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10
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1 /* inflate.c -- zlib interface to inflate modules
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2 * Copyright (C) 1995 Mark Adler
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3 * For conditions of distribution and use, see copyright notice in zlib.h
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4 */
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5
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6 #include "zutil.h"
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7 #include "infblock.h"
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8
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9 struct inflate_blocks_state {int dummy;}; /* for buggy compilers */
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10
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11 /* inflate private state */
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12 struct internal_state {
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13
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14 /* mode */
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15 enum {
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16 METHOD, /* waiting for method byte */
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17 FLAG, /* waiting for flag byte */
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18 BLOCKS, /* decompressing blocks */
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19 CHECK4, /* four check bytes to go */
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20 CHECK3, /* three check bytes to go */
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21 CHECK2, /* two check bytes to go */
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22 CHECK1, /* one check byte to go */
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23 DONE, /* finished check, done */
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24 BAD} /* got an error--stay here */
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25 mode; /* current inflate mode */
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26
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27 /* mode dependent information */
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28 union {
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29 uInt method; /* if FLAGS, method byte */
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30 struct {
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31 uLong was; /* computed check value */
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32 uLong need; /* stream check value */
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33 } check; /* if CHECK, check values to compare */
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34 uInt marker; /* if BAD, inflateSync's marker bytes count */
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35 } sub; /* submode */
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36
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37 /* mode independent information */
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38 int nowrap; /* flag for no wrapper */
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39 uInt wbits; /* log2(window size) (8..15, defaults to 15) */
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40 struct inflate_blocks_state
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41 *blocks; /* current inflate_blocks state */
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42
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43 };
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44
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45
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46 int inflateReset(z)
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47 z_stream *z;
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48 {
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49 uLong c;
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50
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51 if (z == Z_NULL || z->state == Z_NULL)
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52 return Z_STREAM_ERROR;
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53 z->total_in = z->total_out = 0;
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54 z->msg = Z_NULL;
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55 z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
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56 inflate_blocks_reset(z->state->blocks, z, &c);
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57 Trace((stderr, "inflate: reset\n"));
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58 return Z_OK;
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59 }
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60
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61
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62 int inflateEnd(z)
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63 z_stream *z;
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64 {
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65 uLong c;
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66
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67 if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
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68 return Z_STREAM_ERROR;
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69 if (z->state->blocks != Z_NULL)
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70 inflate_blocks_free(z->state->blocks, z, &c);
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71 ZFREE(z, z->state);
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72 z->state = Z_NULL;
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73 Trace((stderr, "inflate: end\n"));
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74 return Z_OK;
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75 }
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76
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77
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78 int inflateInit2(z, w)
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79 z_stream *z;
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80 int w;
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81 {
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82 /* initialize state */
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83 if (z == Z_NULL)
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84 return Z_STREAM_ERROR;
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85 if (z->zalloc == Z_NULL) z->zalloc = zcalloc;
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86 if (z->zfree == Z_NULL) z->zfree = zcfree;
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87 if ((z->state = (struct internal_state *)
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88 ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
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89 return Z_MEM_ERROR;
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90 z->state->blocks = Z_NULL;
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91
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92 /* handle undocumented nowrap option (no zlib header or check) */
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93 z->state->nowrap = 0;
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94 if (w < 0)
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95 {
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96 w = - w;
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97 z->state->nowrap = 1;
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98 }
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99
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100 /* set window size */
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101 if (w < 8 || w > 15)
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102 {
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103 inflateEnd(z);
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104 return Z_STREAM_ERROR;
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105 }
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106 z->state->wbits = (uInt)w;
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107
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108 /* create inflate_blocks state */
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109 if ((z->state->blocks =
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110 inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, 1 << w))
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111 == Z_NULL)
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112 {
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113 inflateEnd(z);
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114 return Z_MEM_ERROR;
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115 }
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116 Trace((stderr, "inflate: allocated\n"));
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117
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118 /* reset state */
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119 inflateReset(z);
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120 return Z_OK;
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121 }
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122
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123
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124 int inflateInit(z)
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125 z_stream *z;
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126 {
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127 return inflateInit2(z, DEF_WBITS);
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128 }
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129
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130
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131 #define NEEDBYTE {if(z->avail_in==0)return r;r=Z_OK;}
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132 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
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133
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134 int inflate(z, f)
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135 z_stream *z;
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136 int f;
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137 {
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138 int r = f; /* to avoid warning about unused f */
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139 uInt b;
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140
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141 if (z == Z_NULL || z->next_in == Z_NULL)
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142 return Z_STREAM_ERROR;
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143 r = Z_BUF_ERROR;
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144 while (1) switch (z->state->mode)
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145 {
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146 case METHOD:
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147 NEEDBYTE
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148 if (((z->state->sub.method = NEXTBYTE) & 0xf) != DEFLATED)
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149 {
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150 z->state->mode = BAD;
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151 z->msg = "unknown compression method";
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152 z->state->sub.marker = 5; /* can't try inflateSync */
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153 break;
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154 }
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155 if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
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156 {
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157 z->state->mode = BAD;
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158 z->msg = "invalid window size";
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159 z->state->sub.marker = 5; /* can't try inflateSync */
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160 break;
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161 }
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162 z->state->mode = FLAG;
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163 case FLAG:
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164 NEEDBYTE
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165 if ((b = NEXTBYTE) & 0x20)
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166 {
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167 z->state->mode = BAD;
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168 z->msg = "invalid reserved bit";
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169 z->state->sub.marker = 5; /* can't try inflateSync */
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170 break;
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171 }
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172 if (((z->state->sub.method << 8) + b) % 31)
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173 {
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174 z->state->mode = BAD;
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175 z->msg = "incorrect header check";
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176 z->state->sub.marker = 5; /* can't try inflateSync */
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177 break;
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178 }
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179 Trace((stderr, "inflate: zlib header ok\n"));
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180 z->state->mode = BLOCKS;
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181 case BLOCKS:
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182 r = inflate_blocks(z->state->blocks, z, r);
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183 if (r == Z_DATA_ERROR)
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184 {
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185 z->state->mode = BAD;
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186 z->state->sub.marker = 0; /* can try inflateSync */
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187 break;
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188 }
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189 if (r != Z_STREAM_END)
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190 return r;
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191 r = Z_OK;
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192 inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
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193 if (z->state->nowrap)
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194 {
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195 z->state->mode = DONE;
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196 break;
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197 }
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198 z->state->mode = CHECK4;
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199 case CHECK4:
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200 NEEDBYTE
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201 z->state->sub.check.need = (uLong)NEXTBYTE << 24;
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202 z->state->mode = CHECK3;
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203 case CHECK3:
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204 NEEDBYTE
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205 z->state->sub.check.need += (uLong)NEXTBYTE << 16;
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206 z->state->mode = CHECK2;
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207 case CHECK2:
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208 NEEDBYTE
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209 z->state->sub.check.need += (uLong)NEXTBYTE << 8;
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210 z->state->mode = CHECK1;
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211 case CHECK1:
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212 NEEDBYTE
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213 z->state->sub.check.need += (uLong)NEXTBYTE;
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214
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215 if (z->state->sub.check.was != z->state->sub.check.need)
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216 {
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217 z->state->mode = BAD;
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218 z->msg = "incorrect data check";
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219 z->state->sub.marker = 5; /* can't try inflateSync */
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220 break;
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221 }
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222 Trace((stderr, "inflate: zlib check ok\n"));
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223 z->state->mode = DONE;
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224 case DONE:
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225 return Z_STREAM_END;
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226 case BAD:
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227 return Z_DATA_ERROR;
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228 default:
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229 return Z_STREAM_ERROR;
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230 }
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231 }
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232
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233
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234 int inflateSync(z)
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235 z_stream *z;
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236 {
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237 uInt n; /* number of bytes to look at */
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238 Byte *p; /* pointer to bytes */
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239 uInt m; /* number of marker bytes found in a row */
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240 uLong r, w; /* temporaries to save total_in and total_out */
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241
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242 /* set up */
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243 if (z == Z_NULL || z->state == Z_NULL)
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244 return Z_STREAM_ERROR;
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245 if (z->state->mode != BAD)
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246 {
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247 z->state->mode = BAD;
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248 z->state->sub.marker = 0;
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249 }
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250 if ((n = z->avail_in) == 0)
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251 return Z_BUF_ERROR;
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252 p = z->next_in;
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253 m = z->state->sub.marker;
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254
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255 /* search */
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256 while (n && m < 4)
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257 {
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258 if (*p == (Byte)(m < 2 ? 0 : 0xff))
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259 m++;
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260 else if (*p)
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261 m = 0;
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262 else
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263 m = 4 - m;
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264 p++, n--;
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265 }
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266
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267 /* restore */
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268 z->total_in += p - z->next_in;
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269 z->next_in = p;
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270 z->avail_in = n;
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271 z->state->sub.marker = m;
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272
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273 /* return no joy or set up to restart on a new block */
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274 if (m != 4)
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275 return Z_DATA_ERROR;
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276 r = z->total_in; w = z->total_out;
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277 inflateReset(z);
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278 z->total_in = r; z->total_out = w;
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279 z->state->mode = BLOCKS;
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280 return Z_OK;
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281 }
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