What “padding” are you referring to? Each must be 2 characters. And there is a standard that covers this https://tools.ietf.org/html/rfc4648
> On Feb 2, 2021, at 10:57 AM, 'Axel Wagner' via golang-nuts > <golang-nuts@googlegroups.com> wrote: > > > Rogers approach seems like the best one to me - wrap the input in a custom > `io.Reader` that transparently replaces `-_` with `+/` respectively (and drop > trailing `=`). The bufio approach doesn't work, because there is no guarantee > that one of the distinguishing characters is early in the stream and the > "send it to multiple decoders" approach duplicates effort and wastes > resources. > >> On Tue, Feb 2, 2021 at 5:43 PM Amnon <amno...@gmail.com> wrote: >> Reading through a bufio.Reader is often useful for these situations. >> You can peek the beginning of the input in order to decide which decoder to >> use. >> >> Another option is to use the io.TeeReader to duplicate the reader, >> and then send one copy to each decoder. >> One will succeed, and give you the output. >> But you will need to drain the one that fails to prevent the TeeReader form >> stalling. >> >> >>> On Tuesday, 2 February 2021 at 14:17:19 UTC axel.wa...@googlemail.com wrote: >>> This question isn't about the decoded data, but about *which* base64 format >>> is used - i.e. if it uses padding or not and what 2 characters are used >>> outside of a-zA-Z0-9. The most common ones use +/ and -_, so it's easy to >>> tell which is used and just accept either (and padding can be viewed as >>> optional during decoding anyway). >>> >>>> On Tue, Feb 2, 2021 at 2:37 PM Robert Engels <ren...@ix.netcom.com> wrote: >>>> Base64 is always ASCII. The encoded data may be in an arbitrary format. >>>> You need to pass additional metadata or try and detect its encoding. >>>> >>>>>> On Feb 2, 2021, at 6:50 AM, roger peppe <rogp...@gmail.com> wrote: >>>>>> >>>>> >>>>> In case you find it helpful, here's a clone of the base64 command that I >>>>> wrote in Go. I did it precisely because I wanted to be able to decode any >>>>> encoding scheme interchangeably. >>>>> >>>>> https://github.com/rogpeppe/misc/blob/master/cmd/base64/base64.go >>>>> >>>>> I agree that it might be useful to have some of this functionality >>>>> available in the standard library. >>>>> >>>>> cheers, >>>>> rog. >>>>> >>>>>> On Tue, 2 Feb 2021 at 09:08, hey...@gmail.com <hey...@gmail.com> wrote: >>>>>> Hi, >>>>>> >>>>>> I have an io.Reader whose content is encoded in base64 with encoding >>>>>> type unknown. Since there shouldn't be any ambiguity between the two, is >>>>>> it possible to make the base64 automatically pick the right one to >>>>>> decode? >>>>>> >>>>>> Currently I have to read everything out to pin down the encoding, which >>>>>> defeats the purpose of using an io.Reader. >>>>>> >>>>>> Is there a solution to this problem? >>>>>> >>>>>> Thanks in advance. >>>>>> >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "golang-nuts" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>>> an email to golang-nuts...@googlegroups.com. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/golang-nuts/0ccee37d-319e-41b3-9bfd-3dc46e0fad78n%40googlegroups.com. >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google Groups >>>>> "golang-nuts" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send an >>>>> email to golang-nuts...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/golang-nuts/CAJhgacjkUUSr-dOPFU-W4vG_AXZRY_dYYe2ti-iPuu_XUL%2BNVw%40mail.gmail.com. >>>> >>>> -- >>>> You received this message because you are subscribed to the Google Groups >>>> "golang-nuts" group. >>>> To unsubscribe from this group and stop receiving emails from it, send an >>>> email to golang-nuts...@googlegroups.com. >>> >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/golang-nuts/CF76EF37-6F82-42FF-B4D6-4B9FC02F25FC%40ix.netcom.com. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/44621cb2-fae7-4f40-9e50-35b157f4e838n%40googlegroups.com. > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CAEkBMfGGkOX9HzF6e178Cu6BD9Hg4x5LT7AutHkUDPvyK%2BFmYg%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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