UNIX: do not automatically restart syscalls on SIGINTHEADmaster-fmsbw-cimaster

* signal() sets SA_RESTART by default.
* Some syscalls can theoretically block indefinitely.
  Even opening a special file could result in an indefinitely
  blocking operation, that should be interruptible.
  You must still poll teco_interrupted in these read() loops of course.
* Also makes sure that clipboard operations are interruptible
  even if $SCITECO_CLIPBOARD_GET blocks.
  Although I couldn't provoke problems in practice,
  I did observe hangs with xclip on Wayland on Linux,
  that could only be resolved by manually killing xclip.

2 files changed, 15 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index 673fb33..e703aed 100644
--- a/configure.ac
+++ b/configure.ac
@@ -215,7 +215,7 @@ case $host in
 *-*-linux* | *-*-*bsd* | *-*-darwin* | *-*-cygwin* | *-*-haiku*)
 	# NOTE: Keep this on a single line for compatibility
 	# with ancient versions of Autoconf.
-	AC_CHECK_FUNCS([realpath readlink pathconf fchown dup dup2 getpid open read kill mmap popen pclose isatty fork execv setsid], , [
+	AC_CHECK_FUNCS([realpath readlink pathconf fchown dup dup2 getpid open read kill mmap popen pclose isatty fork execv setsid sigaction], , [
 		AC_MSG_ERROR([Missing libc function])
 	])
 	AC_SEARCH_LIBS(dladdr, [dl], , [
diff --git a/src/main.c b/src/main.c
index 33ab26f..29ef024 100644
--- a/src/main.c
+++ b/src/main.c
@@ -388,7 +388,21 @@ main(int argc, char **argv)
 	getchar();
 #endif
 
+	/*
+	 * FIXME: Gracefully handle SIGTERM.
+	 * This however would require polling for the flag in Curses
+	 * getch() loops.
+	 * GTK already catches SIGTERM.
+	 */
+#ifdef HAVE_SIGACTION
+	static const struct sigaction sigint = {
+		.sa_handler = teco_sigint_handler,
+		.sa_flags = 0 /* don't auto-restart syscalls */
+	};
+	sigaction(SIGINT, &sigint, NULL);
+#else
 	signal(SIGINT, teco_sigint_handler);
+#endif
 
 	/*
 	 * Important for Unicode handling in curses and glib.