iss #909 add functions to turn on/off SIGCHLD handler (#924)

closes #909

include/trick/Executive.hh

@@ -72,6 +72,9 @@ namespace Trick {
             /** Allows the trapping of SIGABRT signals and graceful shutdown.\n */
             bool trap_sigabrt;               /**< trick_units(--) */
 
+            /** Allows the trapping of SIGCHLD signals\n */
+            bool trap_sigchld;               /**< trick_units(--) */
+
             /** Flags a restart was loaded\n */
             bool restart_called;    /**< trick_io(**) trick_units(--) */
 
@@ -540,6 +543,14 @@ namespace Trick {
             */
             bool get_trap_sigabrt() ;
 
+            /**
+             @userdesc Command to get the trap sigchld toggle value (will SIGCHLD signal be trapped).
+             @par Python Usage:
+             @code <my_int> = trick.exec_get_trap_sigsegv() @endcode
+             @return boolean (C integer 0/1) Executive::trap_sigsegv
+            */
+            bool get_trap_sigchld() ;
+
             /**
              @brief @userdesc Command to set the attach debugger toggle value.
              @param on_off - boolean yes (C integer 1) = attach debugger if signal shuts sim down. no (C integer 0) = do not attach debugger.
@@ -714,6 +725,15 @@ namespace Trick {
             */
             int set_trap_sigabrt(bool on_off) ;
 
+            /**
+             @userdesc Command to enable/disable the trapping of SIGCHILD signals.
+             @par Python Usage:
+             @code trick.exec_set_trap_child(<on_off>) @endcode
+             @param on_off - boolean yes (C integer 1) = enable trap, no (C integer 0) = disable trap
+             @return always 0
+            */
+            int set_trap_sigchld(bool on_off) ;
+
             /**
              @userdesc Command to get the simulation time in seconds.
              Formula for simulation time is time_tics / time_tic_value.

include/trick/exec_proto.h

@@ -39,6 +39,7 @@ extern "C" {
     int exec_get_trap_sigfpe(void) ;
     int exec_get_trap_sigsegv(void) ;
     int exec_get_trap_sigabrt(void) ;
+    int exec_get_trap_sigchld(void) ;
 
     int exec_set_attach_debugger(int on_off) ;
     int exec_set_debugger_command(const char * command) ;
@@ -69,6 +70,7 @@ extern "C" {
     int exec_set_trap_sigfpe(int on_off) ;
     int exec_set_trap_sigsegv(int on_off) ;
     int exec_set_trap_sigabrt(int on_off) ;
+    int exec_set_trap_sigchld(int on_off) ;
     int exec_set_version_date_tag(const char * tag) ;
     int exec_set_build_date(const char * date) ;
     int exec_set_current_version(const char * version) ;

trick_source/sim_services/Executive/Executive.cpp

@@ -76,6 +76,7 @@ Trick::Executive::Executive() {
     trap_sigfpe = false ;
     trap_sigsegv = false ;
     trap_sigabrt = false ;
+    trap_sigchld = false ;
 
     build_date = std::string("unknown") ;
     current_version = std::string("unknown") ;
@@ -284,6 +285,10 @@ bool Trick::Executive::get_trap_sigabrt() {
     return(trap_sigabrt) ;
 }
 
+bool Trick::Executive::get_trap_sigchld() {
+    return(trap_sigchld) ;
+}
+
 void Trick::Executive::reset_job_cycle_times() {
     unsigned int ii ;
     for ( ii = 0 ; ii < all_jobs_vector.size() ; ii++ ) {

trick_source/sim_services/Executive/Executive_c_intf.cpp

@@ -390,6 +390,18 @@ extern "C" int exec_get_trap_sigabrt() {
     return -1 ;
 }
 
+/**
+ * @relates Trick::Executive
+ * @copydoc Trick::Executive::get_trap_sigchld
+ * C wrapper for Trick::Executive::get_trap_sigchld
+ */
+extern "C" int exec_get_trap_sigchld() {
+    if ( the_exec != NULL ) {
+        return (int)the_exec->get_trap_sigchld() ;
+    }
+    return -1 ;
+}
+
 // -------------------------- SET ------------------------
 
 /**
@@ -617,6 +629,18 @@ extern "C" int exec_set_trap_sigabrt( int on_off ) {
     return -1 ;
 }
 
+/**
+ * @relates Trick::Executive
+ * @copydoc Trick::Executive::set_trap_sigsegv
+ * C wrapper for Trick::Executive::set_trap_sigsegv
+ */
+extern "C" int exec_set_trap_sigchld( int on_off ) {
+    if ( the_exec != NULL ) {
+        return the_exec->set_trap_sigchld((bool)on_off) ;
+    }
+    return -1 ;
+}
+
 /**
  * @relates Trick::Executive
  * @copydoc Trick::Executive::set_job_onoff

trick_source/sim_services/Executive/Executive_init_signal_handlers.cpp

@@ -135,6 +135,32 @@ int Trick::Executive::set_trap_sigabrt(bool on_off) {
     return(0) ;
 }
 
+/**
+@details
+-# If incoming on_off flag is true assign sig_hand() as the signal handler for SIGCHLD
+-# Else revert to the default signal handler SIG_DFL.
+-# set trap_sigabrt to the current on_off status
+   Requirement [@ref r_exec_signal_0].
+*/
+
+int Trick::Executive::set_trap_sigchld(bool on_off) {
+    static struct sigaction sigact;
+
+    if ( on_off ) {
+        /* Assign sig_hand() as the signal handler for SIGABRT */
+        sigact.sa_handler = (void (*)(int)) child_handler;
+    } else {
+        sigact.sa_handler = SIG_DFL;
+    }
+
+    if (sigaction(SIGCHLD, &sigact, NULL) < 0) {
+        perror("sigaction() failed for SIGCHLD");
+    } else {
+        trap_sigchld = on_off ;
+    }
+    return(0) ;
+}
+
 /**
 @details
 -# Catch SIGBUS, SIGSEGV, and SIGABRT errors. Don't catch SIGFPE
@@ -149,11 +175,12 @@ int Trick::Executive::init_signal_handlers() {
 
     static struct sigaction sigact;
 
-    /* By default catch SIGBUS and SIGSEGV.  Don't catch SIGFPE */
+    /* By default catch SIGBUS, SIGSEGV, SIGABRT, and SIGCHLD.  Don't catch SIGFPE */
     set_trap_sigbus(true) ;
     set_trap_sigfpe(false) ;
     set_trap_sigsegv(true) ;
     set_trap_sigabrt(true) ;
+    set_trap_sigchld(true) ;
 
     /* Assign ctrl_c_hand() as the default signal handler for SIGINT (<CTRL-C> keypress). */
     sigact.sa_handler = (void (*)(int)) ctrl_c_hand;
@@ -173,12 +200,6 @@ int Trick::Executive::init_signal_handlers() {
         perror("sigaction() failed for SIGUSR1");
     }
 
-    /* Assign child_handler() as the default signal handler for SIGCHLD. */
-    sigact.sa_handler = (void (*)(int)) child_handler;
-    if (sigaction(SIGCHLD, &sigact, NULL) < 0) {
-        perror("sigaction() failed for SIGCHLD");
-    }
-
     return(0) ;
 }