Обсуждение: undefined symbol in create new function

Hello all,
 I am back with my silly little snippet of code. When I try to create a
function with the following code compiled in to an .so:

#include <string.h>
#include <stdlib.h>
#include "postgres.h"
#include "fmgr.h"


PG_FUNCTION_INFO_V1(ssh_exec);

Datum
ssh_exec(PG_FUNCTION_ARGS)
{
        char    *uname = PG_GETARG_CHAR(0);
        char    *uid = PG_GETARG_CHAR(1);
        char    *gid = PG_GETARG_CHAR(2);
        char    sshcmd[255];

        strncpy(sshcmd, "/usr/local/bin/plsshexec ", 255);
        strncat(sshcmd, VARDATA(uname), VARSIZE(uname));
        strncat(sshcmd, " ", 255);
        strncat(sshcmd, VARDATA(uid), VARSIZE(uid));
        strncat(sshcmd, " ", 255);
        strncat(sshcmd, VARDATA(gid), VARSIZE(gid));
        system(sshcmd);
        return 0;

}

I get the following error:

undefined symbol PG_GETARG_CHAR

Is PG_GETARG_CHAR valid? I thought it was. maybe I should re-do it all with
PG_GETARG_TEXT. Thanks for reading my post.

- Joel

Joel Dudley <Joel.Dudley@DevelopOnline.com> writes:
> Is PG_GETARG_CHAR valid? I thought it was. maybe I should re-do it all with
> PG_GETARG_TEXT. Thanks for reading my post.

Nope, neither one.  See src/include/fmgr.h for the predefined GETARG
macros.  You would also do well to read src/backend/utils/fmgr/README.

            regards, tom lane

Joel Dudley <Joel.Dudley@DevelopOnline.com> writes:
> Thanks for your help. I had to clarify though, are you saying that it is
> impossible to do what I am trying to do?  Thank you for your time.

No, you just have to realize that Postgres string values are not
null-terminated and so you can't manipulate them with the usual C
library string functions that expect to work on null-terminated strings.
At least not unless you convert them to null-terminated form first.

Try studying some of the built-in text mashing functions.  textcat()
and nearby routines in src/backend/utils/adt/varlena.c would be good
starting points.

            regards, tom lane