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32 * @(#)memalloc.c 8.3 (Berkeley) 5/4/95
33 * $FreeBSD: head/bin/sh/memalloc.c 217209 2011-01-09 22:47:58Z jilles $
36 #include <sys/param.h>
47 * Like malloc, but returns an error when out of space.
51 ckmalloc(size_t nbytes)
59 error("Out of space");
69 ckrealloc(pointer p, int nbytes)
72 p = realloc(p, nbytes);
75 error("Out of space");
89 * Make a copy of a string in safe storage.
93 savestr(const char *s)
97 p = ckmalloc(strlen(s) + 1);
104 * Parse trees for commands are allocated in lifo order, so we use a stack
105 * to make this more efficient, and also to avoid all sorts of exception
106 * handling code to handle interrupts in the middle of a parse.
108 * The size 496 was chosen because with 16-byte alignment the total size
109 * for the allocated block is 512.
112 #define MINSIZE 496 /* minimum size of a block. */
116 struct stack_block *prev;
119 #define SPACE(sp) ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
121 static struct stack_block *stackp;
122 static struct stackmark *markp;
129 stnewblock(int nbytes)
131 struct stack_block *sp;
134 if (nbytes < MINSIZE)
137 allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
140 sp = ckmalloc(allocsize);
142 stacknxt = SPACE(sp);
143 stacknleft = allocsize - (stacknxt - (char*)sp);
144 sstrend = stacknxt + stacknleft;
155 nbytes = ALIGN(nbytes);
156 if (nbytes > stacknleft)
160 stacknleft -= nbytes;
168 if (p == NULL) { /*DEBUG */
169 write(STDERR_FILENO, "stunalloc\n", 10);
172 stacknleft += stacknxt - (char *)p;
179 setstackmark(struct stackmark *mark)
181 mark->stackp = stackp;
182 mark->stacknxt = stacknxt;
183 mark->stacknleft = stacknleft;
184 mark->marknext = markp;
190 popstackmark(struct stackmark *mark)
192 struct stack_block *sp;
195 markp = mark->marknext;
196 while (stackp != mark->stackp) {
201 stacknxt = mark->stacknxt;
202 stacknleft = mark->stacknleft;
203 sstrend = stacknxt + stacknleft;
209 * When the parser reads in a string, it wants to stick the string on the
210 * stack and only adjust the stack pointer when it knows how big the
211 * string is. Stackblock (defined in stack.h) returns a pointer to a block
212 * of space on top of the stack and stackblocklen returns the length of
213 * this block. Growstackblock will grow this space by at least one byte,
214 * possibly moving it (like realloc). Grabstackblock actually allocates the
215 * part of the block that has been used.
219 growstackblock(int min)
225 struct stack_block *sp;
226 struct stack_block *oldstackp;
227 struct stackmark *xmark;
229 if (min < stacknleft)
231 if (min >= INT_MAX / 2 - (int)ALIGN(sizeof(struct stack_block)))
232 error("Out of space");
234 min += ALIGN(sizeof(struct stack_block));
241 if (stackp != NULL && stacknxt == SPACE(stackp)) {
244 stackp = oldstackp->prev;
245 sp = ckrealloc((pointer)oldstackp, newlen);
248 stacknxt = SPACE(sp);
249 stacknleft = newlen - (stacknxt - (char*)sp);
250 sstrend = stacknxt + stacknleft;
253 * Stack marks pointing to the start of the old block
254 * must be relocated to point to the new block
257 while (xmark != NULL && xmark->stackp == oldstackp) {
258 xmark->stackp = stackp;
259 xmark->stacknxt = stacknxt;
260 xmark->stacknleft = stacknleft;
261 xmark = xmark->marknext;
265 newlen -= ALIGN(sizeof(struct stack_block));
268 memcpy(p, oldspace, oldlen);
276 * The following routines are somewhat easier to use that 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.
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.
294 growstrstackblock(int n, int min)
297 return stackblock() + n;
305 len = stackblocksize();
306 return (growstrstackblock(len, 0));
311 * Called from CHECKSTRSPACE.
315 makestrspace(int min, char *p)
319 len = p - stackblock();
320 return (growstrstackblock(len, min));
325 stputbin(const char *data, int len, char *p)
327 CHECKSTRSPACE(len, p);
328 memcpy(p, data, len);
333 stputs(const char *data, char *p)
335 return (stputbin(data, strlen(data), p));