[PATCH 3/3] unbound-dhcp-leases-bridge: Make comparison work if old file does not exist

[Michael Tremer <michael.tremer@ipfire.org>]

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This patch catches any errors if the file did not previously exist and
therefore skips the comparison.

Signed-off-by: Michael Tremer <michael.tremer(a)ipfire.org>
---
 config/unbound/unbound-dhcp-leases-bridge | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/config/unbound/unbound-dhcp-leases-bridge b/config/unbound/unbound-dhcp-leases-bridge
index 80c8267e8..7f89f620a 100644
--- a/config/unbound/unbound-dhcp-leases-bridge
+++ b/config/unbound/unbound-dhcp-leases-bridge
@@ -535,17 +535,22 @@ class UnboundConfigWriter(object):
 			f.flush()
 
 			# Compare if the new leases file has changed from the previous version
-			if filecmp.cmp(f.name, self.path, shallow=False):
-				log.debug("The generated leases file has not changed")
+			try:
+				if filecmp.cmp(f.name, self.path, shallow=False):
+					log.debug("The generated leases file has not changed")
 
-				return False
+					return False
+
+				# Remove the old file
+				os.unlink(self.path)
+
+			# If the previous file did not exist, just keep falling through
+			except FileNotFoundError:
+				pass
 
 			# Make file readable for everyone
 			os.fchmod(f.fileno(), stat.S_IRUSR|stat.S_IWUSR|stat.S_IRGRP|stat.S_IROTH)
 
-			# Remove the old file
-			os.unlink(self.path)
-
 			# Move the file to its destination
 			os.link(f.name, self.path)
 
-- 
2.39.2