memalloc.c revision 1.31 
1/*	$NetBSD: memalloc.c,v 1.31 2018/07/22 20:37:57 kre Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)memalloc.c	8.3 (Berkeley) 5/4/95";
39#else
40__RCSID("$NetBSD: memalloc.c,v 1.31 2018/07/22 20:37:57 kre Exp $");
41#endif
42#endif /* not lint */
43
44#include <stdlib.h>
45#include <unistd.h>
46
47#include "shell.h"
48#include "output.h"
49#include "memalloc.h"
50#include "error.h"
51#include "machdep.h"
52#include "mystring.h"
53
54/*
55 * Like malloc, but returns an error when out of space.
56 */
57
58pointer
59ckmalloc(size_t nbytes)
60{
61	pointer p;
62
63	p = malloc(nbytes);
64	if (p == NULL)
65		error("Out of space");
66	return p;
67}
68
69
70/*
71 * Same for realloc.
72 */
73
74pointer
75ckrealloc(pointer p, int nbytes)
76{
77	p = realloc(p, nbytes);
78	if (p == 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(const char *s)
90{
91	char *p;
92
93	p = ckmalloc(strlen(s) + 1);
94	scopy(s, p);
95	return p;
96}
97
98
99/*
100 * Parse trees for commands are allocated in lifo order, so we use a stack
101 * to make this more efficient, and also to avoid all sorts of exception
102 * handling code to handle interrupts in the middle of a parse.
103 *
104 * The size 504 was chosen because the Ultrix malloc handles that size
105 * well.
106 */
107
108#define MINSIZE 504		/* minimum size of a block */
109
110struct stack_block {
111	struct stack_block *prev;
112	char space[MINSIZE];
113};
114
115struct stack_block stackbase;
116struct stack_block *stackp = &stackbase;
117struct stackmark *markp;
118char *stacknxt = stackbase.space;
119int stacknleft = MINSIZE;
120int sstrnleft;
121int herefd = -1;
122
123pointer
124stalloc(int nbytes)
125{
126	char *p;
127
128	nbytes = SHELL_ALIGN(nbytes);
129	if (nbytes > stacknleft) {
130		int blocksize;
131		struct stack_block *sp;
132
133		blocksize = nbytes;
134		if (blocksize < MINSIZE)
135			blocksize = MINSIZE;
136		INTOFF;
137		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
138		sp->prev = stackp;
139		stacknxt = sp->space;
140		stacknleft = blocksize;
141		stackp = sp;
142		INTON;
143	}
144	p = stacknxt;
145	stacknxt += nbytes;
146	stacknleft -= nbytes;
147	return p;
148}
149
150
151void
152stunalloc(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(struct stackmark *mark)
166{
167	mark->stackp = stackp;
168	mark->stacknxt = stacknxt;
169	mark->stacknleft = stacknleft;
170	mark->sstrnleft = sstrnleft;
171	mark->marknext = markp;
172	markp = mark;
173}
174
175
176void
177popstackmark(struct stackmark *mark)
178{
179	struct stack_block *sp;
180
181	INTOFF;
182	markp = mark->marknext;
183	while (stackp != mark->stackp) {
184		sp = stackp;
185		stackp = sp->prev;
186		ckfree(sp);
187	}
188	stacknxt = mark->stacknxt;
189	stacknleft = mark->stacknleft;
190	sstrnleft = mark->sstrnleft;
191	INTON;
192}
193
194
195/*
196 * When the parser reads in a string, it wants to stick the string on the
197 * stack and only adjust the stack pointer when it knows how big the
198 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
199 * of space on top of the stack and stackblocklen returns the length of
200 * this block.  Growstackblock will grow this space by at least one byte,
201 * possibly moving it (like realloc).  Grabstackblock actually allocates the
202 * part of the block that has been used.
203 */
204
205void
206growstackblock(void)
207{
208	int newlen = SHELL_ALIGN(stacknleft * 2 + 100);
209
210	INTOFF;
211	if (stacknxt == stackp->space && stackp != &stackbase) {
212		struct stack_block *oldstackp;
213		struct stackmark *xmark;
214		struct stack_block *sp;
215
216		oldstackp = stackp;
217		sp = stackp;
218		stackp = sp->prev;
219		sp = ckrealloc((pointer)sp,
220		    sizeof(struct stack_block) - MINSIZE + newlen);
221		sp->prev = stackp;
222		stackp = sp;
223		stacknxt = sp->space;
224		sstrnleft += newlen - stacknleft;
225		stacknleft = newlen;
226
227		/*
228		 * Stack marks pointing to the start of the old block
229		 * must be relocated to point to the new block
230		 */
231		xmark = markp;
232		while (xmark != NULL && xmark->stackp == oldstackp) {
233			xmark->stackp = stackp;
234			xmark->stacknxt = stacknxt;
235			xmark->sstrnleft += stacknleft - xmark->stacknleft;
236			xmark->stacknleft = stacknleft;
237			xmark = xmark->marknext;
238		}
239	} else {
240		char *oldspace = stacknxt;
241		int oldlen = stacknleft;
242		char *p = stalloc(newlen);
243
244		(void)memcpy(p, oldspace, oldlen);
245		stacknxt = p;			/* free the space */
246		stacknleft += newlen;		/* we just allocated */
247	}
248	INTON;
249}
250
251void
252grabstackblock(int len)
253{
254	len = SHELL_ALIGN(len);
255	stacknxt += len;
256	stacknleft -= len;
257}
258
259/*
260 * The following routines are somewhat easier to use than the above.
261 * The user declares a variable of type STACKSTR, which may be declared
262 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
263 * the user uses the macro STPUTC to add characters to the string.  In
264 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
265 * grown as necessary.  When the user is done, she can just leave the
266 * string there and refer to it using stackblock().  Or she can allocate
267 * the space for it using grabstackstr().  If it is necessary to allow
268 * someone else to use the stack temporarily and then continue to grow
269 * the string, the user should use grabstack to allocate the space, and
270 * then call ungrabstr(p) to return to the previous mode of operation.
271 *
272 * USTPUTC is like STPUTC except that it doesn't check for overflow.
273 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
274 * is space for at least one character.
275 */
276
277char *
278growstackstr(void)
279{
280	int len = stackblocksize();
281	if (herefd >= 0 && len >= 1024) {
282		xwrite(herefd, stackblock(), len);
283		sstrnleft = len - 1;
284		return stackblock();
285	}
286	growstackblock();
287	sstrnleft = stackblocksize() - len - 1;
288	return stackblock() + len;
289}
290
291/*
292 * Called from CHECKSTRSPACE.
293 */
294
295char *
296makestrspace(void)
297{
298	int len = stackblocksize() - sstrnleft;
299	growstackblock();
300	sstrnleft = stackblocksize() - len;
301	return stackblock() + len;
302}
303
304/*
305 * Note that this only works to release stack space for reuse
306 * if nothing else has allocated space on the stack since the grabstackstr()
307 *
308 * "s" is the start of the area to be released, and "p" represents the end
309 * of the string we have stored beyond there and are now releasing.
310 * (ie: "p" should be the same as in the call to grabstackstr()).
311 *
312 * stunalloc(s) and ungrabstackstr(s, p) are almost interchangable after
313 * a grabstackstr(), however the latter also returns string space so we
314 * can just continue with STPUTC() etc without needing a new STARTSTACKSTR(s)
315 */
316void
317ungrabstackstr(char *s, char *p)
318{
319#ifdef DEBUG
320	if (s < stacknxt || stacknxt + stacknleft < s)
321		abort();
322#endif
323	stacknleft += stacknxt - s;
324	stacknxt = s;
325	sstrnleft = stacknleft - (p - s);
326}
327