C Set Returning Function (SRF)

All,

I'm trying to write a simple set returning function that links the GNU pwgen
code. I can't seem to pull it together to return the results reliably.
There are several examples that demonstrate returning tuples, but I can't
seem to find any examples of SRFs returning single (specifically textual)
types. Will someone please offer some insight?

#include "postgres.h"
#include "utils/builtins.h"
#include "fmgr.h"
#include "funcapi.h"
#include <string.h>

#include "pwgen.h"

PG_MODULE_MAGIC;

int (*pw_number)(int max_num);

PG_FUNCTION_INFO_V1(pwgen_srf);

Datum
pwgen_srf(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
int pwgen_flags = PW_DIGITS | PW_UPPERS;
int call_cntr, max_calls, pw_length;

if (SRF_IS_FIRSTCALL()) {
MemoryContext oldcontext;

funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
funcctx->max_calls = PG_GETARG_UINT32(0);
MemoryContextSwitchTo(oldcontext);
}

funcctx = SRF_PERCALL_SETUP();

pw_length = PG_GETARG_INT32(1);
call_cntr = funcctx->call_cntr;
max_calls = funcctx->max_calls;
pw_number = pw_random_number;

if (call_cntr < max_calls) {
char *pw;

pw = (char *)palloc(pw_length);
pw_phonemes(pw, pw_length, pwgen_flags);
SRF_RETURN_NEXT(funcctx, CStringGetDatum(pw));
} else {
SRF_RETURN_DONE(funcctx);
}
}

Thank you!

-- Gary Chambers