fixed CTRL+C interruptions on Windows; optimized CTRL+C polling on Gtk+

* teco_interrupt() turned out to be unsuitable to kill child processes (eg. when <EB> hangs).
  Instead, we have Win32-specific code now.
* Since SIGINT can be ignored on UNIX, pressing CTRL+C was not guaranteed to kill the
  child process (eg. when <EB> hangs).
  At the same time, it makes sense to send SIGINT first, so programs can terminate gracefully.
  The behaviour has therefore been adapted: Interrupting with CTRL+C the first time will kill
  gracefully. The second time, a more agressive signal is sent to kill the child process.
  Unfortunately, this would be relatively tricky and complicated to do on Windows, so CTRL+C will always
  "hard-kill" the child process.
* Moreover, teco_interrupt() killed the entire process on Windows when called the second time.
  This resulted in any interruption to terminate SciTECO unexpectedly when tried the second time on Gtk/Win32.
* teco_sigint_occurred renamed to teco_interrupted:
  There may be several different sources for setting this flag.
* Checking for CTRL+C on Gtk involves driving the main event loop repeatedly.
  This is a very expensive operation. We now do that only every 100ms. This is still sufficient since
  keyboard input comes from humans.
  This optimization saves 75% runtime on Windows and 90% on Linux.
  * The same optimization turned out to be contraproductive on PDCurses/WinGUI.

1 files changed, 8 insertions, 27 deletions

diff --git a/src/main.c b/src/main.c
index c532294..467eb72 100644
--- a/src/main.c
+++ b/src/main.c
@@ -52,32 +52,13 @@
 
 teco_int_t teco_ed = TECO_ED_AUTOEOL;
 
-volatile sig_atomic_t teco_sigint_occurred = FALSE;
-
-#ifdef G_OS_UNIX
-
-void
-teco_interrupt(void)
-{
-	/*
-	 * This sends SIGINT to the entire process group,
-	 * which makes sure that subprocesses are signalled,
-	 * even when called from the wrong thread.
-	 */
-	if (kill(0, SIGINT))
-		teco_sigint_occurred = TRUE;
-}
-
-#else /* !G_OS_UNIX */
-
-void
-teco_interrupt(void)
-{
-	if (raise(SIGINT))
-		teco_sigint_occurred = TRUE;
-}
-
-#endif
+/**
+ * Whether there was an asyncronous interruption (usually after pressing CTRL+C).
+ * However you should always use teco_interface_is_interrupted(),
+ * to check for interruptions because of its side effects.
+ * This variable is safe to set to TRUE from signal handlers and threads.
+ */
+volatile sig_atomic_t teco_interrupted = FALSE;
 
 /*
  * FIXME: Move this into file-utils.c?
@@ -309,7 +290,7 @@ teco_initialize_environment(const gchar *program)
 static void
 teco_sigint_handler(int signal)
 {
-	teco_sigint_occurred = TRUE;
+	teco_interrupted = TRUE;
 }
 
 int