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/*!
* \file db/dbmi_client/start.c
*
* \brief DBMI Library (client) - open database connection
*
* (C) 1999-2008 by the GRASS Development Team
*
* This program is free software under the GNU General Public
* License (>=v2). Read the file COPYING that comes with GRASS
* for details.
*
* \author Joel Jones (CERL/UIUC), Radim Blazek
*/
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef __MINGW32__
#include <windows.h>
#include <process.h>
#include <fcntl.h>
#endif
#include <grass/spawn.h>
#include <grass/dbmi.h>
#define READ 0
#define WRITE 1
static void close_on_exec(int fd)
{
#ifndef __MINGW32__
int flags = fcntl(fd, F_GETFD);
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
#endif
}
/*!
\brief Initialize a new dbDriver for db transaction.
If <i>name</i> is NULL, the db name will be assigned
connection.driverName.
\param name driver name
\return pointer to dbDriver structure
\return NULL on error
*/
dbDriver *db_start_driver(const char *name)
{
dbDriver *driver;
dbDbmscap *list, *cur;
const char *startup;
int p1[2], p2[2];
int pid;
int stat;
dbConnection connection;
char ebuf[5];
/* Set some environment variables which are later read by driver.
* This is necessary when application is running without GISRC file and all
* gis variables are set by application.
* Even if GISRC is set, application may change some variables during
* runtime, if for example reads data from different gdatabase, location or
* mapset */
/* setenv() is not portable, putenv() is POSIX, putenv() in glibc 2.0-2.1.1
* doesn't conform to SUSv2, G_putenv() as well, but that is what we want,
* makes a copy of string */
if (G_get_gisrc_mode() == G_GISRC_MODE_MEMORY) {
G_debug(3, "G_GISRC_MODE_MEMORY\n");
sprintf(ebuf, "%d", G_GISRC_MODE_MEMORY);
G_putenv("GRASS_DB_DRIVER_GISRC_MODE",
ebuf); /* to tell driver that it must read variables */
if (G_getenv_nofatal("DEBUG")) {
G_putenv("DEBUG", G_getenv_nofatal("DEBUG"));
}
else {
G_putenv("DEBUG", "0");
}
G_putenv("GISDBASE", G_getenv_nofatal("GISDBASE"));
G_putenv("LOCATION_NAME", G_getenv_nofatal("LOCATION_NAME"));
G_putenv("MAPSET", G_getenv_nofatal("MAPSET"));
}
else {
/* Warning: GISRC_MODE_MEMORY _must_ be set to G_GISRC_MODE_FILE,
* because the module can be run from an application which previously
* set environment variable to G_GISRC_MODE_MEMORY */
sprintf(ebuf, "%d", G_GISRC_MODE_FILE);
G_putenv("GRASS_DB_DRIVER_GISRC_MODE", ebuf);
}
/* read the dbmscap file */
if (NULL == (list = db_read_dbmscap()))
return (dbDriver *)NULL;
/* if name is empty use connection.driverName, added by RB 4/2000 */
if (name == NULL || name[0] == '\0') {
db_get_connection(&connection);
if (NULL == (name = connection.driverName))
return (dbDriver *)NULL;
}
/* find this system name */
for (cur = list; cur; cur = cur->next)
if (strcmp(cur->driverName, name) == 0)
break;
if (cur == NULL) {
char msg[256];
db_free_dbmscap(list);
sprintf(msg, "%s: no such driver available", name);
db_error(msg);
return (dbDriver *)NULL;
}
/* allocate a driver structure */
driver = (dbDriver *)db_malloc(sizeof(dbDriver));
if (driver == NULL) {
db_free_dbmscap(list);
return (dbDriver *)NULL;
}
/* copy the relevant info from the dbmscap entry into the driver structure
*/
db_copy_dbmscap_entry(&driver->dbmscap, cur);
startup = driver->dbmscap.startup;
/* free the dbmscap list */
db_free_dbmscap(list);
/* run the driver as a child process and create pipes to its stdin, stdout
*/
#ifdef __MINGW32__
#define pipe(fds) _pipe(fds, 250000, _O_BINARY | _O_NOINHERIT)
#endif
/* open the pipes */
if ((pipe(p1) < 0) || (pipe(p2) < 0)) {
db_syserror("can't open any pipes");
return (dbDriver *)NULL;
}
close_on_exec(p1[READ]);
close_on_exec(p1[WRITE]);
close_on_exec(p2[READ]);
close_on_exec(p2[WRITE]);
pid =
G_spawn_ex(startup, SF_BACKGROUND, SF_REDIRECT_DESCRIPTOR, 0, p1[READ],
SF_CLOSE_DESCRIPTOR, p1[WRITE], SF_REDIRECT_DESCRIPTOR, 1,
p2[WRITE], SF_CLOSE_DESCRIPTOR, p2[READ], startup, NULL);
/* create a child */
if (pid < 0) {
db_syserror("can't create fork");
return (dbDriver *)NULL;
}
close(p1[READ]);
close(p2[WRITE]);
/* record driver process id in driver struct */
driver->pid = pid;
/* convert pipes to FILE* */
driver->send = fdopen(p1[WRITE], "wb");
driver->recv = fdopen(p2[READ], "rb");
/* most systems will have to use unbuffered io to get the send/recv to work
*/
#ifndef USE_BUFFERED_IO
setbuf(driver->send, NULL);
setbuf(driver->recv, NULL);
#endif
db__set_protocol_fds(driver->send, driver->recv);
if (db__recv_return_code(&stat) != DB_OK || stat != DB_OK)
driver = NULL;
return driver;
}
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