Prevent unnecessary creation of a PID file

When running in foreground, a PID file should be created only if
the `--pid-file` option is specified.
Rel #25

acme_common/src/lib.rs

@@ -40,12 +40,12 @@ pub fn b64_encode<T: ?Sized + AsRef<[u8]>>(input: &T) -> String {
     base64::encode_config(input, base64::URL_SAFE_NO_PAD)
 }
 
-pub fn init_server(foreground: bool, pid_file: &str) {
+pub fn init_server(foreground: bool, pid_file: Option<&str>, default_pid_file: &str) {
     if !foreground {
-        let daemonize = Daemonize::new().pid_file(pid_file);
+        let daemonize = Daemonize::new().pid_file(pid_file.unwrap_or(default_pid_file));
         exit_match!(daemonize.start());
-    } else {
-        exit_match!(write_pid_file(pid_file));
+    } else if let Some(f) = pid_file {
+        exit_match!(write_pid_file(f));
     }
 }
 

acmed/src/main.rs

@@ -117,7 +117,8 @@ fn main() {
 
     init_server(
         matches.is_present("foreground"),
-        matches.value_of("pid-file").unwrap_or(DEFAULT_PID_FILE),
+        matches.value_of("pid-file"),
+        DEFAULT_PID_FILE,
     );
 
     let config_file = matches.value_of("config").unwrap_or(DEFAULT_CONFIG_FILE);

tacd/src/main.rs

@@ -42,7 +42,8 @@ fn get_acme_value(cnf: &ArgMatches, opt: &str, opt_file: &str) -> Result<String,
 fn init(cnf: &ArgMatches) -> Result<(), Error> {
     acme_common::init_server(
         cnf.is_present("foreground"),
-        cnf.value_of("pid-file").unwrap_or(DEFAULT_PID_FILE),
+        cnf.value_of("pid-file"),
+        DEFAULT_PID_FILE,
     );
     let domain = get_acme_value(cnf, "domain", "domain-file")?;
     let domain = to_idna(&domain)?;