Thread: URL Managment - C Function help

URL Managment - C Function help

From
Samuel ROZE
Date:
Hi,

I'm writing two functions "parse_url_key" and "parse_url_record" which
will have one text argument and will return a record or a specific
column of it. Theses functions are calling "parse_url_exec" which parse
the URL. When theses function will works, i'll purpose them to
PostgreSQL community.

The problem is that they don't work fine... :/

Prototypes of function/struct used by them:
----------------------------------------------------
typedef struct url {char *scheme;char *user;char *pass;char *host;unsigned short port;char *path;char *query;char
*fragment;
} url;

url *parse_url_exec (char* str);
----------------------------------------------------

The parse_url_key function:
----------------------------------------------------
PG_FUNCTION_INFO_V1(parse_url_key);
Datum parse_url_key (PG_FUNCTION_ARGS)
{char str[] = "http://www.ovh.com/intenal.html";//text *my_url = PG_GETARG_TEXT_P(0);//char *char_url =
DatumGetCString(my_url);
url *ret = parse_url_exec(str);
PG_RETURN_TEXT_P(ret->host);
}
----------------------------------------------------
Note: I'm using built-in strings to be sure that the recuperation
doesn't change anything..

This function works well:
----------------------------------------------------
postgres=# CREATE OR REPLACE FUNCTION parse_url_key(text) RETURNS text
AS '/home/samuel/parse_url.so', 'parse_url_key' LANGUAGE C;
CREATE FUNCTION
postgres=# SELECT parse_url_key('') as scheme;  scheme   
------------ww.ovh.com
(1 row)
----------------------------------------------------
Note: there's a little problem here but not important. :-)

The problem is that the other function, "parse_url_record" doesn't
return values ! The code is:
----------------------------------------------------
PG_FUNCTION_INFO_V1(parse_url_record);
Datum parse_url_record (PG_FUNCTION_ARGS)
{// Vars about the params//text *str2 = PG_GETARG_TEXT_P(0);char str[] = "http://www.ovh.com/intenal.html";
// Some vars which will used to create the composite output typeTupleDesc    tupdesc;Datum        values[2]; // 8
valuesHeapTuple   tuple;bool        nulls[2];int            tuplen;
 
// Check NULLs valuesif(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {    PG_RETURN_NULL();}
url *ret = parse_url_exec(str);
// Add datas into the values Datumvalues[0] = PointerGetDatum(ret->scheme);values[1] = PointerGetDatum(ret->host);
// Convert values into a composite type/*tuplen = tupdesc->natts;nulls = palloc(tuplen * sizeof(bool));*/memset(nulls,
0,sizeof(nulls));
 
// build tuple from datum arraytuple = heap_form_tuple(tupdesc, values, nulls);// Free null values/*pfree(nulls);*/
// Return the composite typePG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
----------------------------------------------------
Note: I'm just returning scheme and host fields for test, but others are
too completed by parse_url_exec.

It doesn't works fine:
----------------------------------------------------
postgres=# CREATE OR REPLACE FUNCTION parse_url_record(text) RETURNS
record AS '/home/samuel/parse_url.so', 'parse_url_record' LANGUAGE C;
CREATE FUNCTION
postgres=# SELECT * FROM parse_url_record('') as ("scheme" text, "host"
text);scheme | host 
--------+------       | 
(1 row)
----------------------------------------------------

Is there anybody here who can help me ?

Thanks you very much !
Samuel ROZE.
http://www.d-sites.com




Re: URL Managment - C Function help

From
Tom Lane
Date:
Samuel ROZE <samuel.roze@gmail.com> writes:
> The problem is that they don't work fine... :/

I think the problem is that you are passing C strings to code that
expects pointers to text datums --- which are not the same thing
at all.  (text has a length word, not a null terminator byte.)
It's pure accident that your first example works, and entirely
unsurprising that the second one doesn't.  Some CStringGetTextDatum
calls might help.
        regards, tom lane


Re: URL Managment - C Function help

From
Heikki Linnakangas
Date:
Samuel ROZE wrote:
> PG_FUNCTION_INFO_V1(parse_url_record);
> Datum parse_url_record (PG_FUNCTION_ARGS)
> {
>     // Vars about the params
>     //text *str2 = PG_GETARG_TEXT_P(0);
>     char str[] = "http://www.ovh.com/intenal.html";
> 
>     // Some vars which will used to create the composite output type
>     TupleDesc    tupdesc;
>     Datum        values[2]; // 8 values
>     HeapTuple    tuple;
>     bool        nulls[2];
>     int            tuplen;
> 
>     // Check NULLs values
>     if(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
>         PG_RETURN_NULL();
>     }
> 
>     url *ret = parse_url_exec(str);
> 
>     // Add datas into the values Datum
>     values[0] = PointerGetDatum(ret->scheme);
>     values[1] = PointerGetDatum(ret->host);
> 
>     // Convert values into a composite type
>     /*tuplen = tupdesc->natts;
>     nulls = palloc(tuplen * sizeof(bool));*/
>     memset(nulls, 0, sizeof(nulls));
> 
>     // build tuple from datum array
>     tuple = heap_form_tuple(tupdesc, values, nulls);
>     // Free null values
>     /*pfree(nulls);*/
> 
>     // Return the composite type
>     PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
> }

You haven't initialized tupdesc.

BTW, there's a fine example in the manual:
http://www.postgresql.org/docs/8.4/interactive/xfunc-c.html#AEN44968

--  Heikki Linnakangas EnterpriseDB   http://www.enterprisedb.com


Re: URL Managment - C Function help

From
Samuel ROZE
Date:
Thanks for your reply.

--------------------------------------------------------
PG_FUNCTION_INFO_V1(parse_url_record);
Datum parse_url_record (PG_FUNCTION_ARGS)
{// Vars about the params//text *str2 = PG_GETARG_TEXT_P(0);char str[] = "http://www.ovh.com/intenal.html";
// Some vars which will used to create the composite output typeTupleDesc    tupdesc;char        **values;HeapTuple
tuple;AttInMetadata*attinmeta;bool        nulls[2];int            tuplen;
 
// Check NULLs valuesif(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {    PG_RETURN_NULL();}
url *ret = parse_url_exec(str);
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
{    ereport(ERROR,            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),             errmsg("function returning record
calledin context "             "that cannot accept type record")));}attinmeta = TupleDescGetAttInMetadata(tupdesc);
 
// ...values = (char **) palloc(2 * sizeof(char *));
// Add datas into the values Datumvalues[0] = (char *) ret->scheme;values[1] = (char *) ret->host;
// Convert values into a composite typememset(nulls, 0, sizeof(nulls));
// build tuple from datum arraytuple = BuildTupleFromCStrings(attinmeta, values);
// Return the composite typePG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
-------------------------------------------------------

This code doesn't works better... :/

Le mercredi 21 octobre 2009 à 18:42 +0300, Heikki Linnakangas a écrit :
> Samuel ROZE wrote:
> > PG_FUNCTION_INFO_V1(parse_url_record);
> > Datum parse_url_record (PG_FUNCTION_ARGS)
> > {
> >     // Vars about the params
> >     //text *str2 = PG_GETARG_TEXT_P(0);
> >     char str[] = "http://www.ovh.com/intenal.html";
> > 
> >     // Some vars which will used to create the composite output type
> >     TupleDesc    tupdesc;
> >     Datum        values[2]; // 8 values
> >     HeapTuple    tuple;
> >     bool        nulls[2];
> >     int            tuplen;
> > 
> >     // Check NULLs values
> >     if(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
> >         PG_RETURN_NULL();
> >     }
> > 
> >     url *ret = parse_url_exec(str);
> > 
> >     // Add datas into the values Datum
> >     values[0] = PointerGetDatum(ret->scheme);
> >     values[1] = PointerGetDatum(ret->host);
> > 
> >     // Convert values into a composite type
> >     /*tuplen = tupdesc->natts;
> >     nulls = palloc(tuplen * sizeof(bool));*/
> >     memset(nulls, 0, sizeof(nulls));
> > 
> >     // build tuple from datum array
> >     tuple = heap_form_tuple(tupdesc, values, nulls);
> >     // Free null values
> >     /*pfree(nulls);*/
> > 
> >     // Return the composite type
> >     PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
> > }
> 
> You haven't initialized tupdesc.
> 
> BTW, there's a fine example in the manual:
> http://www.postgresql.org/docs/8.4/interactive/xfunc-c.html#AEN44968
> 




Re: URL Managment - C Function help

From
Samuel ROZE
Date:
Le mercredi 21 octobre 2009 à 11:42 -0400, Tom Lane a écrit :
> CStringGetTextDatum

Can you give me more precisions ?

I'm creating a "user C function", with shared library and
CStringGetTextDatum is in "varlena.h" file which is not in the
"src/include" dir... How can I include it ?

Thanks.
Samuel.



Re: URL Managment - C Function help

From
Andrew Dunstan
Date:

Samuel ROZE wrote:
> Le mercredi 21 octobre 2009 à 11:42 -0400, Tom Lane a écrit :
>   
>> CStringGetTextDatum
>>     
>
> Can you give me more precisions ?
>
> I'm creating a "user C function", with shared library and
> CStringGetTextDatum is in "varlena.h" file which is not in the
> "src/include" dir... How can I include it ?
>
>
>   

It's in utils/builtins.h, as a simple grep search should have told you.

cheers

andrew


Re: URL Managment - C Function help

From
Samuel ROZE
Date:
I've done it but I had no results... strange.

I've a 8.3 version and this lines are NOT in the file:
00668 /* varlena.c */
00669 extern text *cstring_to_text(const char *s);
00670 extern text *cstring_to_text_with_len(const char *s, int len);
00671 extern char *text_to_cstring(const text *t);
00672 extern void text_to_cstring_buffer(const text *src, char *dst, size_t dst_len);
00673 
00674 #define CStringGetTextDatum(s) PointerGetDatum(cstring_to_text(s))
00675 #define TextDatumGetCString(d) text_to_cstring((text *) DatumGetPointer(d))

Le mercredi 21 octobre 2009 à 12:28 -0400, Andrew Dunstan a écrit :
> 
> Samuel ROZE wrote:
> > Le mercredi 21 octobre 2009 à 11:42 -0400, Tom Lane a écrit :
> >   
> >> CStringGetTextDatum
> >>     
> >
> > Can you give me more precisions ?
> >
> > I'm creating a "user C function", with shared library and
> > CStringGetTextDatum is in "varlena.h" file which is not in the
> > "src/include" dir... How can I include it ?
> >
> >
> >   
> 
> It's in utils/builtins.h, as a simple grep search should have told you.
> 
> cheers
> 
> andrew




Re: URL Managment - C Function help

From
Samuel ROZE
Date:
I'm now using C strings. I don't need to use CStringGetTextDatum, but it
still don't works. There's the code:

---------------------------------------------------------------
PG_FUNCTION_INFO_V1(parse_url_record);
Datum parse_url_record (PG_FUNCTION_ARGS)
{// Vars about the params//text *str2 = PG_GETARG_TEXT_P(0);char str[] = "http://www.ovh.com/intenal.html";
// Some vars which will used to create the composite output typeTupleDesc    tupdesc;char        **values;HeapTuple
tuple;AttInMetadata*attinmeta;bool        nulls[2];url         *ret;
 
// Check NULLs valuesif(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {    PG_RETURN_NULL();}
ret = parse_url_exec(str);
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
{    ereport(ERROR,            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),             errmsg("function returning record
calledin context that
 
cannot accept type record")));}attinmeta = TupleDescGetAttInMetadata(tupdesc);
// ...values = (char **) palloc(2 * sizeof(char *));
// Add datas into the values Datumvalues[0] = (char *) ret->scheme;values[1] = (char *) ret->host;
// Convert values into a composite typememset(nulls, 0, sizeof(nulls));
// build tuple from datum arraytuple = BuildTupleFromCStrings(attinmeta, values);
// Return the composite typePG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
---------------------------------------------------------------

Thanks a lot !
Samuel ROZE.

Le mercredi 21 octobre 2009 à 11:42 -0400, Tom Lane a écrit :
> Samuel ROZE <samuel.roze@gmail.com> writes:
> > The problem is that they don't work fine... :/
> 
> I think the problem is that you are passing C strings to code that
> expects pointers to text datums --- which are not the same thing
> at all.  (text has a length word, not a null terminator byte.)
> It's pure accident that your first example works, and entirely
> unsurprising that the second one doesn't.  Some CStringGetTextDatum
> calls might help.
> 
>             regards, tom lane




Re: URL Managment - C Function help

From
Tom Lane
Date:
Samuel ROZE <samuel.roze@gmail.com> writes:
> I've done it but I had no results... strange.
> I've a 8.3 version and this lines are NOT in the file:

Oh, it was changed in 8.4 IIRC.  If you are thinking of submitting
code to the project you should not be developing against a back
release anyway ...
        regards, tom lane


Re: URL Managment - C Function help

From
Andrew Dunstan
Date:

Samuel ROZE wrote:
> I've done it but I had no results... strange.
>
> I've a 8.3 version and this lines are NOT in the file:
>   


You neglected to tell us you were in 8.3 before, I think.

On 8.3 you might need to put a #define for it directly in your C file.

cheers

andrew






Re: URL Managment - C Function help

From
Samuel ROZE
Date:
Le mercredi 21 octobre 2009 à 12:59 -0400, Andrew Dunstan a écrit :
> On 8.3 you might need to put a #define for it directly in your C file.

I can't: cstring_to_text isn't defined.

I'll develop on 8.4.



Re: URL Managment - C Function help

From
Andrew Dunstan
Date:

Samuel ROZE wrote:
> Le mercredi 21 octobre 2009 à 12:59 -0400, Andrew Dunstan a écrit :
>   
>> On 8.3 you might need to put a #define for it directly in your C file.
>>     
>
> I can't: cstring_to_text isn't defined.
>
> I'll develop on 8.4.
>   

or try:

#define CStringGetTextP(c) DatumGetTextP(DirectFunctionCall1(textin, 
CStringGetDatum(c)))


cheers

andrew


Re: URL Managment - C Function help

From
Samuel ROZE
Date:
It is solved. I'll propose my work the next weeks. :-)

Regards,
Samuel.

Le mercredi 21 octobre 2009 à 17:31 +0200, Samuel ROZE a écrit :
> Hi,
> 
> I'm writing two functions "parse_url_key" and "parse_url_record" which
> will have one text argument and will return a record or a specific
> column of it. Theses functions are calling "parse_url_exec" which parse
> the URL. When theses function will works, i'll purpose them to
> PostgreSQL community.
> 
> The problem is that they don't work fine... :/
> 
> Prototypes of function/struct used by them:
> ----------------------------------------------------
> typedef struct url {
>     char *scheme;
>     char *user;
>     char *pass;
>     char *host;
>     unsigned short port;
>     char *path;
>     char *query;
>     char *fragment;
> } url;
> 
> url *parse_url_exec (char* str);
> ----------------------------------------------------
> 
> The parse_url_key function:
> ----------------------------------------------------
> PG_FUNCTION_INFO_V1(parse_url_key);
> Datum parse_url_key (PG_FUNCTION_ARGS)
> {
>     char str[] = "http://www.ovh.com/intenal.html";
>     //text *my_url = PG_GETARG_TEXT_P(0);
>     //char *char_url = DatumGetCString(my_url);
> 
>     url *ret = parse_url_exec(str);
> 
>     PG_RETURN_TEXT_P(ret->host);
> }
> ----------------------------------------------------
> Note: I'm using built-in strings to be sure that the recuperation
> doesn't change anything..
> 
> This function works well:
> ----------------------------------------------------
> postgres=# CREATE OR REPLACE FUNCTION parse_url_key(text) RETURNS text
> AS '/home/samuel/parse_url.so', 'parse_url_key' LANGUAGE C;
> CREATE FUNCTION
> postgres=# SELECT parse_url_key('') as scheme;
>    scheme   
> ------------
>  ww.ovh.com
> (1 row)
> ----------------------------------------------------
> Note: there's a little problem here but not important. :-)
> 
> The problem is that the other function, "parse_url_record" doesn't
> return values ! The code is:
> ----------------------------------------------------
> PG_FUNCTION_INFO_V1(parse_url_record);
> Datum parse_url_record (PG_FUNCTION_ARGS)
> {
>     // Vars about the params
>     //text *str2 = PG_GETARG_TEXT_P(0);
>     char str[] = "http://www.ovh.com/intenal.html";
> 
>     // Some vars which will used to create the composite output type
>     TupleDesc    tupdesc;
>     Datum        values[2]; // 8 values
>     HeapTuple    tuple;
>     bool        nulls[2];
>     int            tuplen;
> 
>     // Check NULLs values
>     if(PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
>         PG_RETURN_NULL();
>     }
> 
>     url *ret = parse_url_exec(str);
> 
>     // Add datas into the values Datum
>     values[0] = PointerGetDatum(ret->scheme);
>     values[1] = PointerGetDatum(ret->host);
> 
>     // Convert values into a composite type
>     /*tuplen = tupdesc->natts;
>     nulls = palloc(tuplen * sizeof(bool));*/
>     memset(nulls, 0, sizeof(nulls));
> 
>     // build tuple from datum array
>     tuple = heap_form_tuple(tupdesc, values, nulls);
>     // Free null values
>     /*pfree(nulls);*/
> 
>     // Return the composite type
>     PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
> }
> ----------------------------------------------------
> Note: I'm just returning scheme and host fields for test, but others are
> too completed by parse_url_exec.
> 
> It doesn't works fine:
> ----------------------------------------------------
> postgres=# CREATE OR REPLACE FUNCTION parse_url_record(text) RETURNS
> record AS '/home/samuel/parse_url.so', 'parse_url_record' LANGUAGE C;
> CREATE FUNCTION
> postgres=# SELECT * FROM parse_url_record('') as ("scheme" text, "host"
> text);
>  scheme | host 
> --------+------
>         | 
> (1 row)
> ----------------------------------------------------
> 
> Is there anybody here who can help me ?
> 
> Thanks you very much !
> Samuel ROZE.
> http://www.d-sites.com
> 
>