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/*-------------------------------------------------------------------------
*
* plsample.c
* Handler for the PL/Sample procedural language
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/test/modules/plsample/plsample.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/event_trigger.h"
#include "commands/trigger.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(plsample_call_handler);
static Datum plsample_func_handler(PG_FUNCTION_ARGS);
/*
* Handle function, procedure, and trigger calls.
*/
Datum
plsample_call_handler(PG_FUNCTION_ARGS)
{
Datum retval = (Datum) 0;
PG_TRY();
{
/*
* Determine if called as function or trigger and call appropriate
* subhandler.
*/
if (CALLED_AS_TRIGGER(fcinfo))
{
/*
* This function has been called as a trigger function, where
* (TriggerData *) fcinfo->context includes the information of the
* context.
*/
}
else if (CALLED_AS_EVENT_TRIGGER(fcinfo))
{
/*
* This function is called as an event trigger function, where
* (EventTriggerData *) fcinfo->context includes the information
* of the context.
*/
}
else
{
/* Regular function handler */
retval = plsample_func_handler(fcinfo);
}
}
PG_FINALLY();
{
}
PG_END_TRY();
return retval;
}
/*
* plsample_func_handler
*
* Function called by the call handler for function execution.
*/
static Datum
plsample_func_handler(PG_FUNCTION_ARGS)
{
HeapTuple pl_tuple;
Datum ret;
char *source;
bool isnull;
FmgrInfo *arg_out_func;
Form_pg_type type_struct;
HeapTuple type_tuple;
Form_pg_proc pl_struct;
volatile MemoryContext proc_cxt = NULL;
Oid *argtypes;
char **argnames;
char *argmodes;
char *proname;
Form_pg_type pg_type_entry;
Oid result_typioparam;
Oid prorettype;
FmgrInfo result_in_func;
int numargs;
/* Fetch the source text of the function. */
pl_tuple = SearchSysCache(PROCOID,
ObjectIdGetDatum(fcinfo->flinfo->fn_oid), 0, 0, 0);
if (!HeapTupleIsValid(pl_tuple))
elog(ERROR, "cache lookup failed for function %u",
fcinfo->flinfo->fn_oid);
/*
* Extract and print the source text of the function. This can be used as
* a base for the function validation and execution.
*/
pl_struct = (Form_pg_proc) GETSTRUCT(pl_tuple);
proname = pstrdup(NameStr(pl_struct->proname));
ret = SysCacheGetAttr(PROCOID, pl_tuple, Anum_pg_proc_prosrc, &isnull);
if (isnull)
elog(ERROR, "could not find source text of function \"%s\"",
proname);
source = DatumGetCString(DirectFunctionCall1(textout, ret));
ereport(NOTICE,
(errmsg("source text of function \"%s\": %s",
proname, source)));
/*
* Allocate a context that will hold all the Postgres data for the
* procedure.
*/
proc_cxt = AllocSetContextCreate(TopMemoryContext,
"PL/Sample function",
ALLOCSET_SMALL_SIZES);
arg_out_func = (FmgrInfo *) palloc0(fcinfo->nargs * sizeof(FmgrInfo));
numargs = get_func_arg_info(pl_tuple, &argtypes, &argnames, &argmodes);
/*
* Iterate through all of the function arguments, printing each input
* value.
*/
for (int i = 0; i < numargs; i++)
{
Oid argtype = pl_struct->proargtypes.values[i];
char *value;
type_tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(argtype));
if (!HeapTupleIsValid(type_tuple))
elog(ERROR, "cache lookup failed for type %u", argtype);
type_struct = (Form_pg_type) GETSTRUCT(type_tuple);
fmgr_info_cxt(type_struct->typoutput, &(arg_out_func[i]), proc_cxt);
ReleaseSysCache(type_tuple);
value = OutputFunctionCall(&arg_out_func[i], fcinfo->args[i].value);
ereport(NOTICE,
(errmsg("argument: %d; name: %s; value: %s",
i, argnames[i], value)));
}
/* Type of the result */
prorettype = pl_struct->prorettype;
ReleaseSysCache(pl_tuple);
/*
* Get the required information for input conversion of the return value.
*
* If the function uses VOID as result, it is better to return NULL.
* Anyway, let's be honest. This is just a template, so there is not much
* we can do here. This returns NULL except if the result type is text,
* where the result is the source text of the function.
*/
if (prorettype != TEXTOID)
PG_RETURN_NULL();
type_tuple = SearchSysCache1(TYPEOID,
ObjectIdGetDatum(prorettype));
if (!HeapTupleIsValid(type_tuple))
elog(ERROR, "cache lookup failed for type %u", prorettype);
pg_type_entry = (Form_pg_type) GETSTRUCT(type_tuple);
result_typioparam = getTypeIOParam(type_tuple);
fmgr_info_cxt(pg_type_entry->typinput, &result_in_func, proc_cxt);
ReleaseSysCache(type_tuple);
ret = InputFunctionCall(&result_in_func, source, result_typioparam, -1);
PG_RETURN_DATUM(ret);
}
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