Ignore all newline characters in Base64 decoder

[hdima]

Ignore all newline characters in Base64 decoder to make it compatible with other Base64 decoders.

Most of the Base64 decoder implementations ignore all newline characters in the input string. There are some examples:

Python:

>>> "\nA\nQ\n=\n=\n".decode("base64")
'\x01'

Ruby:

irb(main):001:0> "\nA\nQ\n=\n=\n".unpack("m")
=> ["\001"]

Erlang:

1> base64:decode("\nA\nQ\n=\n=\n").
<<1>>

Moreover some Base64 encoders append newline character at the end of the output string by default:

Python:

>>> "\1".encode("base64")
'AQ==\n'

Ruby:

irb(main):001:0> ["\1"].pack("m")
=> "AQ==\n"

So I think it's fairly important for Rust Base64 decoder to accept Base64 inputs even with newline characters in the padding.

[sfackler]

The diff seems to only ignore newlines at the end of the string but the PR description seems to say that it should ignore newlines anywhere in the string. Is this intentional?

[hdima]

@sfackler Yes, it's intentional. Newlines already ignored in the Base64 body: https://github.com/mozilla/rust/blob/master/src/libextra/base64.rs#L224 But at the end of the string only '=' padding character was expected: https://github.com/mozilla/rust/blob/master/src/libextra/base64.rs#L240