pw_base64#

Base64 encoding, decoding, and validating

Stable C C++ Rust

This module provides functions for encoding, decoding, and validating Base64 data as specified by RFC 3548 and RFC 4648.

C++ API reference#

namespace base64#

Functions

constexpr size_t EncodedSize(size_t binary_size_bytes)#

Note

Base64 encodes 3-byte groups into 4-character strings. The final group is padded to be 3 bytes if it only has 1 or 2.

Parameters:

binary_size_bytes – [in] The size of the binary data in bytes, before encoding.

Returns:

The size of binary_size_bytes after Base64 encoding.

inline void Encode(span<const std::byte> binary, char *output)#

Encodes the provided data in Base64 and writes the result to the buffer.

Note

Encodes to the standard alphabet with + and / for characters 62 and 63.

Warning

The resulting string in the output is NOT null-terminated!

Parameters:

  • binary – [in] The binary data to encode.

  • The – [out] output buffer where the encoded data is placed. Exactly EncodedSize(binary_size_bytes) bytes is written.

Pre:

  • The output buffer MUST be large enough for the encoded output!

  • The input and output buffers MUST NOT be the same; encoding cannot occur in place.

size_t Encode(span<const std::byte> binary, span<char> output_buffer)#

Encodes the provided data in Base64 if the result fits in the provided buffer.

Warning

The resulting string in the output is NOT null-terminated!

Parameters:

  • binary – [in] The binary data to encode.

  • output_buffer – [out] The output buffer where the encoded data is placed.

Returns:

The number of bytes written. Returns 0 if the output buffer is too small.

void Encode(span<const std::byte> binary, InlineString<> &output)#

Appends Base64 encoded binary data to the provided pw::InlineString.

If the data does not fit in the string, an assertion fails.

Parameters:

  • binary – [in] The binary data that has already been Base64-encoded.

  • output – [out] The pw::InlineString that binary is appended to.

template<size_t kMaxBinaryDataSizeBytes>
inline InlineString<EncodedSize(kMaxBinaryDataSizeBytes)> Encode(
span<const std::byte> binary,
)#

Creates a pw::InlineString<> large enough to hold kMaxBinaryDataSizeBytes of binary data when encoded as Base64 and encodes the provided span into it.

constexpr size_t MaxDecodedSize(size_t base64_size_bytes)#

Calculates the maximum size of Base64-encoded data after decoding.

Parameters:

base64_size_bytes – [in] The size of the Base64-encoded data.

Pre:

base64_size_bytes must be a multiple of 4, since Base64 encodes 3-byte groups into 4-character strings.

Returns:

The maximum size of the Base64-encoded data represented by base64_bytes_size after decoding. If the last 3-byte group has padding, the actual decoded size will be 1 or 2 bytes less than the value returned by MaxDecodedSize().

inline size_t Decode(std::string_view base64, void *output)#

Decodes the provided Base64 data into raw binary.

Parameters:

  • base64 – [in] The Base64 data that should be decoded. Can be encoded with either the standard (+/) or URL-safe (-_) alphabet. The data must be padded to 4-character blocks with =.

  • output – [out] The output buffer where the raw binary will be placed. The output buffer may be the same as the input buffer; decoding can occur in place.

Pre:

  • The output buffer MUST be at least MaxDecodedSize() bytes large.

  • This function does NOT check that the input is valid! Use IsValid() or the four-argument overload to check the input formatting.

Returns:

The number of bytes that were decoded.

size_t Decode(std::string_view base64, span<std::byte> output_buffer)#

Decodes the provided Base64 data, if the data is valid and fits in the output buffer.

Returns:

The number of bytes written, which will be 0 if the data is invalid or doesn’t fit.

template<typename T>
inline void DecodeInPlace(InlineBasicString<T> &buffer)#

Decodes a pw::InlineString<> in place.

inline bool IsValid(std::string_view base64)#
Parameters:

base64 – [in] The string to check. Can be encoded with either the standard (+/) or URL-safe (-_) alphabet.

Returns:

true if the provided string is valid Base64-encoded data.

inline bool IsValidChar(char base64)#
Parameters:

base64 – [in] The character to check. Can be encoded with either the standard (+/) or URL-safe (-_) alphabet.

Returns:

true if the provided character is a valid Base64 character.

Rust API reference#

pw_base64’s Rust API is documented in the pw_base64 crate’s docs.

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