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1 /* inflate.c -- zlib interface to inflate modules
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2 * Copyright (C) 1995-1998 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 typedef enum {
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12 METHOD, /* waiting for method byte */
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13 FLAG, /* waiting for flag byte */
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14 DICT4, /* four dictionary check bytes to go */
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15 DICT3, /* three dictionary check bytes to go */
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16 DICT2, /* two dictionary check bytes to go */
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17 DICT1, /* one dictionary check byte to go */
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18 DICT0, /* waiting for inflateSetDictionary */
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19 BLOCKS, /* decompressing blocks */
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20 CHECK4, /* four check bytes to go */
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21 CHECK3, /* three check bytes to go */
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22 CHECK2, /* two check bytes to go */
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23 CHECK1, /* one check byte to go */
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24 DONE, /* finished check, done */
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25 BAD} /* got an error--stay here */
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26 inflate_mode;
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27
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28 /* inflate private state */
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29 struct internal_state {
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30
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31 /* mode */
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32 inflate_mode mode; /* current inflate mode */
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33
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34 /* mode dependent information */
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35 union {
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36 uInt method; /* if FLAGS, method byte */
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37 struct {
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38 uLong was; /* computed check value */
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39 uLong need; /* stream check value */
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40 } check; /* if CHECK, check values to compare */
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41 uInt marker; /* if BAD, inflateSync's marker bytes count */
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42 } sub; /* submode */
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43
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44 /* mode independent information */
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45 int nowrap; /* flag for no wrapper */
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46 uInt wbits; /* log2(window size) (8..15, defaults to 15) */
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47 inflate_blocks_statef
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48 *blocks; /* current inflate_blocks state */
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49
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50 };
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51
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52
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53 int ZEXPORT inflateReset(z)
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54 z_streamp z;
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55 {
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56 if (z == Z_NULL || z->state == Z_NULL)
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57 return Z_STREAM_ERROR;
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58 z->total_in = z->total_out = 0;
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59 z->msg = Z_NULL;
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60 z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
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61 inflate_blocks_reset(z->state->blocks, z, Z_NULL);
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62 Tracev((stderr, "inflate: reset\n"));
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63 return Z_OK;
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64 }
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65
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66
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67 int ZEXPORT inflateEnd(z)
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68 z_streamp z;
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69 {
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70 if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
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71 return Z_STREAM_ERROR;
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72 if (z->state->blocks != Z_NULL)
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73 inflate_blocks_free(z->state->blocks, z);
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74 ZFREE(z, z->state);
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75 z->state = Z_NULL;
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76 Tracev((stderr, "inflate: end\n"));
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77 return Z_OK;
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78 }
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79
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80
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81 int ZEXPORT inflateInit2_(z, w, version, stream_size)
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82 z_streamp z;
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83 int w;
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84 const char *version;
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85 int stream_size;
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86 {
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87 if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
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88 stream_size != sizeof(z_stream))
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89 return Z_VERSION_ERROR;
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90
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91 /* initialize state */
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92 if (z == Z_NULL)
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93 return Z_STREAM_ERROR;
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94 z->msg = Z_NULL;
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95 if (z->zalloc == Z_NULL)
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96 {
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97 z->zalloc = zcalloc;
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98 z->opaque = (voidpf)0;
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99 }
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100 if (z->zfree == Z_NULL) z->zfree = zcfree;
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101 if ((z->state = (struct internal_state FAR *)
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102 ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
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103 return Z_MEM_ERROR;
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104 z->state->blocks = Z_NULL;
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105
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106 /* handle undocumented nowrap option (no zlib header or check) */
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107 z->state->nowrap = 0;
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108 if (w < 0)
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109 {
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110 w = - w;
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111 z->state->nowrap = 1;
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112 }
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113
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114 /* set window size */
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115 if (w < 8 || w > 15)
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116 {
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117 inflateEnd(z);
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118 return Z_STREAM_ERROR;
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119 }
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120 z->state->wbits = (uInt)w;
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121
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122 /* create inflate_blocks state */
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123 if ((z->state->blocks =
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124 inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
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125 == Z_NULL)
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126 {
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127 inflateEnd(z);
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128 return Z_MEM_ERROR;
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129 }
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130 Tracev((stderr, "inflate: allocated\n"));
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131
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132 /* reset state */
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133 inflateReset(z);
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134 return Z_OK;
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135 }
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136
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137
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138 int ZEXPORT inflateInit_(z, version, stream_size)
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139 z_streamp z;
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140 const char *version;
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141 int stream_size;
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142 {
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143 return inflateInit2_(z, DEF_WBITS, version, stream_size);
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144 }
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145
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146
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147 #define NEEDBYTE {if(z->avail_in==0)return r;r=f;}
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148 #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
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149
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150 int ZEXPORT inflate(z, f)
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151 z_streamp z;
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152 int f;
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153 {
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154 int r;
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155 uInt b;
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156
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157 if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
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158 return Z_STREAM_ERROR;
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159 f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
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160 r = Z_BUF_ERROR;
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161 while (1) switch (z->state->mode)
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162 {
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163 case METHOD:
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164 NEEDBYTE
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165 if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
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166 {
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167 z->state->mode = BAD;
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168 z->msg = (char*)"unknown compression method";
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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 >> 4) + 8 > z->state->wbits)
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173 {
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174 z->state->mode = BAD;
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175 z->msg = (char*)"invalid window size";
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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 z->state->mode = FLAG;
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180 case FLAG:
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181 NEEDBYTE
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182 b = NEXTBYTE;
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183 if (((z->state->sub.method << 8) + b) % 31)
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184 {
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185 z->state->mode = BAD;
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186 z->msg = (char*)"incorrect header check";
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187 z->state->sub.marker = 5; /* can't try inflateSync */
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188 break;
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189 }
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190 Tracev((stderr, "inflate: zlib header ok\n"));
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191 if (!(b & PRESET_DICT))
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192 {
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193 z->state->mode = BLOCKS;
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194 break;
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195 }
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196 z->state->mode = DICT4;
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197 case DICT4:
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198 NEEDBYTE
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199 z->state->sub.check.need = (uLong)NEXTBYTE << 24;
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200 z->state->mode = DICT3;
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201 case DICT3:
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202 NEEDBYTE
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203 z->state->sub.check.need += (uLong)NEXTBYTE << 16;
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204 z->state->mode = DICT2;
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205 case DICT2:
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206 NEEDBYTE
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207 z->state->sub.check.need += (uLong)NEXTBYTE << 8;
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208 z->state->mode = DICT1;
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209 case DICT1:
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210 NEEDBYTE
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211 z->state->sub.check.need += (uLong)NEXTBYTE;
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212 z->adler = z->state->sub.check.need;
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213 z->state->mode = DICT0;
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214 return Z_NEED_DICT;
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215 case DICT0:
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216 z->state->mode = BAD;
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217 z->msg = (char*)"need dictionary";
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218 z->state->sub.marker = 0; /* can try inflateSync */
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219 return Z_STREAM_ERROR;
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220 case BLOCKS:
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221 r = inflate_blocks(z->state->blocks, z, r);
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222 if (r == Z_DATA_ERROR)
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223 {
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224 z->state->mode = BAD;
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225 z->state->sub.marker = 0; /* can try inflateSync */
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226 break;
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227 }
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228 if (r == Z_OK)
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229 r = f;
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230 if (r != Z_STREAM_END)
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231 return r;
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232 r = f;
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233 inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
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234 if (z->state->nowrap)
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235 {
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236 z->state->mode = DONE;
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237 break;
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238 }
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239 z->state->mode = CHECK4;
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240 case CHECK4:
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241 NEEDBYTE
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242 z->state->sub.check.need = (uLong)NEXTBYTE << 24;
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243 z->state->mode = CHECK3;
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244 case CHECK3:
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245 NEEDBYTE
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246 z->state->sub.check.need += (uLong)NEXTBYTE << 16;
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247 z->state->mode = CHECK2;
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248 case CHECK2:
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249 NEEDBYTE
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250 z->state->sub.check.need += (uLong)NEXTBYTE << 8;
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251 z->state->mode = CHECK1;
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252 case CHECK1:
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253 NEEDBYTE
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254 z->state->sub.check.need += (uLong)NEXTBYTE;
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255
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256 if (z->state->sub.check.was != z->state->sub.check.need)
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257 {
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258 z->state->mode = BAD;
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259 z->msg = (char*)"incorrect data check";
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260 z->state->sub.marker = 5; /* can't try inflateSync */
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261 break;
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262 }
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263 Tracev((stderr, "inflate: zlib check ok\n"));
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264 z->state->mode = DONE;
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265 case DONE:
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266 return Z_STREAM_END;
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267 case BAD:
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268 return Z_DATA_ERROR;
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269 default:
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270 return Z_STREAM_ERROR;
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271 }
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272 #ifdef NEED_DUMMY_RETURN
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273 return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
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274 #endif
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275 }
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276
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277
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278 int ZEXPORT inflateSetDictionary(z, dictionary, dictLength)
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279 z_streamp z;
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280 const Bytef *dictionary;
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281 uInt dictLength;
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282 {
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283 uInt length = dictLength;
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284
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285 if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0)
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286 return Z_STREAM_ERROR;
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287
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288 if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR;
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289 z->adler = 1L;
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290
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291 if (length >= ((uInt)1<<z->state->wbits))
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292 {
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293 length = (1<<z->state->wbits)-1;
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294 dictionary += dictLength - length;
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295 }
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296 inflate_set_dictionary(z->state->blocks, dictionary, length);
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297 z->state->mode = BLOCKS;
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298 return Z_OK;
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299 }
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300
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301
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302 int ZEXPORT inflateSync(z)
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303 z_streamp z;
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304 {
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305 uInt n; /* number of bytes to look at */
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306 Bytef *p; /* pointer to bytes */
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307 uInt m; /* number of marker bytes found in a row */
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308 uLong r, w; /* temporaries to save total_in and total_out */
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309
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310 /* set up */
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311 if (z == Z_NULL || z->state == Z_NULL)
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312 return Z_STREAM_ERROR;
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313 if (z->state->mode != BAD)
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314 {
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315 z->state->mode = BAD;
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316 z->state->sub.marker = 0;
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317 }
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318 if ((n = z->avail_in) == 0)
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319 return Z_BUF_ERROR;
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320 p = z->next_in;
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321 m = z->state->sub.marker;
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322
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323 /* search */
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324 while (n && m < 4)
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325 {
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326 static const Byte mark[4] = {0, 0, 0xff, 0xff};
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327 if (*p == mark[m])
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328 m++;
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329 else if (*p)
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330 m = 0;
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331 else
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332 m = 4 - m;
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333 p++, n--;
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334 }
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335
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336 /* restore */
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337 z->total_in += p - z->next_in;
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338 z->next_in = p;
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339 z->avail_in = n;
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340 z->state->sub.marker = m;
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341
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342 /* return no joy or set up to restart on a new block */
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343 if (m != 4)
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344 return Z_DATA_ERROR;
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345 r = z->total_in; w = z->total_out;
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346 inflateReset(z);
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347 z->total_in = r; z->total_out = w;
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348 z->state->mode = BLOCKS;
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349 return Z_OK;
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350 }
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351
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352
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353 /* Returns true if inflate is currently at the end of a block generated
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354 * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
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355 * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
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356 * but removes the length bytes of the resulting empty stored block. When
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357 * decompressing, PPP checks that at the end of input packet, inflate is
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358 * waiting for these length bytes.
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359 */
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360 int ZEXPORT inflateSyncPoint(z)
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361 z_streamp z;
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362 {
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363 if (z == Z_NULL || z->state == Z_NULL || z->state->blocks == Z_NULL)
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364 return Z_STREAM_ERROR;
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365 return inflate_blocks_sync_point(z->state->blocks);
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366 }
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