systems.h

开源的数据库管理系统

/* systems.h - Most of the system dependant code and defines are here. */

/*  This file is part of GDBM, the GNU data base manager, by Philip A. Nelson.
    Copyright (C) 1990, 1991, 1993  Free Software Foundation, Inc.

    GDBM is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2, or (at your option)
    any later version.

    GDBM is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with GDBM; see the file COPYING.  If not, write to
    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

    You may contact the author by:
       e-mail:  [e-mail]
      us-mail:  Philip A. Nelson
                Computer Science Department
                Western Washington University
                Bellingham, WA 98226
       
*************************************************************************/


/* Include all system headers first. */
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <stdio.h>
#if HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
#include <sys/stat.h>
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifndef SEEK_SET
#define SEEK_SET        0
#endif

#ifndef L_SET
#define L_SET SEEK_SET
#endif

/* Do we have flock?  (BSD...) */

#if HAVE_FLOCK

#ifndef LOCK_SH
#define LOCK_SH	1
#endif

#ifndef LOCK_EX
#define LOCK_EX	2
#endif

#ifndef LOCK_NB
#define LOCK_NB 4
#endif

#ifndef LOCK_UN
#define LOCK_UN 8
#endif

#define UNLOCK_FILE(dbf) flock (dbf->desc, LOCK_UN)
#define READLOCK_FILE(dbf) lock_val = flock (dbf->desc, LOCK_SH + LOCK_NB)
#define WRITELOCK_FILE(dbf) lock_val = flock (dbf->desc, LOCK_EX + LOCK_NB)

#else

/* Assume it is done like System V. */

#define UNLOCK_FILE(dbf) \
	{					\
	  struct flock flock;			\
	  flock.l_type = F_UNLCK;		\
	  flock.l_whence = SEEK_SET;		\
	  flock.l_start = flock.l_len = 0L;	\
	  fcntl (dbf->desc, F_SETLK, &flock);	\
	}
#define READLOCK_FILE(dbf) \
	{					\
	  struct flock flock;			\
	  flock.l_type = F_RDLCK;		\
	  flock.l_whence = SEEK_SET;			\
	  flock.l_start = flock.l_len = 0L;	\
	  lock_val = fcntl (dbf->desc, F_SETLK, &flock);	\
	}
#define WRITELOCK_FILE(dbf) \
	{					\
	  struct flock flock;			\
	  flock.l_type = F_WRLCK;		\
	  flock.l_whence = SEEK_SET;			\
	  flock.l_start = flock.l_len = 0L;	\
	  lock_val = fcntl (dbf->desc, F_SETLK, &flock);	\
	}
#endif

/* Do we have bcopy?  */
#if !HAVE_BCOPY
#if HAVE_MEMORY_H
#include <memory.h>
#endif
#define bcmp(d1, d2, n)	memcmp(d1, d2, n)
#define bcopy(d1, d2, n) memcpy(d2, d1, n)
#endif

/* Do we have fsync? */
#if !HAVE_FSYNC
#define fsync(f) {sync(); sync();}
#endif

/* Default block size.  Some systems do not have blocksize in their
   stat record. This code uses the BSD blocksize from stat. */

#if HAVE_STRUCT_STAT_ST_BLKSIZE
#define STATBLKSIZE file_stat.st_blksize
#else
#define STATBLKSIZE 1024
#endif

/* Do we have ftruncate? */
#if HAVE_FTRUNCATE
#define TRUNCATE(dbf) ftruncate (dbf->desc, 0)
#else
#define TRUNCATE(dbf) close( open (dbf->name, O_RDWR|O_TRUNC
#ifdef _WIN32
		| O_BINARY
#endif /* _WIN32 */		
		, mode));
#endif

#ifndef STDERR_FILENO
#define STDERR_FILENO 2
#endif