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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