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Universal::errno - Wrapper for errno modules for Unix and Windows


use Universal::errno;


  say errno;
  say "failed: {errno}";
  say +errno;              #2


Universal::errno is an extension of and wrapper around lizmat's Unix::errno, and exports the same errno and set_errno interface. It works on Linux, Windows, and Macos. BSD support is untested, but should work.

One added feature is the strerror method, which gets the string for the error in a thread-safe way. On platforms that support it, it uses POSIX strerror_l. This allows getting the error string that corresponds to the user's set locale. On platforms that don't support it, strerror_r (XSI) is used. On Windows, this is done using GetLastError() and FormatMessageW. Windows also has a SetLastError function which is used instead of masking the value.

This module provides an Exception class, X::errno. To check the type of error in a portable way, use the symbol method and smartmatch against an entry in the Errno enum.

It also provides a trait: error-model. Mark a sub or method with is error-model<errno> and the trait will automatically box the errno for you and reset errno to 0.

Important note: With a native sub, the is native trait must come before is error-model.

For calls that return -errno, there is also the trait is error-model<neg-errno>.

If high-performance is needed for a native sub that can return errno, use the check-errno and/or check-neg-errno subs. These subs are interchangeable with the traits, but cannot be directly applied to a nativecall subroutine.

As an example of a real-world scenario, this code sets up a socket using socket(2) and handles the errors with a CATCH block.

use NativeCall;
use Constants::Sys::Socket;

sub socket(int32, int32, int32) returns int32 is native is error-model<errno> { ... }
my int32 $socket;

try {
  $socket = socket(AF::INET, SOCK_DGRAM, 0);

  # Do something with $socket

    when X::errno {
      given .symbol {
        when Errno::EINVAL {
          die "Invalid socket type"
        when Errno::EACCES {
          die "Permission denied"

class X::errno

Exception class for errno

method message

method message() returns Mu

Get the Str message for this errno value.

method symbol

method symbol() returns Mu

Get the symbol of this errno value.

method Int

method Int() returns Mu

Get the integer that corresponds to this errno value.


sub check-neg-errno

sub check-neg-errno(
    Int $result
) returns Mu

Check the result against the negative errno form.

sub check-errno

sub check-errno(
    Int $result
) returns Mu

Check the result against the errno() form.


Travis Gibson TGib.Travis@protonmail.com


Uses a heavily-modified Unix::errno module for Unix-like OSes, and uses Windows::errno (also based on lizmat's Unix::errno) for Windows OSes.

Universal::errno::Unix contains all of the modified code, and this README also borrows the SYNOPSIS example above. The original README and COPYRIGHT information for lizmat's Unix::errno has been preserved in Universal::errno::Unix.

lizmat's Unix::errno can be found at https://github.com/lizmat/Unix-errno


Copyright 2020 Travis Gibson

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.