Re: [HACKERS] help wanted (fmgr.c)

2006-09-11 Thread Gevik Babakhani
Thank you for your reply. 
I found my bug in the code which made the function behave strangely.

On Mon, 2006-09-11 at 14:23 +0530, Abhijit Menon-Sen wrote:
> At 2006-09-11 10:25:22 +0200, [EMAIL PROTECTED] wrote:
> >
> > What are we testing to be NULL here?
> > Do we expect str to changed at line 1715 
> 
> No. (Read the comment just above the function.)
> 
> The code is like this, starting from line 1703:
> 
> if (str == NULL && flinfo->fn_strict)
> return (Datum) 0;
> 
> That is, if the function is declared strict, and the argument (str) is
> 0, just return NULL straightaway. Then it sets up the fcinfo and calls
> the function, and then:
> 
> ...
> 
> /* Should get null result if and only if str is NULL */
> if (str == NULL)
> {
> if (!fcinfo.isnull)
> elog(ERROR, "input function %u returned non-NULL",
>  fcinfo.flinfo->fn_oid);
> }
> else
> {
> if (fcinfo.isnull)
> elog(ERROR, "input function %u returned NULL",
>  fcinfo.flinfo->fn_oid);
> }
> 
> This says: If the argument is NULL and the input function didn't return
> a NULL, log an error; but if the argument is non-NULL and the function
> returned NULL, log this other error. (Note that a function would set
> fcinfo->isnull to indicate that it wants to return an SQL NULL, as
> explained in $DOC/plhandler.html)
> 
> -- ams
> 


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Re: [HACKERS] help wanted (fmgr.c)

2006-09-11 Thread Abhijit Menon-Sen
At 2006-09-11 10:25:22 +0200, [EMAIL PROTECTED] wrote:
>
> What are we testing to be NULL here?
> Do we expect str to changed at line 1715 

No. (Read the comment just above the function.)

The code is like this, starting from line 1703:

if (str == NULL && flinfo->fn_strict)
return (Datum) 0;

That is, if the function is declared strict, and the argument (str) is
0, just return NULL straightaway. Then it sets up the fcinfo and calls
the function, and then:

...

/* Should get null result if and only if str is NULL */
if (str == NULL)
{
if (!fcinfo.isnull)
elog(ERROR, "input function %u returned non-NULL",
 fcinfo.flinfo->fn_oid);
}
else
{
if (fcinfo.isnull)
elog(ERROR, "input function %u returned NULL",
 fcinfo.flinfo->fn_oid);
}

This says: If the argument is NULL and the input function didn't return
a NULL, log an error; but if the argument is non-NULL and the function
returned NULL, log this other error. (Note that a function would set
fcinfo->isnull to indicate that it wants to return an SQL NULL, as
explained in $DOC/plhandler.html)

-- ams

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