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4 * Copyright (c) 1991, 1993
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37 static char sccsid[] = "@(#)memalloc.c 8.3 (Berkeley) 5/4/95";
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
43 #include <sys/param.h>
54 * Like malloc, but returns an error when out of space.
58 ckmalloc(size_t nbytes)
66 error("Out of space");
76 ckrealloc(pointer p, int nbytes)
79 p = realloc(p, nbytes);
82 error("Out of space");
96 * Make a copy of a string in safe storage.
100 savestr(const char *s)
106 p = ckmalloc(len + 1);
107 memcpy(p, s, len + 1);
113 * Parse trees for commands are allocated in lifo order, so we use a stack
114 * to make this more efficient, and also to avoid all sorts of exception
115 * handling code to handle interrupts in the middle of a parse.
117 * The size 496 was chosen because with 16-byte alignment the total size
118 * for the allocated block is 512.
121 #define MINSIZE 496 /* minimum size of a block. */
125 struct stack_block *prev;
128 #define SPACE(sp) ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
130 static struct stack_block *stackp;
137 stnewblock(int nbytes)
139 struct stack_block *sp;
142 if (nbytes < MINSIZE)
145 allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
148 sp = ckmalloc(allocsize);
150 stacknxt = SPACE(sp);
151 stacknleft = allocsize - (stacknxt - (char*)sp);
152 sstrend = stacknxt + stacknleft;
163 nbytes = ALIGN(nbytes);
164 if (nbytes > stacknleft)
168 stacknleft -= nbytes;
176 if (p == NULL) { /*DEBUG */
177 write(STDERR_FILENO, "stunalloc\n", 10);
180 stacknleft += stacknxt - (char *)p;
186 stsavestr(const char *s)
192 p = stalloc(len + 1);
193 memcpy(p, s, len + 1);
199 setstackmark(struct stackmark *mark)
201 mark->stackp = stackp;
202 mark->stacknxt = stacknxt;
203 mark->stacknleft = stacknleft;
204 /* Ensure this block stays in place. */
205 if (stackp != NULL && stacknxt == SPACE(stackp))
211 popstackmark(struct stackmark *mark)
213 struct stack_block *sp;
216 while (stackp != mark->stackp) {
221 stacknxt = mark->stacknxt;
222 stacknleft = mark->stacknleft;
223 sstrend = stacknxt + stacknleft;
229 * When the parser reads in a string, it wants to stick the string on the
230 * stack and only adjust the stack pointer when it knows how big the
231 * string is. Stackblock (defined in stack.h) returns a pointer to a block
232 * of space on top of the stack and stackblocklen returns the length of
233 * this block. Growstackblock will grow this space by at least one byte,
234 * possibly moving it (like realloc). Grabstackblock actually allocates the
235 * part of the block that has been used.
239 growstackblock(int min)
245 struct stack_block *sp;
246 struct stack_block *oldstackp;
248 if (min < stacknleft)
250 if ((unsigned int)min >=
251 INT_MAX / 2 - ALIGN(sizeof(struct stack_block)))
252 error("Out of space");
254 min += ALIGN(sizeof(struct stack_block));
261 if (stackp != NULL && stacknxt == SPACE(stackp)) {
264 stackp = oldstackp->prev;
265 sp = ckrealloc((pointer)oldstackp, newlen);
268 stacknxt = SPACE(sp);
269 stacknleft = newlen - (stacknxt - (char*)sp);
270 sstrend = stacknxt + stacknleft;
273 newlen -= ALIGN(sizeof(struct stack_block));
276 memcpy(p, oldspace, oldlen);
284 * The following routines are somewhat easier to use that the above.
285 * The user declares a variable of type STACKSTR, which may be declared
286 * to be a register. The macro STARTSTACKSTR initializes things. Then
287 * the user uses the macro STPUTC to add characters to the string. In
288 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
289 * grown as necessary. When the user is done, she can just leave the
290 * string there and refer to it using stackblock(). Or she can allocate
291 * the space for it using grabstackstr(). If it is necessary to allow
292 * someone else to use the stack temporarily and then continue to grow
293 * the string, the user should use grabstack to allocate the space, and
294 * then call ungrabstr(p) to return to the previous mode of operation.
296 * USTPUTC is like STPUTC except that it doesn't check for overflow.
297 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
298 * is space for at least one character.
302 growstrstackblock(int n, int min)
305 return stackblock() + n;
313 len = stackblocksize();
314 return (growstrstackblock(len, 0));
319 * Called from CHECKSTRSPACE.
323 makestrspace(int min, char *p)
327 len = p - stackblock();
328 return (growstrstackblock(len, min));
333 stputbin(const char *data, size_t len, char *p)
335 CHECKSTRSPACE(len, p);
336 memcpy(p, data, len);
341 stputs(const char *data, char *p)
343 return (stputbin(data, strlen(data), p));