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* writing c functions for postgres
@ 2009-04-06 15:56 eehab hamzeh <eehab40@hotmail.com>
2009-04-07 06:48 ` Re: writing c functions for postgres Albe Laurenz <laurenz.albe@wien.gv.at>
0 siblings, 1 reply; 3+ messages in thread
From: eehab hamzeh @ 2009-04-06 15:56 UTC (permalink / raw)
To: pgsql-general@postgresql.org
Dear Sir
I am trying to build some functions using C language. these functions are
mentioned in the postgresql documentation.
the only function that are work are the one with int32 variable.
the other function bring errors and are not working
any body can give directions
here are the code and the error , i compile them using vc++ 6 and VC++ 2008 and minGW the example below are for minGW
THANKS
#include "postgres.h"
#include <string.h>
#include "fmgr.h"
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
/* by value */
PG_FUNCTION_INFO_V1(add_one);
Datum
add_one(PG_FUNCTION_ARGS)
{
int32 arg = PG_GETARG_INT32(0);
PG_RETURN_INT32(arg + 1);
}
/* by reference, fixed length */
PG_FUNCTION_INFO_V1(add_one_float8);
Datum
add_one_float8(PG_FUNCTION_ARGS)
{
/* The macros for FLOAT8 hide its pass-by-reference nature. */
float8 arg = PG_GETARG_FLOAT8(0);
PG_RETURN_FLOAT8(arg + 1.0);
}
PG_FUNCTION_INFO_V1(makepoint);
Datum
makepoint(PG_FUNCTION_ARGS)
{
/* Here, the pass-by-reference nature of Point is not hidden. */
Point *pointx = PG_GETARG_POINT_P(0);
Point *pointy = PG_GETARG_POINT_P(1);
Point *new_point = (Point *) palloc(sizeof(Point));
new_point->x = pointx->x;
new_point->y = pointy->y;
PG_RETURN_POINT_P(new_point);
}
/* by reference, variable length */
PG_FUNCTION_INFO_V1(copytext);
Datum
copytext(PG_FUNCTION_ARGS)
{
text *t = PG_GETARG_TEXT_P(0);
/*
* VARSIZE is the total size of the struct in bytes.
*/
text *new_t = (text *) palloc(VARSIZE(t));
VARATT_SIZEP(new_t) = VARSIZE(t);
/*
* VARDATA is a pointer to the data region of the struct.
*/
memcpy((void *) VARDATA(new_t), /* destination */
(void *) VARDATA(t), /* source */
VARSIZE(t)-VARHDRSZ); /* how many bytes */
PG_RETURN_TEXT_P(new_t);
}
PG_FUNCTION_INFO_V1(concat_text);
Datum
concat_text(PG_FUNCTION_ARGS)
{
text *arg1 = PG_GETARG_TEXT_P(0);
text *arg2 = PG_GETARG_TEXT_P(1);
int32 new_text_size = VARSIZE(arg1) + VARSIZE(arg2) - VARHDRSZ;
text *new_text = (text *) palloc(new_text_size);
VARATT_SIZEP(new_text) = new_text_size;
memcpy(VARDATA(new_text), VARDATA(arg1), VARSIZE(arg1)-VARHDRSZ);
memcpy(VARDATA(new_text) + (VARSIZE(arg1)-VARHDRSZ),
VARDATA(arg2), VARSIZE(arg2)-VARHDRSZ);
PG_RETURN_TEXT_P(new_text);
}
the error
in function 'makepoint':
error: 'Point' undeclared (first use in this function)
error: (each undeclared identifier is reported only one
error: for each function it appears in.)
error: 'pointx' undeclared (first use in ´this function)
error: 'pointy' undeclared (first use in his fnction)
error 'new_point' undeclared (first use in his function)
error: syntax error befre ')' oken
in function 'copy text':
error: 'invalid lvalue in assinment
In function 'concat_text'
error: invalid lvalue in assignement
warning no new line at end of file
Please any direction of how to solve the problem
here is the command i wrote in MinGW
gcc -shared -o hamzeh.dll tt1.o -L "c:/programme/postgresql/8.3/lib" -lpostgres
thanks
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^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: writing c functions for postgres
2009-04-06 15:56 writing c functions for postgres eehab hamzeh <eehab40@hotmail.com>
@ 2009-04-07 06:48 ` Albe Laurenz <laurenz.albe@wien.gv.at>
2009-04-07 08:35 ` Re: writing c functions for postgres Glyn Astill <glynastill@yahoo.co.uk>
0 siblings, 1 reply; 3+ messages in thread
From: Albe Laurenz @ 2009-04-07 06:48 UTC (permalink / raw)
To: eehab hamzeh *EXTERN* <eehab40@hotmail.com>; pgsql-general@postgresql.org
eehab hamzeh wrote:
> I am trying to build some functions using C language. these functions are
> mentioned in the postgresql documentation.
>
> the only function that are work are the one with int32 variable.
> the other function bring errors and are not working
> any body can give directions
>
> #include "postgres.h"
> #include <string.h>
> #include "fmgr.h"
>
> #ifdef PG_MODULE_MAGIC
> PG_MODULE_MAGIC;
> #endif
>
[...]
>
> PG_FUNCTION_INFO_V1(makepoint);
>
> Datum
> makepoint(PG_FUNCTION_ARGS)
> {
> /* Here, the pass-by-reference nature of Point is not hidden. */
> Point *pointx = PG_GETARG_POINT_P(0);
> Point *pointy = PG_GETARG_POINT_P(1);
> Point *new_point = (Point *) palloc(sizeof(Point));
>
[...]
>
> PG_FUNCTION_INFO_V1(copytext);
>
> Datum
> copytext(PG_FUNCTION_ARGS)
> {
[...]
> VARATT_SIZEP(new_t) = VARSIZE(t);
[...]
> }
>
> PG_FUNCTION_INFO_V1(concat_text);
>
> Datum
> concat_text(PG_FUNCTION_ARGS)
> {
[...]
> VARATT_SIZEP(new_text) = new_text_size;
[...]
> }
>
>
> the error
>
> in function 'makepoint':
> error: 'Point' undeclared (first use in this function)
> error: (each undeclared identifier is reported only one
> error: for each function it appears in.)
> error: 'pointx' undeclared (first use in ´this function)
> error: 'pointy' undeclared (first use in his fnction)
> error 'new_point' undeclared (first use in his function)
> error: syntax error befre ')' oken
> in function 'copy text':
> error: 'invalid lvalue in assinment
> In function 'concat_text'
> error: invalid lvalue in assignement
> warning no new line at end of file
These error messages are certainly not what you saw on the screen.
It is best to copy and paste error messages!
If you want to have Point, you'll have to
#include "utils/geo_decls.h"
The "invalid lvalue" errors are generated because gcc does not
know VARATT_SIZEP and assumes it is a function returning int.
I recommend that you always use gcc with -Wall to see warnings!
I can find no VARATT_SIZEP in the PostgreSQL 8.3 headers.
Where did you get that from?
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: writing c functions for postgres
2009-04-06 15:56 writing c functions for postgres eehab hamzeh <eehab40@hotmail.com>
2009-04-07 06:48 ` Re: writing c functions for postgres Albe Laurenz <laurenz.albe@wien.gv.at>
@ 2009-04-07 08:35 ` Glyn Astill <glynastill@yahoo.co.uk>
0 siblings, 0 replies; 3+ messages in thread
From: Glyn Astill @ 2009-04-07 08:35 UTC (permalink / raw)
To: eehab hamzeh *EXTERN* <eehab40@hotmail.com>; pgsql-general@postgresql.org, Albe Laurenz <laurenz.albe@wien.gv.at>
--- On Tue, 7/4/09, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
> I can find no VARATT_SIZEP in the PostgreSQL 8.3 headers.
> Where did you get that from?
>
> Yours,
> Laurenz Albe
>
I think it's depreciated and he should be using SET_VARSIZE instead ...
^ permalink raw reply [nested|flat] 3+ messages in thread
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2009-04-06 15:56 writing c functions for postgres eehab hamzeh <eehab40@hotmail.com>
2009-04-07 06:48 ` Albe Laurenz <laurenz.albe@wien.gv.at>
2009-04-07 08:35 ` Glyn Astill <glynastill@yahoo.co.uk>
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