1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Copyright 2003, Glenn McGrath
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4 | * Copyright 2006, Rob Landley <rob@landley.net>
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5 | * Copyright 2010, Denys Vlasenko
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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8 | */
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9 |
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10 | #include "libbb.h"
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11 |
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12 | /* Conversion table. for base 64 */
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13 | const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = {
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14 | 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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15 | 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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16 | 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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17 | 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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18 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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19 | 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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20 | 'w', 'x', 'y', 'z', '0', '1', '2', '3',
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21 | '4', '5', '6', '7', '8', '9', '+', '/',
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22 | '=' /* termination character */,
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23 | '\0' /* needed for uudecode.c only */
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24 | };
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25 |
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26 | const char bb_uuenc_tbl_std[65] ALIGN1 = {
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27 | '`', '!', '"', '#', '$', '%', '&', '\'',
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28 | '(', ')', '*', '+', ',', '-', '.', '/',
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29 | '0', '1', '2', '3', '4', '5', '6', '7',
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30 | '8', '9', ':', ';', '<', '=', '>', '?',
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31 | '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
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32 | 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
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33 | 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
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34 | 'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
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35 | '`' /* termination character */
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36 | };
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37 |
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38 | /*
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39 | * Encode bytes at S of length LENGTH to uuencode or base64 format and place it
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40 | * to STORE. STORE will be 0-terminated, and must point to a writable
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41 | * buffer of at least 1+BASE64_LENGTH(length) bytes.
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42 | * where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3))
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43 | */
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44 | void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
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45 | {
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46 | const unsigned char *s = src;
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47 |
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48 | /* Transform the 3x8 bits to 4x6 bits */
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49 | while (length > 0) {
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50 | unsigned s1, s2;
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51 |
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52 | /* Are s[1], s[2] valid or should be assumed 0? */
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53 | s1 = s2 = 0;
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54 | length -= 3; /* can be >=0, -1, -2 */
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55 | if (length >= -1) {
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56 | s1 = s[1];
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57 | if (length >= 0)
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58 | s2 = s[2];
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59 | }
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60 | *p++ = tbl[s[0] >> 2];
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61 | *p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)];
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62 | *p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)];
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63 | *p++ = tbl[s2 & 0x3f];
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64 | s += 3;
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65 | }
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66 | /* Zero-terminate */
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67 | *p = '\0';
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68 | /* If length is -2 or -1, pad last char or two */
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69 | while (length) {
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70 | *--p = tbl[64];
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71 | length++;
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72 | }
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73 | }
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74 |
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75 | /*
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76 | * Decode base64 encoded string. Stops on '\0'.
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77 | *
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78 | * Returns: pointer to the undecoded part of source.
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79 | * If points to '\0', then the source was fully decoded.
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80 | * (*pp_dst): advanced past the last written byte.
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81 | */
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82 | const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
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83 | {
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84 | char *dst = *pp_dst;
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85 | const char *src_tail;
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86 |
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87 | while (1) {
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88 | unsigned char six_bit[4];
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89 | int count = 0;
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90 |
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91 | /* Fetch up to four 6-bit values */
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92 | src_tail = src;
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93 | while (count < 4) {
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94 | char *table_ptr;
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95 | int ch;
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96 |
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97 | /* Get next _valid_ character.
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98 | * bb_uuenc_tbl_base64[] contains this string:
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99 | * 0 1 2 3 4 5 6
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100 | * 01234567890123456789012345678901234567890123456789012345678901234
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101 | * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
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102 | */
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103 | do {
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104 | ch = *src;
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105 | if (ch == '\0') {
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106 | if (count == 0) {
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107 | /* Example:
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108 | * If we decode "QUJD <NUL>", we want
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109 | * to return ptr to NUL, not to ' ',
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110 | * because we did fully decode
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111 | * the string (to "ABC").
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112 | */
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113 | src_tail = src;
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114 | }
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115 | goto ret;
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116 | }
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117 | src++;
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118 | table_ptr = strchr(bb_uuenc_tbl_base64, ch);
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119 | //TODO: add BASE64_FLAG_foo to die on bad char?
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120 | } while (!table_ptr);
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121 |
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122 | /* Convert encoded character to decimal */
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123 | ch = table_ptr - bb_uuenc_tbl_base64;
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124 |
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125 | /* ch is 64 if char was '=', otherwise 0..63 */
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126 | if (ch == 64)
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127 | break;
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128 | six_bit[count] = ch;
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129 | count++;
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130 | }
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131 |
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132 | /* Transform 6-bit values to 8-bit ones.
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133 | * count can be < 4 when we decode the tail:
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134 | * "eQ==" -> "y", not "y NUL NUL".
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135 | * Note that (count > 1) is always true,
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136 | * "x===" encoding is not valid:
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137 | * even a single zero byte encodes as "AA==".
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138 | * However, with current logic we come here with count == 1
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139 | * when we decode "==" tail.
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140 | */
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141 | if (count > 1)
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142 | *dst++ = six_bit[0] << 2 | six_bit[1] >> 4;
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143 | if (count > 2)
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144 | *dst++ = six_bit[1] << 4 | six_bit[2] >> 2;
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145 | if (count > 3)
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146 | *dst++ = six_bit[2] << 6 | six_bit[3];
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147 | /* Note that if we decode "AA==" and ate first '=',
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148 | * we just decoded one char (count == 2) and now we'll
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149 | * do the loop once more to decode second '='.
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150 | */
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151 | } /* while (1) */
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152 | ret:
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153 | *pp_dst = dst;
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154 | return src_tail;
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155 | }
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156 |
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157 | /*
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158 | * Decode base64 encoded stream.
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159 | * Can stop on EOF, specified char, or on uuencode-style "====" line:
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160 | * flags argument controls it.
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161 | */
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162 | void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
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163 | {
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164 | /* Note that EOF _can_ be passed as exit_char too */
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165 | #define exit_char ((int)(signed char)flags)
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166 | #define uu_style_end (flags & BASE64_FLAG_UU_STOP)
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167 |
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168 | /* uuencoded files have 61 byte lines. Use 64 byte buffer
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169 | * to process line at a time.
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170 | */
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171 | enum { BUFFER_SIZE = 64 };
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172 |
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173 | char in_buf[BUFFER_SIZE + 2];
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174 | char out_buf[BUFFER_SIZE / 4 * 3 + 2];
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175 | char *out_tail;
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176 | const char *in_tail;
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177 | int term_seen = 0;
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178 | int in_count = 0;
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179 |
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180 | while (1) {
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181 | while (in_count < BUFFER_SIZE) {
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182 | int ch = fgetc(src_stream);
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183 | if (ch == exit_char) {
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184 | if (in_count == 0)
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185 | return;
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186 | term_seen = 1;
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187 | break;
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188 | }
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189 | if (ch == EOF) {
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190 | term_seen = 1;
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191 | break;
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192 | }
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193 | /* Prevent "====" line to be split: stop if we see '\n'.
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194 | * We can also skip other whitespace and skirt the problem
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195 | * of files with NULs by stopping on any control char or space:
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196 | */
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197 | if (ch <= ' ')
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198 | break;
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199 | in_buf[in_count++] = ch;
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200 | }
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201 | in_buf[in_count] = '\0';
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202 |
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203 | /* Did we encounter "====" line? */
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204 | if (uu_style_end && strcmp(in_buf, "====") == 0)
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205 | return;
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206 |
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207 | out_tail = out_buf;
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208 | in_tail = decode_base64(&out_tail, in_buf);
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209 |
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210 | fwrite(out_buf, (out_tail - out_buf), 1, dst_stream);
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211 |
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212 | if (term_seen) {
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213 | /* Did we consume ALL characters? */
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214 | if (*in_tail == '\0')
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215 | return;
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216 | /* No */
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217 | bb_error_msg_and_die("truncated base64 input");
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218 | }
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219 |
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220 | /* It was partial decode */
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221 | in_count = strlen(in_tail);
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222 | memmove(in_buf, in_tail, in_count);
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223 | }
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224 | }
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