There is a few things to note here to make things much easier. I have
included a working example below including the compilation and installation
steps for my linux system.
1. When creating functions use mi_lvarchar as the input and output
data type when passing by reference. This types cast to just about
everything.
2. Trying to pass things are char * there are many other issues you
are going to run into, including the memory management which
is probably why other attempts crash.
Here is an example that I believe should get you started.
-------------PART 1 compilation and installation script
#!/bin/sh -x
gcc -I$INFORMIXDIR/incl -fPIC -g -c -Wall c_udr.c
gcc -shared -Wl,-soname,c_udr_lib.so \
-o c_udr_lib.so c_udr.o -lc
cp c_udr_lib.so $INFORMIXDIR/lib/.
dbaccess - -<<END
create database d with log;
create function jfm_upshift( input lvarchar(32) )
returning lvarchar(32)
external name "$INFORMIXDIR/lib/c_udr_lib.so(jfm_upshift)" language c;
select first 10
tabname[1,10], jfm_upshift(tabname[1,10])
from systables;
END
-----------PART2 Upshift code
#include "dmi/milib.h"
mi_lvarchar *
jfm_upshift(mi_lvarchar *str)
{
mi_string *tmp;
if ( mi_switch_mem_duration(PER_ROUTINE) == MI_ERROR ||
( tmp = mi_lvarchar_to_string(str)) == NULL )
return NULL;
rupshift(tmp);
return mi_string_to_lvarchar(tmp);
}
----------------OUPTPUT----------------------------
+ gcc -I/work3/DIST/miller3_talos_1150FC6/incl -fPIC -g -c -Wall c_udr.c
c_udr.c: In function ?jfm_upshift?:
c_udr.c:10: warning: implicit declaration of function ?rupshift?
+ gcc -shared -Wl,-soname,c_udr_lib.so -o c_udr_lib.so c_udr.o -lc
+ cp c_udr_lib.so /work3/DIST/miller3_talos_1150FC6/lib/.
+ dbaccess - -.
Database created.
Routine created..
tabname systables
(expression) SYSTABLES
tabname syscolumns
(expression) SYSCOLUMNS
tabname sysindices
(expression) SYSINDICES
tabname systabauth
(expression) SYSTABAUTH
tabname syscolauth
(expression) SYSCOLAUTH
tabname sysviews
(expression) SYSVIEWS
tabname sysusers
(expression) SYSUSERS
tabname sysdepend
(expression) SYSDEPEND
tabname syssynonym
(expression) SYSSYNONYM
tabname syssyntabl
(expression) SYSSYNTABL
10 row(s) retrieved.
Database closed.
John F. Miller III
STSM, Support Architect
miller3@us.ibm.com
503-578-5645
IBM Informix Dynamic Server (IDS)
ids-bounces@iiug.org wrote on 12/15/2009 01:10:06 PM:
> [image removed]
>
> RE: C Shared Library function in IDS 10 [18401]:
>
> Wyza, Jonathon
>
> to:
>
> ids
>
> 12/15/2009 01:11 PM
>
> Sent by:
>
> ids-bounces@iiug.org
>
> Please respond to ids
>
> This wouldn't be so bad if there was some decent documentation. Beyond
> the regular IDS documentation which doesn't spend any time at all on how
> the C functions would actually work (just how to call them), the only
> thing that I've found of any remote help is :
> http://www.ibm.com/developerworks/data/zones/informix/library/techtip/db
> _bad_code.html
> .. Unfortunately this creates more questions than answers. It appears
> there are some headers/functions that are made available for use when
> developing a UDF in C, but there doesn't appear to be any documentation
> for those either. Perhaps I should just contact IDS support and see if
> they know of UDF documentation that is hiding somewhere that Google
> doesn't know how to find.
>
> Jonathon
>
> -----Original Message-----
> From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
> Art Kagel
> Sent: Tuesday, December 15, 2009 3:34 PM
> To: ids@iiug.org
> Subject: Re: C Shared Library function in IDS 10 [18400]
>
> It is odd. I also tried some variations after posting. I tried a
> function
> that upshifts the input string in place and returns the pointer just
> like
> the original did. If I run the function from 'C' it works as expected
> and
> the caller can print the upshifted string. However, when I install it as
> a
> UDR and call it from a similar select statement, the select only prints
> out
> the first letter of the input string not upshifted at all.
>
> Art
>
> Art S. Kagel
> Oninit (www.oninit.com)
> IIUG Board of Directors (art@iiug.org)
>
> See you at the 2010 IIUG Informix Conference
> April 25-28, 2010
> Overland Park (Kansas City), KS
> www.iiug.org/conf
>
> Disclaimer: Please keep in mind that my own opinions are my own opinions
> and
> do not reflect on my employer, Oninit, the IIUG, nor any other
> organization
> with which I am associated either explicitly or implicitly. Neither do
> those opinions reflect those of other individuals affiliated with any
> entity
> with which I am affiliated nor those of the entities themselves.
>
> On Tue, Dec 15, 2009 at 3:15 PM, Wyza, Jonathon
> <wyzaj@bethelcollege.edu>wrote:
>
> > If you don't put in static, when you attempt to return sndx_string
> > (which is the variable being returned by this function) the Informix
> > engine crashes (of course the Informix engine will crash for pretty
> much
> > anything if any part of the function fails for pretty much any
> reason).
> >
> > What's interesting about Art's reply is I did test simply returning
> the
> > passed value and it worked fine, however if you, for example, do a
> > printf("buffer = %s\n", buffer); //buffer is the passed value. Same if
>
> > you try to just print buffer[0] (except instead of a blank you get
> > (null)). Then it prints to the console: "buffer = ". If you do a
> > strcpy on the buffer into another char and try to return the char you
> > get a blank as well. However Informix passes the value, it isn't doing
>
> > it in a way that I'd expect. I thought perhaps it was getting passed
> as
> > a pointer to a string instead, so I tried defining it as char
> > *cx_soundex(char *buffer), but when accessing it I get the same thing,
>
> > null.
> >
> > Jonathon
> >
> > -----Original Message-----
> > From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
> > John Miller iii
> > Sent: Monday, December 14, 2009 7:40 PM
> > To: ids@iiug.org
> > Subject: Re: C Shared Library function in IDS 10 [18376]
> >
> > Why is there a static char variable defined in this function. The
> > use of static is very suspect in a multi-threaded code. There
> > is a very good chance that the contents of this variable will
> > will be lost if any thread switch occurs.
> >
> > static char sndx_string[CRITERIA_LENGTH];
> >
> > John F. Miller III
> > STSM, Support Architect
> > miller3@us.ibm.com
> > 503-578-5645
> > IBM Informix Dynamic Server (IDS)
> >
> > =
> >
> > From: "Art Kagel" <art.kagel@gmail.com> =
> >
> > =
> >
> > To: ids@iiug.org =
> >
> > =
> >
> > Date: 12/14/2009 01:15 PM =
> >
> > =
> >
> > Subject: Re: C Shared Library function in IDS 10 [18375] =
> >
> > =
> >
> > Sent by: ids-bounces@iiug.org =
> >
> > =
> >
> > Works for me. I created the following function:
> >
> > $ cat c_udr.c
> > char *c_udr_test( char in[33] )
> > {
> > return in;
> > }
> >
> > Compiled it to a shared library:
> > $ gcc --shared -o c_udr.so c_udr.c
> >
> > Created the UDR:
> > $ dbaccess art -
> > > create function c_udr_test( input char(32) ) returning char(32) as
> ou=
> >
> > tput
> >
> > > external name "/home/art/c_udr.so(c_udr_test)" language c;
> >
> > Routine created.
> >
> > And was able to use it in a SELECT statement:
> >
> > > select c_udr_test( user ) from systables;
> >
> > (expression)
> >
> > art
> > art
> > art
> > art
> > art
> > art
> > art
> > art
> > ......
> >
> > Art
> >
> > Art S. Kagel
> > Oninit (www.oninit.com)
> > IIUG Board of Directors (art@iiug.org)
> >
> > See you at the 2010 IIUG Informix Conference
> > April 25-28, 2010
> > Overland Park (Kansas City), KS
> > www.iiug.org/conf
> >
> > Disclaimer: Please keep in mind that my own opinions are my own
> opinion=
> >
> > s
> > and
> > do not reflect on my employer, Oninit, the IIUG, nor any other
> organiza=
> >
> > tion
> >
> > with which I am associated either explicitly or implicitly. Neither do
>
> > those opinions reflect those of other individuals affiliated with any
> > entity
> > with which I am affiliated nor those of the entities themselves.
> >
> > On Mon, Dec 14, 2009 at 2:06 PM, Wyza, Jonathon
> > <wyzaj@bethelcollege.edu>wrote:
> >
> > > Thanks for the quick response but still no go. Here is the top and
> > > bottom of the C function: (note that CRITERIA_LENGTH is 32);
> > >
> > > char *cx_soundex(char in_buffer[CRITERIA_LENGTH])
> > > {
> > >
> > > register int s_indx; /* Index into `sndx_string'. */
> > >
> > > register int b_indx; /* Index into `buffer'. */
> > >
> > > char *buffer;
> > >
> > > static char sndx_string[CRITERIA_LENGTH];
> > >
> > > ....logic...
> > >
> > > return sndx_string;
> > > }
> > >
> > > TIA
> > >
> > > Jonathon
> > >
> > > -----Original Message-----
> > > From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf
> Of=
> >
> > > Art Kagel
> > > Sent: Monday, December 14, 2009 1:19 PM
> > > To: ids@iiug.org
> > > Subject: Re: C Shared Library function in IDS 10 [18373]
> > >
> > > You have defined the UDR that calls the function with an argument of
>
> > > type
> > > VARCHAR(32). This does not correspond to the C language type char
> > > ....[32].
> > > You should have used:
> > >
> > > create function cx_soundex( str CHAR(32) ) returning CHAR(4)
> > > EXTERNAL NAME "/pathtolib/BClibsoundex.so( cx_soundex )"
> > > LANGUAGE C;
> > >
> > > Art
> > >
> > > Art S. Kagel
> > > Oninit (www.oninit.com)
> > > IIUG Board of Directors (art@iiug.org)
> > >
> > > See you at the 2010 IIUG Informix Conference
> > > April 25-28, 2010
> > > Overland Park (Kansas City), KS
> > > www.iiug.org/conf
> > >
> > > Disclaimer: Please keep in mind that my own opinions are my own
> opini=
> >
> > ons
> > > and
> > > do not reflect on my employer, Oninit, the IIUG, nor any other
> > > organization
> > > with which I am associated either explicitly or implicitly. Neither
> d=
> >
> > o
> > > those opinions reflect those of other individuals affiliated with
> any=
> >
> > > entity
> > > with which I am affiliated nor those of the entities themselves.
> > >
> > > On Mon, Dec 14, 2009 at 12:43 PM, Wyza, Jonathon
> > > <wyzaj@bethelcollege.edu>wrote:
> > >
> > > > In a piece of software that I use a custom version of soundex
> exist=
> >
> > s.
> > > > I've split this function into its own shared library and tested it
> =
> >
> > to
> > > > show that calling the function works as such from a regular C
> progr=
> >
> > am:
> > >
> > > >
> > > > #include <stdio.h>
> > > >
> > > > char *cx_soundex(char in_buffer[32]);
> > > >
> > > > main (argc, argv)
> > > >
> > > > int argc;
> > > >
> > > > char *argv[];
> > > >
> > > > {
> > > >
> > > > printf(cx_soundex(argv[1]));
> > > >
> > > > }
> > > >
> > > > Now I created a custom function in IDS using:
> > > >
> > > > create function cx_soundex(str VARCHAR(32))
> > > >
> > > > returning VARCHAR(4)
> > > >
> > > > EXTERNAL NAME "/pathtolib/BClibsoundex.so(cx_soundex)"
> > > >
> > > > LANGUAGE C;
> > > >
> > > > And then attempt to use it using:
> > > >
> > > > select cx_soundex("wyza")
> > > >
> > > > from table_name
> > > >
> > > > where where_statements
> > > >
> > > > However I get a blank returned for the expression. I've done some
> > > > debugging and it is because the function doesn't appear to be
> getti=
> >
> > ng
> > > > passed the value "wyza" to it. I've also tried
> cx_soundex(str=3D"wy=
> >
> > za")
> > > > which I've seen in the documentation. The IDS log shows that the
> > > shared
> > > > library is loaded and no error is thrown. The library's debug
> > > > statements shows that no value is being passed to the function but
> =
> >
> > the
> > >
> > > > function is being called.
> > > >
> > > > Has anyone had experience creating and using custom C functions in
>
> > > IDS?
> > > > I tried doing the function in SPL but it is too complicated.
> > > >
> > > > Jonathon Wyza
> > > >
> > > > Programmer/Analyst
> > > >
> > > > Administrative Computing
> > > >
> > > > Bethel College
> > > >
> > > > (574)-257-3381
> > > >
> > > > AIM: Iamwyza
> > > >
> > > > jonathon.wyza@bethelcollege.edu
> > > <?mailto:jonathon.wyza@bethelcollege.edu>
> > > >
> > > >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
>
> > =3D=3D=3D
> > > >
> > > > SLES 10 SP2 & IDS 10.0 HC9
> > > >
> > > > "One machine can do the work of fifty ordinary men. No machine can
> =
> >
> > do
> > > > the work of one extraordinary man. " - Elbert Hubbard
> > > >
> > > >
> > > >
> > > >
> > >
> *********************************************************************=
> >
> > ***
> > > *******
> > > > Forum Note: Use "Reply" to post a response in the discussion
> forum.=
> >
> > > >
> > > >
> > >
> > > --0015173fe52a94046b047ab44d27
> > >
> > >
> *********************************************************************=
> >
> > ***
> > > *******
> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
> > >
> > >
> > >
> >
> ***********************************************************************=
>
> >
> > ********
> >
> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
> > >
> >
> > --0015174762a4ff4ed4047ab6c177
> >
> >
> ***********************************************************************=
>
> >
> > ********
> >
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> > =
> >
> >
> ************************************************************************
>
> > *******
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> >
> >
> >
> ************************************************************************
> *******
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> >
>
> --0015174792d65d44fa047aca50ed
>
> ************************************************************************
> *******
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
>
*******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
