xref: /minix/usr.bin/find/operator.c (revision 0a6a1f1d)
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