tildefriends/deps/base64c

base64c

This is primarily just a fork of a base64 decoder from the FreeBSD codebase. It has received a few modifications:

• removed all allocations, you are expected to pass in a buffer that has sufficient space and you will get an error (-1) if you run out of space
• replaced a dynamically generated lookup table with a hardcoded lookup table
• wrote my own unit tests, i'm sure there are tests for freebsd somewhere but i didn't find them

Embedding

This code is primarily intended to be dropped into an existing code base ( or perhaps using submodules). To do that:

• grab include/base64c.h
• grab src/base64c.h

Usage

Call base64c_encoding_length() to calculate how big a buffer you need to encode a string. It's somewhere around 4 times the size of the input string. This length includes a null terminator.

char input_string[256];

size_t new_len = base64c_encoding_length( strlen(input_string));

unsigned char *buffer = (unsigned char*)malloc(new_len);

Call base64c_encode() to actually encode your input string as base64. It will write to the buffer and return how many characters were written. If there was an error it will return -1.

size_t output_length = base64c_encode(input_string, strlen(input_string), buffer, new_len);

if (output_length == -1) {
  int x = 1/0; // ERROR!
}

Call base64c_decoding_length() to calculate how big a buffer you need to decode. It comes out to about half the size. This number isn't always exact, but it is close to within a byte or two.

size_t decode_len = base64c_decoding_length( strlen(buffer) );

unsigned char *decoded = (unsigned char*)malloc( decode_len );

Call base64c_decode() to decode an encoded base64 string. It will write to the buffer and return how many characters were written. IF there was an error it will return -1. If the string contains invalid number of characters, or has any characters that are not part of the base64 character set an error will be returned.

Building

You need to bootstrap all the autoconf tools by running ./autogen.sh

You need to have autoconf installed to do this.

Once bootstrapped run ./configure

Tests

There are tests in the test/ subfolder. They will be built automatically. There is no special test runner. You can run each of the test cases manually to check whether the code is working properly.

References

(http://web.mit.edu/freebsd/head/contrib/wpa/src/utils/base64.c) (https://github.com/freebsd/freebsd/blob/master/contrib/wpa/src/utils/base64.c)