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36 * @(#)memalloc.c 8.3 (Berkeley) 5/4/95
37 * $FreeBSD: src/bin/sh/memalloc.c,v 1.38 2011/01/09 22:47:58 jilles Exp $
40 #include <sys/param.h>
51 * Like malloc, but returns an error when out of space.
55 ckmalloc(size_t nbytes)
63 error("Out of space");
73 ckrealloc(pointer p, int nbytes)
76 p = realloc(p, nbytes);
79 error("Out of space");
93 * Make a copy of a string in safe storage.
97 savestr(const char *s)
101 p = ckmalloc(strlen(s) + 1);
108 * Parse trees for commands are allocated in lifo order, so we use a stack
109 * to make this more efficient, and also to avoid all sorts of exception
110 * handling code to handle interrupts in the middle of a parse.
112 * The size 496 was chosen because with 16-byte alignment the total size
113 * for the allocated block is 512.
116 #define MINSIZE 496 /* minimum size of a block. */
120 struct stack_block *prev;
123 #define SPACE(sp) ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
125 static struct stack_block *stackp;
126 static struct stackmark *markp;
133 stnewblock(int nbytes)
135 struct stack_block *sp;
138 if (nbytes < MINSIZE)
141 allocsize = ALIGN(sizeof(struct stack_block)) + ALIGN(nbytes);
144 sp = ckmalloc(allocsize);
146 stacknxt = SPACE(sp);
147 stacknleft = allocsize - (stacknxt - (char*)sp);
148 sstrend = stacknxt + stacknleft;
159 nbytes = ALIGN(nbytes);
160 if (nbytes > stacknleft)
164 stacknleft -= nbytes;
172 if (p == NULL) { /*DEBUG */
173 write(STDERR_FILENO, "stunalloc\n", 10);
176 stacknleft += stacknxt - (char *)p;
183 setstackmark(struct stackmark *mark)
185 mark->stackp = stackp;
186 mark->stacknxt = stacknxt;
187 mark->stacknleft = stacknleft;
188 mark->marknext = markp;
194 popstackmark(struct stackmark *mark)
196 struct stack_block *sp;
199 markp = mark->marknext;
200 while (stackp != mark->stackp) {
205 stacknxt = mark->stacknxt;
206 stacknleft = mark->stacknleft;
207 sstrend = stacknxt + stacknleft;
213 * When the parser reads in a string, it wants to stick the string on the
214 * stack and only adjust the stack pointer when it knows how big the
215 * string is. Stackblock (defined in stack.h) returns a pointer to a block
216 * of space on top of the stack and stackblocklen returns the length of
217 * this block. Growstackblock will grow this space by at least one byte,
218 * possibly moving it (like realloc). Grabstackblock actually allocates the
219 * part of the block that has been used.
223 growstackblock(int min)
229 struct stack_block *sp;
230 struct stack_block *oldstackp;
231 struct stackmark *xmark;
233 if (min < stacknleft)
235 if (min >= INT_MAX / 2 - (int)ALIGN(sizeof(struct stack_block)))
236 error("Out of space");
238 min += ALIGN(sizeof(struct stack_block));
245 if (stackp != NULL && stacknxt == SPACE(stackp)) {
248 stackp = oldstackp->prev;
249 sp = ckrealloc((pointer)oldstackp, newlen);
252 stacknxt = SPACE(sp);
253 stacknleft = newlen - (stacknxt - (char*)sp);
254 sstrend = stacknxt + stacknleft;
257 * Stack marks pointing to the start of the old block
258 * must be relocated to point to the new block
261 while (xmark != NULL && xmark->stackp == oldstackp) {
262 xmark->stackp = stackp;
263 xmark->stacknxt = stacknxt;
264 xmark->stacknleft = stacknleft;
265 xmark = xmark->marknext;
269 newlen -= ALIGN(sizeof(struct stack_block));
272 memcpy(p, oldspace, oldlen);
280 * The following routines are somewhat easier to use that the above.
281 * The user declares a variable of type STACKSTR, which may be declared
282 * to be a register. The macro STARTSTACKSTR initializes things. Then
283 * the user uses the macro STPUTC to add characters to the string. In
284 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
285 * grown as necessary. When the user is done, she can just leave the
286 * string there and refer to it using stackblock(). Or she can allocate
287 * the space for it using grabstackstr(). If it is necessary to allow
288 * someone else to use the stack temporarily and then continue to grow
289 * the string, the user should use grabstack to allocate the space, and
290 * then call ungrabstr(p) to return to the previous mode of operation.
292 * USTPUTC is like STPUTC except that it doesn't check for overflow.
293 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
294 * is space for at least one character.
298 growstrstackblock(int n, int min)
301 return stackblock() + n;
309 len = stackblocksize();
310 return (growstrstackblock(len, 0));
315 * Called from CHECKSTRSPACE.
319 makestrspace(int min, char *p)
323 len = p - stackblock();
324 return (growstrstackblock(len, min));
329 stputbin(const char *data, int len, char *p)
331 CHECKSTRSPACE(len, p);
332 memcpy(p, data, len);
337 stputs(const char *data, char *p)
339 return (stputbin(data, strlen(data), p));