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 | //usage:#define expr_trivial_usage
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29 | //usage: "EXPRESSION"
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30 | //usage:#define expr_full_usage "\n\n"
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31 | //usage: "Print the value of EXPRESSION to stdout\n"
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32 | //usage: "\n"
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33 | //usage: "EXPRESSION may be:\n"
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34 | //usage: " ARG1 | ARG2 ARG1 if it is neither null nor 0, otherwise ARG2\n"
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35 | //usage: " ARG1 & ARG2 ARG1 if neither argument is null or 0, otherwise 0\n"
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36 | //usage: " ARG1 < ARG2 1 if ARG1 is less than ARG2, else 0. Similarly:\n"
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37 | //usage: " ARG1 <= ARG2\n"
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38 | //usage: " ARG1 = ARG2\n"
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39 | //usage: " ARG1 != ARG2\n"
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40 | //usage: " ARG1 >= ARG2\n"
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41 | //usage: " ARG1 > ARG2\n"
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42 | //usage: " ARG1 + ARG2 Sum of ARG1 and ARG2. Similarly:\n"
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43 | //usage: " ARG1 - ARG2\n"
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44 | //usage: " ARG1 * ARG2\n"
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45 | //usage: " ARG1 / ARG2\n"
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46 | //usage: " ARG1 % ARG2\n"
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47 | //usage: " STRING : REGEXP Anchored pattern match of REGEXP in STRING\n"
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48 | //usage: " match STRING REGEXP Same as STRING : REGEXP\n"
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49 | //usage: " substr STRING POS LENGTH Substring of STRING, POS counted from 1\n"
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50 | //usage: " index STRING CHARS Index in STRING where any CHARS is found, or 0\n"
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51 | //usage: " length STRING Length of STRING\n"
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52 | //usage: " quote TOKEN Interpret TOKEN as a string, even if\n"
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53 | //usage: " it is a keyword like 'match' or an\n"
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54 | //usage: " operator like '/'\n"
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55 | //usage: " (EXPRESSION) Value of EXPRESSION\n"
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56 | //usage: "\n"
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57 | //usage: "Beware that many operators need to be escaped or quoted for shells.\n"
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58 | //usage: "Comparisons are arithmetic if both ARGs are numbers, else\n"
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59 | //usage: "lexicographical. Pattern matches return the string matched between\n"
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60 | //usage: "\\( and \\) or null; if \\( and \\) are not used, they return the number\n"
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61 | //usage: "of characters matched or 0."
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62 |
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63 | #include "libbb.h"
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64 | #include "xregex.h"
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65 |
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66 | #if ENABLE_EXPR_MATH_SUPPORT_64
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67 | typedef int64_t arith_t;
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68 |
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69 | #define PF_REZ "ll"
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70 | #define PF_REZ_TYPE (long long)
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71 | #define STRTOL(s, e, b) strtoll(s, e, b)
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72 | #else
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73 | typedef long arith_t;
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74 |
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75 | #define PF_REZ "l"
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76 | #define PF_REZ_TYPE (long)
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77 | #define STRTOL(s, e, b) strtol(s, e, b)
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78 | #endif
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79 |
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80 | /* TODO: use bb_strtol[l]? It's easier to check for errors... */
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81 |
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82 | /* The kinds of value we can have. */
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83 | enum {
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84 | INTEGER,
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85 | STRING
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86 | };
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87 |
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88 | /* A value is.... */
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89 | struct valinfo {
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90 | smallint type; /* Which kind. */
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91 | union { /* The value itself. */
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92 | arith_t i;
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93 | char *s;
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94 | } u;
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95 | };
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96 | typedef struct valinfo VALUE;
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97 |
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98 | /* The arguments given to the program, minus the program name. */
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99 | struct globals {
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100 | char **args;
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101 | } FIX_ALIASING;
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102 | #define G (*(struct globals*)&bb_common_bufsiz1)
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103 | #define INIT_G() do { } while (0)
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104 |
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105 | /* forward declarations */
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106 | static VALUE *eval(void);
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107 |
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108 |
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109 | /* Return a VALUE for I. */
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110 |
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111 | static VALUE *int_value(arith_t i)
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112 | {
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113 | VALUE *v;
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114 |
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115 | v = xzalloc(sizeof(VALUE));
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116 | if (INTEGER) /* otherwise xzaaloc did it already */
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117 | v->type = INTEGER;
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118 | v->u.i = i;
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119 | return v;
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120 | }
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121 |
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122 | /* Return a VALUE for S. */
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123 |
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124 | static VALUE *str_value(const char *s)
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125 | {
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126 | VALUE *v;
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127 |
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128 | v = xzalloc(sizeof(VALUE));
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129 | if (STRING) /* otherwise xzaaloc did it already */
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130 | v->type = STRING;
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131 | v->u.s = xstrdup(s);
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132 | return v;
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133 | }
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134 |
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135 | /* Free VALUE V, including structure components. */
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136 |
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137 | static void freev(VALUE *v)
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138 | {
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139 | if (v->type == STRING)
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140 | free(v->u.s);
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141 | free(v);
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142 | }
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143 |
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144 | /* Return nonzero if V is a null-string or zero-number. */
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145 |
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146 | static int null(VALUE *v)
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147 | {
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148 | if (v->type == INTEGER)
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149 | return v->u.i == 0;
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150 | /* STRING: */
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151 | return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
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152 | }
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153 |
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154 | /* Coerce V to a STRING value (can't fail). */
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155 |
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156 | static void tostring(VALUE *v)
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157 | {
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158 | if (v->type == INTEGER) {
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159 | v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
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160 | v->type = STRING;
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161 | }
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162 | }
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163 |
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164 | /* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
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165 |
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166 | static bool toarith(VALUE *v)
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167 | {
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168 | if (v->type == STRING) {
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169 | arith_t i;
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170 | char *e;
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171 |
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172 | /* Don't interpret the empty string as an integer. */
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173 | /* Currently does not worry about overflow or int/long differences. */
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174 | i = STRTOL(v->u.s, &e, 10);
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175 | if ((v->u.s == e) || *e)
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176 | return 0;
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177 | free(v->u.s);
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178 | v->u.i = i;
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179 | v->type = INTEGER;
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180 | }
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181 | return 1;
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182 | }
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183 |
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184 | /* Return str[0]+str[1] if the next token matches STR exactly.
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185 | STR must not be NULL. */
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186 |
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187 | static int nextarg(const char *str)
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188 | {
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189 | if (*G.args == NULL || strcmp(*G.args, str) != 0)
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190 | return 0;
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191 | return (unsigned char)str[0] + (unsigned char)str[1];
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192 | }
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193 |
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194 | /* The comparison operator handling functions. */
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195 |
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196 | static int cmp_common(VALUE *l, VALUE *r, int op)
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197 | {
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198 | arith_t ll, rr;
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199 |
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200 | ll = l->u.i;
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201 | rr = r->u.i;
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202 | if (l->type == STRING || r->type == STRING) {
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203 | tostring(l);
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204 | tostring(r);
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205 | ll = strcmp(l->u.s, r->u.s);
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206 | rr = 0;
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207 | }
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208 | /* calculating ll - rr and checking the result is prone to overflows.
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209 | * We'll do it differently: */
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210 | if (op == '<')
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211 | return ll < rr;
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212 | if (op == ('<' + '='))
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213 | return ll <= rr;
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214 | if (op == '=' || (op == '=' + '='))
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215 | return ll == rr;
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216 | if (op == '!' + '=')
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217 | return ll != rr;
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218 | if (op == '>')
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219 | return ll > rr;
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220 | /* >= */
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221 | return ll >= rr;
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222 | }
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223 |
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224 | /* The arithmetic operator handling functions. */
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225 |
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226 | static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
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227 | {
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228 | arith_t li, ri;
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229 |
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230 | if (!toarith(l) || !toarith(r))
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231 | bb_error_msg_and_die("non-numeric argument");
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232 | li = l->u.i;
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233 | ri = r->u.i;
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234 | if (op == '+')
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235 | return li + ri;
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236 | if (op == '-')
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237 | return li - ri;
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238 | if (op == '*')
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239 | return li * ri;
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240 | if (ri == 0)
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241 | bb_error_msg_and_die("division by zero");
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242 | if (op == '/')
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243 | return li / ri;
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244 | return li % ri;
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245 | }
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246 |
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247 | /* Do the : operator.
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248 | SV is the VALUE for the lhs (the string),
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249 | PV is the VALUE for the rhs (the pattern). */
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250 |
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251 | static VALUE *docolon(VALUE *sv, VALUE *pv)
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252 | {
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253 | enum { NMATCH = 2 };
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254 | VALUE *v;
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255 | regex_t re_buffer;
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256 | regmatch_t re_regs[NMATCH];
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257 |
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258 | tostring(sv);
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259 | tostring(pv);
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260 |
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261 | if (pv->u.s[0] == '^') {
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262 | bb_error_msg(
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263 | "warning: '%s': using '^' as the first character\n"
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264 | "of a basic regular expression is not portable; it is ignored", pv->u.s);
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265 | }
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266 |
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267 | memset(&re_buffer, 0, sizeof(re_buffer));
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268 | memset(re_regs, 0, sizeof(re_regs));
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269 | xregcomp(&re_buffer, pv->u.s, 0);
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270 |
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271 | /* expr uses an anchored pattern match, so check that there was a
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272 | * match and that the match starts at offset 0. */
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273 | if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
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274 | && re_regs[0].rm_so == 0
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275 | ) {
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276 | /* Were \(...\) used? */
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277 | if (re_buffer.re_nsub > 0 && re_regs[1].rm_so >= 0) {
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278 | sv->u.s[re_regs[1].rm_eo] = '\0';
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279 | v = str_value(sv->u.s + re_regs[1].rm_so);
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280 | } else {
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281 | v = int_value(re_regs[0].rm_eo);
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282 | }
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283 | } else {
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284 | /* Match failed -- return the right kind of null. */
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285 | if (re_buffer.re_nsub > 0)
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286 | v = str_value("");
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287 | else
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288 | v = int_value(0);
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289 | }
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290 | regfree(&re_buffer);
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291 | return v;
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292 | }
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293 |
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294 | /* Handle bare operands and ( expr ) syntax. */
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295 |
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296 | static VALUE *eval7(void)
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297 | {
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298 | VALUE *v;
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299 |
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300 | if (!*G.args)
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301 | bb_error_msg_and_die("syntax error");
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302 |
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303 | if (nextarg("(")) {
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304 | G.args++;
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305 | v = eval();
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306 | if (!nextarg(")"))
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307 | bb_error_msg_and_die("syntax error");
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308 | G.args++;
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309 | return v;
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310 | }
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311 |
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312 | if (nextarg(")"))
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313 | bb_error_msg_and_die("syntax error");
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314 |
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315 | return str_value(*G.args++);
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316 | }
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317 |
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318 | /* Handle match, substr, index, length, and quote keywords. */
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319 |
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320 | static VALUE *eval6(void)
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321 | {
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322 | static const char keywords[] ALIGN1 =
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323 | "quote\0""length\0""match\0""index\0""substr\0";
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324 |
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325 | VALUE *r, *i1, *i2;
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326 | VALUE *l = l; /* silence gcc */
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327 | VALUE *v = v; /* silence gcc */
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328 | int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
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329 |
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330 | if (key == 0) /* not a keyword */
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331 | return eval7();
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332 | G.args++; /* We have a valid token, so get the next argument. */
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333 | if (key == 1) { /* quote */
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334 | if (!*G.args)
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335 | bb_error_msg_and_die("syntax error");
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336 | return str_value(*G.args++);
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337 | }
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338 | if (key == 2) { /* length */
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339 | r = eval6();
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340 | tostring(r);
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341 | v = int_value(strlen(r->u.s));
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342 | freev(r);
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343 | } else
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344 | l = eval6();
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345 |
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346 | if (key == 3) { /* match */
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347 | r = eval6();
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348 | v = docolon(l, r);
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349 | freev(l);
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350 | freev(r);
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351 | }
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352 | if (key == 4) { /* index */
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353 | r = eval6();
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354 | tostring(l);
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355 | tostring(r);
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356 | v = int_value(strcspn(l->u.s, r->u.s) + 1);
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357 | if (v->u.i == (arith_t) strlen(l->u.s) + 1)
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358 | v->u.i = 0;
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359 | freev(l);
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360 | freev(r);
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361 | }
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362 | if (key == 5) { /* substr */
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363 | i1 = eval6();
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364 | i2 = eval6();
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365 | tostring(l);
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366 | if (!toarith(i1) || !toarith(i2)
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367 | || i1->u.i > (arith_t) strlen(l->u.s)
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368 | || i1->u.i <= 0 || i2->u.i <= 0)
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369 | v = str_value("");
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370 | else {
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371 | v = xmalloc(sizeof(VALUE));
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372 | v->type = STRING;
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373 | v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
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374 | }
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375 | freev(l);
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376 | freev(i1);
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377 | freev(i2);
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378 | }
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379 | return v;
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380 | }
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381 |
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382 | /* Handle : operator (pattern matching).
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383 | Calls docolon to do the real work. */
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384 |
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385 | static VALUE *eval5(void)
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386 | {
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387 | VALUE *l, *r, *v;
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388 |
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389 | l = eval6();
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390 | while (nextarg(":")) {
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391 | G.args++;
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392 | r = eval6();
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393 | v = docolon(l, r);
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394 | freev(l);
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395 | freev(r);
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396 | l = v;
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397 | }
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398 | return l;
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399 | }
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400 |
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401 | /* Handle *, /, % operators. */
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402 |
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403 | static VALUE *eval4(void)
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404 | {
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405 | VALUE *l, *r;
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406 | int op;
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407 | arith_t val;
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408 |
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409 | l = eval5();
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410 | while (1) {
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411 | op = nextarg("*");
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412 | if (!op) { op = nextarg("/");
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413 | if (!op) { op = nextarg("%");
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414 | if (!op) return l;
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415 | }}
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416 | G.args++;
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417 | r = eval5();
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418 | val = arithmetic_common(l, r, op);
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419 | freev(l);
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420 | freev(r);
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421 | l = int_value(val);
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422 | }
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423 | }
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424 |
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425 | /* Handle +, - operators. */
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426 |
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427 | static VALUE *eval3(void)
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428 | {
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429 | VALUE *l, *r;
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430 | int op;
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431 | arith_t val;
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432 |
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433 | l = eval4();
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434 | while (1) {
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435 | op = nextarg("+");
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436 | if (!op) {
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437 | op = nextarg("-");
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438 | if (!op) return l;
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439 | }
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440 | G.args++;
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441 | r = eval4();
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442 | val = arithmetic_common(l, r, op);
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443 | freev(l);
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444 | freev(r);
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445 | l = int_value(val);
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446 | }
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447 | }
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448 |
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449 | /* Handle comparisons. */
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450 |
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451 | static VALUE *eval2(void)
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452 | {
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453 | VALUE *l, *r;
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454 | int op;
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455 | arith_t val;
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456 |
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457 | l = eval3();
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458 | while (1) {
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459 | op = nextarg("<");
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460 | if (!op) { op = nextarg("<=");
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461 | if (!op) { op = nextarg("=");
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462 | if (!op) { op = nextarg("==");
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463 | if (!op) { op = nextarg("!=");
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464 | if (!op) { op = nextarg(">=");
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465 | if (!op) { op = nextarg(">");
|
---|
466 | if (!op) return l;
|
---|
467 | }}}}}}
|
---|
468 | G.args++;
|
---|
469 | r = eval3();
|
---|
470 | toarith(l);
|
---|
471 | toarith(r);
|
---|
472 | val = cmp_common(l, r, op);
|
---|
473 | freev(l);
|
---|
474 | freev(r);
|
---|
475 | l = int_value(val);
|
---|
476 | }
|
---|
477 | }
|
---|
478 |
|
---|
479 | /* Handle &. */
|
---|
480 |
|
---|
481 | static VALUE *eval1(void)
|
---|
482 | {
|
---|
483 | VALUE *l, *r;
|
---|
484 |
|
---|
485 | l = eval2();
|
---|
486 | while (nextarg("&")) {
|
---|
487 | G.args++;
|
---|
488 | r = eval2();
|
---|
489 | if (null(l) || null(r)) {
|
---|
490 | freev(l);
|
---|
491 | freev(r);
|
---|
492 | l = int_value(0);
|
---|
493 | } else
|
---|
494 | freev(r);
|
---|
495 | }
|
---|
496 | return l;
|
---|
497 | }
|
---|
498 |
|
---|
499 | /* Handle |. */
|
---|
500 |
|
---|
501 | static VALUE *eval(void)
|
---|
502 | {
|
---|
503 | VALUE *l, *r;
|
---|
504 |
|
---|
505 | l = eval1();
|
---|
506 | while (nextarg("|")) {
|
---|
507 | G.args++;
|
---|
508 | r = eval1();
|
---|
509 | if (null(l)) {
|
---|
510 | freev(l);
|
---|
511 | l = r;
|
---|
512 | } else
|
---|
513 | freev(r);
|
---|
514 | }
|
---|
515 | return l;
|
---|
516 | }
|
---|
517 |
|
---|
518 | int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
519 | int expr_main(int argc UNUSED_PARAM, char **argv)
|
---|
520 | {
|
---|
521 | VALUE *v;
|
---|
522 |
|
---|
523 | INIT_G();
|
---|
524 |
|
---|
525 | xfunc_error_retval = 2; /* coreutils compat */
|
---|
526 | G.args = argv + 1;
|
---|
527 | if (*G.args == NULL) {
|
---|
528 | bb_error_msg_and_die("too few arguments");
|
---|
529 | }
|
---|
530 | v = eval();
|
---|
531 | if (*G.args)
|
---|
532 | bb_error_msg_and_die("syntax error");
|
---|
533 | if (v->type == INTEGER)
|
---|
534 | printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
|
---|
535 | else
|
---|
536 | puts(v->u.s);
|
---|
537 | fflush_stdout_and_exit(null(v));
|
---|
538 | }
|
---|