Re: [HACKERS] C Extension woes

Tim Hawes wrote:
> Hello all,
>
> I am trying to write an extension in C that returns a simple environment
> variable. The code compiles without any complaint or warning, and it
> loads fine into the database, however, when I run the function, I get
> disconnected from the server.
>
> Here is my C code:
>
> #include <postgres.h>
> #include <fmgr.h>
> PG_MODULE_MAGIC;
>
> #include <stdio.h>
> #include <stdlib.h>
>
> PG_FUNCTION_INFO_V1(pl_masterkey);
>
> text * pl_masterkey(PG_FUNCTION_ARGS)
> {
> char *e_var = getenv("PGMASTERKEY");
> size_t length = VARSIZE(e_var) - VARHDRSZ;
>
> text * mkey = (text *) palloc(length);
> VARATT_SIZEP(mkey) = length;
> memcpy(VARDATA(mkey), e_var, length);
>
> return mkey;
> }

Oh, you confused a lot of things.
You need something like

Datum pl_masterkey(PG_FUNCTION_ARGS) {
char *e_var = getenv("PGMASTERKEY");
PG_RETURN_TEXT_P(cstring_to_text(e_var));
}

You don't need to mess with anything varlena-related (liek VARSIZE),
it's all handled for you.
Also, read up on how to declare user-defined C functions in Postgres
(they always need to return Datum).

Cheers,
Jan

--
Jan Urbanski
GPG key ID: E583D7D2

ouden estin

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