fixed a bug where sub processes would become zombies because the master process caught SIGCHLD but did not wait()

CHANGES

@@ -22,6 +22,11 @@ corrections:
 	ABSTRACT-CONNECT, ABSTRACT-CLIENT, SOCKSA, SOCKS4A
 	(thanks to Fernanda G Weiden for reporting this problem)
 
+	fixed a bug where sub processes would become zombies because the master
+	process caught SIGCHLD but did not wait(). this affected addresses
+	UDP-RECVFROM, IP-RECVFROM, UNIX-RECVFROM, ABSTRACT-RECVFROM
+	(thanks to Evan Borgstrom for reporting this problem)
+
 	corrected some print statements and variable names
 
 	make uninstall  did not uninstall procan

VERSION

@@ -1 +1 @@
-"1.6.0.0+execpty+servres+fd_setsize+udp_sigchld1"
+"1.6.0.0+execpty+servres+fd_setsize+udp_sigchld"

test.sh

@@ -8029,6 +8029,56 @@ PORT=$((PORT+1))
 N=$((N+1))
 
 
+# there was a bug with udp-recvfrom and fork: terminating sub processes became
+# zombies because the master process did caught SIGCHLD but did not wait()
+NAME=UDP4RECVFROM_SIGCHLD
+case "$TESTS" in
+*%functions%*|*%ip4%*|*%udp%*|*%dgram%*|*%$NAME%*)
+TEST="$NAME: test if UDP4-RECVFROM child becomes zombie"
+# idea: run a udp-recvfrom process with fork and -T. Sent it one packet, so a
+# sub process is forked off. Make some transfer and wait until the -T timeout
+# is over. Now check for the child process: if it is zombie the test failed. 
+# Correct is that child process terminated
+tf="$td/test$N.stdout"
+te="$td/test$N.stderr"
+tdiff="$td/test$N.diff"
+tsl=$PORT
+ts="$LOCALHOST:$tsl"
+da=$(date)
+CMD1="$SOCAT $opts -T 0.5 UDP4-RECVFROM:$tsl,reuseaddr,fork PIPE"
+CMD2="$SOCAT $opts - UDP4-SENDTO:$ts"
+printf "test $F_n $TEST... " $N
+$CMD1 >"$tf" 2>"${te}1" &
+pid1=$!
+waitudp4port $tsl 1
+echo "$da" |$CMD2 >>"$tf" 2>>"${te}2"
+rc2=$?
+sleep 1
+#read -p ">"
+l="$(childprocess $pid1)"
+kill $pid1 2>/dev/null; wait
+if [ $rc2 -ne 0 ]; then
+    $PRINTF "$NO_RESULT\n"	# already handled in test UDP4DGRAM
+    numCANT=$((numCANT+1))
+elif ! echo "$da" |diff - "$tf" >"$tdiff"; then
+    $PRINTF "$NO_RESULT\n"	# already handled in test UDP4DGRAMM
+    numCANT=$((numCANT+1))
+elif $(isdefunct "$l"); then
+    $PRINTF "$FAILED: $SOCAT:\n"
+    echo "$CMD1 &"
+    echo "$CMD2"
+    cat "${te}1" "${te}2"
+    numFAIL=$((numFAIL+1))
+else
+    $PRINTF "$OK\n"
+    if [ -n "$debug" ]; then cat "${te}1" "${te}2"; fi
+    numOK=$((numOK+1))
+fi ;;
+esac
+PORT=$((PORT+1))
+N=$((N+1))
+
+
 echo "summary: $((N-1)) tests; $numOK ok, $numFAIL failed, $numCANT could not be performed"
 
 if [ "$numFAIL" -gt 0 ]; then

xio-socket.c

@@ -512,9 +512,37 @@ int _xioopen_dgram_sendto(/* them is already in xfd->peersa */
 static pid_t xio_waitingfor;
 static bool xio_hashappened;
 void xiosigaction_hasread(int signum, siginfo_t *siginfo, void *ucontext) {
+   pid_t pid;
+   int _errno;
+   int status = 0;
+   bool wassig = false;
    Debug5("xiosigaction_hasread(%d, {%d,%d,%d,"F_pid"}, )",
 	  signum, siginfo->si_signo, siginfo->si_errno, siginfo->si_code,
 	  siginfo->si_pid);
+   _errno = errno;
+   do {
+      pid = Waitpid(-1, &status, WNOHANG);
+      if (pid == 0) {
+	 Msg(wassig?E_INFO:E_WARN,
+	     "waitpid(-1, {}, WNOHANG): no child has exited");
+	 Info("childdied() finished");
+	 errno = _errno;
+	 return;
+      } else if (pid < 0 && errno == ECHILD) {
+	 Msg1(wassig?E_INFO:E_WARN,
+	      "waitpid(-1, {}, WNOHANG): %s", strerror(errno));
+	 Info("childdied() finished");
+	 errno = _errno;
+	 return;
+      }
+      wassig = true;
+      if (pid < 0) {
+	 Warn2("waitpid(-1, {%d}, WNOHANG): %s", status, strerror(errno));
+	 Info("childdied() finished");
+	 errno = _errno;
+	 return;
+      }
+   } while (1);
    if (xio_waitingfor == siginfo->si_pid) {
       xio_hashappened = true;
    }