mongoose/docs/c-api/util.h/mg_base64_decode.md

title	decl_name	symbol_kind	signature
mg_base64_decode()	mg_base64_decode	func	int mg_base64_decode(const unsigned char *s, int len, char *dst);

Decode base64-encoded string s, len into the destination dst. Destination has to have enough space to hold decoded buffer. Decoding stops either when all string has been decoded, or invalid character appeared. Destination is '\0'-terminated. Return number of decoded characters. On success, that should be equal to len. On error (invalid character) the return value is smaller then len.