memalloc.c revision 3044 
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 *	$Id$
37 */
38
39#ifndef lint
40static char sccsid[] = "@(#)memalloc.c	8.1 (Berkeley) 5/31/93";
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
50/*
51 * Like malloc, but returns an error when out of space.
52 */
53
54pointer
55ckmalloc(nbytes) {
56	register pointer p;
57	pointer malloc();
58
59	if ((p = malloc(nbytes)) == NULL)
60		error("Out of space");
61	return p;
62}
63
64
65/*
66 * Same for realloc.
67 */
68
69pointer
70ckrealloc(p, nbytes)
71	register pointer p;
72	{
73	pointer realloc();
74
75	if ((p = realloc(p, nbytes)) == NULL)
76		error("Out of space");
77	return p;
78}
79
80
81/*
82 * Make a copy of a string in safe storage.
83 */
84
85char *
86savestr(s)
87	char *s;
88	{
89	register char *p;
90
91	p = ckmalloc(strlen(s) + 1);
92	scopy(s, p);
93	return p;
94}
95
96
97/*
98 * Parse trees for commands are allocated in lifo order, so we use a stack
99 * to make this more efficient, and also to avoid all sorts of exception
100 * handling code to handle interrupts in the middle of a parse.
101 *
102 * The size 504 was chosen because the Ultrix malloc handles that size
103 * well.
104 */
105
106#define MINSIZE 504		/* minimum size of a block */
107
108
109struct stack_block {
110	struct stack_block *prev;
111	char space[MINSIZE];
112};
113
114struct stack_block stackbase;
115struct stack_block *stackp = &stackbase;
116char *stacknxt = stackbase.space;
117int stacknleft = MINSIZE;
118int sstrnleft;
119int herefd = -1;
120
121
122
123pointer
124stalloc(nbytes) {
125	register char *p;
126
127	nbytes = ALIGN(nbytes);
128	if (nbytes > stacknleft) {
129		int blocksize;
130		struct stack_block *sp;
131
132		blocksize = nbytes;
133		if (blocksize < MINSIZE)
134			blocksize = MINSIZE;
135		INTOFF;
136		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
137		sp->prev = stackp;
138		stacknxt = sp->space;
139		stacknleft = blocksize;
140		stackp = sp;
141		INTON;
142	}
143	p = stacknxt;
144	stacknxt += nbytes;
145	stacknleft -= nbytes;
146	return p;
147}
148
149
150void
151stunalloc(p)
152	pointer p;
153	{
154	if (p == NULL) {		/*DEBUG */
155		write(2, "stunalloc\n", 10);
156		abort();
157	}
158	stacknleft += stacknxt - (char *)p;
159	stacknxt = p;
160}
161
162
163
164void
165setstackmark(mark)
166	struct stackmark *mark;
167	{
168	mark->stackp = stackp;
169	mark->stacknxt = stacknxt;
170	mark->stacknleft = stacknleft;
171}
172
173
174void
175popstackmark(mark)
176	struct stackmark *mark;
177	{
178	struct stack_block *sp;
179
180	INTOFF;
181	while (stackp != mark->stackp) {
182		sp = stackp;
183		stackp = sp->prev;
184		ckfree(sp);
185	}
186	stacknxt = mark->stacknxt;
187	stacknleft = mark->stacknleft;
188	INTON;
189}
190
191
192/*
193 * When the parser reads in a string, it wants to stick the string on the
194 * stack and only adjust the stack pointer when it knows how big the
195 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
196 * of space on top of the stack and stackblocklen returns the length of
197 * this block.  Growstackblock will grow this space by at least one byte,
198 * possibly moving it (like realloc).  Grabstackblock actually allocates the
199 * part of the block that has been used.
200 */
201
202void
203growstackblock() {
204	char *p;
205	int newlen = stacknleft * 2 + 100;
206	char *oldspace = stacknxt;
207	int oldlen = stacknleft;
208	struct stack_block *sp;
209
210	if (stacknxt == stackp->space && stackp != &stackbase) {
211		INTOFF;
212		sp = stackp;
213		stackp = sp->prev;
214		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
215		sp->prev = stackp;
216		stackp = sp;
217		stacknxt = sp->space;
218		stacknleft = newlen;
219		INTON;
220	} else {
221		p = stalloc(newlen);
222		bcopy(oldspace, p, oldlen);
223		stacknxt = p;			/* free the space */
224		stacknleft += newlen;		/* we just allocated */
225	}
226}
227
228
229
230void
231grabstackblock(len) {
232	len = ALIGN(len);
233	stacknxt += len;
234	stacknleft -= len;
235}
236
237
238
239/*
240 * The following routines are somewhat easier to use that the above.
241 * The user declares a variable of type STACKSTR, which may be declared
242 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
243 * the user uses the macro STPUTC to add characters to the string.  In
244 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
245 * grown as necessary.  When the user is done, she can just leave the
246 * string there and refer to it using stackblock().  Or she can allocate
247 * the space for it using grabstackstr().  If it is necessary to allow
248 * someone else to use the stack temporarily and then continue to grow
249 * the string, the user should use grabstack to allocate the space, and
250 * then call ungrabstr(p) to return to the previous mode of operation.
251 *
252 * USTPUTC is like STPUTC except that it doesn't check for overflow.
253 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
254 * is space for at least one character.
255 */
256
257
258char *
259growstackstr() {
260	int len = stackblocksize();
261	if (herefd >= 0 && len >= 1024) {
262		xwrite(herefd, stackblock(), len);
263		sstrnleft = len - 1;
264		return stackblock();
265	}
266	growstackblock();
267	sstrnleft = stackblocksize() - len - 1;
268	return stackblock() + len;
269}
270
271
272/*
273 * Called from CHECKSTRSPACE.
274 */
275
276char *
277makestrspace() {
278	int len = stackblocksize() - sstrnleft;
279	growstackblock();
280	sstrnleft = stackblocksize() - len;
281	return stackblock() + len;
282}
283
284
285
286void
287ungrabstackstr(s, p)
288	char *s;
289	char *p;
290	{
291	stacknleft += stacknxt - s;
292	stacknxt = s;
293	sstrnleft = stacknleft - (p - s);
294}
295