1/* $NetBSD: operator.c,v 1.9 2006/10/11 19:51:10 apb 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 38static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93"; 39#else 40__RCSID("$NetBSD: operator.c,v 1.9 2006/10/11 19:51:10 apb 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 52static PLAN *yanknode(PLAN **); 53static PLAN *yankexpr(PLAN **); 54 55/* 56 * yanknode -- 57 * destructively removes the top from the plan 58 */ 59static PLAN * 60yanknode(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 */ 77static PLAN * 78yankexpr(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 */ 130PLAN * 131paren_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 */ 167PLAN * 168not_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 */ 226PLAN * 227or_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