Function UTIL_ex_lock

src/utilities/guard/util.cpp:230–278

int UTIL_ex_lock(const 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.
 *
 **************************************/

	// get the file name and prepend the complete path etc
	Firebird::PathName expanded_filename = fb_utils::getPrefix(Firebird::IConfigManager::DIR_GUARD, file);

	// file fd for the opened and locked file
	int fd_file = os_utils::open(expanded_filename.c_str(), O_RDWR | O_CREAT, 0660);
	if (fd_file == -1)
	{
		fprintf(stderr, "Could not open %s for write\n", expanded_filename.c_str());
		return (-1);
	}

	fb_assert(fd_file != -2);

#ifndef HAVE_FLOCK
	// get an exclusive lock on the GUARD file without blocking on the call
	struct FLOCK lock;
	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)