1 /* $OpenBSD: operator.c,v 1.10 2009/10/27 23:59:38 deraadt Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Cimarron D. Taylor of the University of California, Berkeley.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/types.h>
36 #include <sys/stat.h>
37
38 #include <err.h>
39 #include <fts.h>
40 #include <stdio.h>
41
42 #include "find.h"
43 #include "extern.h"
44
45 /*
46 * yanknode --
47 * destructively removes the top from the plan
48 */
49 static PLAN *
yanknode(PLAN ** planp)50 yanknode(PLAN **planp) /* pointer to top of plan (modified) */
51 {
52 PLAN *node; /* top node removed from the plan */
53
54 if ((node = (*planp)) == NULL)
55 return (NULL);
56 (*planp) = (*planp)->next;
57 node->next = NULL;
58 return (node);
59 }
60
61 /*
62 * yankexpr --
63 * Removes one expression from the plan. This is used mainly by
64 * paren_squish. In comments below, an expression is either a
65 * simple node or a N_EXPR node containing a list of simple nodes.
66 */
67 static PLAN *
yankexpr(PLAN ** planp)68 yankexpr(PLAN **planp) /* pointer to top of plan (modified) */
69 {
70 PLAN *next; /* temp node holding subexpression results */
71 PLAN *node; /* pointer to returned node or expression */
72 PLAN *tail; /* pointer to tail of subplan */
73 PLAN *subplan; /* pointer to head of ( ) expression */
74 extern int f_expr(PLAN *, FTSENT *);
75
76 /* first pull the top node from the plan */
77 if ((node = yanknode(planp)) == NULL)
78 return (NULL);
79
80 /*
81 * If the node is an '(' then we recursively slurp up expressions
82 * until we find its associated ')'. If it's a closing paren we
83 * just return it and unwind our recursion; all other nodes are
84 * complete expressions, so just return them.
85 */
86 if (node->type == N_OPENPAREN)
87 for (tail = subplan = NULL;;) {
88 if ((next = yankexpr(planp)) == NULL)
89 errx(1, "(: missing closing ')'");
90 /*
91 * If we find a closing ')' we store the collected
92 * subplan in our '(' node and convert the node to
93 * a N_EXPR. The ')' we found is ignored. Otherwise,
94 * we just continue to add whatever we get to our
95 * subplan.
96 */
97 if (next->type == N_CLOSEPAREN) {
98 if (subplan == NULL)
99 errx(1, "(): empty inner expression");
100 node->p_data[0] = subplan;
101 node->type = N_EXPR;
102 node->eval = f_expr;
103 break;
104 } else {
105 if (subplan == NULL)
106 tail = subplan = next;
107 else {
108 tail->next = next;
109 tail = next;
110 }
111 tail->next = NULL;
112 }
113 }
114 return (node);
115 }
116
117 /*
118 * paren_squish --
119 * replaces "parentheisized" plans in our search plan with "expr" nodes.
120 */
121 PLAN *
paren_squish(PLAN * plan)122 paren_squish(PLAN *plan) /* plan with ( ) nodes */
123 {
124 PLAN *expr; /* pointer to next expression */
125 PLAN *tail; /* pointer to tail of result plan */
126 PLAN *result; /* pointer to head of result plan */
127
128 result = tail = NULL;
129
130 /*
131 * the basic idea is to have yankexpr do all our work and just
132 * collect it's results together.
133 */
134 while ((expr = yankexpr(&plan)) != NULL) {
135 /*
136 * if we find an unclaimed ')' it means there is a missing
137 * '(' someplace.
138 */
139 if (expr->type == N_CLOSEPAREN)
140 errx(1, "): no beginning '('");
141
142 /* add the expression to our result plan */
143 if (result == NULL)
144 tail = result = expr;
145 else {
146 tail->next = expr;
147 tail = expr;
148 }
149 tail->next = NULL;
150 }
151 return (result);
152 }
153
154 /*
155 * not_squish --
156 * compresses "!" expressions in our search plan.
157 */
158 PLAN *
not_squish(PLAN * plan)159 not_squish(PLAN *plan) /* plan to process */
160 {
161 PLAN *next; /* next node being processed */
162 PLAN *node; /* temporary node used in N_NOT processing */
163 PLAN *tail; /* pointer to tail of result plan */
164 PLAN *result; /* pointer to head of result plan */
165
166 tail = result = next = NULL;
167
168 while ((next = yanknode(&plan)) != NULL) {
169 /*
170 * if we encounter a ( expression ) then look for nots in
171 * the expr subplan.
172 */
173 if (next->type == N_EXPR)
174 next->p_data[0] = not_squish(next->p_data[0]);
175
176 /*
177 * if we encounter a not, then snag the next node and place
178 * it in the not's subplan. As an optimization we compress
179 * several not's to zero or one not.
180 */
181 if (next->type == N_NOT) {
182 int notlevel = 1;
183
184 node = yanknode(&plan);
185 while (node != NULL && node->type == N_NOT) {
186 ++notlevel;
187 node = yanknode(&plan);
188 }
189 if (node == NULL)
190 errx(1, "!: no following expression");
191 if (node->type == N_OR)
192 errx(1, "!: nothing between ! and -o");
193 if (node->type == N_EXPR)
194 node = not_squish(node);
195 if (notlevel % 2 != 1)
196 next = node;
197 else
198 next->p_data[0] = node;
199 }
200
201 /* add the node to our result plan */
202 if (result == NULL)
203 tail = result = next;
204 else {
205 tail->next = next;
206 tail = next;
207 }
208 tail->next = NULL;
209 }
210 return (result);
211 }
212
213 /*
214 * or_squish --
215 * compresses -o expressions in our search plan.
216 */
217 PLAN *
or_squish(PLAN * plan)218 or_squish(PLAN *plan) /* plan with ors to be squished */
219 {
220 PLAN *next; /* next node being processed */
221 PLAN *tail; /* pointer to tail of result plan */
222 PLAN *result; /* pointer to head of result plan */
223
224 tail = result = next = NULL;
225
226 while ((next = yanknode(&plan)) != NULL) {
227 /*
228 * if we encounter a ( expression ) then look for or's in
229 * the expr subplan.
230 */
231 if (next->type == N_EXPR)
232 next->p_data[0] = or_squish(next->p_data[0]);
233
234 /* if we encounter a not then look for not's in the subplan */
235 if (next->type == N_NOT)
236 next->p_data[0] = or_squish(next->p_data[0]);
237
238 /*
239 * if we encounter an or, then place our collected plan in the
240 * or's first subplan and then recursively collect the
241 * remaining stuff into the second subplan and return the or.
242 */
243 if (next->type == N_OR) {
244 if (result == NULL)
245 errx(1, "-o: no expression before -o");
246 next->p_data[0] = result;
247 next->p_data[1] = or_squish(plan);
248 if (next->p_data[1] == NULL)
249 errx(1, "-o: no expression after -o");
250 return (next);
251 }
252
253 /* add the node to our result plan */
254 if (result == NULL)
255 tail = result = next;
256 else {
257 tail->next = next;
258 tail = next;
259 }
260 tail->next = NULL;
261 }
262 return (result);
263 }
264