Android app fails in locales with Indian-Arabic numerals

[DentonGentry]

What is the issue?

In the Java code where we assemble the list of interfaces we have:

sb.append(String.format("%s %d %d %b %b %b %b %b |", nif.getName(),
               nif.getIndex(), nif.getMTU(), nif.isUp(), nif.supportsMulticast(),
               nif.isLoopback(), nif.isPointToPoint(), nif.supportsMulticast()));

In a locale using Indian-Arabic numerals: ۰ ۱ ۲ ۳ ۴ ۵ ۶ ۷ ۸ ۹
the Java code will format the string as: lo ١ ٦٥٥٣٦ true false true false false |

In the Go code which parses this string, we have:

_, err := fmt.Sscanf(fields[0], "%s %d %d %t %t %t %t %t",
	&name, &index, &mtu, &up, &broadcast, &loopback, &pointToPoint, &multicast)

which does not handle these numerals: unable to parse "lo ١ ٦٥٥٣٦ true false true false false |": expected integer

---

As these strings are purely internal to pass information between the Java runtime and Go environment, they will never be visible to the user. I think the best fix is to set a specific locale in the Java code to format the string.

Steps to reproduce

No response

Are there any recent changes that introduced the issue?

No response

OS

Android

OS version

Android 10

Tailscale version

1.22

Bug report

No response

[bradfitz]

Awesome bug!

[DentonGentry]

"Passing structured data from Java to Go is hard. I know, I'll use strings! What can possibly go wrong with strings?"
^ me, last year.