firebird-mirror/src/utilities/util.cpp

/*
 *      PROGRAM:        InterBase Utility programs
 *      MODULE:         util.c
 *      DESCRIPTION:    Utility routines for fbguard & fbserver
 *
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 */
/*
$Id: util.cpp,v 1.7 2002-09-18 12:50:05 eku Exp $
*/

#include "firebird.h"
#include "../jrd/ib_stdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>				/* for open() and fcntl() */
#include <errno.h>

#ifdef HAVE_FLOCK
#include <sys/file.h>			/* for flock() */
#endif

#ifdef HAVE_STRING_H
#include <string.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>				/* for fork() */
#endif

#ifdef HAVE_WAIT_H
#include <wait.h>				/* for waitpid() */
#endif

#if HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#ifndef WEXITSTATUS
# define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
#endif
#ifndef WIFEXITED
# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
#endif


#include "../jrd/common.h"
#include "../jrd/gdsassert.h"
#include "../utilities/util_proto.h"
#include "../jrd/gds_proto.h"
#include "../jrd/isc_proto.h"

#ifndef MAXPATHLEN
#define MAXPATHLEN      1024
#endif



pid_t UTIL_start_process(char *process, char **argv)
{
/**************************************
 *
 *      U T I L _ s t a r t _ p r o c e s s
 *
 **************************************
 *
 * Functional description
 *      
 *     This function is used to create the specified process, 
 *
 * Returns Codes:
 *	-1		Process spawn failed.
 *	pid		Successful creation. PID is returned. 
 *      
 *     Note: Make sure that the argument list ends with a null  
 *     and the first argument is large enough to hold the complete 
 *     expanded process name. (MAXPATHLEN recommended)
 *
 **************************************/
	TEXT string[MAXPATHLEN];
	pid_t pid;

	assert(process != NULL);
	assert(argv != NULL);

/* prepend InterBase home directory to the program name */
	gds__prefix(string, process);

/* add place in argv for visibility to "ps" */
	strcpy(argv[0], string);

	if (!(pid = vfork())) {
		execv(string, argv);
		_exit(FINI_ERROR);
	}

	return (pid);
}


int UTIL_wait_for_child( pid_t child_pid)
{
/**************************************
 *
 *      U T I L _ w a i t _ f o r _ c h i l d
 *
 **************************************
 *
 * Functional description
 *      
 *     This function is used to wait for the child specified by child_pid
 *
 * Return code:
 *	0	Normal exit
 *	-1	Abnormal exit - unknown reason.
 *	Other	Abnormal exit - process error code returned.
 *
 **************************************/
	int child_exit_status;

	assert(child_pid != 0);

/* wait for the child process with child_pid to exit */

	while (waitpid(child_pid, &child_exit_status, 0) == -1)
		if (SYSCALL_INTERRUPTED(errno))
			continue;
		else
			return (errno);

/* Check for very specific conditions before we assume the child
   did a normal exit. */

	if (WIFEXITED(child_exit_status) && (WEXITSTATUS(child_exit_status) != 0))
		return (WEXITSTATUS(child_exit_status));

	if (
#ifndef AIX_PPC
		   WCOREDUMP(child_exit_status) ||
#endif
		   WIFSIGNALED(child_exit_status) || !WIFEXITED(child_exit_status))
		return (-1);

	return (0);
}


int UTIL_ex_lock( TEXT * file)
{
/**************************************
 *
 *      U T I L _ e x _ l o c k              
 *
 **************************************
 *
 * Functional description
 *  
 *     This function is used to exclusively lock a file.
 *
 * Return Codes:
 *	-1		Failure to open file.
 *	-2		Failure to obtain exclusive lock on file.
 *	otherwise	Success - file descriptor is returned.
 *
 **************************************/

	TEXT expanded_filename[MAXPATHLEN], tmp[MAXPATHLEN], hostname[64];
	int fd_file;				/* file fd for the opened and locked file */

#ifndef HAVE_FLOCK
	struct flock lock;
#endif

/* get the file name and prepend the complete path etc */
	gds__prefix_lock(tmp, file);
	sprintf(expanded_filename, tmp, ISC_get_host(hostname, sizeof(hostname)));

	if ((fd_file = open(expanded_filename, O_RDWR | O_CREAT, 0666)) == -1) {
		ib_fprintf(ib_stderr, "Could not open %s for write\n",
				   expanded_filename);
		return (-1);
	}

	assert(fd_file != -2);

#ifndef HAVE_FLOCK
/* get an exclusive lock on the GUARD file without blocking on the call */
	lock.l_type = F_WRLCK;
	lock.l_whence = 0;
	lock.l_start = 0;
	lock.l_len = 0;
	if (fcntl(fd_file, F_SETLK, &lock) == -1)
#else
	if (flock(fd_file, LOCK_EX))
#endif
	{
		close(fd_file);
		return (-2);
	}
	return (fd_file);
}


void UTIL_ex_unlock( int fd_file)
{
/**************************************
 *
 *      U T I L _ e x _ l o c k              
 *
 **************************************
 *
 * Functional description
 *  
 *     This function is used to unlock the exclusive file.
 *
 **************************************/


#ifndef HAVE_FLOCK

	struct flock lock;

/* get an exclusive lock on the GUARD file with a block */
	lock.l_type = F_UNLCK;
	lock.l_whence = 0;
	lock.l_start = 0;
	lock.l_len = 0;
	fcntl(fd_file, F_SETLKW, &lock);
#else
	flock(fd_file, LOCK_UN);
#endif
	close(fd_file);
}