[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini expr implementation for busybox
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| 4 | *
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| 5 | * based on GNU expr Mike Parker.
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| 6 | * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
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| 7 | *
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| 8 | * Busybox modifications
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| 9 | * Copyright (c) 2000 Edward Betts <edward@debian.org>.
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| 10 | * Copyright (C) 2003-2005 Vladimir Oleynik <dzo@simtreas.ru>
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| 11 | * - reduced 464 bytes.
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| 12 | * - 64 math support
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| 13 | *
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| 14 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 15 | */
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| 16 |
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| 17 | /* This program evaluates expressions. Each token (operator, operand,
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| 18 | * parenthesis) of the expression must be a separate argument. The
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| 19 | * parser used is a reasonably general one, though any incarnation of
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| 20 | * it is language-specific. It is especially nice for expressions.
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| 21 | *
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| 22 | * No parse tree is needed; a new node is evaluated immediately.
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| 23 | * One function can handle multiple operators all of equal precedence,
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| 24 | * provided they all associate ((x op x) op x). */
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| 25 |
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| 26 | /* no getopt needed */
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| 27 |
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| 28 | #include "libbb.h"
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| 29 | #include "xregex.h"
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| 30 |
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| 31 | #if ENABLE_EXPR_MATH_SUPPORT_64
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| 32 | typedef int64_t arith_t;
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| 33 |
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| 34 | #define PF_REZ "ll"
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| 35 | #define PF_REZ_TYPE (long long)
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| 36 | #define STRTOL(s, e, b) strtoll(s, e, b)
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| 37 | #else
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| 38 | typedef long arith_t;
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| 39 |
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| 40 | #define PF_REZ "l"
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| 41 | #define PF_REZ_TYPE (long)
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| 42 | #define STRTOL(s, e, b) strtol(s, e, b)
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| 43 | #endif
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| 44 |
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| 45 | /* TODO: use bb_strtol[l]? It's easier to check for errors... */
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| 46 |
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| 47 | /* The kinds of value we can have. */
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| 48 | enum {
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| 49 | INTEGER,
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| 50 | STRING
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| 51 | };
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| 52 |
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| 53 | /* A value is.... */
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| 54 | struct valinfo {
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| 55 | smallint type; /* Which kind. */
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| 56 | union { /* The value itself. */
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| 57 | arith_t i;
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| 58 | char *s;
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| 59 | } u;
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| 60 | };
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| 61 | typedef struct valinfo VALUE;
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| 62 |
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| 63 | /* The arguments given to the program, minus the program name. */
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| 64 | struct globals {
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| 65 | char **args;
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| 66 | } FIX_ALIASING;
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| 67 | #define G (*(struct globals*)&bb_common_bufsiz1)
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| 68 |
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| 69 | /* forward declarations */
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| 70 | static VALUE *eval(void);
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| 71 |
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| 72 |
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| 73 | /* Return a VALUE for I. */
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| 74 |
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| 75 | static VALUE *int_value(arith_t i)
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| 76 | {
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| 77 | VALUE *v;
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| 78 |
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| 79 | v = xzalloc(sizeof(VALUE));
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| 80 | if (INTEGER) /* otherwise xzaaloc did it already */
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| 81 | v->type = INTEGER;
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| 82 | v->u.i = i;
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| 83 | return v;
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| 84 | }
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| 85 |
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| 86 | /* Return a VALUE for S. */
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| 87 |
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| 88 | static VALUE *str_value(const char *s)
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| 89 | {
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| 90 | VALUE *v;
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| 91 |
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| 92 | v = xzalloc(sizeof(VALUE));
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| 93 | if (STRING) /* otherwise xzaaloc did it already */
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| 94 | v->type = STRING;
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| 95 | v->u.s = xstrdup(s);
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| 96 | return v;
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| 97 | }
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| 98 |
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| 99 | /* Free VALUE V, including structure components. */
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| 100 |
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| 101 | static void freev(VALUE *v)
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| 102 | {
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| 103 | if (v->type == STRING)
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| 104 | free(v->u.s);
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| 105 | free(v);
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| 106 | }
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| 107 |
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| 108 | /* Return nonzero if V is a null-string or zero-number. */
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| 109 |
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| 110 | static int null(VALUE *v)
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| 111 | {
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| 112 | if (v->type == INTEGER)
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| 113 | return v->u.i == 0;
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| 114 | /* STRING: */
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| 115 | return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
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| 116 | }
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| 117 |
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| 118 | /* Coerce V to a STRING value (can't fail). */
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| 119 |
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| 120 | static void tostring(VALUE *v)
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| 121 | {
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| 122 | if (v->type == INTEGER) {
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| 123 | v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
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| 124 | v->type = STRING;
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| 125 | }
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| 126 | }
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| 127 |
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| 128 | /* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
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| 129 |
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| 130 | static bool toarith(VALUE *v)
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| 131 | {
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| 132 | if (v->type == STRING) {
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| 133 | arith_t i;
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| 134 | char *e;
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| 135 |
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| 136 | /* Don't interpret the empty string as an integer. */
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| 137 | /* Currently does not worry about overflow or int/long differences. */
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| 138 | i = STRTOL(v->u.s, &e, 10);
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| 139 | if ((v->u.s == e) || *e)
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| 140 | return 0;
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| 141 | free(v->u.s);
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| 142 | v->u.i = i;
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| 143 | v->type = INTEGER;
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| 144 | }
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| 145 | return 1;
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| 146 | }
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| 147 |
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| 148 | /* Return str[0]+str[1] if the next token matches STR exactly.
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| 149 | STR must not be NULL. */
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| 150 |
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| 151 | static int nextarg(const char *str)
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| 152 | {
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| 153 | if (*G.args == NULL || strcmp(*G.args, str) != 0)
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| 154 | return 0;
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| 155 | return (unsigned char)str[0] + (unsigned char)str[1];
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| 156 | }
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| 157 |
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| 158 | /* The comparison operator handling functions. */
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| 159 |
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| 160 | static int cmp_common(VALUE *l, VALUE *r, int op)
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| 161 | {
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| 162 | arith_t ll, rr;
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| 163 |
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| 164 | ll = l->u.i;
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| 165 | rr = r->u.i;
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| 166 | if (l->type == STRING || r->type == STRING) {
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| 167 | tostring(l);
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| 168 | tostring(r);
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| 169 | ll = strcmp(l->u.s, r->u.s);
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| 170 | rr = 0;
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| 171 | }
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| 172 | /* calculating ll - rr and checking the result is prone to overflows.
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| 173 | * We'll do it differently: */
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| 174 | if (op == '<')
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| 175 | return ll < rr;
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| 176 | if (op == ('<' + '='))
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| 177 | return ll <= rr;
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| 178 | if (op == '=' || (op == '=' + '='))
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| 179 | return ll == rr;
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| 180 | if (op == '!' + '=')
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| 181 | return ll != rr;
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| 182 | if (op == '>')
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| 183 | return ll > rr;
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| 184 | /* >= */
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| 185 | return ll >= rr;
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| 186 | }
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| 187 |
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| 188 | /* The arithmetic operator handling functions. */
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| 189 |
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| 190 | static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
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| 191 | {
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| 192 | arith_t li, ri;
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| 193 |
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| 194 | if (!toarith(l) || !toarith(r))
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| 195 | bb_error_msg_and_die("non-numeric argument");
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| 196 | li = l->u.i;
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| 197 | ri = r->u.i;
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| 198 | if (op == '+')
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| 199 | return li + ri;
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| 200 | if (op == '-')
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| 201 | return li - ri;
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| 202 | if (op == '*')
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| 203 | return li * ri;
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| 204 | if (ri == 0)
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| 205 | bb_error_msg_and_die("division by zero");
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| 206 | if (op == '/')
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| 207 | return li / ri;
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| 208 | return li % ri;
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| 209 | }
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| 210 |
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| 211 | /* Do the : operator.
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| 212 | SV is the VALUE for the lhs (the string),
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| 213 | PV is the VALUE for the rhs (the pattern). */
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| 214 |
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| 215 | static VALUE *docolon(VALUE *sv, VALUE *pv)
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| 216 | {
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| 217 | enum { NMATCH = 2 };
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| 218 | VALUE *v;
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| 219 | regex_t re_buffer;
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| 220 | regmatch_t re_regs[NMATCH];
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| 221 |
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| 222 | tostring(sv);
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| 223 | tostring(pv);
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| 224 |
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| 225 | if (pv->u.s[0] == '^') {
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| 226 | bb_error_msg(
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| 227 | "warning: '%s': using '^' as the first character\n"
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| 228 | "of a basic regular expression is not portable; it is ignored", pv->u.s);
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| 229 | }
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| 230 |
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| 231 | memset(&re_buffer, 0, sizeof(re_buffer));
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| 232 | memset(re_regs, 0, sizeof(re_regs));
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| 233 | xregcomp(&re_buffer, pv->u.s, 0);
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| 234 |
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| 235 | /* expr uses an anchored pattern match, so check that there was a
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| 236 | * match and that the match starts at offset 0. */
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| 237 | if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
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| 238 | && re_regs[0].rm_so == 0
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| 239 | ) {
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| 240 | /* Were \(...\) used? */
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| 241 | if (re_buffer.re_nsub > 0 && re_regs[1].rm_so >= 0) {
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| 242 | sv->u.s[re_regs[1].rm_eo] = '\0';
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| 243 | v = str_value(sv->u.s + re_regs[1].rm_so);
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| 244 | } else {
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| 245 | v = int_value(re_regs[0].rm_eo);
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| 246 | }
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| 247 | } else {
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| 248 | /* Match failed -- return the right kind of null. */
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| 249 | if (re_buffer.re_nsub > 0)
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| 250 | v = str_value("");
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| 251 | else
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| 252 | v = int_value(0);
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| 253 | }
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| 254 | regfree(&re_buffer);
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| 255 | return v;
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| 256 | }
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| 257 |
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| 258 | /* Handle bare operands and ( expr ) syntax. */
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| 259 |
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| 260 | static VALUE *eval7(void)
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| 261 | {
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| 262 | VALUE *v;
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| 263 |
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| 264 | if (!*G.args)
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| 265 | bb_error_msg_and_die("syntax error");
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| 266 |
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| 267 | if (nextarg("(")) {
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| 268 | G.args++;
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| 269 | v = eval();
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| 270 | if (!nextarg(")"))
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| 271 | bb_error_msg_and_die("syntax error");
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| 272 | G.args++;
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| 273 | return v;
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| 274 | }
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| 275 |
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| 276 | if (nextarg(")"))
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| 277 | bb_error_msg_and_die("syntax error");
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| 278 |
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| 279 | return str_value(*G.args++);
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| 280 | }
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| 281 |
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| 282 | /* Handle match, substr, index, length, and quote keywords. */
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| 283 |
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| 284 | static VALUE *eval6(void)
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| 285 | {
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| 286 | static const char keywords[] ALIGN1 =
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| 287 | "quote\0""length\0""match\0""index\0""substr\0";
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| 288 |
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| 289 | VALUE *r, *i1, *i2;
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| 290 | VALUE *l = l; /* silence gcc */
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| 291 | VALUE *v = v; /* silence gcc */
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| 292 | int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
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| 293 |
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| 294 | if (key == 0) /* not a keyword */
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| 295 | return eval7();
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| 296 | G.args++; /* We have a valid token, so get the next argument. */
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| 297 | if (key == 1) { /* quote */
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| 298 | if (!*G.args)
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| 299 | bb_error_msg_and_die("syntax error");
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| 300 | return str_value(*G.args++);
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| 301 | }
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| 302 | if (key == 2) { /* length */
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| 303 | r = eval6();
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| 304 | tostring(r);
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| 305 | v = int_value(strlen(r->u.s));
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| 306 | freev(r);
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| 307 | } else
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| 308 | l = eval6();
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| 309 |
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| 310 | if (key == 3) { /* match */
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| 311 | r = eval6();
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| 312 | v = docolon(l, r);
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| 313 | freev(l);
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| 314 | freev(r);
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| 315 | }
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| 316 | if (key == 4) { /* index */
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| 317 | r = eval6();
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| 318 | tostring(l);
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| 319 | tostring(r);
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| 320 | v = int_value(strcspn(l->u.s, r->u.s) + 1);
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| 321 | if (v->u.i == (arith_t) strlen(l->u.s) + 1)
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| 322 | v->u.i = 0;
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| 323 | freev(l);
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| 324 | freev(r);
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| 325 | }
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| 326 | if (key == 5) { /* substr */
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| 327 | i1 = eval6();
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| 328 | i2 = eval6();
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| 329 | tostring(l);
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| 330 | if (!toarith(i1) || !toarith(i2)
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| 331 | || i1->u.i > (arith_t) strlen(l->u.s)
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| 332 | || i1->u.i <= 0 || i2->u.i <= 0)
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| 333 | v = str_value("");
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| 334 | else {
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| 335 | v = xmalloc(sizeof(VALUE));
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| 336 | v->type = STRING;
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| 337 | v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
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| 338 | }
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| 339 | freev(l);
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| 340 | freev(i1);
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| 341 | freev(i2);
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| 342 | }
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| 343 | return v;
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| 344 | }
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| 345 |
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| 346 | /* Handle : operator (pattern matching).
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| 347 | Calls docolon to do the real work. */
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| 348 |
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| 349 | static VALUE *eval5(void)
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| 350 | {
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| 351 | VALUE *l, *r, *v;
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| 352 |
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| 353 | l = eval6();
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| 354 | while (nextarg(":")) {
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| 355 | G.args++;
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| 356 | r = eval6();
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| 357 | v = docolon(l, r);
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| 358 | freev(l);
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| 359 | freev(r);
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| 360 | l = v;
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| 361 | }
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| 362 | return l;
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| 363 | }
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| 364 |
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| 365 | /* Handle *, /, % operators. */
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| 366 |
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| 367 | static VALUE *eval4(void)
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| 368 | {
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| 369 | VALUE *l, *r;
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| 370 | int op;
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| 371 | arith_t val;
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| 372 |
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| 373 | l = eval5();
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| 374 | while (1) {
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| 375 | op = nextarg("*");
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| 376 | if (!op) { op = nextarg("/");
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| 377 | if (!op) { op = nextarg("%");
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| 378 | if (!op) return l;
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| 379 | }}
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| 380 | G.args++;
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| 381 | r = eval5();
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| 382 | val = arithmetic_common(l, r, op);
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| 383 | freev(l);
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| 384 | freev(r);
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| 385 | l = int_value(val);
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| 386 | }
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| 387 | }
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| 388 |
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| 389 | /* Handle +, - operators. */
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| 390 |
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| 391 | static VALUE *eval3(void)
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| 392 | {
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| 393 | VALUE *l, *r;
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| 394 | int op;
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| 395 | arith_t val;
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| 396 |
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| 397 | l = eval4();
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| 398 | while (1) {
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| 399 | op = nextarg("+");
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| 400 | if (!op) {
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| 401 | op = nextarg("-");
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| 402 | if (!op) return l;
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| 403 | }
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| 404 | G.args++;
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| 405 | r = eval4();
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| 406 | val = arithmetic_common(l, r, op);
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| 407 | freev(l);
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| 408 | freev(r);
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| 409 | l = int_value(val);
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| 410 | }
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| 411 | }
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| 412 |
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| 413 | /* Handle comparisons. */
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| 414 |
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| 415 | static VALUE *eval2(void)
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| 416 | {
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| 417 | VALUE *l, *r;
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| 418 | int op;
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| 419 | arith_t val;
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| 420 |
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| 421 | l = eval3();
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| 422 | while (1) {
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| 423 | op = nextarg("<");
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| 424 | if (!op) { op = nextarg("<=");
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| 425 | if (!op) { op = nextarg("=");
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| 426 | if (!op) { op = nextarg("==");
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| 427 | if (!op) { op = nextarg("!=");
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| 428 | if (!op) { op = nextarg(">=");
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| 429 | if (!op) { op = nextarg(">");
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| 430 | if (!op) return l;
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| 431 | }}}}}}
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| 432 | G.args++;
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| 433 | r = eval3();
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| 434 | toarith(l);
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| 435 | toarith(r);
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| 436 | val = cmp_common(l, r, op);
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| 437 | freev(l);
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| 438 | freev(r);
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| 439 | l = int_value(val);
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| 440 | }
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| 441 | }
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| 442 |
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| 443 | /* Handle &. */
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| 444 |
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| 445 | static VALUE *eval1(void)
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| 446 | {
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| 447 | VALUE *l, *r;
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| 448 |
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| 449 | l = eval2();
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| 450 | while (nextarg("&")) {
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| 451 | G.args++;
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| 452 | r = eval2();
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| 453 | if (null(l) || null(r)) {
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| 454 | freev(l);
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| 455 | freev(r);
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| 456 | l = int_value(0);
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| 457 | } else
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| 458 | freev(r);
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| 459 | }
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| 460 | return l;
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| 461 | }
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| 462 |
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| 463 | /* Handle |. */
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| 464 |
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| 465 | static VALUE *eval(void)
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| 466 | {
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| 467 | VALUE *l, *r;
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| 468 |
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| 469 | l = eval1();
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| 470 | while (nextarg("|")) {
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| 471 | G.args++;
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| 472 | r = eval1();
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| 473 | if (null(l)) {
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| 474 | freev(l);
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| 475 | l = r;
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| 476 | } else
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| 477 | freev(r);
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| 478 | }
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| 479 | return l;
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| 480 | }
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| 481 |
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| 482 | int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 483 | int expr_main(int argc UNUSED_PARAM, char **argv)
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| 484 | {
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| 485 | VALUE *v;
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| 486 |
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| 487 | xfunc_error_retval = 2; /* coreutils compat */
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| 488 | G.args = argv + 1;
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| 489 | if (*G.args == NULL) {
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| 490 | bb_error_msg_and_die("too few arguments");
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| 491 | }
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| 492 | v = eval();
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| 493 | if (*G.args)
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| 494 | bb_error_msg_and_die("syntax error");
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| 495 | if (v->type == INTEGER)
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| 496 | printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
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| 497 | else
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| 498 | puts(v->u.s);
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| 499 | fflush_stdout_and_exit(null(v));
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| 500 | }
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