shared errno for server/client?

Question

Using remote procedure calls, how can we have shared errno for the server side and client machines?

To clarify, here is the context of my question: I am trying to implement a distributed file system. I aim for a centralized design where I keep files on the server and clients access them through remote procedure call. So when a client opens a file, I call open on the server machine and return a buffer to the client. I want to keep shared errno values so the client will be able to detect a failure on the open call and prints the right error message.

`errno` is a bad idea in any case, and a worse idea in a distributed system. Use exceptions or faults instead. — John Saunders, Jun 22 '14 at 00:26

score 1 · Answer 1 · answered Jun 22 '14 at 05:55

Seems like your options are either:

1) add an errno (output) parameter to each of your RPC calls, or

2) define an additional RPC call to "retrieve latest errno"

Option 2 is probably a bad idea if you have any possibility for multiple simultaneous RPCs to occur (for example, threading), leaving option 1 as the remaining choice. That's the straightforward approach in any case: if the client wants to know the status of the open(), it looks at the results of that RPC call.

shared errno for server/client?

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