find/operator.c

   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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #ifndef lint
  38 #if 0
  39 static char sccsid[] = "@(#)operator.c  8.1 (Berkeley) 6/6/93";
  40 #endif
  41 #endif /* not lint */
  42
  43 #include <sys/cdefs.h>
  44 __FBSDID("$FreeBSD: src/usr.bin/find/operator.c,v 1.14 2003/06/14 13:00:21 markm Exp $");
  45
  46 #include <sys/types.h>
  47
  48 #include <err.h>
  49 #include <fts.h>
  50 #include <stdio.h>
  51
  52 #include "find.h"
  53
  54 static PLAN *yanknode(PLAN **);
  55 static PLAN *yankexpr(PLAN **);
  56
  57 /*
  58  * yanknode --
  59  *      destructively removes the top from the plan
  60  */
  61 static PLAN *
  62 yanknode(PLAN **planp)
  63 {
  64         PLAN *node;             /* top node removed from the plan */
  65
  66         if ((node = (*planp)) == NULL)
  67                 return (NULL);
  68         (*planp) = (*planp)->next;
  69         node->next = NULL;
  70         return (node);
  71 }
  72
  73 /*
  74  * yankexpr --
  75  *      Removes one expression from the plan.  This is used mainly by
  76  *      paren_squish.  In comments below, an expression is either a
  77  *      simple node or a f_expr node containing a list of simple nodes.
  78  */
  79 static PLAN *
  80 yankexpr(PLAN **planp)
  81 {
  82         PLAN *next;             /* temp node holding subexpression results */
  83         PLAN *node;             /* pointer to returned node or expression */
  84         PLAN *tail;             /* pointer to tail of subplan */
  85         PLAN *subplan;          /* pointer to head of ( ) expression */
  86
  87         /* first pull the top node from the plan */
  88         if ((node = yanknode(planp)) == NULL)
  89                 return (NULL);
  90
  91         /*
  92          * If the node is an '(' then we recursively slurp up expressions
  93          * until we find its associated ')'.  If it's a closing paren we
  94          * just return it and unwind our recursion; all other nodes are
  95          * complete expressions, so just return them.
  96          */
  97         if (node->execute == f_openparen)
  98                 for (tail = subplan = NULL;;) {
  99                         if ((next = yankexpr(planp)) == NULL)
 100                                 errx(1, "(: missing closing ')'");
 101                         /*
 102                          * If we find a closing ')' we store the collected
 103                          * subplan in our '(' node and convert the node to
 104                          * a f_expr.  The ')' we found is ignored.  Otherwise,
 105                          * we just continue to add whatever we get to our
 106                          * subplan.
 107                          */
 108                         if (next->execute == f_closeparen) {
 109                                 if (subplan == NULL)
 110                                         errx(1, "(): empty inner expression");
 111                                 node->p_data[0] = subplan;
 112                                 node->execute = f_expr;
 113                                 break;
 114                         } else {
 115                                 if (subplan == NULL)
 116                                         tail = subplan = next;
 117                                 else {
 118                                         tail->next = next;
 119                                         tail = next;
 120                                 }
 121                                 tail->next = NULL;
 122                         }
 123                 }
 124         return (node);
 125 }
 126
 127 /*
 128  * paren_squish --
 129  *      replaces "parenthesized" plans in our search plan with "expr" nodes.
 130  */
 131 PLAN *
 132 paren_squish(PLAN *plan)
 133 {
 134         PLAN *expr;             /* pointer to next expression */
 135         PLAN *tail;             /* pointer to tail of result plan */
 136         PLAN *result;           /* pointer to head of result plan */
 137
 138         result = tail = NULL;
 139
 140         /*
 141          * the basic idea is to have yankexpr do all our work and just
 142          * collect its results together.
 143          */
 144         while ((expr = yankexpr(&plan)) != NULL) {
 145                 /*
 146                  * if we find an unclaimed ')' it means there is a missing
 147                  * '(' someplace.
 148                  */
 149                 if (expr->execute == f_closeparen)
 150                         errx(1, "): no beginning '('");
 151
 152                 /* add the expression to our result plan */
 153                 if (result == NULL)
 154                         tail = result = expr;
 155                 else {
 156                         tail->next = expr;
 157                         tail = expr;
 158                 }
 159                 tail->next = NULL;
 160         }
 161         return (result);
 162 }
 163
 164 /*
 165  * not_squish --
 166  *      compresses "!" expressions in our search plan.
 167  */
 168 PLAN *
 169 not_squish(PLAN *plan)
 170 {
 171         PLAN *next;             /* next node being processed */
 172         PLAN *node;             /* temporary node used in f_not processing */
 173         PLAN *tail;             /* pointer to tail of result plan */
 174         PLAN *result;           /* pointer to head of result plan */
 175
 176         tail = result = NULL;
 177
 178         while ((next = yanknode(&plan))) {
 179                 /*
 180                  * if we encounter a ( expression ) then look for nots in
 181                  * the expr subplan.
 182                  */
 183                 if (next->execute == f_expr)
 184                         next->p_data[0] = not_squish(next->p_data[0]);
 185
 186                 /*
 187                  * if we encounter a not, then snag the next node and place
 188                  * it in the not's subplan.  As an optimization we compress
 189                  * several not's to zero or one not.
 190                  */
 191                 if (next->execute == f_not) {
 192                         int notlevel = 1;
 193
 194                         node = yanknode(&plan);
 195                         while (node != NULL && node->execute == f_not) {
 196                                 ++notlevel;
 197                                 node = yanknode(&plan);
 198                         }
 199                         if (node == NULL)
 200                                 errx(1, "!: no following expression");
 201                         if (node->execute == f_or)
 202                                 errx(1, "!: nothing between ! and -o");
 203                         /*
 204                          * If we encounter ! ( expr ) then look for nots in
 205                          * the expr subplan.
 206                          */
 207                         if (node->execute == f_expr)
 208                                 node->p_data[0] = not_squish(node->p_data[0]);
 209                         if (notlevel % 2 != 1)
 210                                 next = node;
 211                         else
 212                                 next->p_data[0] = node;
 213                 }
 214
 215                 /* add the node to our result plan */
 216                 if (result == NULL)
 217                         tail = result = next;
 218                 else {
 219                         tail->next = next;
 220                         tail = next;
 221                 }
 222                 tail->next = NULL;
 223         }
 224         return (result);
 225 }
 226
 227 /*
 228  * or_squish --
 229  *      compresses -o expressions in our search plan.
 230  */
 231 PLAN *
 232 or_squish(PLAN *plan)
 233 {
 234         PLAN *next;             /* next node being processed */
 235         PLAN *tail;             /* pointer to tail of result plan */
 236         PLAN *result;           /* pointer to head of result plan */
 237
 238         tail = result = next = NULL;
 239
 240         while ((next = yanknode(&plan)) != NULL) {
 241                 /*
 242                  * if we encounter a ( expression ) then look for or's in
 243                  * the expr subplan.
 244                  */
 245                 if (next->execute == f_expr)
 246                         next->p_data[0] = or_squish(next->p_data[0]);
 247
 248                 /* if we encounter a not then look for or's in the subplan */
 249                 if (next->execute == f_not)
 250                         next->p_data[0] = or_squish(next->p_data[0]);
 251
 252                 /*
 253                  * if we encounter an or, then place our collected plan in the
 254                  * or's first subplan and then recursively collect the
 255                  * remaining stuff into the second subplan and return the or.
 256                  */
 257                 if (next->execute == f_or) {
 258                         if (result == NULL)
 259                                 errx(1, "-o: no expression before -o");
 260                         next->p_data[0] = result;
 261                         next->p_data[1] = or_squish(plan);
 262                         if (next->p_data[1] == NULL)
 263                                 errx(1, "-o: no expression after -o");
 264                         return (next);
 265                 }
 266
 267                 /* add the node to our result plan */
 268                 if (result == NULL)
 269                         tail = result = next;
 270                 else {
 271                         tail->next = next;
 272                         tail = next;
 273                 }
 274                 tail->next = NULL;
 275         }
 276         return (result);
 277 }