1/*	$NetBSD: memalloc.c,v 1.39 2023/04/07 10:42:28 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 1.39 2023/04/07 10:42:28 kre Exp $");
41#endif
42#endif /* not lint */
43
44#include <limits.h>
45#include <stdarg.h>
46#include <stdlib.h>
47#include <unistd.h>
48
49#include "shell.h"
50#include "output.h"
51#include "memalloc.h"
52#include "error.h"
53#include "machdep.h"
54#include "mystring.h"
55
56/*
57 * Like malloc, but returns an error when out of space.
58 */
59
60pointer
61ckmalloc(size_t nbytes)
62{
63	pointer p;
64
65	p = malloc(nbytes);
66	if (p == NULL)
67		error("Out of space");
68	return p;
69}
70
71
72/*
73 * Same for realloc.
74 */
75
76pointer
77ckrealloc(pointer p, int nbytes)
78{
79	p = realloc(p, nbytes);
80	if (p == NULL)
81		error("Out of space");
82	return p;
83}
84
85
86/*
87 * Make a copy of a string in safe storage.
88 */
89
90char *
91savestr(const char *s)
92{
93	char *p;
94
95	p = ckmalloc(strlen(s) + 1);
96	scopy(s, p);
97	return p;
98}
99
100
101/*
102 * Parse trees for commands are allocated in lifo order, so we use a stack
103 * to make this more efficient, and also to avoid all sorts of exception
104 * handling code to handle interrupts in the middle of a parse.
105 *
106 * The size 504 was chosen because the Ultrix malloc handles that size
107 * well.
108 */
109
110#define MINSIZE 504		/* minimum size of a block */
111
112struct stack_block {
113	struct stack_block *prev;
114	char space[MINSIZE];
115};
116
117struct stack_block stackbase;
118struct stack_block *stackp = &stackbase;
119struct stackmark *markp;
120char *stacknxt = stackbase.space;
121int stacknleft = MINSIZE;
122int sstrnleft;
123int herefd = -1;
124
125pointer
126stalloc(int nbytes)
127{
128	char *p;
129
130	nbytes = SHELL_ALIGN(nbytes);
131	if (nbytes > stacknleft) {
132		int blocksize;
133		struct stack_block *sp;
134
135		blocksize = nbytes;
136		if (blocksize < MINSIZE)
137			blocksize = MINSIZE;
138		INTOFF;
139		sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
140		sp->prev = stackp;
141		stacknxt = sp->space;
142		stacknleft = blocksize;
143		stackp = sp;
144		INTON;
145	}
146	INTOFF;
147	p = stacknxt;
148	stacknxt += nbytes;
149	stacknleft -= nbytes;
150	INTON;
151	return p;
152}
153
154
155void
156stunalloc(pointer p)
157{
158	if (p == NULL) {		/*DEBUG */
159		write(2, "stunalloc\n", 10);
160		abort();
161	}
162	stacknleft += stacknxt - (char *)p;
163	stacknxt = p;
164}
165
166
167/* save the current status of the sh stack */
168void
169setstackmark(struct stackmark *mark)
170{
171	mark->stackp = stackp;
172	mark->stacknxt = stacknxt;
173	mark->stacknleft = stacknleft;
174	mark->sstrnleft = sstrnleft;
175	mark->marknext = markp;
176	markp = mark;
177}
178
179/* reset the stack mark, and remove it from the list of marks */
180void
181popstackmark(struct stackmark *mark)
182{
183	INTOFF;
184	markp = mark->marknext;		/* delete mark from the list */
185	rststackmark(mark);		/* and reset stack */
186	INTON;
187}
188
189/* reset the shell stack to its state recorded in the stack mark */
190void
191rststackmark(struct stackmark *mark)
192{
193	struct stack_block *sp;
194
195	INTOFF;
196	while (stackp != mark->stackp) {
197		/* delete any recently allocated mem blocks */
198		sp = stackp;
199		stackp = sp->prev;
200		ckfree(sp);
201	}
202	stacknxt = mark->stacknxt;
203	stacknleft = mark->stacknleft;
204	sstrnleft = mark->sstrnleft;
205	INTON;
206}
207
208
209/*
210 * When the parser reads in a string, it wants to stick the string on the
211 * stack and only adjust the stack pointer when it knows how big the
212 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
213 * of space on top of the stack and stackblocklen returns the length of
214 * this block.  Growstackblock will grow this space by at least one byte,
215 * possibly moving it (like realloc).  Grabstackblock actually allocates the
216 * part of the block that has been used.
217 */
218
219void
220growstackblock(void)
221{
222	int newlen = SHELL_ALIGN(stacknleft * 2 + 100);
223
224	INTOFF;
225	if (stacknxt == stackp->space && stackp != &stackbase) {
226		struct stack_block *oldstackp;
227		struct stackmark *xmark;
228		struct stack_block *sp;
229
230		oldstackp = stackp;
231		sp = stackp;
232		stackp = sp->prev;
233		sp = ckrealloc((pointer)sp,
234		    sizeof(struct stack_block) - MINSIZE + newlen);
235		sp->prev = stackp;
236		stackp = sp;
237		stacknxt = sp->space;
238		sstrnleft += newlen - stacknleft;
239		stacknleft = newlen;
240
241		/*
242		 * Stack marks pointing to the start of the old block
243		 * must be relocated to point to the new block
244		 */
245		xmark = markp;
246		while (xmark != NULL && xmark->stackp == oldstackp) {
247			xmark->stackp = stackp;
248			xmark->stacknxt = stacknxt;
249			xmark->sstrnleft += stacknleft - xmark->stacknleft;
250			xmark->stacknleft = stacknleft;
251			xmark = xmark->marknext;
252		}
253	} else {
254		char *oldspace = stacknxt;
255		int oldlen = stacknleft;
256		char *p = stalloc(newlen);
257
258		(void)memcpy(p, oldspace, oldlen);
259		stacknxt = p;			/* free the space */
260		stacknleft += newlen;		/* we just allocated */
261	}
262	INTON;
263}
264
265void
266grabstackblock(int len)
267{
268	len = SHELL_ALIGN(len);
269	INTOFF;
270	stacknxt += len;
271	stacknleft -= len;
272	INTON;
273}
274
275/*
276 * The following routines are somewhat easier to use than the above.
277 * The user declares a variable of type STACKSTR, which may be declared
278 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
279 * the user uses the macro STPUTC to add characters to the string.  In
280 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
281 * grown as necessary.  When the user is done, she can just leave the
282 * string there and refer to it using stackblock().  Or she can allocate
283 * the space for it using grabstackstr().  If it is necessary to allow
284 * someone else to use the stack temporarily and then continue to grow
285 * the string, the user should use grabstack to allocate the space, and
286 * then call ungrabstr(p) to return to the previous mode of operation.
287 *
288 * USTPUTC is like STPUTC except that it doesn't check for overflow.
289 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
290 * is space for at least one character.
291 */
292
293char *
294growstackstr(void)
295{
296	int len = stackblocksize();
297	if (herefd >= 0 && len >= 1024) {
298		xwrite(herefd, stackblock(), len);
299		sstrnleft = len - 1;
300		return stackblock();
301	}
302	growstackblock();
303	sstrnleft = stackblocksize() - len - 1;
304	return stackblock() + len;
305}
306
307/*
308 * Called from CHECKSTRSPACE.
309 */
310
311char *
312makestrspace(void)
313{
314	int len = stackblocksize() - sstrnleft;
315	growstackblock();
316	sstrnleft = stackblocksize() - len;
317	return stackblock() + len;
318}
319
320/*
321 * Note that this only works to release stack space for reuse
322 * if nothing else has allocated space on the stack since the grabstackstr()
323 *
324 * "s" is the start of the area to be released, and "p" represents the end
325 * of the string we have stored beyond there and are now releasing.
326 * (ie: "p" should be the same as in the call to grabstackstr()).
327 *
328 * stunalloc(s) and ungrabstackstr(s, p) are almost interchangeable after
329 * a grabstackstr(), however the latter also returns string space so we
330 * can just continue with STPUTC() etc without needing a new STARTSTACKSTR(s)
331 */
332void
333ungrabstackstr(char *s, char *p)
334{
335#ifdef DEBUG
336	if (s < stacknxt || stacknxt + stacknleft < s)
337		abort();
338#endif
339	stacknleft += stacknxt - s;
340	stacknxt = s;
341	sstrnleft = stacknleft - (p - s);
342}
343
344/*
345 * Save the concat of a sequence of strings in stack space
346 *
347 * The first arg (if not NULL) is a pointer to where the final string
348 * length will be returned.
349 *
350 * Remaining args are pointers to strings - sufficient space to hold
351 * the concat of the strings is allocated on the stack, the strings
352 * are copied into that space, and a pointer to its start is returned.
353 * The arg list is terminated with STSTRC_END.
354 *
355 * Use stunalloc(string) (in proper sequence) to release the string
356 */
357char *
358ststrcat(size_t *lp, ...)
359{
360	va_list ap;
361	const char *arg;
362	size_t len, tlen = 0, alen[8];
363	char *str, *nxt;
364	unsigned int n;
365
366	n = 0;
367	va_start(ap, lp);
368	arg = va_arg(ap, const char *);
369	while (arg != STSTRC_END) {
370		len = strlen(arg);
371		if (n < sizeof(alen)/sizeof(alen[0]))
372			alen[n++] = len;
373		tlen += len;
374		arg = va_arg(ap, const char *);
375	}
376	va_end(ap);
377
378	if (lp != NULL)
379		*lp = tlen;
380
381	if (tlen >= INT_MAX)
382		error("ststrcat() over length botch");
383	str = (char *)stalloc((int)tlen + 1);	/* 1 for \0 */
384	str[tlen] = '\0';	/* in case of no args  */
385
386	n = 0;
387	nxt = str;
388	va_start(ap, lp);
389	arg = va_arg(ap, const char *);
390	while (arg != STSTRC_END) {
391		if (n < sizeof(alen)/sizeof(alen[0]))
392			len = alen[n++];
393		else
394			len = strlen(arg);
395
396		scopy(arg, nxt);
397		nxt += len;
398
399		arg = va_arg(ap, const char *);
400	}
401	va_end(ap);
402
403	return str;
404}
405