Merge pull request #7647 from VersatusHPC/refactor/probe-netplan-command-capture

refactor(probe): reuse command capture for netplan

xCAT-probe/lib/perl/probe_utils.pm

@@ -160,16 +160,15 @@ sub get_os {
 
 sub _netplan_get {
     my $key = shift;
-    my $pid = open(my $fh, '-|');
-    return unless defined $pid;
-    if ($pid == 0) {
-        open(STDERR, '>', '/dev/null');
-        exec 'netplan', 'get', $key;
-        exit 1;
-    }
-    my $val = <$fh>;
-    close $fh;
-    return if $?;
+    my ($val, $error) = _capture_command(
+        sub {
+            my $fh = shift;
+            return scalar <$fh>;
+        },
+        1,
+        'netplan', 'get', $key
+    );
+    return if defined $error;
     chomp $val if defined $val;
     return $val;
 }
@@ -183,8 +182,8 @@ sub _command_available {
     return 0;
 }
 
-sub _capture_command_output {
-    my @command = @_;
+sub _capture_command {
+    my ($read_output, $exec_failure_status, @command) = @_;
     my $pid = open(my $fh, '-|');
     unless (defined $pid) {
         my $error = "unable to start '$command[0]': $!";
@@ -193,11 +192,10 @@ sub _capture_command_output {
     if ($pid == 0) {
         open(STDERR, '>', '/dev/null');
         exec @command;
-        exit 127;
+        exit $exec_failure_status;
     }
 
-    local $/;
-    my $output = <$fh>;
+    my $output = $read_output->($fh);
     close $fh;
     my $status = $?;
     if ($status) {
@@ -213,6 +211,22 @@ sub _capture_command_output {
         return wantarray ? (undef, $error) : undef;
     }
 
+    return wantarray ? ($output, undef) : $output;
+}
+
+sub _capture_command_output {
+    my @command = @_;
+    my ($output, $error) = _capture_command(
+        sub {
+            my $fh = shift;
+            local $/;
+            return scalar <$fh>;
+        },
+        127,
+        @command
+    );
+    return wantarray ? (undef, $error) : undef if defined $error;
+
     $output = '' unless defined $output;
     return wantarray ? ($output, undef) : $output;
 }

xCAT-test/unit/probe_utils_netplan_get.t

@@ -0,0 +1,144 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use FindBin;
+use lib "$FindBin::Bin/../../xCAT-probe/lib/perl";
+
+use File::Temp qw(tempdir);
+use Test::More;
+
+require probe_utils;
+
+sub write_file {
+    my ($file, $contents) = @_;
+
+    open(my $fh, '>', $file) or die "Unable to write $file: $!";
+    print $fh $contents;
+    close $fh;
+}
+
+sub read_file {
+    my $file = shift;
+
+    open(my $fh, '<', $file) or die "Unable to read $file: $!";
+    local $/;
+    my $contents = <$fh>;
+    close $fh;
+    return $contents;
+}
+
+my $fake_bin = tempdir(CLEANUP => 1);
+my $argv_file = "$fake_bin/argv";
+my $fake_netplan = "$fake_bin/netplan";
+
+write_file($fake_netplan, <<'EOF');
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+open(my $fh, '>', $ENV{XCAT_TEST_NETPLAN_ARGV}) or die "Unable to record arguments: $!";
+print $fh join("\n", @ARGV), "\n";
+close $fh;
+
+my $mode = $ENV{XCAT_TEST_NETPLAN_MODE} || '';
+if ($mode eq 'multiple-lines') {
+    print "first line\nsecond line\n";
+} elsif ($mode eq 'continued-output') {
+    local $| = 1;
+    print "first line\n";
+    local $SIG{PIPE} = 'IGNORE';
+    for (1 .. 4096) {
+        exit 7 unless print 'x' x 4096;
+    }
+} elsif ($mode eq 'empty-first-line') {
+    print "\nsecond line\n";
+} elsif ($mode eq 'no-trailing-newline') {
+    print "single line";
+} elsif ($mode eq 'empty-output') {
+    exit 0;
+} elsif ($mode eq 'failure') {
+    print "ignored output\n";
+    print STDERR "netplan get failed\n";
+    exit 7;
+} else {
+    die "Unknown test mode: $mode";
+}
+EOF
+chmod oct('755'), $fake_netplan;
+
+local $ENV{PATH} = "$fake_bin:$ENV{PATH}";
+local $ENV{XCAT_TEST_NETPLAN_ARGV} = $argv_file;
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'multiple-lines';
+    is(
+        probe_utils::_netplan_get('ethernets.eth0.addresses'),
+        'first line',
+        'netplan get returns only the first output line'
+    );
+    is(
+        read_file($argv_file),
+        "get\nethernets.eth0.addresses\n",
+        'netplan get receives the exact subcommand and key arguments'
+    );
+}
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'continued-output';
+    ok(
+        !defined(probe_utils::_netplan_get('ethernets.eth0')),
+        'a command failure after the first line still returns undef'
+    );
+}
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'empty-first-line';
+    is(
+        probe_utils::_netplan_get('ethernets.eth0'),
+        '',
+        'an empty first line remains a defined empty value'
+    );
+}
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'no-trailing-newline';
+    is(
+        probe_utils::_netplan_get('ethernets.eth0'),
+        'single line',
+        'output without a trailing newline is preserved'
+    );
+}
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'empty-output';
+    ok(
+        !defined(probe_utils::_netplan_get('ethernets.eth0')),
+        'successful empty output returns undef'
+    );
+    my @values = probe_utils::_netplan_get('ethernets.eth0');
+    is(scalar(@values), 1, 'successful empty output returns one undef value in list context');
+    ok(!defined($values[0]), 'the list-context empty-output value is undef');
+}
+
+{
+    local $ENV{XCAT_TEST_NETPLAN_MODE} = 'failure';
+    ok(
+        !defined(probe_utils::_netplan_get('ethernets.eth0')),
+        'failed netplan get returns undef even when it writes output'
+    );
+    my @values = probe_utils::_netplan_get('ethernets.eth0');
+    is(scalar(@values), 0, 'failed netplan get returns an empty list in list context');
+}
+
+{
+    my $missing_bin = tempdir(CLEANUP => 1);
+    local $ENV{PATH} = $missing_bin;
+    my $value = probe_utils::_netplan_get('ethernets.eth0');
+    my $status = $?;
+
+    ok(!defined($value), 'netplan exec failure returns undef');
+    is($status >> 8, 1, 'netplan exec failure preserves its original exit status');
+}
+
+done_testing();