cosmopolitan/net/http/encodebase64.c
Justine Tunney dcbd2b8668 Add base64 support
Lua Server Pages may now call the EncodeBase64() and DecodeBase64()
functions should they wish to do things like emit embeded data URIs

See #97
2021-03-27 18:17:54 -07:00

48 lines
2.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/mem/mem.h"
#include "net/http/base64.h"
#define CHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
/**
* Encodes binary to base64 ascii representation.
*/
char *EncodeBase64(const void *data, size_t size, size_t *out_size) {
size_t n;
unsigned w;
char *r, *q;
const unsigned char *p, *pe;
if ((n = size) % 3) n += 3 - size % 3;
n /= 3, n *= 4;
if ((r = malloc(n + 1))) {
if (out_size) *out_size = n;
for (q = r, p = data, pe = p + size; p < pe; p += 3) {
w = p[0] << 020;
if (p + 1 < pe) w |= p[1] << 010;
if (p + 2 < pe) w |= p[2] << 000;
*q++ = CHARS[(w >> 18) & 077];
*q++ = CHARS[(w >> 12) & 077];
*q++ = p + 1 < pe ? CHARS[(w >> 6) & 077] : '=';
*q++ = p + 2 < pe ? CHARS[w & 077] : '=';
}
*q++ = '\0';
}
return r;
}