From c31092b8ac06d845f3022339f55f482308e02b6e Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Sat, 4 Jan 2020 13:58:52 -0800
Subject: [PATCH] Block signals for the helper thread

Let another thread than the helper thread handle signals. This simplifies
error handling. As an example, the next patch will check the return value
of select() and won't have to check for EINTR due to this patch.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 configure       | 24 ++++++++++++++++++++++++
 helper_thread.c | 13 +++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/configure b/configure
index 2671c325..fa6df532 100755
--- a/configure
+++ b/configure
@@ -726,6 +726,27 @@ elif compile_prog "" "$LIBS -lpthread" "pthread_condattr_setclock" ; then
 fi
 print_config "pthread_condattr_setclock()" "$pthread_condattr_setclock"
 
+##########################################
+# pthread_sigmask() probe
+if test "$pthread_sigmask" != "yes" ; then
+  pthread_sigmask="no"
+fi
+cat > $TMPC <<EOF
+#include <stddef.h> /* NULL */
+#include <signal.h> /* pthread_sigmask() */
+int main(void)
+{
+  return pthread_sigmask(0, NULL, NULL);
+}
+EOF
+if compile_prog "" "$LIBS" "pthread_sigmask" ; then
+  pthread_sigmask=yes
+elif compile_prog "" "$LIBS -lpthread" "pthread_sigmask" ; then
+  pthread_sigmask=yes
+  LIBS="$LIBS -lpthread"
+fi
+print_config "pthread_sigmask()" "$pthread_sigmask"
+
 ##########################################
 # solaris aio probe
 if test "$solaris_aio" != "yes" ; then
@@ -2534,6 +2555,9 @@ fi
 if test "$pthread_condattr_setclock" = "yes" ; then
   output_sym "CONFIG_PTHREAD_CONDATTR_SETCLOCK"
 fi
+if test "$pthread_sigmask" = "yes" ; then
+  output_sym "CONFIG_PTHREAD_SIGMASK"
+fi
 if test "$have_asprintf" = "yes" ; then
     output_sym "CONFIG_HAVE_ASPRINTF"
 fi
diff --git a/helper_thread.c b/helper_thread.c
index 28f6cca3..ad2e83b4 100644
--- a/helper_thread.c
+++ b/helper_thread.c
@@ -1,3 +1,4 @@
+#include <signal.h>
 #ifdef CONFIG_VALGRIND_DEV
 #include <valgrind/drd.h>
 #else
@@ -137,6 +138,18 @@ static void *helper_thread_main(void *data)
 
 	sk_out_assign(hd->sk_out);
 
+#ifdef HAVE_PTHREAD_SIGMASK
+	{
+	sigset_t sigmask;
+
+	/* Let another thread handle signals. */
+	ret = pthread_sigmask(SIG_UNBLOCK, NULL, &sigmask);
+	assert(ret == 0);
+	ret = pthread_sigmask(SIG_BLOCK, &sigmask, NULL);
+	assert(ret == 0);
+	}
+#endif
+
 #ifdef CONFIG_PTHREAD_CONDATTR_SETCLOCK
 	clock_gettime(CLOCK_MONOTONIC, &ts);
 #else
-- 
2.25.1