diff options
Diffstat (limited to 'lib/base64.c')
| -rw-r--r-- | lib/base64.c | 45 |
1 files changed, 38 insertions, 7 deletions
diff --git a/lib/base64.c b/lib/base64.c index 8da969c0..c7f7ac58 100644 --- a/lib/base64.c +++ b/lib/base64.c @@ -1,5 +1,5 @@ /* base64.c -- Encode binary data using printable characters. - Copyright (C) 1999-2001, 2004-2006, 2009-2013 Free Software Foundation, Inc. + Copyright (C) 1999-2001, 2004-2006, 2009-2014 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -59,6 +59,27 @@ to_uchar (char ch) return ch; } +static const char b64c[64] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/* Base64 encode IN array of size INLEN into OUT array. OUT needs + to be of length >= BASE64_LENGTH(INLEN), and INLEN needs to be + a multiple of 3. */ +static void +base64_encode_fast (const char *restrict in, size_t inlen, char *restrict out) +{ + while (inlen) + { + *out++ = b64c[to_uchar (in[0]) >> 2]; + *out++ = b64c[((to_uchar (in[0]) << 4) + (to_uchar (in[1]) >> 4)) & 0x3f]; + *out++ = b64c[((to_uchar (in[1]) << 2) + (to_uchar (in[2]) >> 6)) & 0x3f]; + *out++ = b64c[to_uchar (in[2]) & 0x3f]; + + inlen -= 3; + in += 3; + } +} + /* Base64 encode IN array of size INLEN into OUT array of size OUTLEN. If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero @@ -67,28 +88,38 @@ void base64_encode (const char *restrict in, size_t inlen, char *restrict out, size_t outlen) { - static const char b64str[64] = - "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + /* Note this outlen constraint can be enforced at compile time. + I.E. that the output buffer is exactly large enough to hold + the encoded inlen bytes. The inlen constraints (of corresponding + to outlen, and being a multiple of 3) can change at runtime + at the end of input. However the common case when reading + large inputs is to have both constraints satisfied, so we depend + on both in base_encode_fast(). */ + if (outlen % 4 == 0 && inlen == outlen / 4 * 3) + { + base64_encode_fast (in, inlen, out); + return; + } while (inlen && outlen) { - *out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f]; + *out++ = b64c[to_uchar (in[0]) >> 2]; if (!--outlen) break; - *out++ = b64str[((to_uchar (in[0]) << 4) + *out++ = b64c[((to_uchar (in[0]) << 4) + (--inlen ? to_uchar (in[1]) >> 4 : 0)) & 0x3f]; if (!--outlen) break; *out++ = (inlen - ? b64str[((to_uchar (in[1]) << 2) + ? b64c[((to_uchar (in[1]) << 2) + (--inlen ? to_uchar (in[2]) >> 6 : 0)) & 0x3f] : '='); if (!--outlen) break; - *out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '='; + *out++ = inlen ? b64c[to_uchar (in[2]) & 0x3f] : '='; if (!--outlen) break; if (inlen) |