memalloc.c revision 297749 
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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)memalloc.c	8.3 (Berkeley) 5/4/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/10/bin/sh/memalloc.c 297749 2016-04-09 14:09:14Z jilles $");
40
41#include <sys/param.h>
42#include "shell.h"
43#include "output.h"
44#include "memalloc.h"
45#include "error.h"
46#include "mystring.h"
47#include "expand.h"
48#include <stdlib.h>
49#include <unistd.h>
50
51/*
52 * Like malloc, but returns an error when out of space.
53 */
54
55pointer
56ckmalloc(size_t nbytes)
57{
58	pointer p;
59
60	INTOFF;
61	p = malloc(nbytes);
62	INTON;
63	if (p == NULL)
64		error("Out of space");
65	return p;
66}
67
68
69/*
70 * Same for realloc.
71 */
72
73pointer
74ckrealloc(pointer p, int nbytes)
75{
76	INTOFF;
77	p = realloc(p, nbytes);
78	INTON;
79	if (p == NULL)
80		error("Out of space");
81	return p;
82}
83
84void
85ckfree(pointer p)
86{
87	INTOFF;
88	free(p);
89	INTON;
90}
91
92
93/*
94 * Make a copy of a string in safe storage.
95 */
96
97char *
98savestr(const char *s)
99{
100	char *p;
101	size_t len;
102
103	len = strlen(s);
104	p = ckmalloc(len + 1);
105	memcpy(p, s, len + 1);
106	return p;
107}
108
109
110/*
111 * Parse trees for commands are allocated in lifo order, so we use a stack
112 * to make this more efficient, and also to avoid all sorts of exception
113 * handling code to handle interrupts in the middle of a parse.
114 *
115 * The size 496 was chosen because with 16-byte alignment the total size
116 * for the allocated block is 512.
117 */
118
119#define MINSIZE 496		/* minimum size of a block. */
120
121
122struct stack_block {
123	struct stack_block *prev;
124	/* Data follows */
125};
126#define SPACE(sp)	((char*)(sp) + ALIGN(sizeof(struct stack_block)))
127
128static struct stack_block *stackp;
129char *stacknxt;
130int stacknleft;
131char *sstrend;
132
133
134static void
135stnewblock(int nbytes)
136{
137	struct stack_block *sp;
138	int allocsize;
139
140	if (nbytes < MINSIZE)
141		nbytes = MINSIZE;
142
143	allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
144
145	INTOFF;
146	sp = ckmalloc(allocsize);
147	sp->prev = stackp;
148	stacknxt = SPACE(sp);
149	stacknleft = allocsize - (stacknxt - (char*)sp);
150	sstrend = stacknxt + stacknleft;
151	stackp = sp;
152	INTON;
153}
154
155
156pointer
157stalloc(int nbytes)
158{
159	char *p;
160
161	nbytes = ALIGN(nbytes);
162	if (nbytes > stacknleft)
163		stnewblock(nbytes);
164	p = stacknxt;
165	stacknxt += nbytes;
166	stacknleft -= nbytes;
167	return p;
168}
169
170
171void
172stunalloc(pointer p)
173{
174	if (p == NULL) {		/*DEBUG */
175		write(STDERR_FILENO, "stunalloc\n", 10);
176		abort();
177	}
178	stacknleft += stacknxt - (char *)p;
179	stacknxt = p;
180}
181
182
183char *
184stsavestr(const char *s)
185{
186	char *p;
187	size_t len;
188
189	len = strlen(s);
190	p = stalloc(len + 1);
191	memcpy(p, s, len + 1);
192	return p;
193}
194
195
196void
197setstackmark(struct stackmark *mark)
198{
199	mark->stackp = stackp;
200	mark->stacknxt = stacknxt;
201	mark->stacknleft = stacknleft;
202	/* Ensure this block stays in place. */
203	if (stackp != NULL && stacknxt == SPACE(stackp))
204		stalloc(1);
205}
206
207
208void
209popstackmark(struct stackmark *mark)
210{
211	struct stack_block *sp;
212
213	INTOFF;
214	while (stackp != mark->stackp) {
215		sp = stackp;
216		stackp = sp->prev;
217		ckfree(sp);
218	}
219	stacknxt = mark->stacknxt;
220	stacknleft = mark->stacknleft;
221	sstrend = stacknxt + stacknleft;
222	INTON;
223}
224
225
226/*
227 * When the parser reads in a string, it wants to stick the string on the
228 * stack and only adjust the stack pointer when it knows how big the
229 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
230 * of space on top of the stack and stackblocklen returns the length of
231 * this block.  Growstackblock will grow this space by at least one byte,
232 * possibly moving it (like realloc).  Grabstackblock actually allocates the
233 * part of the block that has been used.
234 */
235
236static void
237growstackblock(int min)
238{
239	char *p;
240	int newlen;
241	char *oldspace;
242	int oldlen;
243	struct stack_block *sp;
244	struct stack_block *oldstackp;
245
246	if (min < stacknleft)
247		min = stacknleft;
248	if ((unsigned int)min >=
249	    INT_MAX / 2 - ALIGN(sizeof(struct stack_block)))
250		error("Out of space");
251	min += stacknleft;
252	min += ALIGN(sizeof(struct stack_block));
253	newlen = 512;
254	while (newlen < min)
255		newlen <<= 1;
256	oldspace = stacknxt;
257	oldlen = stacknleft;
258
259	if (stackp != NULL && stacknxt == SPACE(stackp)) {
260		INTOFF;
261		oldstackp = stackp;
262		stackp = oldstackp->prev;
263		sp = ckrealloc((pointer)oldstackp, newlen);
264		sp->prev = stackp;
265		stackp = sp;
266		stacknxt = SPACE(sp);
267		stacknleft = newlen - (stacknxt - (char*)sp);
268		sstrend = stacknxt + stacknleft;
269		INTON;
270	} else {
271		newlen -= ALIGN(sizeof(struct stack_block));
272		p = stalloc(newlen);
273		if (oldlen != 0)
274			memcpy(p, oldspace, oldlen);
275		stunalloc(p);
276	}
277}
278
279
280
281/*
282 * The following routines are somewhat easier to use that the above.
283 * The user declares a variable of type STACKSTR, which may be declared
284 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
285 * the user uses the macro STPUTC to add characters to the string.  In
286 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
287 * grown as necessary.  When the user is done, she can just leave the
288 * string there and refer to it using stackblock().  Or she can allocate
289 * the space for it using grabstackstr().  If it is necessary to allow
290 * someone else to use the stack temporarily and then continue to grow
291 * the string, the user should use grabstack to allocate the space, and
292 * then call ungrabstr(p) to return to the previous mode of operation.
293 *
294 * USTPUTC is like STPUTC except that it doesn't check for overflow.
295 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
296 * is space for at least one character.
297 */
298
299static char *
300growstrstackblock(int n, int min)
301{
302	growstackblock(min);
303	return stackblock() + n;
304}
305
306char *
307growstackstr(void)
308{
309	int len;
310
311	len = stackblocksize();
312	return (growstrstackblock(len, 0));
313}
314
315
316/*
317 * Called from CHECKSTRSPACE.
318 */
319
320char *
321makestrspace(int min, char *p)
322{
323	int len;
324
325	len = p - stackblock();
326	return (growstrstackblock(len, min));
327}
328
329
330char *
331stputbin(const char *data, size_t len, char *p)
332{
333	CHECKSTRSPACE(len, p);
334	memcpy(p, data, len);
335	return (p + len);
336}
337
338char *
339stputs(const char *data, char *p)
340{
341	return (stputbin(data, strlen(data), p));
342}
343