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