1/* 2 * Copyright 2020, Data61 3 * Commonwealth Scientific and Industrial Research Organisation (CSIRO) 4 * ABN 41 687 119 230. 5 * 6 * This software may be distributed and modified according to the terms of 7 * the BSD 2-Clause license. Note that NO WARRANTY is provided. 8 * See "LICENSE_BSD2.txt" for details. 9 * 10 * @TAG(DATA61_BSD) 11 */ 12 13#pragma once 14 15#include <stdio.h> 16#include <stdint.h> 17#include <stddef.h> 18#include <utils/arith.h> 19 20/* A streaming base64 encoder */ 21 22typedef struct { 23 FILE *output; 24 uint16_t buffer; 25 size_t bits; 26} base64_t; 27 28#define BASE64_LOOKUP (\ 29 "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \ 30 "abcdefghijklmnopqrstuvwxyz" \ 31 "0123456789+/" \ 32) 33 34/* Create a new base64 streamer that streams to the given output */ 35static inline base64_t base64_new(FILE *output) 36{ 37 return (base64_t) { 38 .output = output, 39 .buffer = 0, 40 .bits = 0, 41 }; 42} 43 44/* Lookup the character for a given bit pattern */ 45static inline uint8_t base64_lookup(uint8_t bit) 46{ 47 return BASE64_LOOKUP[bit & MASK(6)]; 48} 49 50/* Write a byte to a base64 stream */ 51static inline int base64_putbyte(base64_t *streamer, uint8_t byte) 52{ 53 /* Buffer the byte */ 54 streamer->buffer <<= 8; 55 streamer->buffer |= byte; 56 streamer->bits += 8; 57 58 /* Write any bits to the output */ 59 while (streamer->bits >= 6) { 60 streamer->bits -= 6; 61 uint8_t part = streamer->buffer >> streamer->bits; 62 fputc(base64_lookup(part), streamer->output); 63 } 64 65 return 0; 66} 67 68/* Write any remaining data to the output */ 69static inline int base64_terminate(base64_t *streamer) 70{ 71 if (streamer->bits > 0) { 72 size_t padding = 6 - streamer->bits; 73 streamer->buffer <<= padding; 74 fputc(base64_lookup(streamer->buffer), streamer->output); 75 while (padding > 0) { 76 fputc('=', streamer->output); 77 padding -= 2; 78 } 79 } 80 81 /* Reset the streamer */ 82 streamer->bits = 0; 83 84 return 0; 85} 86