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From "Bill Stoddard" <b...@wstoddard.com>
Subject [PATCH] Discussion of apache -k start -n apache2 problem...
Date Mon, 03 Jun 2002 21:33:09 GMT
This patch allows apache -k start -n apache2 to start the server.  This is certainly not
the correct fix but it should illustrate the problem for someone more familier with the
services code.  The problem (step-by-step):

1. Issue apache -k restart -n apache2
2. The SCM issues apache -k runservice (using values from the registry)
3. winnt_rewrite_args rewrites the args to

   apache -d c:/apache2/  (ie, apache -d server_root)

and saves the rewritten args in a global variable, mpm_new_argv. Everything is okay to
this point (I think :-). I.e.
mpm_new_argv[0] = c:/apache/bin/apache.exe
mpm_new_argv[1] = -d
mpm_new_argv[2] = server_root

Okay up to this point...

4. winnt_rewrite_args calls mpm_service_to_start, which among other things calls the Win32
call StartService() passing as one of its arguments, the string "apache2" (my patch passes
NULL instead)...

5. As a result of the STartService() call, Windows create a new thread which which calls
service_nt_main_fn (defined in service.c).  The code in service_nt_main_fn adds the
apache2 to the mpm_new_argv argument list, so the new argv looks like this:

apache -d c:/apache2/bin apache2

The trailing apache2 (which is the service name) is causing the (opt->ind < opt->argc)
check to fail and dumping us into usage() (from main.c)

    /* bad cmdline option?  then we die */
    if (rv != APR_EOF || opt->ind < opt->argc) {
        usage(process);
    }

I am thinking that the broken code is in service_nt_main_fn because it is not properly
updating the mpm_new_argv.

Another problem is that there is a race condition between the Win32 thread that gets
kicked off by the call to StartService() and the thread that is in mpm_rewrite_args.
Really nasty. A good Chianti and some grated parmesan and We'd have a meal :-)

Index: service.c
===================================================================
RCS file: /home/cvs/httpd-2.0/server/mpm/winnt/service.c,v
retrieving revision 1.51
diff -u -r1.51 service.c
--- service.c 17 May 2002 11:11:39 -0000 1.51
+++ service.c 3 Jun 2002 21:04:38 -0000
@@ -1059,12 +1061,11 @@

         argc += 1;
         start_argv = malloc(argc * sizeof(const char **));
-        start_argv[0] = mpm_service_name;
         if (argc > 1)
             memcpy(start_argv + 1, argv, (argc - 1) * sizeof(const char **));

         rv = APR_EINIT;
-        if (StartService(schService, argc, start_argv)
+        if (StartService(schService, 0, NULL)
             && signal_service_transition(schService, 0, /* test only */
                                          SERVICE_START_PENDING,
                                          SERVICE_RUNNING))


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