在Erlang中从IoDevice获取文件名

Question

I have a function which tries to read from an open IoDevice. In the case of {error, Reason} I want to print out the filename.

How can I do that?

Source code:

read_file(IoDevice) ->
    case read_file(IoDevice, []) of
        {ok, OpCodes} ->
            OpCodes;
        {error, Reason} ->
            io:format("Unable to read file ~s: ~s ~n", [File, Reason]),
            []
    end.

Answer 1

An IoDevice can be either a process ID or a file descriptor. If it's a process ID, you can use file:pid2name/1 to obtain the filename:

1> {ok,IoDevice} = file:open("/tmp/x.erl", [read]).
{ok,<0.43.0>}
2> {ok, Filename} = file:pid2name(IoDevice).
{ok,"/tmp/x.erl"}

If the IoDevice is a file descriptor, though, pid2name won't work, and I don't know of a way to obtain the filename in that case.