Per Richard, replace LLProcessLauncher with LLProcess.

LLProcessLauncher had the somewhat fuzzy mandate of (1) accumulating
parameters with which to launch a child process and (2) sometimes tracking the
lifespan of the ensuing child process. But a valid LLProcessLauncher object
might or might not have ever been associated with an actual child process.
LLProcess specifically tracks a child process. In effect, it's a fairly thin
wrapper around a process HANDLE (on Windows) or pid_t (elsewhere), with
lifespan management thrown in. A static LLProcess::create() method launches a
new child; create() accepts an LLSD bundle with child parameters. So building
up a parameter bundle is deferred to LLSD rather than conflated with the
process management object.
Reconcile all known LLProcessLauncher consumers in the viewer code base,
notably the class unit tests.

1 files changed, 706 insertions, 0 deletions

diff --git a/indra/llcommon/tests/llprocess_test.cpp b/indra/llcommon/tests/llprocess_test.cpp
new file mode 100644
index 0000000000..55e22abd81
--- /dev/null
+++ b/indra/llcommon/tests/llprocess_test.cpp
@@ -0,0 +1,706 @@
+/**
+ * @file   llprocess_test.cpp
+ * @author Nat Goodspeed
+ * @date   2011-12-19
+ * @brief  Test for llprocess.
+ * 
+ * $LicenseInfo:firstyear=2011&license=viewerlgpl$
+ * Copyright (c) 2011, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "llprocess.h"
+// STL headers
+#include <vector>
+#include <list>
+// std headers
+#include <fstream>
+// external library headers
+#include "llapr.h"
+#include "apr_thread_proc.h"
+#include <boost/foreach.hpp>
+#include <boost/function.hpp>
+#include <boost/algorithm/string/find_iterator.hpp>
+#include <boost/algorithm/string/finder.hpp>
+//#include <boost/lambda/lambda.hpp>
+//#include <boost/lambda/bind.hpp>
+// other Linden headers
+#include "../test/lltut.h"
+#include "../test/manageapr.h"
+#include "../test/namedtempfile.h"
+#include "stringize.h"
+#include "llsdutil.h"
+
+#if defined(LL_WINDOWS)
+#define sleep(secs) _sleep((secs) * 1000)
+#define EOL "\r\n"
+#else
+#define EOL "\n"
+#include <sys/wait.h>
+#endif
+
+//namespace lambda = boost::lambda;
+
+// static instance of this manages APR init/cleanup
+static ManageAPR manager;
+
+/*****************************************************************************
+*   Helpers
+*****************************************************************************/
+
+#define ensure_equals_(left, right) \
+        ensure_equals(STRINGIZE(#left << " != " << #right), (left), (right))
+
+#define aprchk(expr) aprchk_(#expr, (expr))
+static void aprchk_(const char* call, apr_status_t rv, apr_status_t expected=APR_SUCCESS)
+{
+    tut::ensure_equals(STRINGIZE(call << " => " << rv << ": " << manager.strerror(rv)),
+                       rv, expected);
+}
+
+/**
+ * Read specified file using std::getline(). It is assumed to be an error if
+ * the file is empty: don't use this function if that's an acceptable case.
+ * Last line will not end with '\n'; this is to facilitate the usual case of
+ * string compares with a single line of output.
+ * @param pathname The file to read.
+ * @param desc Optional description of the file for error message;
+ * defaults to "in <pathname>"
+ */
+static std::string readfile(const std::string& pathname, const std::string& desc="")
+{
+    std::string use_desc(desc);
+    if (use_desc.empty())
+    {
+        use_desc = STRINGIZE("in " << pathname);
+    }
+    std::ifstream inf(pathname.c_str());
+    std::string output;
+    tut::ensure(STRINGIZE("No output " << use_desc), std::getline(inf, output));
+    std::string more;
+    while (std::getline(inf, more))
+    {
+        output += '\n' + more;
+    }
+    return output;
+}
+
+/**
+ * Construct an LLProcess to run a Python script.
+ */
+struct PythonProcessLauncher
+{
+    /**
+     * @param desc Arbitrary description for error messages
+     * @param script Python script, any form acceptable to NamedTempFile,
+     * typically either a std::string or an expression of the form
+     * (lambda::_1 << "script content with " << variable_data)
+     */
+    template <typename CONTENT>
+    PythonProcessLauncher(const std::string& desc, const CONTENT& script):
+        mDesc(desc),
+        mScript("py", script)
+    {
+        const char* PYTHON(getenv("PYTHON"));
+        tut::ensure("Set $PYTHON to the Python interpreter", PYTHON);
+
+        mParams["executable"] = PYTHON;
+        mParams["args"].append(mScript.getName());
+    }
+
+    /// Run Python script and wait for it to complete.
+    void run()
+    {
+        mPy = LLProcess::create(mParams);
+        tut::ensure(STRINGIZE("Couldn't launch " << mDesc << " script"), mPy);
+        // One of the irritating things about LLProcess is that
+        // there's no API to wait for the child to terminate -- but given
+        // its use in our graphics-intensive interactive viewer, it's
+        // understandable.
+        while (mPy->isRunning())
+        {
+            sleep(1);
+        }
+    }
+
+    /**
+     * Run a Python script using LLProcess, expecting that it will
+     * write to the file passed as its sys.argv[1]. Retrieve that output.
+     *
+     * Until January 2012, LLProcess provided distressingly few
+     * mechanisms for a child process to communicate back to its caller --
+     * not even its return code. We've introduced a convention by which we
+     * create an empty temp file, pass the name of that file to our child
+     * as sys.argv[1] and expect the script to write its output to that
+     * file. This function implements the C++ (parent process) side of
+     * that convention.
+     */
+    std::string run_read()
+    {
+        NamedTempFile out("out", ""); // placeholder
+        // pass name of this temporary file to the script
+        mParams["args"].append(out.getName());
+        run();
+        // assuming the script wrote to that file, read it
+        return readfile(out.getName(), STRINGIZE("from " << mDesc << " script"));
+    }
+
+    LLSD mParams;
+    LLProcessPtr mPy;
+    std::string mDesc;
+    NamedTempFile mScript;
+};
+
+/// convenience function for PythonProcessLauncher::run()
+template <typename CONTENT>
+static void python(const std::string& desc, const CONTENT& script)
+{
+    PythonProcessLauncher py(desc, script);
+    py.run();
+}
+
+/// convenience function for PythonProcessLauncher::run_read()
+template <typename CONTENT>
+static std::string python_out(const std::string& desc, const CONTENT& script)
+{
+    PythonProcessLauncher py(desc, script);
+    return py.run_read();
+}
+
+/// Create a temporary directory and clean it up later.
+class NamedTempDir: public boost::noncopyable
+{
+public:
+    // Use python() function to create a temp directory: I've found
+    // nothing in either Boost.Filesystem or APR quite like Python's
+    // tempfile.mkdtemp().
+    // Special extra bonus: on Mac, mkdtemp() reports a pathname
+    // starting with /var/folders/something, whereas that's really a
+    // symlink to /private/var/folders/something. Have to use
+    // realpath() to compare properly.
+    NamedTempDir():
+        mPath(python_out("mkdtemp()",
+                         "from __future__ import with_statement\n"
+                         "import os.path, sys, tempfile\n"
+                         "with open(sys.argv[1], 'w') as f:\n"
+                         "    f.write(os.path.realpath(tempfile.mkdtemp()))\n"))
+    {}
+
+    ~NamedTempDir()
+    {
+        aprchk(apr_dir_remove(mPath.c_str(), gAPRPoolp));
+    }
+
+    std::string getName() const { return mPath; }
+
+private:
+    std::string mPath;
+};
+
+/*****************************************************************************
+*   TUT
+*****************************************************************************/
+namespace tut
+{
+    struct llprocess_data
+    {
+        LLAPRPool pool;
+    };
+    typedef test_group<llprocess_data> llprocess_group;
+    typedef llprocess_group::object object;
+    llprocess_group llprocessgrp("llprocess");
+
+    struct Item
+    {
+        Item(): tries(0) {}
+        unsigned    tries;
+        std::string which;
+        std::string what;
+    };
+
+/*==========================================================================*|
+#define tabent(symbol) { symbol, #symbol }
+    static struct ReasonCode
+    {
+        int code;
+        const char* name;
+    } reasons[] =
+    {
+        tabent(APR_OC_REASON_DEATH),
+        tabent(APR_OC_REASON_UNWRITABLE),
+        tabent(APR_OC_REASON_RESTART),
+        tabent(APR_OC_REASON_UNREGISTER),
+        tabent(APR_OC_REASON_LOST),
+        tabent(APR_OC_REASON_RUNNING)
+    };
+#undef tabent
+|*==========================================================================*/
+
+    struct WaitInfo
+    {
+        WaitInfo(apr_proc_t* child_):
+            child(child_),
+            rv(-1),                 // we haven't yet called apr_proc_wait()
+            rc(0),
+            why(apr_exit_why_e(0))
+        {}
+        apr_proc_t* child;          // which subprocess
+        apr_status_t rv;            // return from apr_proc_wait()
+        int rc;                     // child's exit code
+        apr_exit_why_e why;         // APR_PROC_EXIT, APR_PROC_SIGNAL, APR_PROC_SIGNAL_CORE
+    };
+
+    void child_status_callback(int reason, void* data, int status)
+    {
+/*==========================================================================*|
+        std::string reason_str;
+        BOOST_FOREACH(const ReasonCode& rcp, reasons)
+        {
+            if (reason == rcp.code)
+            {
+                reason_str = rcp.name;
+                break;
+            }
+        }
+        if (reason_str.empty())
+        {
+            reason_str = STRINGIZE("unknown reason " << reason);
+        }
+        std::cout << "child_status_callback(" << reason_str << ")\n";
+|*==========================================================================*/
+
+        if (reason == APR_OC_REASON_DEATH || reason == APR_OC_REASON_LOST)
+        {
+            // Somewhat oddly, APR requires that you explicitly unregister
+            // even when it already knows the child has terminated.
+            apr_proc_other_child_unregister(data);
+
+            WaitInfo* wi(static_cast<WaitInfo*>(data));
+            // It's just wrong to call apr_proc_wait() here. The only way APR
+            // knows to call us with APR_OC_REASON_DEATH is that it's already
+            // reaped this child process, so calling wait() will only produce
+            // "huh?" from the OS. We must rely on the status param passed in,
+            // which unfortunately comes straight from the OS wait() call.
+//          wi->rv = apr_proc_wait(wi->child, &wi->rc, &wi->why, APR_NOWAIT);
+            wi->rv = APR_CHILD_DONE; // fake apr_proc_wait() results
+#if defined(LL_WINDOWS)
+            wi->why = APR_PROC_EXIT;
+            wi->rc  = status;         // no encoding on Windows (no signals)
+#else  // Posix
+            if (WIFEXITED(status))
+            {
+                wi->why = APR_PROC_EXIT;
+                wi->rc  = WEXITSTATUS(status);
+            }
+            else if (WIFSIGNALED(status))
+            {
+                wi->why = APR_PROC_SIGNAL;
+                wi->rc  = WTERMSIG(status);
+            }
+            else                    // uh, shouldn't happen?
+            {
+                wi->why = APR_PROC_EXIT;
+                wi->rc  = status;   // someone else will have to decode
+            }
+#endif // Posix
+        }
+    }
+
+    template<> template<>
+    void object::test<1>()
+    {
+        set_test_name("raw APR nonblocking I/O");
+
+        // Create a script file in a temporary place.
+        NamedTempFile script("py",
+            "import sys" EOL
+            "import time" EOL
+            EOL
+            "time.sleep(2)" EOL
+            "print >>sys.stdout, 'stdout after wait'" EOL
+            "sys.stdout.flush()" EOL
+            "time.sleep(2)" EOL
+            "print >>sys.stderr, 'stderr after wait'" EOL
+            "sys.stderr.flush()" EOL
+            );
+
+        // Arrange to track the history of our interaction with child: what we
+        // fetched, which pipe it came from, how many tries it took before we
+        // got it.
+        std::vector<Item> history;
+        history.push_back(Item());
+
+        // Run the child process.
+        apr_procattr_t *procattr = NULL;
+        aprchk(apr_procattr_create(&procattr, pool.getAPRPool()));
+        aprchk(apr_procattr_io_set(procattr, APR_CHILD_BLOCK, APR_CHILD_BLOCK, APR_CHILD_BLOCK));
+        aprchk(apr_procattr_cmdtype_set(procattr, APR_PROGRAM_PATH));
+
+        std::vector<const char*> argv;
+        apr_proc_t child;
+        argv.push_back("python");
+        // Have to have a named copy of this std::string so its c_str() value
+        // will persist.
+        std::string scriptname(script.getName());
+        argv.push_back(scriptname.c_str());
+        argv.push_back(NULL);
+
+        aprchk(apr_proc_create(&child, argv[0],
+                               &argv[0],
+                               NULL, // if we wanted to pass explicit environment
+                               procattr,
+                               pool.getAPRPool()));
+
+        // We do not want this child process to outlive our APR pool. On
+        // destruction of the pool, forcibly kill the process. Tell APR to try
+        // SIGTERM and wait 3 seconds. If that didn't work, use SIGKILL.
+        apr_pool_note_subprocess(pool.getAPRPool(), &child, APR_KILL_AFTER_TIMEOUT);
+
+        // arrange to call child_status_callback()
+        WaitInfo wi(&child);
+        apr_proc_other_child_register(&child, child_status_callback, &wi, child.in, pool.getAPRPool());
+
+        // TODO:
+        // Stuff child.in until it (would) block to verify EWOULDBLOCK/EAGAIN.
+        // Have child script clear it later, then write one more line to prove
+        // that it gets through.
+
+        // Monitor two different output pipes. Because one will be closed
+        // before the other, keep them in a list so we can drop whichever of
+        // them is closed first.
+        typedef std::pair<std::string, apr_file_t*> DescFile;
+        typedef std::list<DescFile> DescFileList;
+        DescFileList outfiles;
+        outfiles.push_back(DescFile("out", child.out));
+        outfiles.push_back(DescFile("err", child.err));
+
+        while (! outfiles.empty())
+        {
+            // This peculiar for loop is designed to let us erase(dfli). With
+            // a list, that invalidates only dfli itself -- but even so, we
+            // lose the ability to increment it for the next item. So at the
+            // top of every loop, while dfli is still valid, increment
+            // dflnext. Then before the next iteration, set dfli to dflnext.
+            for (DescFileList::iterator
+                     dfli(outfiles.begin()), dflnext(outfiles.begin()), dflend(outfiles.end());
+                 dfli != dflend; dfli = dflnext)
+            {
+                // Only valid to increment dflnext once we're sure it's not
+                // already at dflend.
+                ++dflnext;
+
+                char buf[4096];
+
+                apr_status_t rv = apr_file_gets(buf, sizeof(buf), dfli->second);
+                if (APR_STATUS_IS_EOF(rv))
+                {
+//                  std::cout << "(EOF on " << dfli->first << ")\n";
+//                  history.back().which = dfli->first;
+//                  history.back().what  = "*eof*";
+//                  history.push_back(Item());
+                    outfiles.erase(dfli);
+                    continue;
+                }
+                if (rv == EWOULDBLOCK || rv == EAGAIN)
+                {
+//                  std::cout << "(waiting; apr_file_gets(" << dfli->first << ") => " << rv << ": " << manager.strerror(rv) << ")\n";
+                    ++history.back().tries;
+                    continue;
+                }
+                aprchk_("apr_file_gets(buf, sizeof(buf), dfli->second)", rv);
+                // Is it even possible to get APR_SUCCESS but read 0 bytes?
+                // Hope not, but defend against that anyway.
+                if (buf[0])
+                {
+//                  std::cout << dfli->first << ": " << buf;
+                    history.back().which = dfli->first;
+                    history.back().what.append(buf);
+                    if (buf[strlen(buf) - 1] == '\n')
+                        history.push_back(Item());
+                    else
+                    {
+                        // Just for pretty output... if we only read a partial
+                        // line, terminate it.
+//                      std::cout << "...\n";
+                    }
+                }
+            }
+            // Do this once per tick, as we expect the viewer will
+            apr_proc_other_child_refresh_all(APR_OC_REASON_RUNNING);
+            sleep(1);
+        }
+        apr_file_close(child.in);
+        apr_file_close(child.out);
+        apr_file_close(child.err);
+
+        // Okay, we've broken the loop because our pipes are all closed. If we
+        // haven't yet called wait, give the callback one more chance. This
+        // models the fact that unlike this small test program, the viewer
+        // will still be running.
+        if (wi.rv == -1)
+        {
+            std::cout << "last gasp apr_proc_other_child_refresh_all()\n";
+            apr_proc_other_child_refresh_all(APR_OC_REASON_RUNNING);
+        }
+
+        if (wi.rv == -1)
+        {
+            std::cout << "child_status_callback(APR_OC_REASON_DEATH) wasn't called" << std::endl;
+            wi.rv = apr_proc_wait(wi.child, &wi.rc, &wi.why, APR_NOWAIT);
+        }
+//      std::cout << "child done: rv = " << rv << " (" << manager.strerror(rv) << "), why = " << why << ", rc = " << rc << '\n';
+        aprchk_("apr_proc_wait(wi->child, &wi->rc, &wi->why, APR_NOWAIT)", wi.rv, APR_CHILD_DONE);
+        ensure_equals_(wi.why, APR_PROC_EXIT);
+        ensure_equals_(wi.rc, 0);
+
+        // Beyond merely executing all the above successfully, verify that we
+        // obtained expected output -- and that we duly got control while
+        // waiting, proving the non-blocking nature of these pipes.
+        try
+        {
+            unsigned i = 0;
+            ensure("blocking I/O on child pipe (0)", history[i].tries);
+            ensure_equals_(history[i].which, "out");
+            ensure_equals_(history[i].what,  "stdout after wait" EOL);
+//          ++i;
+//          ensure_equals_(history[i].which, "out");
+//          ensure_equals_(history[i].what,  "*eof*");
+            ++i;
+            ensure("blocking I/O on child pipe (1)", history[i].tries);
+            ensure_equals_(history[i].which, "err");
+            ensure_equals_(history[i].what,  "stderr after wait" EOL);
+//          ++i;
+//          ensure_equals_(history[i].which, "err");
+//          ensure_equals_(history[i].what,  "*eof*");
+        }
+        catch (const failure&)
+        {
+            std::cout << "History:\n";
+            BOOST_FOREACH(const Item& item, history)
+            {
+                std::string what(item.what);
+                if ((! what.empty()) && what[what.length() - 1] == '\n')
+                {
+                    what.erase(what.length() - 1);
+                    if ((! what.empty()) && what[what.length() - 1] == '\r')
+                    {
+                        what.erase(what.length() - 1);
+                        what.append("\\r");
+                    }
+                    what.append("\\n");
+                }
+                std::cout << "  " << item.which << ": '" << what << "' ("
+                          << item.tries << " tries)\n";
+            }
+            std::cout << std::flush;
+            // re-raise same error; just want to enrich the output
+            throw;
+        }
+    }
+
+    template<> template<>
+    void object::test<2>()
+    {
+        set_test_name("setWorkingDirectory()");
+        // We want to test setWorkingDirectory(). But what directory is
+        // guaranteed to exist on every machine, under every OS? Have to
+        // create one. Naturally, ensure we clean it up when done.
+        NamedTempDir tempdir;
+        PythonProcessLauncher py("getcwd()",
+                                 "from __future__ import with_statement\n"
+                                 "import os, sys\n"
+                                 "with open(sys.argv[1], 'w') as f:\n"
+                                 "    f.write(os.getcwd())\n");
+        // Before running, call setWorkingDirectory()
+        py.mParams["cwd"] = tempdir.getName();
+        ensure_equals("os.getcwd()", py.run_read(), tempdir.getName());
+    }
+
+    template<> template<>
+    void object::test<3>()
+    {
+        set_test_name("arguments");
+        PythonProcessLauncher py("args",
+                                 "from __future__ import with_statement\n"
+                                 "import sys\n"
+                                 // note nonstandard output-file arg!
+                                 "with open(sys.argv[3], 'w') as f:\n"
+                                 "    for arg in sys.argv[1:]:\n"
+                                 "        print >>f, arg\n");
+        // We expect that PythonProcessLauncher has already appended
+        // its own NamedTempFile to mParams["args"] (sys.argv[0]).
+        py.mParams["args"].append("first arg");          // sys.argv[1]
+        py.mParams["args"].append("second arg");         // sys.argv[2]
+        // run_read() appends() one more argument, hence [3]
+        std::string output(py.run_read());
+        boost::split_iterator<std::string::const_iterator>
+            li(output, boost::first_finder("\n")), lend;
+        ensure("didn't get first arg", li != lend);
+        std::string arg(li->begin(), li->end());
+        ensure_equals(arg, "first arg");
+        ++li;
+        ensure("didn't get second arg", li != lend);
+        arg.assign(li->begin(), li->end());
+        ensure_equals(arg, "second arg");
+        ++li;
+        ensure("didn't get output filename?!", li != lend);
+        arg.assign(li->begin(), li->end());
+        ensure("output filename empty?!", ! arg.empty());
+        ++li;
+        ensure("too many args", li == lend);
+    }
+
+    template<> template<>
+    void object::test<4>()
+    {
+        set_test_name("explicit kill()");
+        PythonProcessLauncher py("kill()",
+                                 "from __future__ import with_statement\n"
+                                 "import sys, time\n"
+                                 "with open(sys.argv[1], 'w') as f:\n"
+                                 "    f.write('ok')\n"
+                                 "# now sleep; expect caller to kill\n"
+                                 "time.sleep(120)\n"
+                                 "# if caller hasn't managed to kill by now, bad\n"
+                                 "with open(sys.argv[1], 'w') as f:\n"
+                                 "    f.write('bad')\n");
+        NamedTempFile out("out", "not started");
+        py.mParams["args"].append(out.getName());
+        py.mPy = LLProcess::create(py.mParams);
+        ensure("couldn't launch kill() script", py.mPy);
+        // Wait for the script to wake up and do its first write
+        int i = 0, timeout = 60;
+        for ( ; i < timeout; ++i)
+        {
+            sleep(1);
+            if (readfile(out.getName(), "from kill() script") == "ok")
+                break;
+        }
+        // If we broke this loop because of the counter, something's wrong
+        ensure("script never started", i < timeout);
+        // script has performed its first write and should now be sleeping.
+        py.mPy->kill();
+        // wait for the script to terminate... one way or another.
+        while (py.mPy->isRunning())
+        {
+            sleep(1);
+        }
+        // If kill() failed, the script would have woken up on its own and
+        // overwritten the file with 'bad'. But if kill() succeeded, it should
+        // not have had that chance.
+        ensure_equals("kill() script output", readfile(out.getName()), "ok");
+    }
+
+    template<> template<>
+    void object::test<5>()
+    {
+        set_test_name("implicit kill()");
+        NamedTempFile out("out", "not started");
+        LLProcess::id pid(0);
+        {
+            PythonProcessLauncher py("kill()",
+                                     "from __future__ import with_statement\n"
+                                     "import sys, time\n"
+                                     "with open(sys.argv[1], 'w') as f:\n"
+                                     "    f.write('ok')\n"
+                                     "# now sleep; expect caller to kill\n"
+                                     "time.sleep(120)\n"
+                                     "# if caller hasn't managed to kill by now, bad\n"
+                                     "with open(sys.argv[1], 'w') as f:\n"
+                                     "    f.write('bad')\n");
+            py.mParams["args"].append(out.getName());
+            py.mPy = LLProcess::create(py.mParams);
+            ensure("couldn't launch kill() script", py.mPy);
+            // Capture id for later
+            pid = py.mPy->getProcessID();
+            // Wait for the script to wake up and do its first write
+            int i = 0, timeout = 60;
+            for ( ; i < timeout; ++i)
+            {
+                sleep(1);
+                if (readfile(out.getName(), "from kill() script") == "ok")
+                    break;
+            }
+            // If we broke this loop because of the counter, something's wrong
+            ensure("script never started", i < timeout);
+            // Script has performed its first write and should now be sleeping.
+            // Destroy the LLProcess, which should kill the child.
+        }
+        // wait for the script to terminate... one way or another.
+        while (LLProcess::isRunning(pid))
+        {
+            sleep(1);
+        }
+        // If kill() failed, the script would have woken up on its own and
+        // overwritten the file with 'bad'. But if kill() succeeded, it should
+        // not have had that chance.
+        ensure_equals("kill() script output", readfile(out.getName()), "ok");
+    }
+
+    template<> template<>
+    void object::test<6>()
+    {
+        set_test_name("autokill");
+        NamedTempFile from("from", "not started");
+        NamedTempFile to("to", "");
+        LLProcess::id pid(0);
+        {
+            PythonProcessLauncher py("autokill",
+                                     "from __future__ import with_statement\n"
+                                     "import sys, time\n"
+                                     "with open(sys.argv[1], 'w') as f:\n"
+                                     "    f.write('ok')\n"
+                                     "# wait for 'go' from test program\n"
+                                     "for i in xrange(60):\n"
+                                     "    time.sleep(1)\n"
+                                     "    with open(sys.argv[2]) as f:\n"
+                                     "        go = f.read()\n"
+                                     "    if go == 'go':\n"
+                                     "        break\n"
+                                     "else:\n"
+                                     "    with open(sys.argv[1], 'w') as f:\n"
+                                     "        f.write('never saw go')\n"
+                                     "    sys.exit(1)\n"
+                                     "# okay, saw 'go', write 'ack'\n"
+                                     "with open(sys.argv[1], 'w') as f:\n"
+                                     "    f.write('ack')\n");
+            py.mParams["args"].append(from.getName());
+            py.mParams["args"].append(to.getName());
+            py.mParams["autokill"] = false;
+            py.mPy = LLProcess::create(py.mParams);
+            ensure("couldn't launch kill() script", py.mPy);
+            // Capture id for later
+            pid = py.mPy->getProcessID();
+            // Wait for the script to wake up and do its first write
+            int i = 0, timeout = 60;
+            for ( ; i < timeout; ++i)
+            {
+                sleep(1);
+                if (readfile(from.getName(), "from autokill script") == "ok")
+                    break;
+            }
+            // If we broke this loop because of the counter, something's wrong
+            ensure("script never started", i < timeout);
+            // Now destroy the LLProcess, which should NOT kill the child!
+        }
+        // If the destructor killed the child anyway, give it time to die
+        sleep(2);
+        // How do we know it's not terminated? By making it respond to
+        // a specific stimulus in a specific way.
+        {
+            std::ofstream outf(to.getName().c_str());
+            outf << "go";
+        } // flush and close.
+        // now wait for the script to terminate... one way or another.
+        while (LLProcess::isRunning(pid))
+        {
+            sleep(1);
+        }
+        // If the LLProcess destructor implicitly called kill(), the
+        // script could not have written 'ack' as we expect.
+        ensure_equals("autokill script output", readfile(from.getName()), "ack");
+    }
+} // namespace tut