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Nugine / simd

SIMD-accelerated operations
MIT License
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base64_simd: Forgiving mode should handle missing padding #40

Closed richarddd closed 6 months ago

richarddd commented 7 months ago

Currently forgiving mode handles no padding properly:

decoding SGVsbG8sIHdvcmxkIQ = Hello, world!

but decoding to little padding SGVsbG8sIHdvcmxkIQ= errors.

It would be great if forgiving mode appends the correct padding. Similarly it could also ignore extra padding:

aGVsbG8== = hello

Nugine commented 6 months ago

See https://infra.spec.whatwg.org/#forgiving-base64-decode

The spec does not allow your cases. You can test the behavior via any js runtime. A workaround is to strip all '=' characters from the end of string.

Welcome to Node.js v20.9.0.
Type ".help" for more information.
> atob("SGVsbG8sIHdvcmxkIQ")
'Hello, world!'
> atob("SGVsbG8sIHdvcmxkIQ=")
Uncaught:
DOMException [InvalidCharacterError]: Invalid character
    at new DOMException (node:internal/per_context/domexception:53:5)
    at __node_internal_ (node:internal/util:695:10)
    at atob (node:buffer:1343:11)
> atob("aGVsbG8")
'hello'
> atob("aGVsbG8==")
Uncaught:
DOMException [InvalidCharacterError]: Invalid character
    at new DOMException (node:internal/per_context/domexception:53:5)
    at __node_internal_ (node:internal/util:695:10)
    at atob (node:buffer:1343:11)