pginterface.c

/*
 * pginterface.c
 *
*/

#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <stdarg.h>

#include <halt.h>
#include <libpq-fe.h>
#include "pginterface.h"

static void sig_disconnect();
static void set_signals();

#define NUL '\0'

/* GLOBAL VARIABLES */
static PGconn* conn;
static PGresult* res = NULL;
int	skip_query_errors = 0;

/* LOCAL VARIABLES */
static sigset_t block_sigs, unblock_sigs;
static int tuple;

/*
**
**	connectdb - returns PGconn structure
**
*/
PGconn *connectdb(	char *dbName,
					char *pghost,
					char *pgport,
					char *pgoptions,
					char *pgtty)
{
	/* make a connection to the database */
	conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
	if (PQstatus(conn) == CONNECTION_BAD)
		halt("Connection to database '%s' failed.\n%s\n", dbName,
			PQerrorMessage(conn));
	set_signals();
	return conn;
}

/*
**
**	disconnectdb
**
*/
void disconnectdb()
{
	PQfinish(conn);
}

/*
**
**	doquery	- returns PGresult structure
**
*/
PGresult *doquery(char *query)
{
	if (res != NULL)
		PQclear(res);

	sigprocmask(SIG_SETMASK,&block_sigs,NULL);
	res = PQexec(conn, query);
	sigprocmask(SIG_SETMASK,&unblock_sigs,NULL);

	if (skip_query_errors == 0 &&
		(res == NULL ||
		 PQresultStatus(res) ==	PGRES_BAD_RESPONSE ||
		 PQresultStatus(res) ==	PGRES_NONFATAL_ERROR ||
		 PQresultStatus(res) ==	PGRES_FATAL_ERROR))
	{
		if (res != NULL)
				fprintf(stderr,"query error:  %s\n",PQcmdStatus(res));
		else	fprintf(stderr,"connection error:  %s\n",PQerrorMessage(conn));
		PQfinish(conn);
		halt("failed request:  %s\n", query);
	}
	tuple = 0;
	return res;
}

/*
**
**	fetch - returns tuple number (starts at 0), or the value END_OF_TUPLES
**			NULL pointers are skipped
**
*/
int fetch(void *param, ...)
{
	va_list ap;
	int arg, num_args;

	num_args = PQnfields(res);

	if (tuple >= PQntuples(res))
		return END_OF_TUPLES;
	va_start(ap, param);
	for (arg = 0; arg < num_args; arg++)
	{
		if (param != NULL)
		{
			if (PQfsize(res, arg) == -1)
			{
				memcpy(param,PQgetvalue(res,tuple,arg),PQgetlength(res,tuple,arg));
				((char *)param)[PQgetlength(res,tuple,arg)] = NUL;
			}
			else
				memcpy(param,PQgetvalue(res,tuple,arg),PQfsize(res,arg));
		}
		param = va_arg(ap, char *);
	}
	va_end(ap);
	return tuple++;
}

/*
**
**	sig_disconnect
**
*/
static void sig_disconnect()
{
	fprintf(stderr,"exiting...\n");
	PQfinish(conn);
	exit(1);
}

/*
**
**	set_signals
**
*/
static void set_signals()
{
	sigemptyset(&block_sigs);
	sigemptyset(&unblock_sigs);
	sigaddset(&block_sigs,SIGTERM);
	sigaddset(&block_sigs,SIGHUP);
	sigaddset(&block_sigs,SIGINT);
/*	sigaddset(&block_sigs,SIGQUIT); no block */
	sigprocmask(SIG_SETMASK,&unblock_sigs,NULL);
	signal(SIGTERM,sig_disconnect);
	signal(SIGHUP,sig_disconnect);
	signal(SIGINT,sig_disconnect);
	signal(SIGQUIT,sig_disconnect);
}