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/**
* `encode.c' - b64
*
* copyright (c) 2014 joseph werle
*/
#include <stdio.h>
#include <stdlib.h>
#include "b64.h"
#ifdef b64_USE_CUSTOM_MALLOC
extern void* b64_malloc(size_t);
#endif
#ifdef b64_USE_CUSTOM_REALLOC
extern void* b64_realloc(void*, size_t);
#endif
char *
b64_encode (const unsigned char *src, size_t len) {
int i = 0;
int j = 0;
char *enc = NULL;
size_t size = 0;
unsigned char buf[4];
unsigned char tmp[3];
// alloc
enc = (char *) b64_malloc(1);
if (NULL == enc) { return NULL; }
// parse until end of source
while (len--) {
// read up to 3 bytes at a time into `tmp'
tmp[i++] = *(src++);
// if 3 bytes read then encode into `buf'
if (3 == i) {
buf[0] = (tmp[0] & 0xfc) >> 2;
buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
buf[3] = tmp[2] & 0x3f;
// allocate 4 new byts for `enc` and
// then translate each encoded buffer
// part by index from the base 64 index table
// into `enc' unsigned char array
enc = (char *) b64_realloc(enc, size + 4);
for (i = 0; i < 4; ++i) {
enc[size++] = b64_table[buf[i]];
}
// reset index
i = 0;
}
}
// remainder
if (i > 0) {
// fill `tmp' with `\0' at most 3 times
for (j = i; j < 3; ++j) {
tmp[j] = '\0';
}
// perform same codec as above
buf[0] = (tmp[0] & 0xfc) >> 2;
buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
buf[3] = tmp[2] & 0x3f;
// perform same write to `enc` with new allocation
for (j = 0; (j < i + 1); ++j) {
enc = (char *) b64_realloc(enc, size + 1);
enc[size++] = b64_table[buf[j]];
}
// while there is still a remainder
// append `=' to `enc'
while ((i++ < 3)) {
enc = (char *) b64_realloc(enc, size + 1);
enc[size++] = '=';
}
}
// Make sure we have enough space to add '\0' character at end.
enc = (char *) b64_realloc(enc, size + 1);
enc[size] = '\0';
return enc;
}
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