Avoid subthread signal handling (#1752)

* Avoid subthread signal handling

* subthread signal handling

Since multiple threads responding simultaneously to a signal leading
to race condition, this is used to ensure that only the main thread
handles the signal.

* aesthetic improvements

* Revert IEPTHREADATTRDESTROY to original value

Author: xTire

src/iperf_api.h

@@ -475,6 +475,7 @@ enum {
     IEPTHREADJOIN=152,		// Unable to join thread (check perror)
     IEPTHREADATTRINIT=153,      // Unable to initialize thread attribute (check perror)
     IEPTHREADATTRDESTROY=154,      // Unable to destroy thread attribute (check perror)
+    IEPTHREADSIGMASK=155,      // Unable to initialize sub thread signal mask (check perror)
     /* Stream errors */
     IECREATESTREAM = 200,   // Unable to create a new stream (check herror/perror)
     IEINITSTREAM = 201,     // Unable to initialize stream (check herror/perror)

src/iperf_client_api.c

@@ -36,6 +36,7 @@
 #include <sys/select.h>
 #include <sys/uio.h>
 #include <arpa/inet.h>
+#include <signal.h>
 
 #include "iperf.h"
 #include "iperf_api.h"
@@ -56,6 +57,23 @@ iperf_client_worker_run(void *s) {
     struct iperf_stream *sp = (struct iperf_stream *) s;
     struct iperf_test *test = sp->test;
 
+    /* Blocking signal to make sure that signal will be handled by main thread */
+    sigset_t set;
+    sigemptyset(&set);
+#ifdef SIGTERM
+    sigaddset(&set, SIGTERM);
+#endif
+#ifdef SIGHUP
+    sigaddset(&set, SIGHUP);
+#endif
+#ifdef SIGINT
+    sigaddset(&set, SIGINT);
+#endif
+    if (pthread_sigmask(SIG_BLOCK, &set, NULL) != 0) {
+	    i_errno = IEPTHREADSIGMASK;
+	    goto cleanup_and_fail;
+    }
+
     /* Allow this thread to be cancelled even if it's in a syscall */
     pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
     pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);

src/iperf_error.c

@@ -505,6 +505,9 @@ iperf_strerror(int int_errno)
             snprintf(errstr, len, "unable to create thread attributes");
             perr = 1;
             break;
+	case IEPTHREADSIGMASK:
+	    snprintf(errstr, len, "unable to change mask of blocked signals");
+	    break;
 	case IEPTHREADATTRDESTROY:
             snprintf(errstr, len, "unable to destroy thread attributes");
             perr = 1;

src/iperf_server_api.c

@@ -45,6 +45,7 @@
 #include <sys/resource.h>
 #include <sched.h>
 #include <setjmp.h>
+#include <signal.h>
 
 #include "iperf.h"
 #include "iperf_api.h"
@@ -69,6 +70,23 @@ iperf_server_worker_run(void *s) {
     struct iperf_stream *sp = (struct iperf_stream *) s;
     struct iperf_test *test = sp->test;
 
+    /* Blocking signal to make sure that signal will be handled by main thread */
+    sigset_t set;
+    sigemptyset(&set);
+#ifdef SIGTERM
+    sigaddset(&set, SIGTERM);
+#endif
+#ifdef SIGHUP
+    sigaddset(&set, SIGHUP);
+#endif
+#ifdef SIGINT
+    sigaddset(&set, SIGINT);
+#endif
+    if (pthread_sigmask(SIG_BLOCK, &set, NULL) != 0) {
+	    i_errno = IEPTHREADSIGMASK;
+	    goto cleanup_and_fail;
+    }
+
     /* Allow this thread to be cancelled even if it's in a syscall */
     pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
     pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);