Also handle SIGHUP to reload the configuration

Because that’s what is typically done on other deamons, and we don’t want to
suprise users.

CHANGELOG.rst

@@ -1,6 +1,8 @@
 Version 9.0
 ===========
 
+- SIGHUP is now caught and reloads the configuration like SIGUSR1 and 2.
+
 Version 8.0 - 2018-05-02
 ========================
 

doc/biboumi.1.rst

@@ -42,10 +42,10 @@ variables, with the name all in upper case and prefixed with "BIBOUMI_".
 For example, if the environment contains “BIBOUMI_PASSWORD=blah", this will
 override the value of the “password” option in the configuration file.
 
-Sending SIGUSR1 or SIGUSR2 (see kill(1)) to the process will force it to
+Sending SIGUSR1, SIGUSR2 or SIGHUP (see kill(1)) to the process will force
-re-read the configuration and make it close and re-open the log files. You
+it to re-read the configuration and make it close and re-open the log
-can use this to change any configuration option at runtime, or do a log
+files. You can use this to change any configuration option at runtime, or
-rotation.
+do a log rotation.
 
 Here is a description of every possible option:
 

src/main.cpp

@@ -103,6 +103,7 @@ int main(int ac, char** av)
   sigaddset(&mask, SIGTERM);
   sigaddset(&mask, SIGUSR1);
   sigaddset(&mask, SIGUSR2);
+  sigaddset(&mask, SIGHUP);
   sigprocmask(SIG_BLOCK, &mask, nullptr);
 
   // Install the signals used to exit the process cleanly, or reload the
@@ -124,6 +125,7 @@ int main(int ac, char** av)
   on_sigusr.sa_flags = 0;
   sigaction(SIGUSR1, &on_sigusr, nullptr);
   sigaction(SIGUSR2, &on_sigusr, nullptr);
+  sigaction(SIGHUP, &on_sigusr, nullptr);
 
   auto p = std::make_shared<Poller>();