B64decode

$b64decode(text) is now a script-provided compatibility function in builtins, not a registered C built-in. It returns $xform(-b64 text), decoding ordinary Base64 text into bytes. The reverse wrapper is b64encode.

For direct use, see xform:

$xform(-b64 aGVsbG8=)

This returns hello. The wrapper is available only when its defining script has been loaded; default startup normally loads builtins.

Base64 encodes groups of three bytes as four characters, with padding for a final partial group. A final decoded NUL byte inside the returned data terminates the visible C-string result, so the wrapper is unsuitable for returning arbitrary binary data intact. For binary work, keep decoding and a final text-safe encoding in one xform chain; intermediate lengths are retained there.

The decoder stops on a decoding error and can return an already decoded prefix rather than a separate validity flag. Do not treat a nonempty result as proof that all input was valid. This is ordinary Base64, not the former FiSH encoding; the current transform registry does not provide fish64.

Source references

• script/builtins: b64decode and b64encode wrappers.
• source/ircaux.c: b64 transform registry and decoder.
• source/functions.c: xform interface and current built-in registry.