usr.bin/find/operator.c

   1 /*      $NetBSD: operator.c,v 1.8 2003/08/07 11:13:43 agc 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 1.8 2003/08/07 11:13:43 agc 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 *
  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 *
  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 *
 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 it's 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 *
 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 *
 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 }