Record the errno if exec fails

src/lib/Hydra/Plugin/RunCommand.pm

@@ -161,9 +161,9 @@ sub buildFinished {
         $runlog->started();
 
         system("$command") == 0
-            or warn "notification command '$command' failed with exit status $?\n";
+            or warn "notification command '$command' failed with exit status $? ($!)\n";
 
-        $runlog->completed_with_child_error($?);
+        $runlog->completed_with_child_error($?, $!);
     }
 }
 

src/lib/Hydra/Schema/Result/RunCommandLogs.pm

@@ -197,7 +197,10 @@ sub completed_with_child_error {
     if ($child_error == -1) {
       # -1 indicates `exec` failed, and this is the only
       # case where the reported errno is valid.
-      $errno = $reported_errno;
+      #
+      # The `+ 0` is because $! is a dual var and likes to be a string
+      # if it can. +0 forces it to not be. Sigh.
+      $errno = $reported_errno + 0;
     }
 
     if (WIFEXITED($child_error)) {

t/plugins/RunCommand/errno.t

@@ -0,0 +1,50 @@
+use feature 'unicode_strings';
+use strict;
+use warnings;
+use JSON::MaybeXS;
+use Setup;
+
+my %ctx = test_init(
+    hydra_config => q|
+    <runcommand>
+      command = invalid-command-this-does-not-exist
+    </runcommand>
+|);
+
+require Hydra::Schema;
+require Hydra::Model::DB;
+
+use Test2::V0;
+
+my $db = Hydra::Model::DB->new;
+hydra_setup($db);
+
+my $project = $db->resultset('Projects')->create({name => "tests", displayname => "", owner => "root"});
+
+# Most basic test case, no parameters
+my $jobset = createBaseJobset("basic", "runcommand.nix", $ctx{jobsdir});
+
+ok(evalSucceeds($jobset), "Evaluating jobs/runcommand.nix should exit with return code 0");
+is(nrQueuedBuildsForJobset($jobset), 1, "Evaluating jobs/runcommand.nix should result in 1 build1");
+
+(my $build) = queuedBuildsForJobset($jobset);
+
+is($build->job, "metrics", "The only job should be metrics");
+ok(runBuild($build), "Build should exit with return code 0");
+my $newbuild = $db->resultset('Builds')->find($build->id);
+is($newbuild->finished, 1, "Build should be finished.");
+is($newbuild->buildstatus, 0, "Build should have buildstatus 0.");
+
+ok(sendNotifications(), "Notifications execute successfully.");
+
+subtest "Validate a run log was created" => sub {
+    my $runlog = $build->runcommandlogs->find({});
+    is($runlog->job_matcher, "*:*:*", "An unspecified job matcher is defaulted to *:*:*");
+    is($runlog->command, 'invalid-command-this-does-not-exist', "The executed command is saved.");
+    is($runlog->start_time, within(time() - 1, 2), "The start time is recent.");
+    is($runlog->end_time, within(time() - 1, 2), "The end time is also recent.");
+    is($runlog->exit_code, undef, "This command should not have executed.");
+    is($runlog->error_number, 2, "This command failed to exec.");
+};
+
+done_testing;