| 1 | /*
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| 2 | * The expr and test commands.
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| 3 | *
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| 4 | * Copyright (C) 1989 by Kenneth Almquist. All rights reserved.
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| 5 | * This file is part of ash, which is distributed under the terms specified
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| 6 | * by the Ash General Public License. See the file named LICENSE.
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| 7 | */
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| 8 |
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| 9 |
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| 10 | #define main exprcmd
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| 11 |
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| 12 | #include "bltin.h"
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| 13 | #include "operators.h"
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| 14 | #include <sys/types.h>
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| 15 | #include <sys/stat.h>
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| 16 |
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| 17 | #ifndef S_ISLNK
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| 18 | #define lstat stat
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| 19 | #define S_ISLNK(mode) (0)
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| 20 | #endif
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| 21 |
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| 22 | #define STACKSIZE 12
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| 23 | #define NESTINCR 16
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| 24 |
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| 25 | /* data types */
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| 26 | #define STRING 0
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| 27 | #define INTEGER 1
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| 28 | #define BOOLEAN 2
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| 29 |
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| 30 |
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| 31 | /*
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| 32 | * This structure hold a value. The type keyword specifies the type of
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| 33 | * the value, and the union u holds the value. The value of a boolean
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| 34 | * is stored in u.num (1 = TRUE, 0 = FALSE).
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| 35 | */
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| 36 |
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| 37 | struct value {
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| 38 | int type;
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| 39 | union {
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| 40 | char *string;
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| 41 | long num;
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| 42 | } u;
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| 43 | };
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| 44 |
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| 45 |
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| 46 | struct operator {
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| 47 | short op; /* which operator */
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| 48 | short pri; /* priority of operator */
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| 49 | };
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| 50 |
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| 51 |
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| 52 | struct filestat {
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| 53 | int op; /* OP_FILE or OP_LFILE */
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| 54 | char *name; /* name of file */
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| 55 | int rcode; /* return code from stat */
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| 56 | struct stat stat; /* status info on file */
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| 57 | };
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| 58 |
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| 59 |
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| 60 | extern char *match_begin[10]; /* matched string */
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| 61 | extern short match_length[10]; /* defined in regexp.c */
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| 62 | extern short number_parens; /* number of \( \) pairs */
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| 63 |
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| 64 |
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| 65 | #ifdef __STDC__
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| 66 | int expr_is_false(struct value *);
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| 67 | void expr_operator(int, struct value *, struct filestat *);
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| 68 | int lookup_op(char *, char *const*);
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| 69 | char *re_compile(char *); /* defined in regexp.c */
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| 70 | int re_match(char *, char *); /* defined in regexp.c */
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| 71 | long atol(const char *);
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| 72 | #else
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| 73 | int expr_is_false();
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| 74 | void expr_operator();
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| 75 | int lookup_op();
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| 76 | char *re_compile(); /* defined in regexp.c */
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| 77 | int re_match(); /* defined in regexp.c */
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| 78 | long atol();
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| 79 | #endif
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| 80 |
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| 81 |
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| 82 |
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| 83 | main(argc, argv) char **argv; {
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| 84 | char **ap;
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| 85 | char *opname;
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| 86 | char c;
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| 87 | char *p;
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| 88 | int print;
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| 89 | int nest; /* parenthises nesting */
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| 90 | int op;
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| 91 | int pri;
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| 92 | int skipping;
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| 93 | int binary;
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| 94 | struct operator opstack[STACKSIZE];
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| 95 | struct operator *opsp;
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| 96 | struct value valstack[STACKSIZE + 1];
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| 97 | struct value *valsp;
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| 98 | struct filestat fs;
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| 99 |
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| 100 | INITARGS(argv);
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| 101 | c = **argv;
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| 102 | print = 1;
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| 103 | if (c == 't')
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| 104 | print = 0;
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| 105 | else if (c == '[') {
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| 106 | if (! equal(argv[argc - 1], "]"))
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| 107 | error("missing ]");
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| 108 | argv[argc - 1] = NULL;
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| 109 | print = 0;
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| 110 | }
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| 111 | ap = argv + 1;
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| 112 | fs.name = NULL;
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| 113 |
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| 114 | /*
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| 115 | * We use operator precedence parsing, evaluating the expression
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| 116 | * as we parse it. Parentheses are handled by bumping up the
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| 117 | * priority of operators using the variable "nest." We use the
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| 118 | * variable "skipping" to turn off evaluation temporarily for the
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| 119 | * short circuit boolean operators. (It is important do the short
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| 120 | * circuit evaluation because under NFS a stat operation can take
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| 121 | * infinitely long.)
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| 122 | */
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| 123 |
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| 124 | nest = 0;
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| 125 | skipping = 0;
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| 126 | opsp = opstack + STACKSIZE;
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| 127 | valsp = valstack;
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| 128 | if (*ap == NULL) {
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| 129 | valstack[0].type = BOOLEAN;
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| 130 | valstack[0].u.num = 0;
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| 131 | goto done;
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| 132 | }
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| 133 | for (;;) {
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| 134 | opname = *ap++;
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| 135 | if (opname == NULL)
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| 136 | syntax: error("syntax error");
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| 137 | if (opname[0] == '(' && opname[1] == '\0') {
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| 138 | nest += NESTINCR;
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| 139 | continue;
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| 140 | } else if (*ap && (op = lookup_op(opname, unary_op)) >= 0) {
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| 141 | if (opsp == &opstack[0])
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| 142 | overflow: error("Expression too complex");
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| 143 | --opsp;
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| 144 | opsp->op = op;
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| 145 | opsp->pri = op_priority[op] + nest;
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| 146 | continue;
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| 147 |
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| 148 | } else {
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| 149 | valsp->type = STRING;
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| 150 | valsp->u.string = opname;
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| 151 | valsp++;
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| 152 | }
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| 153 | for (;;) {
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| 154 | opname = *ap++;
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| 155 | if (opname == NULL) {
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| 156 | if (nest != 0)
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| 157 | goto syntax;
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| 158 | pri = 0;
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| 159 | break;
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| 160 | }
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| 161 | if (opname[0] != ')' || opname[1] != '\0') {
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| 162 | if ((op = lookup_op(opname, binary_op)) < 0)
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| 163 | goto syntax;
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| 164 | op += FIRST_BINARY_OP;
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| 165 | pri = op_priority[op] + nest;
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| 166 | break;
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| 167 | }
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| 168 | if ((nest -= NESTINCR) < 0)
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| 169 | goto syntax;
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| 170 | }
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| 171 | while (opsp < &opstack[STACKSIZE] && opsp->pri >= pri) {
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| 172 | binary = opsp->op;
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| 173 | for (;;) {
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| 174 | valsp--;
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| 175 | c = op_argflag[opsp->op];
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| 176 | if (c == OP_INT) {
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| 177 | if (valsp->type == STRING)
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| 178 | valsp->u.num = atol(valsp->u.string);
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| 179 | valsp->type = INTEGER;
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| 180 | } else if (c >= OP_STRING) { /* OP_STRING or OP_FILE */
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| 181 | if (valsp->type == INTEGER) {
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| 182 | p = stalloc(32);
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| 183 | #ifdef SHELL
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| 184 | fmtstr(p, 32, "%d", valsp->u.num);
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| 185 | #else
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| 186 | sprintf(p, "%d", valsp->u.num);
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| 187 | #endif
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| 188 | valsp->u.string = p;
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| 189 | } else if (valsp->type == BOOLEAN) {
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| 190 | if (valsp->u.num)
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| 191 | valsp->u.string = "true";
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| 192 | else
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| 193 | valsp->u.string = "";
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| 194 | }
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| 195 | valsp->type = STRING;
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| 196 | if (c >= OP_FILE
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| 197 | && (fs.op != c
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| 198 | || fs.name == NULL
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| 199 | || ! equal(fs.name, valsp->u.string))) {
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| 200 | fs.op = c;
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| 201 | fs.name = valsp->u.string;
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| 202 | if (c == OP_FILE) {
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| 203 | fs.rcode = stat(valsp->u.string,
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| 204 | &fs.stat);
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| 205 | } else {
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| 206 | fs.rcode = lstat(valsp->u.string,
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| 207 | &fs.stat);
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| 208 | }
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| 209 | }
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| 210 | }
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| 211 | if (binary < FIRST_BINARY_OP)
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| 212 | break;
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| 213 | binary = 0;
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| 214 | }
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| 215 | if (! skipping)
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| 216 | expr_operator(opsp->op, valsp, &fs);
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| 217 | else if (opsp->op == AND1 || opsp->op == OR1)
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| 218 | skipping--;
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| 219 | valsp++; /* push value */
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| 220 | opsp++; /* pop operator */
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| 221 | }
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| 222 | if (opname == NULL)
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| 223 | break;
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| 224 | if (opsp == &opstack[0])
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| 225 | goto overflow;
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| 226 | if (op == AND1 || op == AND2) {
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| 227 | op = AND1;
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| 228 | if (skipping || expr_is_false(valsp - 1))
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| 229 | skipping++;
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| 230 | }
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| 231 | if (op == OR1 || op == OR2) {
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| 232 | op = OR1;
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| 233 | if (skipping || ! expr_is_false(valsp - 1))
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| 234 | skipping++;
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| 235 | }
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| 236 | opsp--;
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| 237 | opsp->op = op;
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| 238 | opsp->pri = pri;
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| 239 | }
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| 240 | done:
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| 241 | if (print) {
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| 242 | if (valstack[0].type == STRING)
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| 243 | printf("%s\n", valstack[0].u.string);
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| 244 | else if (valstack[0].type == INTEGER)
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| 245 | printf("%ld\n", valstack[0].u.num);
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| 246 | else if (valstack[0].u.num != 0)
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| 247 | printf("true\n");
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| 248 | }
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| 249 | return expr_is_false(&valstack[0]);
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| 250 | }
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| 251 |
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| 252 |
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| 253 | int
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| 254 | expr_is_false(val)
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| 255 | struct value *val;
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| 256 | {
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| 257 | if (val->type == STRING) {
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| 258 | if (val->u.string[0] == '\0')
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| 259 | return 1;
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| 260 | } else { /* INTEGER or BOOLEAN */
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| 261 | if (val->u.num == 0)
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| 262 | return 1;
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| 263 | }
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| 264 | return 0;
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| 265 | }
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| 266 |
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| 267 |
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| 268 | /*
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| 269 | * Execute an operator. Op is the operator. Sp is the stack pointer;
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| 270 | * sp[0] refers to the first operand, sp[1] refers to the second operand
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| 271 | * (if any), and the result is placed in sp[0]. The operands are converted
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| 272 | * to the type expected by the operator before expr_operator is called.
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| 273 | * Fs is a pointer to a structure which holds the value of the last call
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| 274 | * to stat, to avoid repeated stat calls on the same file.
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| 275 | */
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| 276 |
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| 277 | void
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| 278 | expr_operator(op, sp, fs)
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| 279 | int op;
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| 280 | struct value *sp;
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| 281 | struct filestat *fs;
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| 282 | {
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| 283 | int i;
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| 284 | struct stat st1, st2;
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| 285 |
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| 286 | switch (op) {
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| 287 | case NOT:
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| 288 | sp->u.num = expr_is_false(sp);
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| 289 | sp->type = BOOLEAN;
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| 290 | break;
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| 291 | case ISREAD:
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| 292 | i = 04;
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| 293 | goto permission;
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| 294 | case ISWRITE:
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| 295 | i = 02;
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| 296 | goto permission;
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| 297 | case ISEXEC:
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| 298 | i = 01;
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| 299 | permission:
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| 300 | if (fs->stat.st_uid == geteuid())
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| 301 | i <<= 6;
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| 302 | else if (fs->stat.st_gid == getegid())
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| 303 | i <<= 3;
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| 304 | goto filebit; /* true if (stat.st_mode & i) != 0 */
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| 305 | case ISFILE:
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| 306 | i = S_IFREG;
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| 307 | goto filetype;
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| 308 | case ISDIR:
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| 309 | i = S_IFDIR;
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| 310 | goto filetype;
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| 311 | case ISCHAR:
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| 312 | i = S_IFCHR;
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| 313 | goto filetype;
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| 314 | case ISBLOCK:
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| 315 | i = S_IFBLK;
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| 316 | goto filetype;
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| 317 | case ISFIFO:
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| 318 | #ifdef S_IFIFO
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| 319 | i = S_IFIFO;
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| 320 | goto filetype;
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| 321 | #else
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| 322 | goto false;
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| 323 | #endif
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| 324 | filetype:
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| 325 | if ((fs->stat.st_mode & S_IFMT) == i && fs->rcode >= 0) {
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| 326 | true:
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| 327 | sp->u.num = 1;
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| 328 | } else {
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| 329 | false:
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| 330 | sp->u.num = 0;
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| 331 | }
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| 332 | sp->type = BOOLEAN;
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| 333 | break;
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| 334 | case ISSETUID:
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| 335 | i = S_ISUID;
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| 336 | goto filebit;
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| 337 | case ISSETGID:
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| 338 | i = S_ISGID;
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| 339 | goto filebit;
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| 340 | case ISSTICKY:
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| 341 | i = S_ISVTX;
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| 342 | filebit:
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| 343 | if (fs->stat.st_mode & i && fs->rcode >= 0)
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| 344 | goto true;
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| 345 | goto false;
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| 346 | case ISSIZE:
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| 347 | sp->u.num = fs->rcode >= 0? fs->stat.st_size : 0L;
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| 348 | sp->type = INTEGER;
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| 349 | break;
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| 350 | case ISLINK1:
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| 351 | case ISLINK2:
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| 352 | if (S_ISLNK(fs->stat.st_mode) && fs->rcode >= 0)
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| 353 | goto true;
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| 354 | fs->op = OP_FILE; /* not a symlink, so expect a -d or so next */
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| 355 | goto false;
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| 356 | case NEWER:
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| 357 | if (stat(sp->u.string, &st1) != 0) {
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| 358 | sp->u.num = 0;
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| 359 | } else if (stat((sp + 1)->u.string, &st2) != 0) {
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| 360 | sp->u.num = 1;
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| 361 | } else {
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| 362 | sp->u.num = st1.st_mtime >= st2.st_mtime;
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| 363 | }
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| 364 | sp->type = INTEGER;
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| 365 | break;
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| 366 | case ISTTY:
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| 367 | sp->u.num = isatty(sp->u.num);
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| 368 | sp->type = BOOLEAN;
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| 369 | break;
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| 370 | case NULSTR:
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| 371 | if (sp->u.string[0] == '\0')
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| 372 | goto true;
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| 373 | goto false;
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| 374 | case STRLEN:
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| 375 | sp->u.num = strlen(sp->u.string);
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| 376 | sp->type = INTEGER;
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| 377 | break;
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| 378 | case OR1:
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| 379 | case AND1:
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| 380 | /*
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| 381 | * These operators are mostly handled by the parser. If we
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| 382 | * get here it means that both operands were evaluated, so
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| 383 | * the value is the value of the second operand.
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| 384 | */
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| 385 | *sp = *(sp + 1);
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| 386 | break;
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| 387 | case STREQ:
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| 388 | case STRNE:
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| 389 | i = 0;
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| 390 | if (equal(sp->u.string, (sp + 1)->u.string))
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| 391 | i++;
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| 392 | if (op == STRNE)
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| 393 | i = 1 - i;
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| 394 | sp->u.num = i;
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| 395 | sp->type = BOOLEAN;
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| 396 | break;
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| 397 | case EQ:
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| 398 | if (sp->u.num == (sp + 1)->u.num)
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| 399 | goto true;
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| 400 | goto false;
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| 401 | case NE:
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| 402 | if (sp->u.num != (sp + 1)->u.num)
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| 403 | goto true;
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| 404 | goto false;
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| 405 | case GT:
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| 406 | if (sp->u.num > (sp + 1)->u.num)
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| 407 | goto true;
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| 408 | goto false;
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| 409 | case LT:
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| 410 | if (sp->u.num < (sp + 1)->u.num)
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| 411 | goto true;
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| 412 | goto false;
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| 413 | case LE:
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| 414 | if (sp->u.num <= (sp + 1)->u.num)
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| 415 | goto true;
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| 416 | goto false;
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| 417 | case GE:
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| 418 | if (sp->u.num >= (sp + 1)->u.num)
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| 419 | goto true;
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| 420 | goto false;
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| 421 | case PLUS:
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| 422 | sp->u.num += (sp + 1)->u.num;
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| 423 | break;
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| 424 | case MINUS:
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| 425 | sp->u.num -= (sp + 1)->u.num;
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| 426 | break;
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| 427 | case TIMES:
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| 428 | sp->u.num *= (sp + 1)->u.num;
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| 429 | break;
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| 430 | case DIVIDE:
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| 431 | if ((sp + 1)->u.num == 0)
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| 432 | error("Division by zero");
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| 433 | sp->u.num /= (sp + 1)->u.num;
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| 434 | break;
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| 435 | case REM:
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| 436 | if ((sp + 1)->u.num == 0)
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| 437 | error("Division by zero");
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|---|
| 438 | sp->u.num %= (sp + 1)->u.num;
|
|---|
| 439 | break;
|
|---|
| 440 | case MATCHPAT:
|
|---|
| 441 | {
|
|---|
| 442 | char *pat;
|
|---|
| 443 |
|
|---|
| 444 | pat = re_compile((sp + 1)->u.string);
|
|---|
| 445 | if (re_match(pat, sp->u.string)) {
|
|---|
| 446 | if (number_parens > 0) {
|
|---|
| 447 | sp->u.string = match_begin[1];
|
|---|
| 448 | sp->u.string[match_length[1]] = '\0';
|
|---|
| 449 | } else {
|
|---|
| 450 | sp->u.num = match_length[0];
|
|---|
| 451 | sp->type = INTEGER;
|
|---|
| 452 | }
|
|---|
| 453 | } else {
|
|---|
| 454 | if (number_parens > 0) {
|
|---|
| 455 | sp->u.string[0] = '\0';
|
|---|
| 456 | } else {
|
|---|
| 457 | sp->u.num = 0;
|
|---|
| 458 | sp->type = INTEGER;
|
|---|
| 459 | }
|
|---|
| 460 | }
|
|---|
| 461 | }
|
|---|
| 462 | break;
|
|---|
| 463 | }
|
|---|
| 464 | }
|
|---|
| 465 |
|
|---|
| 466 |
|
|---|
| 467 | int
|
|---|
| 468 | lookup_op(name, table)
|
|---|
| 469 | char *name;
|
|---|
| 470 | char *const*table;
|
|---|
| 471 | {
|
|---|
| 472 | register char *const*tp;
|
|---|
| 473 | register char const *p;
|
|---|
| 474 | char c = name[1];
|
|---|
| 475 |
|
|---|
| 476 | for (tp = table ; (p = *tp) != NULL ; tp++) {
|
|---|
| 477 | if (p[1] == c && equal(p, name))
|
|---|
| 478 | return tp - table;
|
|---|
| 479 | }
|
|---|
| 480 | return -1;
|
|---|
| 481 | }
|
|---|
