[3759] Update LFC check in server

Update the LFC check in the server to check see that neigher
the finish file nor the copy file exists before moving the current
lease information to the copy file.

Add tests to verify that the current file isn't moved if either
of the two files exist.

src/lib/dhcpsrv/memfile_lease_mgr.cc

@@ -806,12 +806,14 @@ template<typename LeaseFileType>
 void Memfile_LeaseMgr::lfcExecute(boost::shared_ptr<LeaseFileType>& lease_file) {
     bool do_lfc = true;
 
-    // Check if the copy of the lease file exists already. If it does, it
+    // Check the status of the LFC instance.
+    // If the finish file exists or the copy of the lease file exists it
     // is an indication that another LFC instance may be in progress or
     // may be stalled. In that case we don't want to rotate the current
     // lease file to avoid overriding the contents of the existing file.
+    CSVFile lease_file_finish(appendSuffix(lease_file->getFilename(), FILE_FINISH));
     CSVFile lease_file_copy(appendSuffix(lease_file->getFilename(), FILE_INPUT));
-    if (!lease_file_copy.exists()) {
+    if (!lease_file_finish.exists() && !lease_file_copy.exists()) {
         // Close the current file so as we can move it to the copy file.
         lease_file->close();
         // Move the current file to the copy file. Remember the result

src/lib/dhcpsrv/tests/memfile_lease_mgr_unittest.cc

@@ -395,7 +395,7 @@ TEST_F(MemfileLeaseMgrTest, lfcTimerDisabled) {
     EXPECT_EQ(0, lease_mgr->getLFCCount());
 }
 
-// This test that the callback function executing the cleanup of the
+// This test checks that the callback function executing the cleanup of the
 // DHCPv4 lease file works as expected.
 TEST_F(MemfileLeaseMgrTest, leaseFileCleanup4) {
     // This string contains the lease file header, which matches
@@ -470,7 +470,7 @@ TEST_F(MemfileLeaseMgrTest, leaseFileCleanup4) {
     EXPECT_EQ(result_file_contents, input_file.readFile());
 }
 
-// This test that the callback function executing the cleanup of the
+// This test checks that the callback function executing the cleanup of the
 // DHCPv6 lease file works as expected.
 TEST_F(MemfileLeaseMgrTest, leaseFileCleanup6) {
     // This string contains the lease file header, which matches
@@ -595,6 +595,129 @@ TEST_F(MemfileLeaseMgrTest, leaseFileCleanupStartFail) {
         " the kea-lfc program has been compiled.";
 }
 
+// This test checks that the callback function executing the cleanup of the
+// files doesn't move the current file if the finish file exists
+TEST_F(MemfileLeaseMgrTest, leaseFileFinish) {
+    // This string contains the lease file header, which matches
+    // the contents of the new file in which no leases have been
+    // stored.
+    std::string new_file_contents =
+        "address,duid,valid_lifetime,expire,subnet_id,"
+        "pref_lifetime,lease_type,iaid,prefix_len,fqdn_fwd,"
+        "fqdn_rev,hostname,hwaddr\n";
+
+    // This string contains the contents of the current lease file.
+    // It should not be moved.
+    std::string current_file_contents = new_file_contents +
+        "2001:db8:1::1,00:01:02:03:04:05:06:0a:0b:0c:0d:0e:0f,200,200,"
+        "8,100,0,7,0,1,1,,\n"
+        "2001:db8:1::1,00:01:02:03:04:05:06:0a:0b:0c:0d:0e:0f,200,800,"
+        "8,100,0,7,0,1,1,,\n";
+    LeaseFileIO current_file(getLeaseFilePath("leasefile6_0.csv"));
+    current_file.writeFile(current_file_contents);
+
+    // This string contains the contens of the finish file.  It should
+    // be moved to the previous file.
+    std::string finish_file_contents = new_file_contents +
+        "2001:db8:1::2,01:01:01:01:01:01:01:01:01:01:01:01:01,200,800,"
+        "8,100,0,7,0,1,1,,\n";
+    LeaseFileIO finish_file(getLeaseFilePath("leasefile6_0.csv.completed"));
+    finish_file.writeFile(finish_file_contents);
+
+    // Create the backend.
+    LeaseMgr::ParameterMap pmap;
+    pmap["type"] = "memfile";
+    pmap["universe"] = "6";
+    pmap["name"] = getLeaseFilePath("leasefile6_0.csv");
+    pmap["lfc-interval"] = "1";
+    boost::scoped_ptr<NakedMemfileLeaseMgr> lease_mgr(new NakedMemfileLeaseMgr(pmap));
+
+    // Try to run the lease file cleanup.
+    ASSERT_NO_THROW(lease_mgr->lfcCallback());
+
+    // The current lease file should not have been touched.
+    ASSERT_TRUE(current_file.exists());
+    EXPECT_EQ(current_file_contents, current_file.readFile());
+
+    // Wait for the LFC process to complete.
+    ASSERT_TRUE(waitForProcess(*lease_mgr, 2));
+
+    // And make sure it has returned an exit status of 0.
+    EXPECT_EQ(0, lease_mgr->getLFCExitStatus())
+        << "Executing the LFC process failed: make sure that"
+        " the kea-lfc program has been compiled.";
+
+    // The LFC should have moved the finish file to the previous file -
+    // leasefile6_0.csv.2
+    LeaseFileIO previous_file(getLeaseFilePath("leasefile6_0.csv.2"), false);
+    ASSERT_TRUE(previous_file.exists());
+    // And this file should contain the contents of the finish file.
+    EXPECT_EQ(finish_file_contents, previous_file.readFile());
+}
+
+// This test checks that the callback function executing the cleanup of the
+// files doesn't move the current file if the copy file exists
+TEST_F(MemfileLeaseMgrTest, leaseFileCopy) {
+    // This string contains the lease file header, which matches
+    // the contents of the new file in which no leases have been
+    // stored.
+    std::string new_file_contents =
+        "address,duid,valid_lifetime,expire,subnet_id,"
+        "pref_lifetime,lease_type,iaid,prefix_len,fqdn_fwd,"
+        "fqdn_rev,hostname,hwaddr\n";
+
+    // This string contains the contents of the current lease file.
+    // It should not be moved.
+    std::string current_file_contents = new_file_contents +
+        "2001:db8:1::1,00:01:02:03:04:05:06:0a:0b:0c:0d:0e:0f,200,200,"
+        "8,100,0,7,0,1,1,,\n"
+        "2001:db8:1::1,00:01:02:03:04:05:06:0a:0b:0c:0d:0e:0f,200,800,"
+        "8,100,0,7,0,1,1,,\n";
+    LeaseFileIO current_file(getLeaseFilePath("leasefile6_0.csv"));
+    current_file.writeFile(current_file_contents);
+
+    // This string contains the contents of the copy file.  It should
+    // be processed and moved to the previous file.  As there is only
+    // one lease the processing should result in the previous file being
+    // the same.
+    std::string input_file_contents = new_file_contents +
+        "2001:db8:1::2,01:01:01:01:01:01:01:01:01:01:01:01:01,200,800,"
+        "8,100,0,7,0,1,1,,\n";
+    LeaseFileIO input_file(getLeaseFilePath("leasefile6_0.csv.1"));
+    input_file.writeFile(input_file_contents);
+
+    // Create the backend.
+    LeaseMgr::ParameterMap pmap;
+    pmap["type"] = "memfile";
+    pmap["universe"] = "6";
+    pmap["name"] = getLeaseFilePath("leasefile6_0.csv");
+    pmap["lfc-interval"] = "1";
+    boost::scoped_ptr<NakedMemfileLeaseMgr> lease_mgr(new NakedMemfileLeaseMgr(pmap));
+
+    // Try to run the lease file cleanup.
+    ASSERT_NO_THROW(lease_mgr->lfcCallback());
+
+    // The current lease file should not have been touched.
+    ASSERT_TRUE(current_file.exists());
+    EXPECT_EQ(current_file_contents, current_file.readFile());
+
+    // Wait for the LFC process to complete.
+    ASSERT_TRUE(waitForProcess(*lease_mgr, 2));
+
+    // And make sure it has returned an exit status of 0.
+    EXPECT_EQ(0, lease_mgr->getLFCExitStatus())
+        << "Executing the LFC process failed: make sure that"
+        " the kea-lfc program has been compiled.";
+
+    // The LFC should have processed the lease and moved it to the previous
+    // file - leasefile6_0.csv.2
+    LeaseFileIO previous_file(getLeaseFilePath("leasefile6_0.csv.2"), false);
+    ASSERT_TRUE(previous_file.exists());
+    // And this file should contain the contents of the copy file.
+    EXPECT_EQ(input_file_contents, previous_file.readFile());
+}
+
+
 // Test that the backend returns a correct value of the interval
 // at which the IOService must be executed to run the handlers
 // for the installed timers.