Try harder to kill bad processes

src/iostream.c

@@ -601,7 +601,17 @@ Obj FuncCLOSE_PTY_IOSTREAM(Obj self, Obj stream)
     if (retcode)
         Pr("Strange close return code %d\n", retcode, 0);
     kill(PtyIOStreams[pty].childPID, SIGTERM);
-    retcode = waitpid(PtyIOStreams[pty].childPID, &status, 0);
+    retcode = waitpid(PtyIOStreams[pty].childPID, &status, WNOHANG);
+    if (retcode == 0) {
+        // Give process a second to quit
+        SySleep(1);
+        retcode = waitpid(PtyIOStreams[pty].childPID, &status, WNOHANG);
+    }
+    if (retcode == 0) {
+        // Hard kill process
+        kill(PtyIOStreams[pty].childPID, SIGKILL);
+        retcode = waitpid(PtyIOStreams[pty].childPID, &status, 0);
+    }
     FreeStream(pty);
     HashUnlock(PtyIOStreams);
     return 0;

tst/testbugfix/2017-10-20-runprocess.tst

@@ -0,0 +1,44 @@
+# This is based on an older fragile test - 2006/01/11 (MC)
+# We want to check two cases:
+# Firstly we ensure we read a whole line, by using a while loop
+gap> d := DirectoryCurrent();;
+gap> f := Filename(DirectoriesSystemPrograms(), "rev");;
+gap> func1 := function()
+>    local line,s;
+>    if f <> fail then
+>      s := InputOutputLocalProcess(d,f,[]);;
+>      if PrintFormattingStatus(s) <> false then
+>        Print( "unexpected PrintFormattingStatus value\n" );
+>      fi;
+>      SetPrintFormattingStatus(s,false);
+>      AppendTo(s,"The cat sat on the mat\n");
+>      line := ReadLine(s);
+>      while line[Length(line)] <> '\n' do
+>        line := Concatenation(line, ReadLine(s));
+>      od;
+>      if line <> "tam eht no tas tac ehT\n" then
+>        Print( "There is a problem concerning a cat on a mat.\n" );
+>      fi;
+>      CloseStream(s);
+>    fi;
+>  end;;
+gap>  for i in [1..1000] do func1(); od;
+
+# Here we might only get part of the line
+# This is mainly to check we kill the process when it still has output
+gap> func2 := function()
+>    local line,s;
+>    if f <> fail then
+>      s := InputOutputLocalProcess(d,f,[]);;
+>      if PrintFormattingStatus(s) <> false then
+>        Print( "unexpected PrintFormattingStatus value\n" );
+>      fi;
+>      SetPrintFormattingStatus(s,false);
+>      AppendTo(s,"The cat sat on the mat\n");
+>      if not StartsWith("tam eht no tas tac ehT\n", ReadLine(s)) then
+>        Print( "There is a problem concerning a cat on a mat.\n" );
+>      fi;
+>      CloseStream(s);
+>    fi;
+>  end;;
+gap>  for i in [1..1000] do func2(); od;