Include $! in error messages

Signed-off-by: Niels Thykier <niels@thykier.net>

4 files changed, 13 insertions, 4 deletions

diff --git a/debian/changelog b/debian/changelog
index 1c3c74dc..98a9d4a1 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+debhelper (10.9.3) UNRELEASED; urgency=medium
+
+  * dh_installsystemd: Improve error messages to include the actual
+    error caused by attempted to open the file.
+  * dh_systemd_enable: Ditto.
+  * dh_systemd_start: Ditto.
+
+ -- Niels Thykier <niels@thykier.net>  Sat, 14 Oct 2017 11:18:19 +0000
+
 debhelper (10.9.2) unstable; urgency=medium
 
   [ Niels Thykier ]
diff --git a/dh_installsystemd b/dh_installsystemd
index 29c60db4..8cd826b9 100755
--- a/dh_installsystemd
+++ b/dh_installsystemd
@@ -156,7 +156,7 @@ init(options => {
 sub contains_install_section {
 	my ($unit_path) = @_;
 
-	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) for extracting the Also= line(s)");
+	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) to check for [Install]: $!");
 
 	while (my $line = <$fh>) {
 		chomp($line);
@@ -185,7 +185,7 @@ sub extract_key {
 
 	return @values if $dh{NO_ALSO};
 
-	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) for extracting the Also= line(s)");
+	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) for extracting the Also= line(s): $!");
 
 	while (my $line = <$fh>) {
 		chomp($line);
diff --git a/dh_systemd_enable b/dh_systemd_enable
index a05aab1e..e2e5add6 100755
--- a/dh_systemd_enable
+++ b/dh_systemd_enable
@@ -124,7 +124,7 @@ init(options => {
 
 sub contains_install_section {
 	my ($unit_path) = @_;
-	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) to check for [Install]");
+	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) to check for [Install]: $!");
 	while (my $line = <$fh>) {
 		chomp($line);
 		return 1 if $line =~ /^\s*\[Install\]$/i;
diff --git a/dh_systemd_start b/dh_systemd_start
index 0c3a51d8..362d00ab 100755
--- a/dh_systemd_start
+++ b/dh_systemd_start
@@ -104,7 +104,7 @@ sub extract_key {
 
 	return if $dh{NO_ALSO};
 
-	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) for extracting the Also= line(s)");
+	open(my $fh, '<', $unit_path) or error("Cannot open($unit_path) for extracting the Also= line(s): $!");
 
 	while (my $line = <$fh>) {
 		chomp($line);