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/* base64.c -- Encode binary data using printable characters. |
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Copyright (C) 1999, 2000, 2001, 2004, 2005, 2006 Free Software |
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Foundation, Inc. |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2, or (at your option) |
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any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software Foundation, |
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ |
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|
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/* Written by Simon Josefsson. Partially adapted from GNU MailUtils |
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* (mailbox/filter_trans.c, as of 2004-11-28). Improved by review |
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* from Paul Eggert, Bruno Haible, and Stepan Kasal. |
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* |
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* See also RFC 3548 <http://www.ietf.org/rfc/rfc3548.txt>. |
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* |
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* Be careful with error checking. Here is how you would typically |
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* use these functions: |
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* |
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* bool ok = base64_decode_alloc (in, inlen, &out, &outlen); |
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* if (!ok) |
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* FAIL: input was not valid base64 |
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* if (out == NULL) |
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* FAIL: memory allocation error |
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* OK: data in OUT/OUTLEN |
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* |
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* size_t outlen = base64_encode_alloc (in, inlen, &out); |
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* if (out == NULL && outlen == 0 && inlen != 0) |
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* FAIL: input too long |
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* if (out == NULL) |
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* FAIL: memory allocation error |
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* OK: data in OUT/OUTLEN. |
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* |
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*/ |
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|
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#include <config.h> |
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|
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/* Get prototype. */ |
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#include "base64.h" |
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|
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/* Get malloc. */ |
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#include <stdlib.h> |
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|
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/* Get UCHAR_MAX. */ |
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#include <limits.h> |
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|
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/* C89 compliant way to cast 'char' to 'unsigned char'. */ |
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static inline unsigned char |
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to_uchar (char ch) |
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{ |
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return ch; |
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} |
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|
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/* Base64 encode IN array of size INLEN into OUT array of size OUTLEN. |
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If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as |
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possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero |
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terminate the output buffer. */ |
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void |
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base64_encode (const char *restrict in, size_t inlen, |
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char *restrict out, size_t outlen) |
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{ |
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static const char b64str[64] = |
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
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|
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while (inlen && outlen) |
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{ |
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*out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f]; |
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if (!--outlen) |
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break; |
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*out++ = b64str[((to_uchar (in[0]) << 4) |
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+ (--inlen ? to_uchar (in[1]) >> 4 : 0)) |
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& 0x3f]; |
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if (!--outlen) |
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break; |
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*out++ = |
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(inlen |
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? b64str[((to_uchar (in[1]) << 2) |
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+ (--inlen ? to_uchar (in[2]) >> 6 : 0)) |
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& 0x3f] |
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: '='); |
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if (!--outlen) |
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break; |
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*out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '='; |
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if (!--outlen) |
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break; |
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if (inlen) |
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inlen--; |
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if (inlen) |
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in += 3; |
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} |
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|
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if (outlen) |
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*out = '\0'; |
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} |
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|
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/* Allocate a buffer and store zero terminated base64 encoded data |
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from array IN of size INLEN, returning BASE64_LENGTH(INLEN), i.e., |
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the length of the encoded data, excluding the terminating zero. On |
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return, the OUT variable will hold a pointer to newly allocated |
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memory that must be deallocated by the caller. If output string |
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length would overflow, 0 is returned and OUT is set to NULL. If |
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memory allocation failed, OUT is set to NULL, and the return value |
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indicates length of the requested memory block, i.e., |
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BASE64_LENGTH(inlen) + 1. */ |
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size_t |
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base64_encode_alloc (const char *in, size_t inlen, char **out) |
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{ |
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size_t outlen = 1 + BASE64_LENGTH (inlen); |
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|
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/* Check for overflow in outlen computation. |
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* |
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* If there is no overflow, outlen >= inlen. |
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* |
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* If the operation (inlen + 2) overflows then it yields at most +1, so |
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* outlen is 0. |
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* |
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* If the multiplication overflows, we lose at least half of the |
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* correct value, so the result is < ((inlen + 2) / 3) * 2, which is |
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* less than (inlen + 2) * 0.66667, which is less than inlen as soon as |
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* (inlen > 4). |
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*/ |
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if (inlen > outlen) |
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{ |
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*out = NULL; |
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return 0; |
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} |
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|
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*out = malloc (outlen); |
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if (!*out) |
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return outlen; |
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|
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base64_encode (in, inlen, *out, outlen); |
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|
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return outlen - 1; |
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} |
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|
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/* With this approach this file works independent of the charset used |
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(think EBCDIC). However, it does assume that the characters in the |
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Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255. POSIX |
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1003.1-2001 require that char and unsigned char are 8-bit |
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quantities, though, taking care of that problem. But this may be a |
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potential problem on non-POSIX C99 platforms. |
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|
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IBM C V6 for AIX mishandles "#define B64(x) ...'x'...", so use "_" |
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as the formal parameter rather than "x". */ |
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#define B64(_) \ |
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((_) == 'A' ? 0 \ |
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: (_) == 'B' ? 1 \ |
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: (_) == 'C' ? 2 \ |
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: (_) == 'D' ? 3 \ |
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: (_) == 'E' ? 4 \ |
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: (_) == 'F' ? 5 \ |
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: (_) == 'G' ? 6 \ |
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: (_) == 'H' ? 7 \ |
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: (_) == 'I' ? 8 \ |
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: (_) == 'J' ? 9 \ |
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: (_) == 'K' ? 10 \ |
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: (_) == 'L' ? 11 \ |
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: (_) == 'M' ? 12 \ |
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: (_) == 'N' ? 13 \ |
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: (_) == 'O' ? 14 \ |
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: (_) == 'P' ? 15 \ |
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: (_) == 'Q' ? 16 \ |
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: (_) == 'R' ? 17 \ |
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: (_) == 'S' ? 18 \ |
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: (_) == 'T' ? 19 \ |
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: (_) == 'U' ? 20 \ |
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: (_) == 'V' ? 21 \ |
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: (_) == 'W' ? 22 \ |
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: (_) == 'X' ? 23 \ |
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: (_) == 'Y' ? 24 \ |
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: (_) == 'Z' ? 25 \ |
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: (_) == 'a' ? 26 \ |
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: (_) == 'b' ? 27 \ |
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: (_) == 'c' ? 28 \ |
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: (_) == 'd' ? 29 \ |
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: (_) == 'e' ? 30 \ |
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: (_) == 'f' ? 31 \ |
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: (_) == 'g' ? 32 \ |
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: (_) == 'h' ? 33 \ |
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: (_) == 'i' ? 34 \ |
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: (_) == 'j' ? 35 \ |
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: (_) == 'k' ? 36 \ |
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: (_) == 'l' ? 37 \ |
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: (_) == 'm' ? 38 \ |
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: (_) == 'n' ? 39 \ |
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: (_) == 'o' ? 40 \ |
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: (_) == 'p' ? 41 \ |
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: (_) == 'q' ? 42 \ |
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: (_) == 'r' ? 43 \ |
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: (_) == 's' ? 44 \ |
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: (_) == 't' ? 45 \ |
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: (_) == 'u' ? 46 \ |
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: (_) == 'v' ? 47 \ |
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: (_) == 'w' ? 48 \ |
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: (_) == 'x' ? 49 \ |
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: (_) == 'y' ? 50 \ |
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: (_) == 'z' ? 51 \ |
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: (_) == '0' ? 52 \ |
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: (_) == '1' ? 53 \ |
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: (_) == '2' ? 54 \ |
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: (_) == '3' ? 55 \ |
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: (_) == '4' ? 56 \ |
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: (_) == '5' ? 57 \ |
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: (_) == '6' ? 58 \ |
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: (_) == '7' ? 59 \ |
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: (_) == '8' ? 60 \ |
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: (_) == '9' ? 61 \ |
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: (_) == '+' ? 62 \ |
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: (_) == '/' ? 63 \ |
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: -1) |
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|
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static const signed char b64[0x100] = { |
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B64 (0), B64 (1), B64 (2), B64 (3), |
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B64 (4), B64 (5), B64 (6), B64 (7), |
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B64 (8), B64 (9), B64 (10), B64 (11), |
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B64 (12), B64 (13), B64 (14), B64 (15), |
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B64 (16), B64 (17), B64 (18), B64 (19), |
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B64 (20), B64 (21), B64 (22), B64 (23), |
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B64 (24), B64 (25), B64 (26), B64 (27), |
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B64 (28), B64 (29), B64 (30), B64 (31), |
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B64 (32), B64 (33), B64 (34), B64 (35), |
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B64 (36), B64 (37), B64 (38), B64 (39), |
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B64 (40), B64 (41), B64 (42), B64 (43), |
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B64 (44), B64 (45), B64 (46), B64 (47), |
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B64 (48), B64 (49), B64 (50), B64 (51), |
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B64 (52), B64 (53), B64 (54), B64 (55), |
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B64 (56), B64 (57), B64 (58), B64 (59), |
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B64 (60), B64 (61), B64 (62), B64 (63), |
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B64 (64), B64 (65), B64 (66), B64 (67), |
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B64 (68), B64 (69), B64 (70), B64 (71), |
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B64 (72), B64 (73), B64 (74), B64 (75), |
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B64 (76), B64 (77), B64 (78), B64 (79), |
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B64 (80), B64 (81), B64 (82), B64 (83), |
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B64 (84), B64 (85), B64 (86), B64 (87), |
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B64 (88), B64 (89), B64 (90), B64 (91), |
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B64 (92), B64 (93), B64 (94), B64 (95), |
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B64 (96), B64 (97), B64 (98), B64 (99), |
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B64 (100), B64 (101), B64 (102), B64 (103), |
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B64 (104), B64 (105), B64 (106), B64 (107), |
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B64 (108), B64 (109), B64 (110), B64 (111), |
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B64 (112), B64 (113), B64 (114), B64 (115), |
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B64 (116), B64 (117), B64 (118), B64 (119), |
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B64 (120), B64 (121), B64 (122), B64 (123), |
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B64 (124), B64 (125), B64 (126), B64 (127), |
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B64 (128), B64 (129), B64 (130), B64 (131), |
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B64 (132), B64 (133), B64 (134), B64 (135), |
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B64 (136), B64 (137), B64 (138), B64 (139), |
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B64 (140), B64 (141), B64 (142), B64 (143), |
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B64 (144), B64 (145), B64 (146), B64 (147), |
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B64 (148), B64 (149), B64 (150), B64 (151), |
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B64 (152), B64 (153), B64 (154), B64 (155), |
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B64 (156), B64 (157), B64 (158), B64 (159), |
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B64 (160), B64 (161), B64 (162), B64 (163), |
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B64 (164), B64 (165), B64 (166), B64 (167), |
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B64 (168), B64 (169), B64 (170), B64 (171), |
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B64 (172), B64 (173), B64 (174), B64 (175), |
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B64 (176), B64 (177), B64 (178), B64 (179), |
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B64 (180), B64 (181), B64 (182), B64 (183), |
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B64 (184), B64 (185), B64 (186), B64 (187), |
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B64 (188), B64 (189), B64 (190), B64 (191), |
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B64 (192), B64 (193), B64 (194), B64 (195), |
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B64 (196), B64 (197), B64 (198), B64 (199), |
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B64 (200), B64 (201), B64 (202), B64 (203), |
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B64 (204), B64 (205), B64 (206), B64 (207), |
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B64 (208), B64 (209), B64 (210), B64 (211), |
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B64 (212), B64 (213), B64 (214), B64 (215), |
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B64 (216), B64 (217), B64 (218), B64 (219), |
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B64 (220), B64 (221), B64 (222), B64 (223), |
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B64 (224), B64 (225), B64 (226), B64 (227), |
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B64 (228), B64 (229), B64 (230), B64 (231), |
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B64 (232), B64 (233), B64 (234), B64 (235), |
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B64 (236), B64 (237), B64 (238), B64 (239), |
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B64 (240), B64 (241), B64 (242), B64 (243), |
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B64 (244), B64 (245), B64 (246), B64 (247), |
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B64 (248), B64 (249), B64 (250), B64 (251), |
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B64 (252), B64 (253), B64 (254), B64 (255) |
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}; |
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|
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#if UCHAR_MAX == 255 |
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# define uchar_in_range(c) true |
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#else |
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# define uchar_in_range(c) ((c) <= 255) |
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#endif |
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|
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/* Return true if CH is a character from the Base64 alphabet, and |
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false otherwise. Note that '=' is padding and not considered to be |
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part of the alphabet. */ |
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bool |
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isbase64 (char ch) |
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{ |
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return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)]; |
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} |
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|
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/* Decode base64 encoded input array IN of length INLEN to output |
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array OUT that can hold *OUTLEN bytes. Return true if decoding was |
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successful, i.e. if the input was valid base64 data, false |
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otherwise. If *OUTLEN is too small, as many bytes as possible will |
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be written to OUT. On return, *OUTLEN holds the length of decoded |
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bytes in OUT. Note that as soon as any non-alphabet characters are |
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encountered, decoding is stopped and false is returned. This means |
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that, when applicable, you must remove any line terminators that is |
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part of the data stream before calling this function. */ |
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bool |
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base64_decode (const char *restrict in, size_t inlen, |
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char *restrict out, size_t *outlen) |
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{ |
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size_t outleft = *outlen; |
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|
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while (inlen >= 2) |
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{ |
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if (!isbase64 (in[0]) || !isbase64 (in[1])) |
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break; |
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|
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if (outleft) |
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{ |
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*out++ = ((b64[to_uchar (in[0])] << 2) |
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| (b64[to_uchar (in[1])] >> 4)); |
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outleft--; |
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} |
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|
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if (inlen == 2) |
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break; |
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|
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if (in[2] == '=') |
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{ |
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if (inlen != 4) |
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break; |
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|
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if (in[3] != '=') |
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break; |
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|
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} |
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else |
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{ |
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if (!isbase64 (in[2])) |
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break; |
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|
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if (outleft) |
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{ |
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*out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0) |
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| (b64[to_uchar (in[2])] >> 2)); |
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outleft--; |
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} |
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|
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if (inlen == 3) |
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break; |
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|
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if (in[3] == '=') |
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{ |
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if (inlen != 4) |
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break; |
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} |
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else |
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{ |
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if (!isbase64 (in[3])) |
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break; |
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|
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if (outleft) |
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{ |
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*out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0) |
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| b64[to_uchar (in[3])]); |
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outleft--; |
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} |
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} |
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} |
375 |
|
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in += 4; |
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inlen -= 4; |
378 |
} |
379 |
|
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*outlen -= outleft; |
381 |
|
382 |
if (inlen != 0) |
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return false; |
384 |
|
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return true; |
386 |
} |
387 |
|
388 |
/* Allocate an output buffer in *OUT, and decode the base64 encoded |
389 |
data stored in IN of size INLEN to the *OUT buffer. On return, the |
390 |
size of the decoded data is stored in *OUTLEN. OUTLEN may be NULL, |
391 |
if the caller is not interested in the decoded length. *OUT may be |
392 |
NULL to indicate an out of memory error, in which case *OUTLEN |
393 |
contains the size of the memory block needed. The function returns |
394 |
true on successful decoding and memory allocation errors. (Use the |
395 |
*OUT and *OUTLEN parameters to differentiate between successful |
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decoding and memory error.) The function returns false if the |
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input was invalid, in which case *OUT is NULL and *OUTLEN is |
398 |
undefined. */ |
399 |
bool |
400 |
base64_decode_alloc (const char *in, size_t inlen, char **out, |
401 |
size_t *outlen) |
402 |
{ |
403 |
/* This may allocate a few bytes too much, depending on input, |
404 |
but it's not worth the extra CPU time to compute the exact amount. |
405 |
The exact amount is 3 * inlen / 4, minus 1 if the input ends |
406 |
with "=" and minus another 1 if the input ends with "==". |
407 |
Dividing before multiplying avoids the possibility of overflow. */ |
408 |
size_t needlen = 3 * (inlen / 4) + 2; |
409 |
|
410 |
*out = malloc (needlen); |
411 |
if (!*out) |
412 |
return true; |
413 |
|
414 |
if (!base64_decode (in, inlen, *out, &needlen)) |
415 |
{ |
416 |
free (*out); |
417 |
*out = NULL; |
418 |
return false; |
419 |
} |
420 |
|
421 |
if (outlen) |
422 |
*outlen = needlen; |
423 |
|
424 |
return true; |
425 |
} |