Show last log if no ID specified

CHANGELOG.md

@@ -22,6 +22,9 @@
 - Flag `--disable-preload` to ignore `[[preload]]` section of
   configuration file.
 
+- Now `out-of-tree log dump` will show the last log if no ID
+  specified.
+
 ## [1.3.0] 2020-05-30
 
 ### Added

db.go

@@ -254,6 +254,24 @@ func getLogByID(db *sql.DB, id int) (le logEntry, err error) {
 	return
 }
 
+func getLastLog(db *sql.DB) (le logEntry, err error) {
+	err = db.QueryRow("SELECT MAX(id), time, name, type, tag, "+
+		"distro_type, distro_release, kernel_release, "+
+		"build_ok, run_ok, test_ok, "+
+		"build_output, run_output, test_output, "+
+		"qemu_stdout, qemu_stderr, "+
+		"kernel_panic, timeout_kill "+
+		"FROM log").Scan(&le.ID, &le.Timestamp,
+		&le.Name, &le.Type, &le.Tag,
+		&le.DistroType, &le.DistroRelease, &le.KernelRelease,
+		&le.Build.Ok, &le.Run.Ok, &le.Test.Ok,
+		&le.Build.Output, &le.Run.Output, &le.Test.Output,
+		&le.Stdout, &le.Stderr,
+		&le.KernelPanic, &le.KilledByTimeout,
+	)
+	return
+}
+
 func createSchema(db *sql.DB) (err error) {
 	err = createMetadataTable(db)
 	if err != nil {

log.go

@@ -100,7 +100,12 @@ func logHandler(db *sql.DB, path, tag string, num int, rate bool) (err error) {
 }
 
 func logDumpHandler(db *sql.DB, id int) (err error) {
-	l, err := getLogByID(db, id)
+	var l logEntry
+	if id > 0 {
+		l, err = getLogByID(db, id)
+	} else {
+		l, err = getLastLog(db)
+	}
 	if err != nil {
 		return
 	}

main.go

@@ -217,7 +217,7 @@ func main() {
 
 	logDumpCommand := logCommand.Command("dump",
 		"Show all info for log entry with ID")
-	logDumpID := logDumpCommand.Arg("ID", "").Required().Int()
+	logDumpID := logDumpCommand.Arg("ID", "").Default("-1").Int()
 
 	logJSONCommand := logCommand.Command("json", "Generate json statistics")
 	logJSONTag := logJSONCommand.Flag("tag", "Filter tag").Required().String()