1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * %sccs.include.redist.c%
9 */
10
11 #ifndef lint
12 static char sccsid[] = "@(#)memalloc.c 8.3 (Berkeley) 05/04/95";
13 #endif /* not lint */
14
15 #include "shell.h"
16 #include "output.h"
17 #include "memalloc.h"
18 #include "error.h"
19 #include "machdep.h"
20 #include "mystring.h"
21 #include <stdlib.h>
22 #include <unistd.h>
23
24 /*
25 * Like malloc, but returns an error when out of space.
26 */
27
28 pointer
ckmalloc(nbytes)29 ckmalloc(nbytes)
30 int nbytes;
31 {
32 register pointer p;
33
34 if ((p = malloc(nbytes)) == NULL)
35 error("Out of space");
36 return p;
37 }
38
39
40 /*
41 * Same for realloc.
42 */
43
44 pointer
ckrealloc(p,nbytes)45 ckrealloc(p, nbytes)
46 register pointer p;
47 int nbytes;
48 {
49
50 if ((p = realloc(p, nbytes)) == NULL)
51 error("Out of space");
52 return p;
53 }
54
55
56 /*
57 * Make a copy of a string in safe storage.
58 */
59
60 char *
savestr(s)61 savestr(s)
62 char *s;
63 {
64 register char *p;
65
66 p = ckmalloc(strlen(s) + 1);
67 scopy(s, p);
68 return p;
69 }
70
71
72 /*
73 * Parse trees for commands are allocated in lifo order, so we use a stack
74 * to make this more efficient, and also to avoid all sorts of exception
75 * handling code to handle interrupts in the middle of a parse.
76 *
77 * The size 504 was chosen because the Ultrix malloc handles that size
78 * well.
79 */
80
81 #define MINSIZE 504 /* minimum size of a block */
82
83
84 struct stack_block {
85 struct stack_block *prev;
86 char space[MINSIZE];
87 };
88
89 struct stack_block stackbase;
90 struct stack_block *stackp = &stackbase;
91 char *stacknxt = stackbase.space;
92 int stacknleft = MINSIZE;
93 int sstrnleft;
94 int herefd = -1;
95
96
97
98 pointer
stalloc(nbytes)99 stalloc(nbytes)
100 int nbytes;
101 {
102 register char *p;
103
104 nbytes = ALIGN(nbytes);
105 if (nbytes > stacknleft) {
106 int blocksize;
107 struct stack_block *sp;
108
109 blocksize = nbytes;
110 if (blocksize < MINSIZE)
111 blocksize = MINSIZE;
112 INTOFF;
113 sp = ckmalloc(sizeof(struct stack_block) - MINSIZE + blocksize);
114 sp->prev = stackp;
115 stacknxt = sp->space;
116 stacknleft = blocksize;
117 stackp = sp;
118 INTON;
119 }
120 p = stacknxt;
121 stacknxt += nbytes;
122 stacknleft -= nbytes;
123 return p;
124 }
125
126
127 void
stunalloc(p)128 stunalloc(p)
129 pointer p;
130 {
131 if (p == NULL) { /*DEBUG */
132 write(2, "stunalloc\n", 10);
133 abort();
134 }
135 stacknleft += stacknxt - (char *)p;
136 stacknxt = p;
137 }
138
139
140
141 void
setstackmark(mark)142 setstackmark(mark)
143 struct stackmark *mark;
144 {
145 mark->stackp = stackp;
146 mark->stacknxt = stacknxt;
147 mark->stacknleft = stacknleft;
148 }
149
150
151 void
popstackmark(mark)152 popstackmark(mark)
153 struct stackmark *mark;
154 {
155 struct stack_block *sp;
156
157 INTOFF;
158 while (stackp != mark->stackp) {
159 sp = stackp;
160 stackp = sp->prev;
161 ckfree(sp);
162 }
163 stacknxt = mark->stacknxt;
164 stacknleft = mark->stacknleft;
165 INTON;
166 }
167
168
169 /*
170 * When the parser reads in a string, it wants to stick the string on the
171 * stack and only adjust the stack pointer when it knows how big the
172 * string is. Stackblock (defined in stack.h) returns a pointer to a block
173 * of space on top of the stack and stackblocklen returns the length of
174 * this block. Growstackblock will grow this space by at least one byte,
175 * possibly moving it (like realloc). Grabstackblock actually allocates the
176 * part of the block that has been used.
177 */
178
179 void
growstackblock()180 growstackblock() {
181 char *p;
182 int newlen = stacknleft * 2 + 100;
183 char *oldspace = stacknxt;
184 int oldlen = stacknleft;
185 struct stack_block *sp;
186
187 if (stacknxt == stackp->space && stackp != &stackbase) {
188 INTOFF;
189 sp = stackp;
190 stackp = sp->prev;
191 sp = ckrealloc((pointer)sp, sizeof(struct stack_block) - MINSIZE + newlen);
192 sp->prev = stackp;
193 stackp = sp;
194 stacknxt = sp->space;
195 stacknleft = newlen;
196 INTON;
197 } else {
198 p = stalloc(newlen);
199 memcpy(p, oldspace, oldlen);
200 stacknxt = p; /* free the space */
201 stacknleft += ALIGN(newlen); /* we just allocated */
202 }
203 }
204
205
206
207 void
grabstackblock(len)208 grabstackblock(len)
209 int len;
210 {
211 len = ALIGN(len);
212 stacknxt += len;
213 stacknleft -= len;
214 }
215
216
217
218 /*
219 * The following routines are somewhat easier to use that the above.
220 * The user declares a variable of type STACKSTR, which may be declared
221 * to be a register. The macro STARTSTACKSTR initializes things. Then
222 * the user uses the macro STPUTC to add characters to the string. In
223 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
224 * grown as necessary. When the user is done, she can just leave the
225 * string there and refer to it using stackblock(). Or she can allocate
226 * the space for it using grabstackstr(). If it is necessary to allow
227 * someone else to use the stack temporarily and then continue to grow
228 * the string, the user should use grabstack to allocate the space, and
229 * then call ungrabstr(p) to return to the previous mode of operation.
230 *
231 * USTPUTC is like STPUTC except that it doesn't check for overflow.
232 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
233 * is space for at least one character.
234 */
235
236
237 char *
growstackstr()238 growstackstr() {
239 int len = stackblocksize();
240 if (herefd >= 0 && len >= 1024) {
241 xwrite(herefd, stackblock(), len);
242 sstrnleft = len - 1;
243 return stackblock();
244 }
245 growstackblock();
246 sstrnleft = stackblocksize() - len - 1;
247 return stackblock() + len;
248 }
249
250
251 /*
252 * Called from CHECKSTRSPACE.
253 */
254
255 char *
makestrspace()256 makestrspace() {
257 int len = stackblocksize() - sstrnleft;
258 growstackblock();
259 sstrnleft = stackblocksize() - len;
260 return stackblock() + len;
261 }
262
263
264
265 void
ungrabstackstr(s,p)266 ungrabstackstr(s, p)
267 char *s;
268 char *p;
269 {
270 stacknleft += stacknxt - s;
271 stacknxt = s;
272 sstrnleft = stacknleft - (p - s);
273 }
274