96 lines
1.5 KiB
C
96 lines
1.5 KiB
C
/*
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* Output a base64 string.
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*
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* Options include:
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* - Character 62 and 63;
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* - To pad or not to pad.
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*/
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#include <inttypes.h>
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#include <base64.h>
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size_t genbase64(char *output, const void *input, size_t size, int flags)
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{
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static char charz[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_";
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uint8_t buf[3];
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int j;
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const uint8_t *p;
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char *q;
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uint32_t bv;
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int left = size;
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charz[62] = (char)flags;
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charz[63] = (char)(flags >> 8);
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p = input;
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q = output;
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while (left > 0) {
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if (left < 3) {
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buf[0] = p[0];
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buf[1] = (left > 1) ? p[1] : 0;
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buf[2] = 0;
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p = buf;
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}
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bv = (p[0] << 16) | (p[1] << 8) | p[2];
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p += 3;
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left -= 3;
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for (j = 0; j < 4; j++) {
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*q++ = charz[(bv >> 18) & 0x3f];
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bv <<= 6;
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}
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}
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switch (left) {
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case -1:
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if (flags & BASE64_PAD)
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q[-1] = '=';
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else
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q--;
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break;
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case -2:
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if (flags & BASE64_PAD)
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q[-2] = q[-1] = '=';
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else
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q -= 2;
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break;
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default:
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break;
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}
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*q = '\0';
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return q - output;
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}
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#ifdef TEST
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#include <stdio.h>
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#include <string.h>
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int main(int argc, char *argv[])
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{
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int i;
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char buf[4096];
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int len, bytes;
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for (i = 1; i < argc; i++) {
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printf("Original: \"%s\"\n", argv[i]);
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len = strlen(argv[i]);
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bytes = genbase64(buf, argv[i], len, BASE64_MIME | BASE64_PAD);
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printf(" MIME: \"%s\" (%d)\n", buf, bytes);
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bytes = genbase64(buf, argv[i], len, BASE64_SAFE);
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printf(" Safe: \"%s\" (%d)\n", buf, bytes);
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}
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return 0;
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}
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#endif
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