rts: Split up Itimer.c

This shouldn't have any functional changes. It merely splits up what are
essentially three distinct codepaths which are melding together with
CPP.

At the moment I merely #include the implementation to use with CPP
although this really feels very yucky.

Reviewers: erikd, austin, simonmar

Reviewed By: simonmar

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2130

1 files changed, 29 insertions, 0 deletions

diff --git a/rts/posix/Signals.c b/rts/posix/Signals.c
index bfc7e82e15..7fb854b894 100644
--- a/rts/posix/Signals.c
+++ b/rts/posix/Signals.c
@@ -14,6 +14,7 @@
 #include "Signals.h"
 #include "RtsUtils.h"
 #include "Prelude.h"
+#include "Ticker.h"
 #include "Stable.h"
 #include "Libdw.h"
 
@@ -626,6 +627,34 @@ set_sigtstp_action (rtsBool handle)
     }
 }
 
+/* Used by ItimerTimerCreate and ItimerSetitimer implementations */
+void
+install_vtalrm_handler(int sig, TickProc handle_tick)
+{
+    struct sigaction action;
+
+    action.sa_handler = handle_tick;
+
+    sigemptyset(&action.sa_mask);
+
+#ifdef SA_RESTART
+    // specify SA_RESTART.  One consequence if we don't do this is
+    // that readline gets confused by the -threaded RTS.  It seems
+    // that if a SIGALRM handler is installed without SA_RESTART,
+    // readline installs its own SIGALRM signal handler (see
+    // readline's signals.c), and this somehow causes readline to go
+    // wrong when the input exceeds a single line (try it).
+    action.sa_flags = SA_RESTART;
+#else
+    action.sa_flags = 0;
+#endif
+
+    if (sigaction(sig, &action, NULL) == -1) {
+        sysErrorBelch("sigaction");
+        stg_exit(EXIT_FAILURE);
+    }
+}
+
 /* -----------------------------------------------------------------------------
  * Install default signal handlers.
  *