[1765] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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[2725] | 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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[1765] | 6 | *
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[2725] | 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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[1765] | 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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[3232] | 13 | const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = {
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[1765] | 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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[3232] | 23 | '\0' /* needed for uudecode.c only */
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[1765] | 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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[2725] | 44 | void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl)
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[1765] | 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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[2725] | 74 |
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| 75 | /*
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[3232] | 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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[2725] | 81 | */
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[3232] | 82 | const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
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[2725] | 83 | {
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[3232] | 84 | char *dst = *pp_dst;
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| 85 | const char *src_tail;
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[2725] | 86 |
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| 87 | while (1) {
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[3232] | 88 | unsigned char six_bit[4];
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[2725] | 89 | int count = 0;
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| 90 |
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[3232] | 91 | /* Fetch up to four 6-bit values */
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| 92 | src_tail = src;
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[2725] | 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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[3232] | 100 | * 01234567890123456789012345678901234567890123456789012345678901234
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| 101 | * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
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[2725] | 102 | */
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| 103 | do {
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[3232] | 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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[2725] | 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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[3232] | 126 | if (ch == 64)
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[2725] | 127 | break;
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[3232] | 128 | six_bit[count] = ch;
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[2725] | 129 | count++;
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| 130 | }
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| 131 |
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[3232] | 132 | /* Transform 6-bit values to 8-bit ones.
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[2725] | 133 | * count can be < 4 when we decode the tail:
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[3232] | 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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[2725] | 140 | */
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| 141 | if (count > 1)
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[3232] | 142 | *dst++ = six_bit[0] << 2 | six_bit[1] >> 4;
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[2725] | 143 | if (count > 2)
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[3232] | 144 | *dst++ = six_bit[1] << 4 | six_bit[2] >> 2;
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[2725] | 145 | if (count > 3)
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[3232] | 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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[2725] | 151 | } /* while (1) */
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[3232] | 152 | ret:
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| 153 | *pp_dst = dst;
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| 154 | return src_tail;
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[2725] | 155 | }
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[3232] | 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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