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 * 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 * 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 * 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 * 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 * 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