1 /* $OpenBSD: operator.c,v 1.10 2009/10/27 23:59:38 deraadt 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/types.h> 36 #include <sys/stat.h> 37 38 #include <err.h> 39 #include <fts.h> 40 #include <stdio.h> 41 42 #include "find.h" 43 #include "extern.h" 44 45 /* 46 * yanknode -- 47 * destructively removes the top from the plan 48 */ 49 static PLAN * 50 yanknode(PLAN **planp) /* pointer to top of plan (modified) */ 51 { 52 PLAN *node; /* top node removed from the plan */ 53 54 if ((node = (*planp)) == NULL) 55 return (NULL); 56 (*planp) = (*planp)->next; 57 node->next = NULL; 58 return (node); 59 } 60 61 /* 62 * yankexpr -- 63 * Removes one expression from the plan. This is used mainly by 64 * paren_squish. In comments below, an expression is either a 65 * simple node or a N_EXPR node containing a list of simple nodes. 66 */ 67 static PLAN * 68 yankexpr(PLAN **planp) /* pointer to top of plan (modified) */ 69 { 70 PLAN *next; /* temp node holding subexpression results */ 71 PLAN *node; /* pointer to returned node or expression */ 72 PLAN *tail; /* pointer to tail of subplan */ 73 PLAN *subplan; /* pointer to head of ( ) expression */ 74 extern int f_expr(PLAN *, FTSENT *); 75 76 /* first pull the top node from the plan */ 77 if ((node = yanknode(planp)) == NULL) 78 return (NULL); 79 80 /* 81 * If the node is an '(' then we recursively slurp up expressions 82 * until we find its associated ')'. If it's a closing paren we 83 * just return it and unwind our recursion; all other nodes are 84 * complete expressions, so just return them. 85 */ 86 if (node->type == N_OPENPAREN) 87 for (tail = subplan = NULL;;) { 88 if ((next = yankexpr(planp)) == NULL) 89 errx(1, "(: missing closing ')'"); 90 /* 91 * If we find a closing ')' we store the collected 92 * subplan in our '(' node and convert the node to 93 * a N_EXPR. The ')' we found is ignored. Otherwise, 94 * we just continue to add whatever we get to our 95 * subplan. 96 */ 97 if (next->type == N_CLOSEPAREN) { 98 if (subplan == NULL) 99 errx(1, "(): empty inner expression"); 100 node->p_data[0] = subplan; 101 node->type = N_EXPR; 102 node->eval = f_expr; 103 break; 104 } else { 105 if (subplan == NULL) 106 tail = subplan = next; 107 else { 108 tail->next = next; 109 tail = next; 110 } 111 tail->next = NULL; 112 } 113 } 114 return (node); 115 } 116 117 /* 118 * paren_squish -- 119 * replaces "parentheisized" plans in our search plan with "expr" nodes. 120 */ 121 PLAN * 122 paren_squish(PLAN *plan) /* plan with ( ) nodes */ 123 { 124 PLAN *expr; /* pointer to next expression */ 125 PLAN *tail; /* pointer to tail of result plan */ 126 PLAN *result; /* pointer to head of result plan */ 127 128 result = tail = NULL; 129 130 /* 131 * the basic idea is to have yankexpr do all our work and just 132 * collect it's results together. 133 */ 134 while ((expr = yankexpr(&plan)) != NULL) { 135 /* 136 * if we find an unclaimed ')' it means there is a missing 137 * '(' someplace. 138 */ 139 if (expr->type == N_CLOSEPAREN) 140 errx(1, "): no beginning '('"); 141 142 /* add the expression to our result plan */ 143 if (result == NULL) 144 tail = result = expr; 145 else { 146 tail->next = expr; 147 tail = expr; 148 } 149 tail->next = NULL; 150 } 151 return (result); 152 } 153 154 /* 155 * not_squish -- 156 * compresses "!" expressions in our search plan. 157 */ 158 PLAN * 159 not_squish(PLAN *plan) /* plan to process */ 160 { 161 PLAN *next; /* next node being processed */ 162 PLAN *node; /* temporary node used in N_NOT processing */ 163 PLAN *tail; /* pointer to tail of result plan */ 164 PLAN *result; /* pointer to head of result plan */ 165 166 tail = result = next = NULL; 167 168 while ((next = yanknode(&plan)) != NULL) { 169 /* 170 * if we encounter a ( expression ) then look for nots in 171 * the expr subplan. 172 */ 173 if (next->type == N_EXPR) 174 next->p_data[0] = not_squish(next->p_data[0]); 175 176 /* 177 * if we encounter a not, then snag the next node and place 178 * it in the not's subplan. As an optimization we compress 179 * several not's to zero or one not. 180 */ 181 if (next->type == N_NOT) { 182 int notlevel = 1; 183 184 node = yanknode(&plan); 185 while (node != NULL && node->type == N_NOT) { 186 ++notlevel; 187 node = yanknode(&plan); 188 } 189 if (node == NULL) 190 errx(1, "!: no following expression"); 191 if (node->type == N_OR) 192 errx(1, "!: nothing between ! and -o"); 193 if (node->type == N_EXPR) 194 node = not_squish(node); 195 if (notlevel % 2 != 1) 196 next = node; 197 else 198 next->p_data[0] = node; 199 } 200 201 /* add the node to our result plan */ 202 if (result == NULL) 203 tail = result = next; 204 else { 205 tail->next = next; 206 tail = next; 207 } 208 tail->next = NULL; 209 } 210 return (result); 211 } 212 213 /* 214 * or_squish -- 215 * compresses -o expressions in our search plan. 216 */ 217 PLAN * 218 or_squish(PLAN *plan) /* plan with ors to be squished */ 219 { 220 PLAN *next; /* next node being processed */ 221 PLAN *tail; /* pointer to tail of result plan */ 222 PLAN *result; /* pointer to head of result plan */ 223 224 tail = result = next = NULL; 225 226 while ((next = yanknode(&plan)) != NULL) { 227 /* 228 * if we encounter a ( expression ) then look for or's in 229 * the expr subplan. 230 */ 231 if (next->type == N_EXPR) 232 next->p_data[0] = or_squish(next->p_data[0]); 233 234 /* if we encounter a not then look for not's in the subplan */ 235 if (next->type == N_NOT) 236 next->p_data[0] = or_squish(next->p_data[0]); 237 238 /* 239 * if we encounter an or, then place our collected plan in the 240 * or's first subplan and then recursively collect the 241 * remaining stuff into the second subplan and return the or. 242 */ 243 if (next->type == N_OR) { 244 if (result == NULL) 245 errx(1, "-o: no expression before -o"); 246 next->p_data[0] = result; 247 next->p_data[1] = or_squish(plan); 248 if (next->p_data[1] == NULL) 249 errx(1, "-o: no expression after -o"); 250 return (next); 251 } 252 253 /* add the node to our result plan */ 254 if (result == NULL) 255 tail = result = next; 256 else { 257 tail->next = next; 258 tail = next; 259 } 260 tail->next = NULL; 261 } 262 return (result); 263 } 264