Always provide exit() & friends prototypes.

[Jonathan Larmour]

Sergei Organov wrote:
> 
> Yeah, I see. I'll first try the CYGSEM_LIBC_STARTUP_MAIN_THREAD that
> I've somehow missed, then we will see...

It's possible you might have to enable CYGSEM_LIBC_STARTUP_MAIN_OTHER as 
well, I'm not sure. Let me know about any problems (preferably with patches 
;-)).

> It seems that GCC uses atexit() facility to register destructors for
> static objects found inside functions, like this:
> 
> void foo() {
>   [...]
>   static SomeClassWithCtor_Dtor var;
>   [...]
> }
> As 'var' should be initialized at the first pass through the function,
> GCC registers a function calling destructor with atexit() after
> constructor of the variable is actually called.

Interesting - it doesn't do this normally. I believe this may be a property 
of the toolchain. I do vaguely recall there's some option within GCC (i.e. 
when you do a GCC port) for whether to use a .dtor section for global 
destructors, or atexit. So far, it's always been .dtor.

> Even if user app is plain C, silently calling atexit() seems to be
> dangerous as user application code might still register something with
> atexit() at startup.

True.

>> Unfortunately we have to have a default main, otherwise in our many
>> templates and configurations with the libc_startup package included,
>> any eCos test programs that don't use main() will not link.
> 
> Yeah, I see. Maybe Cyg_Thread::self()->suspend() in the main() when
> there is kernel there will help.

That's a good idea. Patch below, and applied.

Jifl

Index: ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/language/c/libc/startup/current/ChangeLog,v
retrieving revision 1.10
diff -u -5 -p -r1.10 ChangeLog
--- ChangeLog   11 Sep 2007 16:50:54 -0000      1.10
+++ ChangeLog   5 Oct 2007 17:41:22 -0000
@@ -1,5 +1,10 @@
+2007-10-05  Jonathan Larmour  <jifl@eCosCentric.com>
+
+       * src/main.cxx (main): Suspend main thread, rather than exit.
+       Thanks to Sergei Organov for the idea.
+
  2007-09-11  Andrew Lunn  <andrew.lunn@ascom.ch>

         * src/cstartup.cxx: Change the INIT priority of
         cyg_libc_startup_obj so that it is always called after the thread
         has been constructed. Reported by taiyun@sunnorth.com.cn
Index: src/main.cxx
===================================================================
RCS file: 
/cvs/ecos/ecos/packages/language/c/libc/startup/current/src/main.cxx,v
retrieving revision 1.3
diff -u -5 -p -r1.3 main.cxx
--- src/main.cxx        23 May 2002 23:07:12 -0000      1.3
+++ src/main.cxx        5 Oct 2007 17:41:22 -0000
@@ -64,10 +64,16 @@

  #include <cyg/infra/cyg_type.h>    // Common type definitions and support
  #include <cyg/infra/cyg_trac.h>    // Common tracing support
  #include <cyg/infra/cyg_ass.h>     // Common assertion support

+#ifdef CYGPKG_KERNEL
+# include <pkgconf/kernel.h>       // kernel configuration
+# include <cyg/kernel/thread.hxx>  // For thread suspend
+# include <cyg/kernel/thread.inl>
+#endif
+
  // FUNCTION PROTOTYPES

  // We provide a weakly named main to allow this to link if the user
  // doesn't provide their own main. This isn't strictly good behaviour,
  // but if the user wants good performance then of _course_ they should
@@ -101,10 +107,14 @@ main( int argc, char *argv[] )
      // evidently the user didn't supply one - which can't be right. So we
      // assume that they have useful code to run in cyg_user_start() instead.
      // Its better than just exiting
  #ifndef CYGPKG_KERNEL
      cyg_user_start();
+#else
+    // Otherwise we suspend ourselves. This prevents problems caused by
+    // running atexit() handlers.
+    Cyg_Thread::self()->suspend();
  #endif

      CYG_REPORT_RETVAL(0);
      return 0; // some CPUs have 0 hard-wired - faster than a reg
  } // main()


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