memalloc.c revision 25222 
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 *	$Id: memalloc.c,v 1.7 1997/02/22 13:58:34 peter Exp $
37 */
38
39#ifndef lint
40static char const sccsid[] = "@(#)memalloc.c	8.3 (Berkeley) 5/4/95";
41#endif /* not lint */
42
43#include "shell.h"
44#include "output.h"
45#include "memalloc.h"
46#include "error.h"
47#include "machdep.h"
48#include "mystring.h"
49#include <stdlib.h>
50#include <unistd.h>
51
52/*
53 * Like malloc, but returns an error when out of space.
54 */
55
56pointer
57ckmalloc(nbytes)
58	int nbytes;
59{
60	pointer p;
61
62	if ((p = malloc(nbytes)) == NULL)
63		error("Out of space");
64	return p;
65}
66
67
68/*
69 * Same for realloc.
70 */
71
72pointer
73ckrealloc(p, nbytes)
74	pointer p;
75	int nbytes;
76{
77
78	if ((p = realloc(p, nbytes)) == NULL)
79		error("Out of space");
80	return p;
81}
82
83
84/*
85 * Make a copy of a string in safe storage.
86 */
87
88char *
89savestr(s)
90	char *s;
91	{
92	char *p;
93
94	p = ckmalloc(strlen(s) + 1);
95	scopy(s, p);
96	return p;
97}
98
99
100/*
101 * Parse trees for commands are allocated in lifo order, so we use a stack
102 * to make this more efficient, and also to avoid all sorts of exception
103 * handling code to handle interrupts in the middle of a parse.
104 *
105 * The size 504 was chosen because the Ultrix malloc handles that size
106 * well.
107 */
108
109#define MINSIZE 504		/* minimum size of a block */
110
111
112struct stack_block {
113	struct stack_block *prev;
114	char space[MINSIZE];
115};
116
117struct stack_block stackbase;
118struct stack_block *stackp = &stackbase;
119char *stacknxt = stackbase.space;
120int stacknleft = MINSIZE;
121int sstrnleft;
122int herefd = -1;
123
124
125
126pointer
127stalloc(nbytes)
128	int nbytes;
129{
130	char *p;
131
132	nbytes = ALIGN(nbytes);
133	if (nbytes > stacknleft) {
134		int blocksize;
135		struct stack_block *sp;
136
137		blocksize = nbytes;
138		if (blocksize < MINSIZE)
139			blocksize = MINSIZE;
140		INTOFF;
141		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
142		sp->prev = stackp;
143		stacknxt = sp->space;
144		stacknleft = blocksize;
145		stackp = sp;
146		INTON;
147	}
148	p = stacknxt;
149	stacknxt += nbytes;
150	stacknleft -= nbytes;
151	return p;
152}
153
154
155void
156stunalloc(p)
157	pointer p;
158	{
159	if (p == NULL) {		/*DEBUG */
160		write(2, "stunalloc\n", 10);
161		abort();
162	}
163	stacknleft += stacknxt - (char *)p;
164	stacknxt = p;
165}
166
167
168
169void
170setstackmark(mark)
171	struct stackmark *mark;
172	{
173	mark->stackp = stackp;
174	mark->stacknxt = stacknxt;
175	mark->stacknleft = stacknleft;
176}
177
178
179void
180popstackmark(mark)
181	struct stackmark *mark;
182	{
183	struct stack_block *sp;
184
185	INTOFF;
186	while (stackp != mark->stackp) {
187		sp = stackp;
188		stackp = sp->prev;
189		ckfree(sp);
190	}
191	stacknxt = mark->stacknxt;
192	stacknleft = mark->stacknleft;
193	INTON;
194}
195
196
197/*
198 * When the parser reads in a string, it wants to stick the string on the
199 * stack and only adjust the stack pointer when it knows how big the
200 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
201 * of space on top of the stack and stackblocklen returns the length of
202 * this block.  Growstackblock will grow this space by at least one byte,
203 * possibly moving it (like realloc).  Grabstackblock actually allocates the
204 * part of the block that has been used.
205 */
206
207void
208growstackblock() {
209	char *p;
210	int newlen = ALIGN(stacknleft * 2 + 100);
211	char *oldspace = stacknxt;
212	int oldlen = stacknleft;
213	struct stack_block *sp;
214
215	if (stacknxt == stackp->space && stackp != &stackbase) {
216		INTOFF;
217		sp = stackp;
218		stackp = sp->prev;
219		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
220		sp->prev = stackp;
221		stackp = sp;
222		stacknxt = sp->space;
223		stacknleft = newlen;
224		INTON;
225	} else {
226		p = stalloc(newlen);
227		memcpy(p, oldspace, oldlen);
228		stacknxt = p;			/* free the space */
229		stacknleft += newlen;		/* we just allocated */
230	}
231}
232
233
234
235void
236grabstackblock(len)
237	int len;
238{
239	len = ALIGN(len);
240	stacknxt += len;
241	stacknleft -= len;
242}
243
244
245
246/*
247 * The following routines are somewhat easier to use that the above.
248 * The user declares a variable of type STACKSTR, which may be declared
249 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
250 * the user uses the macro STPUTC to add characters to the string.  In
251 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
252 * grown as necessary.  When the user is done, she can just leave the
253 * string there and refer to it using stackblock().  Or she can allocate
254 * the space for it using grabstackstr().  If it is necessary to allow
255 * someone else to use the stack temporarily and then continue to grow
256 * the string, the user should use grabstack to allocate the space, and
257 * then call ungrabstr(p) to return to the previous mode of operation.
258 *
259 * USTPUTC is like STPUTC except that it doesn't check for overflow.
260 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
261 * is space for at least one character.
262 */
263
264
265char *
266growstackstr() {
267	int len = stackblocksize();
268	if (herefd >= 0 && len >= 1024) {
269		xwrite(herefd, stackblock(), len);
270		sstrnleft = len - 1;
271		return stackblock();
272	}
273	growstackblock();
274	sstrnleft = stackblocksize() - len - 1;
275	return stackblock() + len;
276}
277
278
279/*
280 * Called from CHECKSTRSPACE.
281 */
282
283char *
284makestrspace() {
285	int len = stackblocksize() - sstrnleft;
286	growstackblock();
287	sstrnleft = stackblocksize() - len;
288	return stackblock() + len;
289}
290
291
292
293void
294ungrabstackstr(s, p)
295	char *s;
296	char *p;
297	{
298	stacknleft += stacknxt - s;
299	stacknxt = s;
300	sstrnleft = stacknleft - (p - s);
301}
302