1 /* $OpenBSD: operator.c,v 1.9 2004/06/02 15:00:51 tom 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 #ifndef lint
36 /*static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93";*/
37 static char rcsid[] = "$OpenBSD: operator.c,v 1.9 2004/06/02 15:00:51 tom Exp $";
38 #endif /* not lint */
39
40 #include <sys/types.h>
41 #include <sys/stat.h>
42
43 #include <err.h>
44 #include <fts.h>
45 #include <stdio.h>
46
47 #include "find.h"
48 #include "extern.h"
49
50 /*
51 * yanknode --
52 * destructively removes the top from the plan
53 */
54 static PLAN *
yanknode(PLAN ** planp)55 yanknode(PLAN **planp) /* pointer to top of plan (modified) */
56 {
57 PLAN *node; /* top node removed from the plan */
58
59 if ((node = (*planp)) == NULL)
60 return (NULL);
61 (*planp) = (*planp)->next;
62 node->next = NULL;
63 return (node);
64 }
65
66 /*
67 * yankexpr --
68 * Removes one expression from the plan. This is used mainly by
69 * paren_squish. In comments below, an expression is either a
70 * simple node or a N_EXPR node containing a list of simple nodes.
71 */
72 static PLAN *
yankexpr(PLAN ** planp)73 yankexpr(PLAN **planp) /* pointer to top of plan (modified) */
74 {
75 PLAN *next; /* temp node holding subexpression results */
76 PLAN *node; /* pointer to returned node or expression */
77 PLAN *tail; /* pointer to tail of subplan */
78 PLAN *subplan; /* pointer to head of ( ) expression */
79 extern int f_expr(PLAN *, FTSENT *);
80
81 /* first pull the top node from the plan */
82 if ((node = yanknode(planp)) == NULL)
83 return (NULL);
84
85 /*
86 * If the node is an '(' then we recursively slurp up expressions
87 * until we find its associated ')'. If it's a closing paren we
88 * just return it and unwind our recursion; all other nodes are
89 * complete expressions, so just return them.
90 */
91 if (node->type == N_OPENPAREN)
92 for (tail = subplan = NULL;;) {
93 if ((next = yankexpr(planp)) == NULL)
94 errx(1, "(: missing closing ')'");
95 /*
96 * If we find a closing ')' we store the collected
97 * subplan in our '(' node and convert the node to
98 * a N_EXPR. The ')' we found is ignored. Otherwise,
99 * we just continue to add whatever we get to our
100 * subplan.
101 */
102 if (next->type == N_CLOSEPAREN) {
103 if (subplan == NULL)
104 errx(1, "(): empty inner expression");
105 node->p_data[0] = subplan;
106 node->type = N_EXPR;
107 node->eval = f_expr;
108 break;
109 } else {
110 if (subplan == NULL)
111 tail = subplan = next;
112 else {
113 tail->next = next;
114 tail = next;
115 }
116 tail->next = NULL;
117 }
118 }
119 return (node);
120 }
121
122 /*
123 * paren_squish --
124 * replaces "parentheisized" plans in our search plan with "expr" nodes.
125 */
126 PLAN *
paren_squish(PLAN * plan)127 paren_squish(PLAN *plan) /* plan with ( ) nodes */
128 {
129 PLAN *expr; /* pointer to next expression */
130 PLAN *tail; /* pointer to tail of result plan */
131 PLAN *result; /* pointer to head of result plan */
132
133 result = tail = NULL;
134
135 /*
136 * the basic idea is to have yankexpr do all our work and just
137 * collect it's results together.
138 */
139 while ((expr = yankexpr(&plan)) != NULL) {
140 /*
141 * if we find an unclaimed ')' it means there is a missing
142 * '(' someplace.
143 */
144 if (expr->type == N_CLOSEPAREN)
145 errx(1, "): no beginning '('");
146
147 /* add the expression to our result plan */
148 if (result == NULL)
149 tail = result = expr;
150 else {
151 tail->next = expr;
152 tail = expr;
153 }
154 tail->next = NULL;
155 }
156 return (result);
157 }
158
159 /*
160 * not_squish --
161 * compresses "!" expressions in our search plan.
162 */
163 PLAN *
not_squish(PLAN * plan)164 not_squish(PLAN *plan) /* plan to process */
165 {
166 PLAN *next; /* next node being processed */
167 PLAN *node; /* temporary node used in N_NOT processing */
168 PLAN *tail; /* pointer to tail of result plan */
169 PLAN *result; /* pointer to head of result plan */
170
171 tail = result = next = NULL;
172
173 while ((next = yanknode(&plan)) != NULL) {
174 /*
175 * if we encounter a ( expression ) then look for nots in
176 * the expr subplan.
177 */
178 if (next->type == N_EXPR)
179 next->p_data[0] = not_squish(next->p_data[0]);
180
181 /*
182 * if we encounter a not, then snag the next node and place
183 * it in the not's subplan. As an optimization we compress
184 * several not's to zero or one not.
185 */
186 if (next->type == N_NOT) {
187 int notlevel = 1;
188
189 node = yanknode(&plan);
190 while (node != NULL && node->type == N_NOT) {
191 ++notlevel;
192 node = yanknode(&plan);
193 }
194 if (node == NULL)
195 errx(1, "!: no following expression");
196 if (node->type == N_OR)
197 errx(1, "!: nothing between ! and -o");
198 if (node->type == N_EXPR)
199 node = not_squish(node);
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) /* plan with ors to be squished */
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->type == N_EXPR)
237 next->p_data[0] = or_squish(next->p_data[0]);
238
239 /* if we encounter a not then look for not's in the subplan */
240 if (next->type == N_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->type == N_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