memalloc.c revision 1557 
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
48/*
49 * Like malloc, but returns an error when out of space.
50 */
51
52pointer
53ckmalloc(nbytes) {
54	register pointer p;
55	pointer malloc();
56
57	if ((p = malloc(nbytes)) == NULL)
58		error("Out of space");
59	return p;
60}
61
62
63/*
64 * Same for realloc.
65 */
66
67pointer
68ckrealloc(p, nbytes)
69	register pointer p;
70	{
71	pointer realloc();
72
73	if ((p = realloc(p, nbytes)) == NULL)
74		error("Out of space");
75	return p;
76}
77
78
79/*
80 * Make a copy of a string in safe storage.
81 */
82
83char *
84savestr(s)
85	char *s;
86	{
87	register char *p;
88
89	p = ckmalloc(strlen(s) + 1);
90	scopy(s, p);
91	return p;
92}
93
94
95/*
96 * Parse trees for commands are allocated in lifo order, so we use a stack
97 * to make this more efficient, and also to avoid all sorts of exception
98 * handling code to handle interrupts in the middle of a parse.
99 *
100 * The size 504 was chosen because the Ultrix malloc handles that size
101 * well.
102 */
103
104#define MINSIZE 504		/* minimum size of a block */
105
106
107struct stack_block {
108	struct stack_block *prev;
109	char space[MINSIZE];
110};
111
112struct stack_block stackbase;
113struct stack_block *stackp = &stackbase;
114char *stacknxt = stackbase.space;
115int stacknleft = MINSIZE;
116int sstrnleft;
117int herefd = -1;
118
119
120
121pointer
122stalloc(nbytes) {
123	register char *p;
124
125	nbytes = ALIGN(nbytes);
126	if (nbytes > stacknleft) {
127		int blocksize;
128		struct stack_block *sp;
129
130		blocksize = nbytes;
131		if (blocksize < MINSIZE)
132			blocksize = MINSIZE;
133		INTOFF;
134		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
135		sp->prev = stackp;
136		stacknxt = sp->space;
137		stacknleft = blocksize;
138		stackp = sp;
139		INTON;
140	}
141	p = stacknxt;
142	stacknxt += nbytes;
143	stacknleft -= nbytes;
144	return p;
145}
146
147
148void
149stunalloc(p)
150	pointer p;
151	{
152	if (p == NULL) {		/*DEBUG */
153		write(2, "stunalloc\n", 10);
154		abort();
155	}
156	stacknleft += stacknxt - (char *)p;
157	stacknxt = p;
158}
159
160
161
162void
163setstackmark(mark)
164	struct stackmark *mark;
165	{
166	mark->stackp = stackp;
167	mark->stacknxt = stacknxt;
168	mark->stacknleft = stacknleft;
169}
170
171
172void
173popstackmark(mark)
174	struct stackmark *mark;
175	{
176	struct stack_block *sp;
177
178	INTOFF;
179	while (stackp != mark->stackp) {
180		sp = stackp;
181		stackp = sp->prev;
182		ckfree(sp);
183	}
184	stacknxt = mark->stacknxt;
185	stacknleft = mark->stacknleft;
186	INTON;
187}
188
189
190/*
191 * When the parser reads in a string, it wants to stick the string on the
192 * stack and only adjust the stack pointer when it knows how big the
193 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
194 * of space on top of the stack and stackblocklen returns the length of
195 * this block.  Growstackblock will grow this space by at least one byte,
196 * possibly moving it (like realloc).  Grabstackblock actually allocates the
197 * part of the block that has been used.
198 */
199
200void
201growstackblock() {
202	char *p;
203	int newlen = stacknleft * 2 + 100;
204	char *oldspace = stacknxt;
205	int oldlen = stacknleft;
206	struct stack_block *sp;
207
208	if (stacknxt == stackp->space && stackp != &stackbase) {
209		INTOFF;
210		sp = stackp;
211		stackp = sp->prev;
212		sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
213		sp->prev = stackp;
214		stackp = sp;
215		stacknxt = sp->space;
216		stacknleft = newlen;
217		INTON;
218	} else {
219		p = stalloc(newlen);
220		bcopy(oldspace, p, oldlen);
221		stacknxt = p;			/* free the space */
222		stacknleft += newlen;		/* we just allocated */
223	}
224}
225
226
227
228void
229grabstackblock(len) {
230	len = ALIGN(len);
231	stacknxt += len;
232	stacknleft -= len;
233}
234
235
236
237/*
238 * The following routines are somewhat easier to use that the above.
239 * The user declares a variable of type STACKSTR, which may be declared
240 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
241 * the user uses the macro STPUTC to add characters to the string.  In
242 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
243 * grown as necessary.  When the user is done, she can just leave the
244 * string there and refer to it using stackblock().  Or she can allocate
245 * the space for it using grabstackstr().  If it is necessary to allow
246 * someone else to use the stack temporarily and then continue to grow
247 * the string, the user should use grabstack to allocate the space, and
248 * then call ungrabstr(p) to return to the previous mode of operation.
249 *
250 * USTPUTC is like STPUTC except that it doesn't check for overflow.
251 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
252 * is space for at least one character.
253 */
254
255
256char *
257growstackstr() {
258	int len = stackblocksize();
259	if (herefd >= 0 && len >= 1024) {
260		xwrite(herefd, stackblock(), len);
261		sstrnleft = len - 1;
262		return stackblock();
263	}
264	growstackblock();
265	sstrnleft = stackblocksize() - len - 1;
266	return stackblock() + len;
267}
268
269
270/*
271 * Called from CHECKSTRSPACE.
272 */
273
274char *
275makestrspace() {
276	int len = stackblocksize() - sstrnleft;
277	growstackblock();
278	sstrnleft = stackblocksize() - len;
279	return stackblock() + len;
280}
281
282
283
284void
285ungrabstackstr(s, p)
286	char *s;
287	char *p;
288	{
289	stacknleft += stacknxt - s;
290	stacknxt = s;
291	sstrnleft = stacknleft - (p - s);
292}
293