memalloc.c revision 1.33 
1/*	$NetBSD: memalloc.c,v 1.33 2019/02/09 03:35:55 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 1.33 2019/02/09 03:35:55 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	INTOFF;
145	p = stacknxt;
146	stacknxt += nbytes;
147	stacknleft -= nbytes;
148	INTON;
149	return p;
150}
151
152
153void
154stunalloc(pointer p)
155{
156	if (p == NULL) {		/*DEBUG */
157		write(2, "stunalloc\n", 10);
158		abort();
159	}
160	stacknleft += stacknxt - (char *)p;
161	stacknxt = p;
162}
163
164
165/* save the current status of the sh stack */
166void
167setstackmark(struct stackmark *mark)
168{
169	mark->stackp = stackp;
170	mark->stacknxt = stacknxt;
171	mark->stacknleft = stacknleft;
172	mark->sstrnleft = sstrnleft;
173	mark->marknext = markp;
174	markp = mark;
175}
176
177/* reset the stack mark, and remove it from the list of marks */
178void
179popstackmark(struct stackmark *mark)
180{
181	INTOFF;
182	markp = mark->marknext;		/* delete mark from the list */
183	rststackmark(mark);		/* and reset stack */
184	INTON;
185}
186
187/* reset the shell stack to its state recorded in the stack mark */
188void
189rststackmark(struct stackmark *mark)
190{
191	struct stack_block *sp;
192
193	INTOFF;
194	while (stackp != mark->stackp) {
195		/* delete any recently allocated mem blocks */
196		sp = stackp;
197		stackp = sp->prev;
198		ckfree(sp);
199	}
200	stacknxt = mark->stacknxt;
201	stacknleft = mark->stacknleft;
202	sstrnleft = mark->sstrnleft;
203	INTON;
204}
205
206
207/*
208 * When the parser reads in a string, it wants to stick the string on the
209 * stack and only adjust the stack pointer when it knows how big the
210 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
211 * of space on top of the stack and stackblocklen returns the length of
212 * this block.  Growstackblock will grow this space by at least one byte,
213 * possibly moving it (like realloc).  Grabstackblock actually allocates the
214 * part of the block that has been used.
215 */
216
217void
218growstackblock(void)
219{
220	int newlen = SHELL_ALIGN(stacknleft * 2 + 100);
221
222	INTOFF;
223	if (stacknxt == stackp->space && stackp != &stackbase) {
224		struct stack_block *oldstackp;
225		struct stackmark *xmark;
226		struct stack_block *sp;
227
228		oldstackp = stackp;
229		sp = stackp;
230		stackp = sp->prev;
231		sp = ckrealloc((pointer)sp,
232		    sizeof(struct stack_block) - MINSIZE + newlen);
233		sp->prev = stackp;
234		stackp = sp;
235		stacknxt = sp->space;
236		sstrnleft += newlen - stacknleft;
237		stacknleft = newlen;
238
239		/*
240		 * Stack marks pointing to the start of the old block
241		 * must be relocated to point to the new block
242		 */
243		xmark = markp;
244		while (xmark != NULL && xmark->stackp == oldstackp) {
245			xmark->stackp = stackp;
246			xmark->stacknxt = stacknxt;
247			xmark->sstrnleft += stacknleft - xmark->stacknleft;
248			xmark->stacknleft = stacknleft;
249			xmark = xmark->marknext;
250		}
251	} else {
252		char *oldspace = stacknxt;
253		int oldlen = stacknleft;
254		char *p = stalloc(newlen);
255
256		(void)memcpy(p, oldspace, oldlen);
257		stacknxt = p;			/* free the space */
258		stacknleft += newlen;		/* we just allocated */
259	}
260	INTON;
261}
262
263void
264grabstackblock(int len)
265{
266	len = SHELL_ALIGN(len);
267	INTOFF;
268	stacknxt += len;
269	stacknleft -= len;
270	INTON;
271}
272
273/*
274 * The following routines are somewhat easier to use than the above.
275 * The user declares a variable of type STACKSTR, which may be declared
276 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
277 * the user uses the macro STPUTC to add characters to the string.  In
278 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
279 * grown as necessary.  When the user is done, she can just leave the
280 * string there and refer to it using stackblock().  Or she can allocate
281 * the space for it using grabstackstr().  If it is necessary to allow
282 * someone else to use the stack temporarily and then continue to grow
283 * the string, the user should use grabstack to allocate the space, and
284 * then call ungrabstr(p) to return to the previous mode of operation.
285 *
286 * USTPUTC is like STPUTC except that it doesn't check for overflow.
287 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
288 * is space for at least one character.
289 */
290
291char *
292growstackstr(void)
293{
294	int len = stackblocksize();
295	if (herefd >= 0 && len >= 1024) {
296		xwrite(herefd, stackblock(), len);
297		sstrnleft = len - 1;
298		return stackblock();
299	}
300	growstackblock();
301	sstrnleft = stackblocksize() - len - 1;
302	return stackblock() + len;
303}
304
305/*
306 * Called from CHECKSTRSPACE.
307 */
308
309char *
310makestrspace(void)
311{
312	int len = stackblocksize() - sstrnleft;
313	growstackblock();
314	sstrnleft = stackblocksize() - len;
315	return stackblock() + len;
316}
317
318/*
319 * Note that this only works to release stack space for reuse
320 * if nothing else has allocated space on the stack since the grabstackstr()
321 *
322 * "s" is the start of the area to be released, and "p" represents the end
323 * of the string we have stored beyond there and are now releasing.
324 * (ie: "p" should be the same as in the call to grabstackstr()).
325 *
326 * stunalloc(s) and ungrabstackstr(s, p) are almost interchangable after
327 * a grabstackstr(), however the latter also returns string space so we
328 * can just continue with STPUTC() etc without needing a new STARTSTACKSTR(s)
329 */
330void
331ungrabstackstr(char *s, char *p)
332{
333#ifdef DEBUG
334	if (s < stacknxt || stacknxt + stacknleft < s)
335		abort();
336#endif
337	stacknleft += stacknxt - s;
338	stacknxt = s;
339	sstrnleft = stacknleft - (p - s);
340}
341