Re: reading array[text] in C extension function

[Rémi Cura <remi.cura@xxxxxxxxx>]

I'll auto-answer ;-)

Based on the function "btoptions" from postgres source, which takes aas a first arg a text[] :

ArrayType  *array;

Datum      *dimdatums;

int         ndim;

array = DatumGetArrayTypeP(dimensions);

Assert(ARR_ELEMTYPE(array) == TEXTOID);

pcinfo("after assert \n");

deconstruct_array(array, TEXTOID, -1, false, 'i',

 &dimdatums, NULL, &ndim);

 

//construct the array to hold the result :

char ** final_dimension_array = (char **) pcalloc(ndim * sizeof(char * ) ); 

for (i = 0; i < ndim; i++)

{

 text       *dimensiontext = DatumGetTextP(dimdatums[i]);

char       *text_str = VARDATA(dimensiontext);

int         text_len = VARSIZE(dimensiontext) - VARHDRSZ;

char       *s;

char       *p;

s = TextDatumGetCString(dimdatums[i]);

final_dimension_array[i] = s;

}

//pcinfo("end of the text retrieval\n");  

Cheers,

Rémi-C

2014/1/15 Rémi Cura <remi.cura@xxxxxxxxx>

Hey,

I'm trying to use an array of text as input in a C function in a custom extension.

the prototype of the sql function is  :

CREATE OR REPLACE FUNCTION pc_subset(  dimensions TEXT[])

 

it is called like :

pc_subset(  ARRAY['X'::text,'Y'::text])

and the C function trying to read the text array (converting it to cstring ) :

text ** vals;

char ** cstring_array;

nelems = ARR_DIMS(arrptr)[0];

vals = (text**) ARR_DATA_PTR(arrptr);

cstring_array = (char **) pcalloc(nelems * sizeof(char * ) );

for (i3=0;i3<nelems;i3++)

{ 

cstring_array[i3] = text_to_cstring( vals[i3]);

elog(INFO, "elem %d of dim_array : %s\n",i3,cstring_array[i3]);

}

I crashes postgres because of a segfault.

Any help appreciated =)

Cheers,

Rémi-C