String formatting for error message can be done by using Errorf and
ErrnoErrorf. e.g. `return Errorf("{} failures", num_failure);`
The string format follows that of fmtlib, not printf.
Bug: 132145659
Test: libbase_test
Change-Id: I65f45d5f12ed23e2c14d6eb442278f467cc42e83
It is typical to pass error to callers like following;
if (!result) {
return Error() << result.error();
}
To transfer errno(or ResultError#code()), Error defines a specialization
operator<<(const ResultError&).
This change fixes so that ResultError is properly handled
Bug: 132145659
Test: atest libbase_test
Change-Id: Ib35457da2d4b923d8e652c54ac510a75546cf918
The Result, Error, ErrnoError are quite generic. Moving them from init
to libbase so that they can be used from other places.
Bug: 132145659
Test: libbase_test
Change-Id: Id774a587f74380fadd7a0fc88c0aa892c3d9a489