1 | /*
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2 | * Arithmetic code ripped out of ash shell for code sharing.
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3 | *
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4 | * This code is derived from software contributed to Berkeley by
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5 | * Kenneth Almquist.
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6 | *
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7 | * Original BSD copyright notice is retained at the end of this file.
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8 | *
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9 | * Copyright (c) 1989, 1991, 1993, 1994
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10 | * The Regents of the University of California. All rights reserved.
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11 | *
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12 | * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
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13 | * was re-ported from NetBSD and debianized.
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14 | *
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15 | * rewrite arith.y to micro stack based cryptic algorithm by
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16 | * Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
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17 | *
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18 | * Modified by Paul Mundt <lethal@linux-sh.org> (c) 2004 to support
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19 | * dynamic variables.
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20 | *
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21 | * Modified by Vladimir Oleynik <dzo@simtreas.ru> (c) 2001-2005 to be
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22 | * used in busybox and size optimizations,
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23 | * rewrote arith (see notes to this), added locale support,
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24 | * rewrote dynamic variables.
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25 | *
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26 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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27 | */
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28 | /* Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
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29 | *
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30 | * Permission is hereby granted, free of charge, to any person obtaining
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31 | * a copy of this software and associated documentation files (the
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32 | * "Software"), to deal in the Software without restriction, including
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33 | * without limitation the rights to use, copy, modify, merge, publish,
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34 | * distribute, sublicense, and/or sell copies of the Software, and to
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35 | * permit persons to whom the Software is furnished to do so, subject to
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36 | * the following conditions:
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37 | *
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38 | * The above copyright notice and this permission notice shall be
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39 | * included in all copies or substantial portions of the Software.
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40 | *
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41 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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42 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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43 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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44 | * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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45 | * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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46 | * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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47 | * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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48 | */
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49 |
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50 | /* This is my infix parser/evaluator. It is optimized for size, intended
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51 | * as a replacement for yacc-based parsers. However, it may well be faster
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52 | * than a comparable parser written in yacc. The supported operators are
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53 | * listed in #defines below. Parens, order of operations, and error handling
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54 | * are supported. This code is thread safe. The exact expression format should
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55 | * be that which POSIX specifies for shells.
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56 | *
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57 | * The code uses a simple two-stack algorithm. See
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58 | * http://www.onthenet.com.au/~grahamis/int2008/week02/lect02.html
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59 | * for a detailed explanation of the infix-to-postfix algorithm on which
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60 | * this is based (this code differs in that it applies operators immediately
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61 | * to the stack instead of adding them to a queue to end up with an
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62 | * expression).
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63 | */
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64 |
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65 | /*
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66 | * Aug 24, 2001 Manuel Novoa III
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67 | *
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68 | * Reduced the generated code size by about 30% (i386) and fixed several bugs.
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69 | *
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70 | * 1) In arith_apply():
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71 | * a) Cached values of *numptr and &(numptr[-1]).
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72 | * b) Removed redundant test for zero denominator.
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73 | *
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74 | * 2) In arith():
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75 | * a) Eliminated redundant code for processing operator tokens by moving
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76 | * to a table-based implementation. Also folded handling of parens
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77 | * into the table.
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78 | * b) Combined all 3 loops which called arith_apply to reduce generated
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79 | * code size at the cost of speed.
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80 | *
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81 | * 3) The following expressions were treated as valid by the original code:
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82 | * 1() , 0! , 1 ( *3 ) .
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83 | * These bugs have been fixed by internally enclosing the expression in
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84 | * parens and then checking that all binary ops and right parens are
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85 | * preceded by a valid expression (NUM_TOKEN).
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86 | *
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87 | * Note: It may be desirable to replace Aaron's test for whitespace with
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88 | * ctype's isspace() if it is used by another busybox applet or if additional
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89 | * whitespace chars should be considered. Look below the "#include"s for a
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90 | * precompiler test.
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91 | */
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92 | /*
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93 | * Aug 26, 2001 Manuel Novoa III
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94 | *
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95 | * Return 0 for null expressions. Pointed out by Vladimir Oleynik.
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96 | *
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97 | * Merge in Aaron's comments previously posted to the busybox list,
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98 | * modified slightly to take account of my changes to the code.
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99 | *
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100 | */
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101 | /*
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102 | * (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
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103 | *
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104 | * - allow access to variable,
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105 | * use recursive value indirection: c="2*2"; a="c"; echo $((a+=2)) produce 6
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106 | * - implement assign syntax (VAR=expr, +=, *= etc)
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107 | * - implement exponentiation (** operator)
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108 | * - implement comma separated - expr, expr
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109 | * - implement ++expr --expr expr++ expr--
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110 | * - implement expr ? expr : expr (but second expr is always calculated)
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111 | * - allow hexadecimal and octal numbers
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112 | * - restore lost XOR operator
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113 | * - protect $((num num)) as true zero expr (Manuel's error)
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114 | * - always use special isspace(), see comment from bash ;-)
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115 | */
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116 | #include "libbb.h"
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117 | #include "math.h"
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118 |
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119 | #define lookupvar (math_state->lookupvar)
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120 | #define setvar (math_state->setvar )
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121 | //#define endofname (math_state->endofname)
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122 |
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123 | typedef unsigned char operator;
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124 |
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125 | /* An operator's token id is a bit of a bitfield. The lower 5 bits are the
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126 | * precedence, and 3 high bits are an ID unique across operators of that
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127 | * precedence. The ID portion is so that multiple operators can have the
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128 | * same precedence, ensuring that the leftmost one is evaluated first.
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129 | * Consider * and /
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130 | */
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131 | #define tok_decl(prec,id) (((id)<<5) | (prec))
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132 | #define PREC(op) ((op) & 0x1F)
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133 |
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134 | #define TOK_LPAREN tok_decl(0,0)
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135 |
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136 | #define TOK_COMMA tok_decl(1,0)
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137 |
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138 | /* All assignments are right associative and have the same precedence,
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139 | * but there are 11 of them, which doesn't fit into 3 bits for unique id.
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140 | * Abusing another precedence level:
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141 | */
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142 | #define TOK_ASSIGN tok_decl(2,0)
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143 | #define TOK_AND_ASSIGN tok_decl(2,1)
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144 | #define TOK_OR_ASSIGN tok_decl(2,2)
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145 | #define TOK_XOR_ASSIGN tok_decl(2,3)
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146 | #define TOK_PLUS_ASSIGN tok_decl(2,4)
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147 | #define TOK_MINUS_ASSIGN tok_decl(2,5)
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148 | #define TOK_LSHIFT_ASSIGN tok_decl(2,6)
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149 | #define TOK_RSHIFT_ASSIGN tok_decl(2,7)
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150 |
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151 | #define TOK_MUL_ASSIGN tok_decl(3,0)
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152 | #define TOK_DIV_ASSIGN tok_decl(3,1)
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153 | #define TOK_REM_ASSIGN tok_decl(3,2)
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154 |
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155 | #define fix_assignment_prec(prec) do { if (prec == 3) prec = 2; } while (0)
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156 |
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157 | /* Ternary conditional operator is right associative too */
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158 | #define TOK_CONDITIONAL tok_decl(4,0)
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159 | #define TOK_CONDITIONAL_SEP tok_decl(4,1)
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160 |
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161 | #define TOK_OR tok_decl(5,0)
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162 |
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163 | #define TOK_AND tok_decl(6,0)
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164 |
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165 | #define TOK_BOR tok_decl(7,0)
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166 |
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167 | #define TOK_BXOR tok_decl(8,0)
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168 |
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169 | #define TOK_BAND tok_decl(9,0)
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170 |
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171 | #define TOK_EQ tok_decl(10,0)
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172 | #define TOK_NE tok_decl(10,1)
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173 |
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174 | #define TOK_LT tok_decl(11,0)
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175 | #define TOK_GT tok_decl(11,1)
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176 | #define TOK_GE tok_decl(11,2)
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177 | #define TOK_LE tok_decl(11,3)
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178 |
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179 | #define TOK_LSHIFT tok_decl(12,0)
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180 | #define TOK_RSHIFT tok_decl(12,1)
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181 |
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182 | #define TOK_ADD tok_decl(13,0)
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183 | #define TOK_SUB tok_decl(13,1)
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184 |
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185 | #define TOK_MUL tok_decl(14,0)
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186 | #define TOK_DIV tok_decl(14,1)
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187 | #define TOK_REM tok_decl(14,2)
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188 |
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189 | /* Exponent is right associative */
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190 | #define TOK_EXPONENT tok_decl(15,1)
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191 |
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192 | /* Unary operators */
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193 | #define UNARYPREC 16
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194 | #define TOK_BNOT tok_decl(UNARYPREC,0)
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195 | #define TOK_NOT tok_decl(UNARYPREC,1)
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196 |
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197 | #define TOK_UMINUS tok_decl(UNARYPREC+1,0)
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198 | #define TOK_UPLUS tok_decl(UNARYPREC+1,1)
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199 |
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200 | #define PREC_PRE (UNARYPREC+2)
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201 |
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202 | #define TOK_PRE_INC tok_decl(PREC_PRE, 0)
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203 | #define TOK_PRE_DEC tok_decl(PREC_PRE, 1)
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204 |
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205 | #define PREC_POST (UNARYPREC+3)
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206 |
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207 | #define TOK_POST_INC tok_decl(PREC_POST, 0)
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208 | #define TOK_POST_DEC tok_decl(PREC_POST, 1)
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209 |
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210 | #define SPEC_PREC (UNARYPREC+4)
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211 |
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212 | #define TOK_NUM tok_decl(SPEC_PREC, 0)
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213 | #define TOK_RPAREN tok_decl(SPEC_PREC, 1)
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214 |
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215 | static int
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216 | is_assign_op(operator op)
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217 | {
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218 | operator prec = PREC(op);
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219 | fix_assignment_prec(prec);
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220 | return prec == PREC(TOK_ASSIGN)
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221 | || prec == PREC_PRE
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222 | || prec == PREC_POST;
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223 | }
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224 |
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225 | static int
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226 | is_right_associative(operator prec)
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227 | {
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228 | return prec == PREC(TOK_ASSIGN)
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229 | || prec == PREC(TOK_EXPONENT)
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230 | || prec == PREC(TOK_CONDITIONAL);
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231 | }
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232 |
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233 |
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234 | typedef struct {
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235 | arith_t val;
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236 | /* We acquire second_val only when "expr1 : expr2" part
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237 | * of ternary ?: op is evaluated.
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238 | * We treat ?: as two binary ops: (expr ? (expr1 : expr2)).
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239 | * ':' produces a new value which has two parts, val and second_val;
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240 | * then '?' selects one of them based on its left side.
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241 | */
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242 | arith_t second_val;
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243 | char second_val_present;
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244 | /* If NULL then it's just a number, else it's a named variable */
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245 | char *var;
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246 | } var_or_num_t;
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247 |
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248 | typedef struct remembered_name {
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249 | struct remembered_name *next;
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250 | const char *var;
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251 | } remembered_name;
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252 |
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253 |
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254 | static arith_t FAST_FUNC
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255 | evaluate_string(arith_state_t *math_state, const char *expr);
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256 |
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257 | static const char*
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258 | arith_lookup_val(arith_state_t *math_state, var_or_num_t *t)
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259 | {
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260 | if (t->var) {
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261 | const char *p = lookupvar(t->var);
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262 | if (p) {
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263 | remembered_name *cur;
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264 | remembered_name cur_save;
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265 |
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266 | /* did we already see this name?
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267 | * testcase: a=b; b=a; echo $((a))
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268 | */
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269 | for (cur = math_state->list_of_recursed_names; cur; cur = cur->next) {
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270 | if (strcmp(cur->var, t->var) == 0) {
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271 | /* Yes */
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272 | return "expression recursion loop detected";
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273 | }
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274 | }
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275 |
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276 | /* push current var name */
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277 | cur = math_state->list_of_recursed_names;
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278 | cur_save.var = t->var;
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279 | cur_save.next = cur;
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280 | math_state->list_of_recursed_names = &cur_save;
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281 |
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282 | /* recursively evaluate p as expression */
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283 | t->val = evaluate_string(math_state, p);
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284 |
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285 | /* pop current var name */
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286 | math_state->list_of_recursed_names = cur;
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287 |
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288 | return math_state->errmsg;
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289 | }
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290 | /* treat undefined var as 0 */
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291 | t->val = 0;
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292 | }
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293 | return 0;
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294 | }
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295 |
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296 | /* "Applying" a token means performing it on the top elements on the integer
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297 | * stack. For an unary operator it will only change the top element, but a
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298 | * binary operator will pop two arguments and push the result */
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299 | static NOINLINE const char*
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300 | arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_or_num_t **numstackptr)
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301 | {
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302 | #define NUMPTR (*numstackptr)
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303 |
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304 | var_or_num_t *top_of_stack;
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305 | arith_t rez;
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306 | const char *err;
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307 |
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308 | /* There is no operator that can work without arguments */
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309 | if (NUMPTR == numstack)
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310 | goto err;
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311 |
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312 | top_of_stack = NUMPTR - 1;
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313 |
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314 | /* Resolve name to value, if needed */
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315 | err = arith_lookup_val(math_state, top_of_stack);
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316 | if (err)
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317 | return err;
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318 |
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319 | rez = top_of_stack->val;
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320 | if (op == TOK_UMINUS)
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321 | rez = -rez;
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322 | else if (op == TOK_NOT)
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323 | rez = !rez;
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324 | else if (op == TOK_BNOT)
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325 | rez = ~rez;
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326 | else if (op == TOK_POST_INC || op == TOK_PRE_INC)
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327 | rez++;
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328 | else if (op == TOK_POST_DEC || op == TOK_PRE_DEC)
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329 | rez--;
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330 | else if (op != TOK_UPLUS) {
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331 | /* Binary operators */
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332 | arith_t right_side_val;
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333 | char bad_second_val;
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334 |
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335 | /* Binary operators need two arguments */
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336 | if (top_of_stack == numstack)
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337 | goto err;
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338 | /* ...and they pop one */
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339 | NUMPTR = top_of_stack; /* this decrements NUMPTR */
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340 |
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341 | bad_second_val = top_of_stack->second_val_present;
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342 | if (op == TOK_CONDITIONAL) { /* ? operation */
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343 | /* Make next if (...) protect against
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344 | * $((expr1 ? expr2)) - that is, missing ": expr" */
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345 | bad_second_val = !bad_second_val;
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346 | }
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347 | if (bad_second_val) {
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348 | /* Protect against $((expr <not_?_op> expr1 : expr2)) */
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349 | return "malformed ?: operator";
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350 | }
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351 |
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352 | top_of_stack--; /* now points to left side */
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353 |
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354 | if (op != TOK_ASSIGN) {
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355 | /* Resolve left side value (unless the op is '=') */
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356 | err = arith_lookup_val(math_state, top_of_stack);
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357 | if (err)
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358 | return err;
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359 | }
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360 |
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361 | right_side_val = rez;
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362 | rez = top_of_stack->val;
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363 | if (op == TOK_CONDITIONAL) /* ? operation */
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364 | rez = (rez ? right_side_val : top_of_stack[1].second_val);
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365 | else if (op == TOK_CONDITIONAL_SEP) { /* : operation */
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366 | if (top_of_stack == numstack) {
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367 | /* Protect against $((expr : expr)) */
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368 | return "malformed ?: operator";
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369 | }
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370 | top_of_stack->second_val_present = op;
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371 | top_of_stack->second_val = right_side_val;
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372 | }
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373 | else if (op == TOK_BOR || op == TOK_OR_ASSIGN)
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374 | rez |= right_side_val;
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375 | else if (op == TOK_OR)
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376 | rez = right_side_val || rez;
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377 | else if (op == TOK_BAND || op == TOK_AND_ASSIGN)
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378 | rez &= right_side_val;
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379 | else if (op == TOK_BXOR || op == TOK_XOR_ASSIGN)
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380 | rez ^= right_side_val;
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381 | else if (op == TOK_AND)
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382 | rez = rez && right_side_val;
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383 | else if (op == TOK_EQ)
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384 | rez = (rez == right_side_val);
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385 | else if (op == TOK_NE)
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386 | rez = (rez != right_side_val);
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387 | else if (op == TOK_GE)
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388 | rez = (rez >= right_side_val);
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389 | else if (op == TOK_RSHIFT || op == TOK_RSHIFT_ASSIGN)
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390 | rez >>= right_side_val;
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391 | else if (op == TOK_LSHIFT || op == TOK_LSHIFT_ASSIGN)
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392 | rez <<= right_side_val;
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393 | else if (op == TOK_GT)
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394 | rez = (rez > right_side_val);
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395 | else if (op == TOK_LT)
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396 | rez = (rez < right_side_val);
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397 | else if (op == TOK_LE)
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398 | rez = (rez <= right_side_val);
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399 | else if (op == TOK_MUL || op == TOK_MUL_ASSIGN)
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400 | rez *= right_side_val;
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401 | else if (op == TOK_ADD || op == TOK_PLUS_ASSIGN)
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402 | rez += right_side_val;
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403 | else if (op == TOK_SUB || op == TOK_MINUS_ASSIGN)
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404 | rez -= right_side_val;
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405 | else if (op == TOK_ASSIGN || op == TOK_COMMA)
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406 | rez = right_side_val;
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407 | else if (op == TOK_EXPONENT) {
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408 | arith_t c;
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409 | if (right_side_val < 0)
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410 | return "exponent less than 0";
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411 | c = 1;
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412 | while (--right_side_val >= 0)
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413 | c *= rez;
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414 | rez = c;
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415 | }
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416 | else if (right_side_val == 0)
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417 | return "divide by zero";
|
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418 | else if (op == TOK_DIV || op == TOK_DIV_ASSIGN
|
---|
419 | || op == TOK_REM || op == TOK_REM_ASSIGN) {
|
---|
420 | /*
|
---|
421 | * bash 4.2.45 x86 64bit: SEGV on 'echo $((2**63 / -1))'
|
---|
422 | *
|
---|
423 | * MAX_NEGATIVE_INT / -1 = MAX_POSITIVE_INT+1
|
---|
424 | * and thus is not representable.
|
---|
425 | * Some CPUs segfault trying such op.
|
---|
426 | * Others overflow MAX_POSITIVE_INT+1 to
|
---|
427 | * MAX_NEGATIVE_INT (0x7fff+1 = 0x8000).
|
---|
428 | * Make sure to at least not SEGV here:
|
---|
429 | */
|
---|
430 | if (right_side_val == -1
|
---|
431 | && rez << 1 == 0 /* MAX_NEGATIVE_INT or 0 */
|
---|
432 | ) {
|
---|
433 | right_side_val = 1;
|
---|
434 | }
|
---|
435 | if (op == TOK_DIV || op == TOK_DIV_ASSIGN)
|
---|
436 | rez /= right_side_val;
|
---|
437 | else {
|
---|
438 | rez %= right_side_val;
|
---|
439 | }
|
---|
440 | }
|
---|
441 | }
|
---|
442 |
|
---|
443 | if (is_assign_op(op)) {
|
---|
444 | char buf[sizeof(arith_t)*3 + 2];
|
---|
445 |
|
---|
446 | if (top_of_stack->var == NULL) {
|
---|
447 | /* Hmm, 1=2 ? */
|
---|
448 | //TODO: actually, bash allows ++7 but for some reason it evals to 7, not 8
|
---|
449 | goto err;
|
---|
450 | }
|
---|
451 | /* Save to shell variable */
|
---|
452 | sprintf(buf, ARITH_FMT, rez);
|
---|
453 | setvar(top_of_stack->var, buf);
|
---|
454 | /* After saving, make previous value for v++ or v-- */
|
---|
455 | if (op == TOK_POST_INC)
|
---|
456 | rez--;
|
---|
457 | else if (op == TOK_POST_DEC)
|
---|
458 | rez++;
|
---|
459 | }
|
---|
460 |
|
---|
461 | top_of_stack->val = rez;
|
---|
462 | /* Erase var name, it is just a number now */
|
---|
463 | top_of_stack->var = NULL;
|
---|
464 | return NULL;
|
---|
465 | err:
|
---|
466 | return "arithmetic syntax error";
|
---|
467 | #undef NUMPTR
|
---|
468 | }
|
---|
469 |
|
---|
470 | /* longest must be first */
|
---|
471 | static const char op_tokens[] ALIGN1 = {
|
---|
472 | '<','<','=',0, TOK_LSHIFT_ASSIGN,
|
---|
473 | '>','>','=',0, TOK_RSHIFT_ASSIGN,
|
---|
474 | '<','<', 0, TOK_LSHIFT,
|
---|
475 | '>','>', 0, TOK_RSHIFT,
|
---|
476 | '|','|', 0, TOK_OR,
|
---|
477 | '&','&', 0, TOK_AND,
|
---|
478 | '!','=', 0, TOK_NE,
|
---|
479 | '<','=', 0, TOK_LE,
|
---|
480 | '>','=', 0, TOK_GE,
|
---|
481 | '=','=', 0, TOK_EQ,
|
---|
482 | '|','=', 0, TOK_OR_ASSIGN,
|
---|
483 | '&','=', 0, TOK_AND_ASSIGN,
|
---|
484 | '*','=', 0, TOK_MUL_ASSIGN,
|
---|
485 | '/','=', 0, TOK_DIV_ASSIGN,
|
---|
486 | '%','=', 0, TOK_REM_ASSIGN,
|
---|
487 | '+','=', 0, TOK_PLUS_ASSIGN,
|
---|
488 | '-','=', 0, TOK_MINUS_ASSIGN,
|
---|
489 | '-','-', 0, TOK_POST_DEC,
|
---|
490 | '^','=', 0, TOK_XOR_ASSIGN,
|
---|
491 | '+','+', 0, TOK_POST_INC,
|
---|
492 | '*','*', 0, TOK_EXPONENT,
|
---|
493 | '!', 0, TOK_NOT,
|
---|
494 | '<', 0, TOK_LT,
|
---|
495 | '>', 0, TOK_GT,
|
---|
496 | '=', 0, TOK_ASSIGN,
|
---|
497 | '|', 0, TOK_BOR,
|
---|
498 | '&', 0, TOK_BAND,
|
---|
499 | '*', 0, TOK_MUL,
|
---|
500 | '/', 0, TOK_DIV,
|
---|
501 | '%', 0, TOK_REM,
|
---|
502 | '+', 0, TOK_ADD,
|
---|
503 | '-', 0, TOK_SUB,
|
---|
504 | '^', 0, TOK_BXOR,
|
---|
505 | /* uniq */
|
---|
506 | '~', 0, TOK_BNOT,
|
---|
507 | ',', 0, TOK_COMMA,
|
---|
508 | '?', 0, TOK_CONDITIONAL,
|
---|
509 | ':', 0, TOK_CONDITIONAL_SEP,
|
---|
510 | ')', 0, TOK_RPAREN,
|
---|
511 | '(', 0, TOK_LPAREN,
|
---|
512 | 0
|
---|
513 | };
|
---|
514 | #define ptr_to_rparen (&op_tokens[sizeof(op_tokens)-7])
|
---|
515 |
|
---|
516 | static arith_t FAST_FUNC
|
---|
517 | evaluate_string(arith_state_t *math_state, const char *expr)
|
---|
518 | {
|
---|
519 | operator lasttok;
|
---|
520 | const char *errmsg;
|
---|
521 | const char *start_expr = expr = skip_whitespace(expr);
|
---|
522 | unsigned expr_len = strlen(expr) + 2;
|
---|
523 | /* Stack of integers */
|
---|
524 | /* The proof that there can be no more than strlen(startbuf)/2+1
|
---|
525 | * integers in any given correct or incorrect expression
|
---|
526 | * is left as an exercise to the reader. */
|
---|
527 | var_or_num_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
|
---|
528 | var_or_num_t *numstackptr = numstack;
|
---|
529 | /* Stack of operator tokens */
|
---|
530 | operator *const stack = alloca(expr_len * sizeof(stack[0]));
|
---|
531 | operator *stackptr = stack;
|
---|
532 |
|
---|
533 | /* Start with a left paren */
|
---|
534 | *stackptr++ = lasttok = TOK_LPAREN;
|
---|
535 | errmsg = NULL;
|
---|
536 |
|
---|
537 | while (1) {
|
---|
538 | const char *p;
|
---|
539 | operator op;
|
---|
540 | operator prec;
|
---|
541 | char arithval;
|
---|
542 |
|
---|
543 | expr = skip_whitespace(expr);
|
---|
544 | arithval = *expr;
|
---|
545 | if (arithval == '\0') {
|
---|
546 | if (expr == start_expr) {
|
---|
547 | /* Null expression */
|
---|
548 | numstack->val = 0;
|
---|
549 | goto ret;
|
---|
550 | }
|
---|
551 |
|
---|
552 | /* This is only reached after all tokens have been extracted from the
|
---|
553 | * input stream. If there are still tokens on the operator stack, they
|
---|
554 | * are to be applied in order. At the end, there should be a final
|
---|
555 | * result on the integer stack */
|
---|
556 |
|
---|
557 | if (expr != ptr_to_rparen + 1) {
|
---|
558 | /* If we haven't done so already,
|
---|
559 | * append a closing right paren
|
---|
560 | * and let the loop process it */
|
---|
561 | expr = ptr_to_rparen;
|
---|
562 | continue;
|
---|
563 | }
|
---|
564 | /* At this point, we're done with the expression */
|
---|
565 | if (numstackptr != numstack + 1) {
|
---|
566 | /* ...but if there isn't, it's bad */
|
---|
567 | goto err;
|
---|
568 | }
|
---|
569 | if (numstack->var) {
|
---|
570 | /* expression is $((var)) only, lookup now */
|
---|
571 | errmsg = arith_lookup_val(math_state, numstack);
|
---|
572 | }
|
---|
573 | goto ret;
|
---|
574 | }
|
---|
575 |
|
---|
576 | p = endofname(expr);
|
---|
577 | if (p != expr) {
|
---|
578 | /* Name */
|
---|
579 | size_t var_name_size = (p-expr) + 1; /* +1 for NUL */
|
---|
580 | numstackptr->var = alloca(var_name_size);
|
---|
581 | safe_strncpy(numstackptr->var, expr, var_name_size);
|
---|
582 | expr = p;
|
---|
583 | num:
|
---|
584 | numstackptr->second_val_present = 0;
|
---|
585 | numstackptr++;
|
---|
586 | lasttok = TOK_NUM;
|
---|
587 | continue;
|
---|
588 | }
|
---|
589 |
|
---|
590 | if (isdigit(arithval)) {
|
---|
591 | /* Number */
|
---|
592 | numstackptr->var = NULL;
|
---|
593 | errno = 0;
|
---|
594 | numstackptr->val = strto_arith_t(expr, (char**) &expr, 0);
|
---|
595 | if (errno)
|
---|
596 | numstackptr->val = 0; /* bash compat */
|
---|
597 | goto num;
|
---|
598 | }
|
---|
599 |
|
---|
600 | /* Should be an operator */
|
---|
601 | p = op_tokens;
|
---|
602 | while (1) {
|
---|
603 | // TODO: bash allows 7+++v, treats it as 7 + ++v
|
---|
604 | // we treat it as 7++ + v and reject
|
---|
605 | /* Compare expr to current op_tokens[] element */
|
---|
606 | const char *e = expr;
|
---|
607 | while (1) {
|
---|
608 | if (*p == '\0') {
|
---|
609 | /* Match: operator is found */
|
---|
610 | expr = e;
|
---|
611 | goto tok_found;
|
---|
612 | }
|
---|
613 | if (*p != *e)
|
---|
614 | break;
|
---|
615 | p++;
|
---|
616 | e++;
|
---|
617 | }
|
---|
618 | /* No match, go to next element of op_tokens[] */
|
---|
619 | while (*p)
|
---|
620 | p++;
|
---|
621 | p += 2; /* skip NUL and TOK_foo bytes */
|
---|
622 | if (*p == '\0') {
|
---|
623 | /* No next element, operator not found */
|
---|
624 | //math_state->syntax_error_at = expr;
|
---|
625 | goto err;
|
---|
626 | }
|
---|
627 | }
|
---|
628 | tok_found:
|
---|
629 | op = p[1]; /* fetch TOK_foo value */
|
---|
630 | /* NB: expr now points past the operator */
|
---|
631 |
|
---|
632 | /* post grammar: a++ reduce to num */
|
---|
633 | if (lasttok == TOK_POST_INC || lasttok == TOK_POST_DEC)
|
---|
634 | lasttok = TOK_NUM;
|
---|
635 |
|
---|
636 | /* Plus and minus are binary (not unary) _only_ if the last
|
---|
637 | * token was a number, or a right paren (which pretends to be
|
---|
638 | * a number, since it evaluates to one). Think about it.
|
---|
639 | * It makes sense. */
|
---|
640 | if (lasttok != TOK_NUM) {
|
---|
641 | switch (op) {
|
---|
642 | case TOK_ADD:
|
---|
643 | op = TOK_UPLUS;
|
---|
644 | break;
|
---|
645 | case TOK_SUB:
|
---|
646 | op = TOK_UMINUS;
|
---|
647 | break;
|
---|
648 | case TOK_POST_INC:
|
---|
649 | op = TOK_PRE_INC;
|
---|
650 | break;
|
---|
651 | case TOK_POST_DEC:
|
---|
652 | op = TOK_PRE_DEC;
|
---|
653 | break;
|
---|
654 | }
|
---|
655 | }
|
---|
656 | /* We don't want an unary operator to cause recursive descent on the
|
---|
657 | * stack, because there can be many in a row and it could cause an
|
---|
658 | * operator to be evaluated before its argument is pushed onto the
|
---|
659 | * integer stack.
|
---|
660 | * But for binary operators, "apply" everything on the operator
|
---|
661 | * stack until we find an operator with a lesser priority than the
|
---|
662 | * one we have just extracted. If op is right-associative,
|
---|
663 | * then stop "applying" on the equal priority too.
|
---|
664 | * Left paren is given the lowest priority so it will never be
|
---|
665 | * "applied" in this way.
|
---|
666 | */
|
---|
667 | prec = PREC(op);
|
---|
668 | if ((prec > 0 && prec < UNARYPREC) || prec == SPEC_PREC) {
|
---|
669 | /* not left paren or unary */
|
---|
670 | if (lasttok != TOK_NUM) {
|
---|
671 | /* binary op must be preceded by a num */
|
---|
672 | goto err;
|
---|
673 | }
|
---|
674 | while (stackptr != stack) {
|
---|
675 | operator prev_op = *--stackptr;
|
---|
676 | if (op == TOK_RPAREN) {
|
---|
677 | /* The algorithm employed here is simple: while we don't
|
---|
678 | * hit an open paren nor the bottom of the stack, pop
|
---|
679 | * tokens and apply them */
|
---|
680 | if (prev_op == TOK_LPAREN) {
|
---|
681 | /* Any operator directly after a
|
---|
682 | * close paren should consider itself binary */
|
---|
683 | lasttok = TOK_NUM;
|
---|
684 | goto next;
|
---|
685 | }
|
---|
686 | } else {
|
---|
687 | operator prev_prec = PREC(prev_op);
|
---|
688 | fix_assignment_prec(prec);
|
---|
689 | fix_assignment_prec(prev_prec);
|
---|
690 | if (prev_prec < prec
|
---|
691 | || (prev_prec == prec && is_right_associative(prec))
|
---|
692 | ) {
|
---|
693 | stackptr++;
|
---|
694 | break;
|
---|
695 | }
|
---|
696 | }
|
---|
697 | errmsg = arith_apply(math_state, prev_op, numstack, &numstackptr);
|
---|
698 | if (errmsg)
|
---|
699 | goto err_with_custom_msg;
|
---|
700 | }
|
---|
701 | if (op == TOK_RPAREN)
|
---|
702 | goto err;
|
---|
703 | }
|
---|
704 |
|
---|
705 | /* Push this operator to the stack and remember it */
|
---|
706 | *stackptr++ = lasttok = op;
|
---|
707 | next: ;
|
---|
708 | } /* while (1) */
|
---|
709 |
|
---|
710 | err:
|
---|
711 | errmsg = "arithmetic syntax error";
|
---|
712 | err_with_custom_msg:
|
---|
713 | numstack->val = -1;
|
---|
714 | ret:
|
---|
715 | math_state->errmsg = errmsg;
|
---|
716 | return numstack->val;
|
---|
717 | }
|
---|
718 |
|
---|
719 | arith_t FAST_FUNC
|
---|
720 | arith(arith_state_t *math_state, const char *expr)
|
---|
721 | {
|
---|
722 | math_state->errmsg = NULL;
|
---|
723 | math_state->list_of_recursed_names = NULL;
|
---|
724 | return evaluate_string(math_state, expr);
|
---|
725 | }
|
---|
726 |
|
---|
727 | /*
|
---|
728 | * Copyright (c) 1989, 1991, 1993, 1994
|
---|
729 | * The Regents of the University of California. All rights reserved.
|
---|
730 | *
|
---|
731 | * This code is derived from software contributed to Berkeley by
|
---|
732 | * Kenneth Almquist.
|
---|
733 | *
|
---|
734 | * Redistribution and use in source and binary forms, with or without
|
---|
735 | * modification, are permitted provided that the following conditions
|
---|
736 | * are met:
|
---|
737 | * 1. Redistributions of source code must retain the above copyright
|
---|
738 | * notice, this list of conditions and the following disclaimer.
|
---|
739 | * 2. Redistributions in binary form must reproduce the above copyright
|
---|
740 | * notice, this list of conditions and the following disclaimer in the
|
---|
741 | * documentation and/or other materials provided with the distribution.
|
---|
742 | * 3. Neither the name of the University nor the names of its contributors
|
---|
743 | * may be used to endorse or promote products derived from this software
|
---|
744 | * without specific prior written permission.
|
---|
745 | *
|
---|
746 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
---|
747 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
---|
748 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
---|
749 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
---|
750 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
---|
751 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
---|
752 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
---|
753 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
---|
754 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
---|
755 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
---|
756 | * SUCH DAMAGE.
|
---|
757 | */
|
---|