1 /*-
2 * Copyright (c) 1990, 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 * Cimarron D. Taylor of the University of California, Berkeley.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: src/usr.bin/find/operator.c,v 1.17 2010/12/11 08:32:16 joel Exp $
33 *
34 * @(#)operator.c 8.1 (Berkeley) 6/6/93
35 */
36
37 #include <sys/types.h>
38
39 #include <err.h>
40 #include <fts.h>
41 #include <stdio.h>
42
43 #include "find.h"
44
45 static PLAN *yanknode(PLAN **);
46 static PLAN *yankexpr(PLAN **);
47
48 /*
49 * yanknode --
50 * destructively removes the top from the plan
51 */
52 static PLAN *
yanknode(PLAN ** planp)53 yanknode(PLAN **planp)
54 {
55 PLAN *node; /* top node removed from the plan */
56
57 if ((node = (*planp)) == NULL)
58 return (NULL);
59 (*planp) = (*planp)->next;
60 node->next = NULL;
61 return (node);
62 }
63
64 /*
65 * yankexpr --
66 * Removes one expression from the plan. This is used mainly by
67 * paren_squish. In comments below, an expression is either a
68 * simple node or a f_expr node containing a list of simple nodes.
69 */
70 static PLAN *
yankexpr(PLAN ** planp)71 yankexpr(PLAN **planp)
72 {
73 PLAN *next; /* temp node holding subexpression results */
74 PLAN *node; /* pointer to returned node or expression */
75 PLAN *tail; /* pointer to tail of subplan */
76 PLAN *subplan; /* pointer to head of ( ) expression */
77
78 /* first pull the top node from the plan */
79 if ((node = yanknode(planp)) == NULL)
80 return (NULL);
81
82 /*
83 * If the node is an '(' then we recursively slurp up expressions
84 * until we find its associated ')'. If it's a closing paren we
85 * just return it and unwind our recursion; all other nodes are
86 * complete expressions, so just return them.
87 */
88 if (node->execute == f_openparen)
89 for (tail = subplan = NULL;;) {
90 if ((next = yankexpr(planp)) == NULL)
91 errx(1, "(: missing closing ')'");
92 /*
93 * If we find a closing ')' we store the collected
94 * subplan in our '(' node and convert the node to
95 * a f_expr. The ')' we found is ignored. Otherwise,
96 * we just continue to add whatever we get to our
97 * subplan.
98 */
99 if (next->execute == f_closeparen) {
100 if (subplan == NULL)
101 errx(1, "(): empty inner expression");
102 node->p_data[0] = subplan;
103 node->execute = f_expr;
104 break;
105 } else {
106 if (subplan == NULL)
107 tail = subplan = next;
108 else {
109 tail->next = next;
110 tail = next;
111 }
112 tail->next = NULL;
113 }
114 }
115 return (node);
116 }
117
118 /*
119 * paren_squish --
120 * replaces "parenthesized" plans in our search plan with "expr" nodes.
121 */
122 PLAN *
paren_squish(PLAN * plan)123 paren_squish(PLAN *plan)
124 {
125 PLAN *expr; /* pointer to next expression */
126 PLAN *tail; /* pointer to tail of result plan */
127 PLAN *result; /* pointer to head of result plan */
128
129 result = tail = NULL;
130
131 /*
132 * the basic idea is to have yankexpr do all our work and just
133 * collect its results together.
134 */
135 while ((expr = yankexpr(&plan)) != NULL) {
136 /*
137 * if we find an unclaimed ')' it means there is a missing
138 * '(' someplace.
139 */
140 if (expr->execute == f_closeparen)
141 errx(1, "): no beginning '('");
142
143 /* add the expression to our result plan */
144 if (result == NULL)
145 tail = result = expr;
146 else {
147 tail->next = expr;
148 tail = expr;
149 }
150 tail->next = NULL;
151 }
152 return (result);
153 }
154
155 /*
156 * not_squish --
157 * compresses "!" expressions in our search plan.
158 */
159 PLAN *
not_squish(PLAN * plan)160 not_squish(PLAN *plan)
161 {
162 PLAN *next; /* next node being processed */
163 PLAN *node; /* temporary node used in f_not processing */
164 PLAN *tail; /* pointer to tail of result plan */
165 PLAN *result; /* pointer to head of result plan */
166
167 tail = result = NULL;
168
169 while ((next = yanknode(&plan))) {
170 /*
171 * if we encounter a ( expression ) then look for nots in
172 * the expr subplan.
173 */
174 if (next->execute == f_expr)
175 next->p_data[0] = not_squish(next->p_data[0]);
176
177 /*
178 * if we encounter a not, then snag the next node and place
179 * it in the not's subplan. As an optimization we compress
180 * several not's to zero or one not.
181 */
182 if (next->execute == f_not) {
183 int notlevel = 1;
184
185 node = yanknode(&plan);
186 while (node != NULL && node->execute == f_not) {
187 ++notlevel;
188 node = yanknode(&plan);
189 }
190 if (node == NULL)
191 errx(1, "!: no following expression");
192 if (node->execute == f_or)
193 errx(1, "!: nothing between ! and -o");
194 /*
195 * If we encounter ! ( expr ) then look for nots in
196 * the expr subplan.
197 */
198 if (node->execute == f_expr)
199 node->p_data[0] = not_squish(node->p_data[0]);
200 if (notlevel % 2 != 1)
201 next = node;
202 else
203 next->p_data[0] = node;
204 }
205
206 /* add the node to our result plan */
207 if (result == NULL)
208 tail = result = next;
209 else {
210 tail->next = next;
211 tail = next;
212 }
213 tail->next = NULL;
214 }
215 return (result);
216 }
217
218 /*
219 * or_squish --
220 * compresses -o expressions in our search plan.
221 */
222 PLAN *
or_squish(PLAN * plan)223 or_squish(PLAN *plan)
224 {
225 PLAN *next; /* next node being processed */
226 PLAN *tail; /* pointer to tail of result plan */
227 PLAN *result; /* pointer to head of result plan */
228
229 tail = result = next = NULL;
230
231 while ((next = yanknode(&plan)) != NULL) {
232 /*
233 * if we encounter a ( expression ) then look for or's in
234 * the expr subplan.
235 */
236 if (next->execute == f_expr)
237 next->p_data[0] = or_squish(next->p_data[0]);
238
239 /* if we encounter a not then look for or's in the subplan */
240 if (next->execute == f_not)
241 next->p_data[0] = or_squish(next->p_data[0]);
242
243 /*
244 * if we encounter an or, then place our collected plan in the
245 * or's first subplan and then recursively collect the
246 * remaining stuff into the second subplan and return the or.
247 */
248 if (next->execute == f_or) {
249 if (result == NULL)
250 errx(1, "-o: no expression before -o");
251 next->p_data[0] = result;
252 next->p_data[1] = or_squish(plan);
253 if (next->p_data[1] == NULL)
254 errx(1, "-o: no expression after -o");
255 return (next);
256 }
257
258 /* add the node to our result plan */
259 if (result == NULL)
260 tail = result = next;
261 else {
262 tail->next = next;
263 tail = next;
264 }
265 tail->next = NULL;
266 }
267 return (result);
268 }
269