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 >>> >>> <https://groups.google.com/d/msgid/golang-nuts/0ccee37d-319e-41b3-9bfd-3dc46e0fad78n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> 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 >> >> <https://groups.google.com/d/msgid/golang-nuts/CAJhgacjkUUSr-dOPFU-W4vG_AXZRY_dYYe2ti-iPuu_XUL%2BNVw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> -- >> 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 >> >> <https://groups.google.com/d/msgid/golang-nuts/CF76EF37-6F82-42FF-B4D6-4B9FC02F25FC%40ix.netcom.com?utm_medium=email&utm_source=footer> >> . >> > -- 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.
