2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
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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.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 static char sccsid[] = "@(#)memalloc.c 8.3 (Berkeley) 5/4/95";
41 static const char rcsid[] =
56 * Like malloc, but returns an error when out of space.
65 if ((p = malloc(nbytes)) == NULL)
66 error("Out of space");
80 if ((p = realloc(p, nbytes)) == NULL)
81 error("Out of space");
87 * Make a copy of a string in safe storage.
96 p = ckmalloc(strlen(s) + 1);
103 * Parse trees for commands are allocated in lifo order, so we use a stack
104 * to make this more efficient, and also to avoid all sorts of exception
105 * handling code to handle interrupts in the middle of a parse.
107 * The size 504 was chosen because the Ultrix malloc handles that size
111 #define MINSIZE 504 /* minimum size of a block */
115 struct stack_block *prev;
119 struct stack_block stackbase;
120 struct stack_block *stackp = &stackbase;
121 struct stackmark *markp;
122 char *stacknxt = stackbase.space;
123 int stacknleft = MINSIZE;
135 nbytes = ALIGN(nbytes);
136 if (nbytes > stacknleft) {
138 struct stack_block *sp;
141 if (blocksize < MINSIZE)
144 sp = ckmalloc(sizeof(struct stack_block) - MINSIZE +
147 stacknxt = sp->space;
148 stacknleft = blocksize;
154 stacknleft -= nbytes;
163 if (p == NULL) { /*DEBUG */
164 write(2, "stunalloc\n", 10);
167 stacknleft += stacknxt - (char *)p;
175 struct stackmark *mark;
177 mark->stackp = stackp;
178 mark->stacknxt = stacknxt;
179 mark->stacknleft = stacknleft;
180 mark->marknext = markp;
187 struct stackmark *mark;
189 struct stack_block *sp;
192 markp = mark->marknext;
193 while (stackp != mark->stackp) {
198 stacknxt = mark->stacknxt;
199 stacknleft = mark->stacknleft;
205 * When the parser reads in a string, it wants to stick the string on the
206 * stack and only adjust the stack pointer when it knows how big the
207 * string is. Stackblock (defined in stack.h) returns a pointer to a block
208 * of space on top of the stack and stackblocklen returns the length of
209 * this block. Growstackblock will grow this space by at least one byte,
210 * possibly moving it (like realloc). Grabstackblock actually allocates the
211 * part of the block that has been used.
221 struct stack_block *sp;
222 struct stack_block *oldstackp;
224 newlen = ALIGN(stacknleft * 2 + 100);
228 if (stacknxt == stackp->space && stackp != &stackbase) {
233 sp = ckrealloc((pointer)sp, sizeof(struct stack_block) -
237 stacknxt = sp->space;
240 /* Stack marks pointing to the start of the old block
241 * must be relocated to point to the new block
243 struct stackmark *xmark;
245 while (xmark != NULL && xmark->stackp == oldstackp) {
246 xmark->stackp = stackp;
247 xmark->stacknxt = stacknxt;
248 xmark->stacknleft = stacknleft;
249 xmark = xmark->marknext;
255 memcpy(p, oldspace, oldlen);
256 stacknxt = p; /* free the space */
257 stacknleft += newlen; /* we just allocated */
275 * The following routines are somewhat easier to use that the above.
276 * The user declares a variable of type STACKSTR, which may be declared
277 * to be a register. The macro STARTSTACKSTR initializes things. Then
278 * the user uses the macro STPUTC to add characters to the string. In
279 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
280 * grown as necessary. When the user is done, she can just leave the
281 * string there and refer to it using stackblock(). Or she can allocate
282 * the space for it using grabstackstr(). If it is necessary to allow
283 * someone else to use the stack temporarily and then continue to grow
284 * the string, the user should use grabstack to allocate the space, and
285 * then call ungrabstr(p) to return to the previous mode of operation.
287 * USTPUTC is like STPUTC except that it doesn't check for overflow.
288 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
289 * is space for at least one character.
298 len = stackblocksize();
299 if (herefd >= 0 && len >= 1024) {
300 xwrite(herefd, stackblock(), len);
305 sstrnleft = stackblocksize() - len - 1;
306 return stackblock() + len;
311 * Called from CHECKSTRSPACE.
319 len = stackblocksize() - sstrnleft;
321 sstrnleft = stackblocksize() - len;
322 return stackblock() + len;
332 stacknleft += stacknxt - s;
334 sstrnleft = stacknleft - (p - s);