OpenEuphoria

1. Wrapping FastCGI - Function howto?

• Posted by Jeremy Cowgar <jeremy at cowga?.c?m> Apr 23, 2008
• 683 views

Hey guys,

I am trying to wrap fast cgi and here's the C signature:

DLLAPI int FCGX_Accept(
        FCGX_Stream **in,
        FCGX_Stream **out,
        FCGX_Stream **err,
        FCGX_ParamArray *envp);

DLLAPI is nothing on Unix (where I am testing right now).

I wrapped it as:

constant hAccept = define_c_func(hFcgi, "FCGX_Accept", {P, P, P, P}, I),

global function FCGX_Accept()
    integer result
    atom pIn, pOut, pErr, pEnv

    pIn  = allocate(4)
    pOut = allocate(4)
    pErr = allocate(4)
    pEnv = allocate(4)

    if c_func(hAccept, {pIn, pOut, pErr, pEnv}) >= 0 then
        return {pIn, pOut, pErr, pEnv}
    end if

    return 0
end function

Does that seem right? When I call this function on 3.2, I immediately get a
machine level error when calling hAccept. On released 3.1, I get a glibc memory
error:

*** glibc detected *** exu: malloc(): memory corruption: 0x080e9990 ***
======= Backtrace: =========
/lib/libc.so.6[0xb7eaac64]
/lib/libc.so.6[0xb7ead22a]
/lib/libc.so.6(__libc_malloc+0x9c)[0xb7eae9ec]
/lib/libc.so.6[0xb7e9b7af]
/lib/libc.so.6(fopen+0x2c)[0xb7e9b87c]
exu[0x8086650]
/usr/lib/libfcgi.so(FCGX_PutS+0x35)[0xb7e39345]
exu[0x8079feb]
exu[0x807c93b]
======= Memory map: ========
08048000-08090000 r-xp 00000000 08:01 22003817   /opt/euphoria-3.1/bin/exu
08090000-08091000 rwxp 00048000 08:01 22003817   /opt/euphoria-3.1/bin/exu
08091000-08102000 rwxp 08091000 00:00 0          [heap]
b7d00000-b7d21000 rwxp b7d00000 00:00 0 
b7d21000-b7e00000 ---p b7d21000 00:00 0 
b7e12000-b7e1e000 r-xp 00000000 08:01 639287     /usr/lib/libgcc_s.so.1
b7e1e000-b7e1f000 rwxp 0000b000 08:01 639287     /usr/lib/libgcc_s.so.1
b7e1f000-b7e32000 r-xp 00000000 08:01 10207268   /lib/libnsl-2.7.so
b7e32000-b7e34000 rwxp 00012000 08:01 10207268   /lib/libnsl-2.7.so
b7e34000-b7e36000 rwxp b7e34000 00:00 0 
b7e36000-b7e3e000 r-xp 00000000 08:01 6963639    /usr/lib/libfcgi.so.0.0.0
b7e3e000-b7e3f000 rwxp 00008000 08:01 6963639    /usr/lib/libfcgi.so.0.0.0
b7e3f000-b7e40000 rwxp b7e3f000 00:00 0 
b7e40000-b7f7a000 r-xp 00000000 08:01 10207256   /lib/libc-2.7.so
b7f7a000-b7f7b000 r-xp 0013a000 08:01 10207256   /lib/libc-2.7.so
b7f7b000-b7f7d000 rwxp 0013b000 08:01 10207256   /lib/libc-2.7.so
b7f7d000-b7f80000 rwxp b7f7d000 00:00 0 
b7f80000-b7f82000 r-xp 00000000 08:01 10207260   /lib/libdl-2.7.so
b7f82000-b7f84000 rwxp 00001000 08:01 10207260   /lib/libdl-2.7.so
b7f84000-b7fa8000 r-xp 00000000 08:01 10207266   /lib/libm-2.7.so
b7fa8000-b7faa000 rwxp 00023000 08:01 10207266   /lib/libm-2.7.so
b7faa000-b7fab000 rwxp b7faa000 00:00 0 
b7fbf000-b7fc0000 r-xp b7fbf000 00:00 0          [vdso]
b7fc0000-b7fdb000 r-xp 00000000 08:01 10208712   /lib/ld-2.7.so
b7fdb000-b7fdd000 rwxp 0001a000 08:01 10208712   /lib/ld-2.7.so
bfb3d000-bfb52000 rw-p bffeb000 00:00 0          [stack]

Any thoughts?

--
Jeremy Cowgar
http://jeremy.cowgar.com

3. Re: Wrapping FastCGI - Function howto?

• Posted by Jeremy Cowgar <jeremy at cowga?.?om> Apr 23, 2008
• 653 views

Bernie Ryan wrote:
> 
> Jeremy:
> 
> pEnv should be just a pointer not a allocated location
> 
> pEnv = allocate(4)

Bernie,

I have the simple wrappings down with Euphoria, but how do I give it just a
pointer?

--
Jeremy Cowgar
http://jeremy.cowgar.com

5. Re: Wrapping FastCGI - Function howto?

• Posted by Jeremy Cowgar <jeremy at cow??r.com> Apr 23, 2008
• 647 views

Bernie Ryan wrote:
> 
> When you see a ** this means a POINTER to a 4-byte location in memory that
> contains
> the POINTER that the function will use.
> 
> When you see a SINGLE * this means a POINTER that the function will use
> directly.
> 

Yes. I have been programming in C for many years. However, this is not a value
passed to the FCGX_Accept function, it's a value that is populated by the
FCGX_Accept function. So, I pass no data (at least no useful data) to it.

It should populate it with information about the request. It will then be passed
to functions yet to be wrapped such as FCGX_GetParam("QUERY_STRING", pEnv).

--
Jeremy Cowgar
http://jeremy.cowgar.com

7. Re: Wrapping FastCGI - Function howto?

• Posted by Jeremy Cowgar <jeremy at cow?ar.?om> Apr 23, 2008
• 660 views

Ok, here is an example C usage:

FCGX_ParamArray envp;
while (FCGX_Accept(&in, &out, &err, &envp) >= 0) { ... }


FCGX_ParamArray = typedef char **FCGX_ParamArray;

I'm just drawing at straws, allocating, allocating strings, string arrays,
poking, poking4, etc... nothing work so far and I realize my method is terrible,
but I'm not sure what to give it, thus I was hoping with wild guesses I'd get
lucky, but not yet.

--
Jeremy Cowgar
http://jeremy.cowgar.com

9. Re: Wrapping FastCGI - Function howto?

• Posted by Matt Lewis <matthewwalkerlewis at gm?il?com> Apr 23, 2008
• 687 views

Jeremy Cowgar wrote:
> 
> Ok, here is an example C usage:
> 
> FCGX_ParamArray envp;
> while (FCGX_Accept(&in, &out, &err, &envp) >= 0) { ... }
> 
> 
> FCGX_ParamArray = typedef char **FCGX_ParamArray;
> 
> I'm just drawing at straws, allocating, allocating strings, string arrays,
> poking, poking4, etc... nothing work so far and I realize my method is
> terrible, but I'm not sure what to give it, thus I was hoping with wild
> guesses I'd get lucky, but not yet.

I don't see anything obviously wrong with your wrapper.  From glancing at
manpages and such, it looks like all of those will be populated by FastCGI.
I have two thoughts.  Make sure that the memory is all zeroed out:

in = allocate(4)
   poke4( in, 0 )
   -- ....

   -- or..
   ptrs = allocate( 16 )
   poke4( ptrs, repeat( 0, 4 ) )

If this doesn't help, then you could try running under valgrind.  Print out
the pointers that you're using, so you can compare to whatever error you
get.  You'll typically get better results, of course, if you use a debug
build of euphoria.

Matt

11. Re: Wrapping FastCGI - Function howto?

• Posted by Jeremy Cowgar <jeremy at cowgar.?om> Apr 23, 2008
• 661 views
• Last edited Apr 24, 2008

gshingles wrote:
> 
> 
> Where I come from envp is the pointer to the environment variables.
> It if is that then it's a pointer to a null terminated array of null
> terminated
> strings
> ie char **envp;
> 
> This would make sense for a CGI library, maybe it wants a pointer to the 
> environment block, or maybe it wants to give you one from where the
> query is coming from?
> 

Gary,

Yes, it's the environment. It want's to populate that array with the environment
as the FastCGI application may be running locally, under it's own session, or it
could be running on a totally different server in another country. So, it passes
the web servers environment to your application via the FCGX_Accept function.

I have yet to make this work, btw...  I get various memory errors. I have not
been working on it solid, only touching it here and there between my real job.
FastCGI or SCGI would be very nice to have for Euphoria. I am really surprised it
has not been done already.

--
Jeremy Cowgar
http://jeremy.cowgar.com