1 /* $NetBSD: operator.c,v 1.10 2014/10/18 08:33:30 snj 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/cdefs.h>
36 #ifndef lint
37 #if 0
38 static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93";
39 #else
40 __RCSID("$NetBSD: operator.c,v 1.10 2014/10/18 08:33:30 snj Exp $");
41 #endif
42 #endif /* not lint */
43
44 #include <sys/types.h>
45
46 #include <err.h>
47 #include <fts.h>
48 #include <stdio.h>
49
50 #include "find.h"
51
52 static PLAN *yanknode(PLAN **);
53 static PLAN *yankexpr(PLAN **);
54
55 /*
56 * yanknode --
57 * destructively removes the top from the plan
58 */
59 static PLAN *
yanknode(PLAN ** planp)60 yanknode(PLAN **planp) /* pointer to top of plan (modified) */
61 {
62 PLAN *node; /* top node removed from the plan */
63
64 if ((node = (*planp)) == NULL)
65 return (NULL);
66 (*planp) = (*planp)->next;
67 node->next = NULL;
68 return (node);
69 }
70
71 /*
72 * yankexpr --
73 * Removes one expression from the plan. This is used mainly by
74 * paren_squish. In comments below, an expression is either a
75 * simple node or a N_EXPR node containing a list of simple nodes.
76 */
77 static PLAN *
yankexpr(PLAN ** planp)78 yankexpr(PLAN **planp) /* pointer to top of plan (modified) */
79 {
80 PLAN *next; /* temp node holding subexpression results */
81 PLAN *node; /* pointer to returned node or expression */
82 PLAN *tail; /* pointer to tail of subplan */
83 PLAN *subplan; /* pointer to head of ( ) expression */
84
85 /* first pull the top node from the plan */
86 if ((node = yanknode(planp)) == NULL)
87 return (NULL);
88
89 /*
90 * If the node is an '(' then we recursively slurp up expressions
91 * until we find its associated ')'. If it's a closing paren we
92 * just return it and unwind our recursion; all other nodes are
93 * complete expressions, so just return them.
94 */
95 if (node->type == N_OPENPAREN)
96 for (tail = subplan = NULL;;) {
97 if ((next = yankexpr(planp)) == NULL)
98 err(1, "(: missing closing ')'");
99 /*
100 * If we find a closing ')' we store the collected
101 * subplan in our '(' node and convert the node to
102 * a N_EXPR. The ')' we found is ignored. Otherwise,
103 * we just continue to add whatever we get to our
104 * subplan.
105 */
106 if (next->type == N_CLOSEPAREN) {
107 if (subplan == NULL)
108 errx(1, "(): empty inner expression");
109 node->p_data[0] = subplan;
110 node->type = N_EXPR;
111 node->eval = f_expr;
112 break;
113 } else {
114 if (subplan == NULL)
115 tail = subplan = next;
116 else {
117 tail->next = next;
118 tail = next;
119 }
120 tail->next = NULL;
121 }
122 }
123 return (node);
124 }
125
126 /*
127 * paren_squish --
128 * replaces "parentheisized" plans in our search plan with "expr" nodes.
129 */
130 PLAN *
paren_squish(PLAN * plan)131 paren_squish(PLAN *plan) /* plan with ( ) nodes */
132 {
133 PLAN *expr; /* pointer to next expression */
134 PLAN *tail; /* pointer to tail of result plan */
135 PLAN *result; /* pointer to head of result plan */
136
137 result = tail = NULL;
138
139 /*
140 * the basic idea is to have yankexpr do all our work and just
141 * collect its results together.
142 */
143 while ((expr = yankexpr(&plan)) != NULL) {
144 /*
145 * if we find an unclaimed ')' it means there is a missing
146 * '(' someplace.
147 */
148 if (expr->type == N_CLOSEPAREN)
149 errx(1, "): no beginning '('");
150
151 /* add the expression to our result plan */
152 if (result == NULL)
153 tail = result = expr;
154 else {
155 tail->next = expr;
156 tail = expr;
157 }
158 tail->next = NULL;
159 }
160 return (result);
161 }
162
163 /*
164 * not_squish --
165 * compresses "!" expressions in our search plan.
166 */
167 PLAN *
not_squish(PLAN * plan)168 not_squish(PLAN *plan) /* plan to process */
169 {
170 PLAN *next; /* next node being processed */
171 PLAN *node; /* temporary node used in N_NOT processing */
172 PLAN *tail; /* pointer to tail of result plan */
173 PLAN *result; /* pointer to head of result plan */
174
175 tail = result = next = NULL;
176
177 while ((next = yanknode(&plan)) != NULL) {
178 /*
179 * if we encounter a ( expression ) then look for nots in
180 * the expr subplan.
181 */
182 if (next->type == N_EXPR)
183 next->p_data[0] = not_squish(next->p_data[0]);
184
185 /*
186 * if we encounter a not, then snag the next node and place
187 * it in the not's subplan. As an optimization we compress
188 * several not's to zero or one not.
189 */
190 if (next->type == N_NOT) {
191 int notlevel = 1;
192
193 node = yanknode(&plan);
194 while (node != NULL && node->type == N_NOT) {
195 ++notlevel;
196 node = yanknode(&plan);
197 }
198 if (node == NULL)
199 errx(1, "!: no following expression");
200 if (node->type == N_OR)
201 errx(1, "!: nothing between ! and -o");
202 if (node->type == N_EXPR)
203 node = not_squish(node);
204 if (notlevel % 2 != 1)
205 next = node;
206 else
207 next->p_data[0] = node;
208 }
209
210 /* add the node to our result plan */
211 if (result == NULL)
212 tail = result = next;
213 else {
214 tail->next = next;
215 tail = next;
216 }
217 tail->next = NULL;
218 }
219 return (result);
220 }
221
222 /*
223 * or_squish --
224 * compresses -o expressions in our search plan.
225 */
226 PLAN *
or_squish(PLAN * plan)227 or_squish(PLAN *plan) /* plan with ors to be squished */
228 {
229 PLAN *next; /* next node being processed */
230 PLAN *tail; /* pointer to tail of result plan */
231 PLAN *result; /* pointer to head of result plan */
232
233 tail = result = next = NULL;
234
235 while ((next = yanknode(&plan)) != NULL) {
236 /*
237 * if we encounter a ( expression ) then look for or's in
238 * the expr subplan.
239 */
240 if (next->type == N_EXPR)
241 next->p_data[0] = or_squish(next->p_data[0]);
242
243 /* if we encounter a not then look for not's in the subplan */
244 if (next->type == N_NOT)
245 next->p_data[0] = or_squish(next->p_data[0]);
246
247 /*
248 * if we encounter an or, then place our collected plan in the
249 * or's first subplan and then recursively collect the
250 * remaining stuff into the second subplan and return the or.
251 */
252 if (next->type == N_OR) {
253 if (result == NULL)
254 errx(1, "-o: no expression before -o");
255 next->p_data[0] = result;
256 next->p_data[1] = or_squish(plan);
257 if (next->p_data[1] == NULL)
258 errx(1, "-o: no expression after -o");
259 return (next);
260 }
261
262 /* add the node to our result plan */
263 if (result == NULL)
264 tail = result = next;
265 else {
266 tail->next = next;
267 tail = next;
268 }
269 tail->next = NULL;
270 }
271 return (result);
272 }
273