Base64

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Header

#include <encode/base64.h>

Functions

uint32_t	b64_encoded_size (...)
uint32_t	b64_decoded_size (...)
uint32_t	b64_encode (...)
uint32_t	b64_decode (...)
String*	b64_encode_from_stm (...)
String*	b64_encode_from_file (...)
String*	b64_encode_from_data (...)
String*	b64_encode_from_str (...)
String*	b64_encode_from_cstr (...)
Buffer*	b64_decode_from_str (...)
Buffer*	b64_decode_from_data (...)

Base64 is a coding system that converts binary data (such as images or files) into a text string composed of ASCII characters for transmission and storage, especially in environments that only admit text (such as emails, URLs, JSON, XML). As the name implies, 64 symbols are used for coding that are A-Z, a-z, 0-9 in this order for the first 62 digits, plus two additional characters +/. The protocol is relatively simple and can be summarized in:

Divide the binary data into blocks of 3 bytes (24 bits).
Each block is divided into 4 groups of 6 bits.
Each 6-bit group translates to a character of the 64 allowed.
Base64 encoding increases data size by approximately 33%, since every 3 bytes become 4 characters.
It allows to send and store binary data in systems that only accept flat text.
Does not encrypt or protect the data, it only represents them in a textual way.

b64_encoded_size ()

Get the number of bytes needed to encode a memory block in format base64.

uint32_t
b64_encoded_size(const uint32_t data_size);

data_size

The original block size.

Return

Base64 size.

b64_decoded_size ()

Get the number of bytes needed to decode a block of memory in base64 format.

uint32_t
b64_decoded_size(const uint32_t data_size);

data_size

The block size encoded in base64.

Return

The size in bytes.

b64_encode ()

Encode a block of memory in base64.

uint32_t
b64_encode(const byte_t *data,
           const uint32_t size,
           char_t *base64);

data	The data block.
size	Block size.
base64	The buffer where to store the result.

Return

The size in bytes.

Remarks

The buffer base64 must be at least the size returned by b64_encoded_size.

b64_decode ()

Decodes a block base64.

uint32_t
b64_decode(const char_t *base64,
           const uint32_t size,
           byte_t *data);

base64	The base64 block.
size	Block size.
data	The buffer where to store the result.

Return

The size in bytes.

Remarks

The buffer data must be at least the size returned by b64_decoded_size.

b64_encode_from_stm ()

Create a base64 with the contents of an input stream.

String*
b64_encode_from_stm(Stream *stm);

stm	Input stream.

Return

Base64 text string.

b64_encode_from_file ()

Create a base64 with the contents of a file.

String*
b64_encode_from_file(const char_t *pathname,
                     ferror_t *error);

pathname	File path.
error	Error code file opening fails. It can be `NULL`.

Return

Base64 text string.

Remarks

Will return an empty string (not NULL) if it cannot open the file.

b64_encode_from_data ()

Create a base64 from an in-memory buffer.

String*
b64_encode_from_data(const byte_t *data,
                     const uint32_t size);

data	Data block.
size	Data block size.

Return

Base64 text string.

b64_encode_from_str ()

Create a base64 from a String.

String*
b64_encode_from_str(const String *str);

str

String.

Return

Base64 text string.

b64_encode_from_cstr ()

Create a base64 from a C string.

String*
b64_encode_from_cstr(const char_t *str);

str	Char string in UTF8, finished in a null character (`'\n'`).

Return

Base64 text string.

b64_decode_from_str ()

Decodes a text in base64.

Buffer*
b64_decode_from_str(const String *base64);

base64

Base64 string.

Return

Buffer with the result.

b64_decode_from_data ()

Decodes a text in base64.

Buffer*
b64_decode_from_data(const byte_t *data,
                     const uint32_t size);

data	Data buffer containing base64 text.
size	Size in bytes of `data`.

Return

Buffer with the result.