloc.h"
44#include "error.h"
45#include "machdep.h"
46#include "mystring.h"
47#include <unistd.h>
48
49/*
50 * Like malloc, but returns an error when out of space.
51 */
52
53pointer
54ckmalloc(nbytes) {
55	register pointer p;
56	pointer malloc();
57
58	if ((p = malloc(nbytes)) == NULL)
59		error("Out of space");
60	return p;
61}
62
63
64/*
65 * Same for realloc.
66 */
67
68pointer
69ckrealloc(p, nbytes)
70	register pointer p;
71	{
72	pointer realloc();
73
74	if ((p = realloc(p, nbytes)) == NULL)
75		error("Out of space");
76	return p;
77}
78
79
80/*
81 * Make a copy of a string in safe storage.
82 */
83
84char *
85savestr(s)
86	char *s;
87	{
88	register char *p;
89
90	p = ckmalloc(strlen(s) + 1);
91	scopy(s, p);
92	return p;
93}
94
95
96/*
97 * Parse trees for commands are allocated in lifo order, so we use a stack
98 * to make this more efficient, and also to avoid all sorts of exception
99 * handling code to handle interrupts in the middle of a parse.
100 *
101 * The size 504 was chosen because the Ultrix malloc handles that size
102 * well.
103 */
104
105#define MINSIZE 504		/* minimum size of a block */
106
107
108struct stack_block {
109	struct stack_block *prev;
110	char space[MINSIZE];
111};
112
113struct stack_block stackbase;
114struct stack_block *stackp = &stackbase;
115char *stacknxt = stackbase.space;
116int stacknleft = MINSIZE;
117int sstrnleft;
118int herefd = -1;
119
120
121
122pointer
123stalloc(nbytes) {
124	register char *p;
125
126	nbytes = ALIGN(nbytes);
127	if (nbytes > stacknleft) {
128		int blocksize;
129		struct stack_block *sp;
130
131		blocksize = nbytes;
132		if (blocksize < MINSIZE)
133			blocksize = MINSIZE;
134		INTOFF;
135		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
136		sp->prev = stackp;
137		stacknxt = sp->space;
138		stacknleft = blocksize;
139		stackp = sp;
140		INTON;
141	}
142	p = stacknxt;
143	stacknxt += nbytes;
144	stacknleft -= nbytes;
145	return p;
146}
147
148
149void
150stunalloc(p)
151	pointer p;
152	{
153	if (p == NULL) {		/*DEBUG */
154		write(2, "stunalloc\n", 10);
155		abort();
156	}
157	stacknleft += stacknxt - (char *)p;
158	stacknxt = p;
159}
160
161
162
163void
164setstackmark(mark)
165	struct stackmark *mark;
166	{
167	mark->stackp = stackp;
168	mark->stacknxt = stacknxt;
169	mark->stacknleft = stacknleft;
170}
171
172
173void
174popstackmark(mark)
175	struct stackmark *mark;
176	{
177	struct stack_block *sp;
178
179	INTOFF;
180	while (stackp != mark->stackp) {
181		sp = stackp;
182		stackp = sp->prev;
183		ckfree(sp);
184	}
185	stacknxt = mark->stacknxt;
186	stacknleft = mark->stacknleft;
187	INTON;
188}
189
190
191/*
192 * When the parser reads in a string, it wants to stick the string on the
193 * stack and only adjust the stack pointer when it knows how big the
194 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
195 * of space on top of the stack and stackblocklen returns the length of
196 * this block.  Growstackblock will grow this space by at least one byte,
197 * possibly moving it (like realloc).  Grabstackblock actually allocates the
198 * part of the block that has been used.
199 */
200
201void
202growstackblock() {
203	char *p;
204	int newlen = stacknleft * 2 + 100;
205	char *oldspace = stacknxt;
206	int oldlen = stacknleft;
207	struct stack_block *sp;
208
209	if (stacknxt == stackp->space && stackp != &stackbase) {
210		INTOFF;
211		sp = stackp;
212		stackp = sp->prev;
213		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
214		sp->prev = stackp;
215		stackp = sp;
216		stacknxt = sp->space;
217		stacknleft = newlen;
218		INTON;
219	} else {
220		p = stalloc(newlen);
221		bcopy(oldspace, p, oldlen);
222		stacknxt = p;			/* free the space */
223		stacknleft += newlen;		/* we just allocated */
224	}
225}
226
227
228
229void
230grabstackblock(len) {
231	len = ALIGN(len);
232	stacknxt += len;
233	stacknleft -= len;
234}
235
236
237
238/*
239 * The following routines are somewhat easier to use that the above.
240 * The user declares a variable of type STACKSTR, which may be declared
241 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
242 * the user uses the macro STPUTC to add characters to the string.  In
243 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
244 * grown as necessary.  When the user is done, she can just leave the
245 * string there and refer to it using stackblock().  Or she can allocate
246 * the space for it using grabstackstr().  If it is necessary to allow
247 * someone else to use the stack temporarily and then continue to grow
248 * the string, the user should use grabstack to allocate the space, and
249 * then call ungrabstr(p) to return to the previous mode of operation.
250 *
251 * USTPUTC is like STPUTC except that it doesn't check for overflow.
252 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
253 * is space for at least one character.
254 */
255
256
257char *
258growstackstr() {
259	int len = stackblocksize();
260	if (herefd >= 0 && len >= 1024) {
261		xwrite(herefd, stackblock(), len);
262		sstrnleft = len - 1;
263		return stackblock();
264	}
265	growstackblock();
266	sstrnleft = stackblocksize() - len - 1;
267	return stackblock() + len;
268}
269
270
271/*
272 * Called from CHECKSTRSPACE.
273 */
274
275char *
276makestrspace() {
277	int len = stackblocksize() - sstrnleft;
278	growstackblock();
279	sstrnleft = stackblocksize() - len;
280	return stackblock() + len;
281}
282
283
284
285void
286ungrabstackstr(s, p)
287	char *s;
288	char *p;
289	{
290	stacknleft += stacknxt - s;
291	stacknxt = s;
292	sstrnleft = stacknleft - (p - s);
293}
294