i am trying to figure out what is the IFilePtr? (int, pointer, char?)
Code:
/* filesys - header information file system interface */
/*  $Id: filesys.h,v 1.97.4.4.2.3 2003/02/04 16:51:47 mark Exp $  */

#ifndef	ACU_FSI_FILESYS_H
#define	ACU_FSI_FILESYS_H

/*
** LargeFileOff_t should be "long" or "off64_t" for UNIX systems, and
** "__int64" for Windows.
*/
#ifndef LargeFileOff_t
#ifdef  WIN32
/* Win32 API */
#define LargeFileOff_t  __int64
#else   /* WIN32 */
/* UNIX API */
#ifdef	HAVE_LARGE_FILE_API
#define LargeFileOff_t  off64_t
#else	/* HAVE_LARGE_FILE_API */
#define LargeFileOff_t  long
#endif	/* HAVE_LARGE_FILE_API */
#endif  /* WIN32 */
#endif  /* LargeFileOff_t */

/* Define PROTOTYPE if your compiler understands ANSI-style prototypes */
#ifndef	P_
#ifdef  PROTOTYPE
#define P_(x)   x
#else   /* PROTOTYPE */
#define P_(x)   ()
#endif  /* PROTOTYPE */
#endif	/* P_ */

/* Allow "region locks" (ie, record locks that are applied to the	*/
/* entire record) by setting WANT_REGION_LOCKS to "1".  Region locks	*/
/* improve performance in cases where very many locks are applied in a	*/
/* file at once (because adjacent record locks will collapse into a	*/
/* single lock region in the Unix lock manager).  */

#define	WANT_REGION_LOCKS	0

#if	WANT_REGION_LOCKS
#ifdef	O_UNIX
#ifndef	ENFORCED_LOCKS
#define	REGION_LOCKS_OK
#endif	/* ENFORCED_LOCKS */
#endif	/* O_UNIX */
#endif	/* WANT_REGION_LOCKS */

typedef	struct _i_abilities {
	unsigned	has_previous : 1;
	unsigned	alternate_collate : 1;
} I_ABILITIES;

#ifdef	__cplusplus
extern "C" {
#endif	/* __cplusplus */

#ifdef	INTERNAL_USE

typedef	struct _i_file		*IFilePtr;
typedef	struct _r_file		*RFilePtr;
typedef	struct _s_file		*SFilePtr;

#ifndef	ACU_GENERIC_PROC_DEFINED
/* generic proc for registering functions */
typedef int             (*GenericProc)();
#define	ACU_GENERIC_PROC_DEFINED
#endif	/* ACU_GENERIC_PROC_DEFINED */

typedef	int		(*FSIInitProc) P_((int, int *));
typedef	void		(*FSIExitProc) P_((void));
typedef	int		(*FSIMakeProc) P_((char *, char *, char *, char *, char *, char *));
typedef	IFilePtr	(*FSIOpenProc) P_((char *, int, char *));
typedef	int		(*FSICloseProc) P_((IFilePtr));
typedef	unsigned	(*FSIReadProc) P_((IFilePtr, char *, int));
typedef	unsigned	(*FSINextProc) P_((IFilePtr, char *));
typedef	unsigned	(*FSIPreviousProc) P_((IFilePtr, char *));
typedef	int		(*FSIStartProc) P_((IFilePtr, char *, int, int, int));
typedef	int		(*FSIWriteProc) P_((IFilePtr, char *, unsigned));
typedef	int		(*FSIRewriteProc) P_((IFilePtr, char *, unsigned));
typedef	int		(*FSIDeleteProc) P_((IFilePtr, char *));
typedef	int		(*FSIUnlockProc) P_((IFilePtr));
typedef	int		(*FSIInfoProc) P_((IFilePtr, int, char *));
typedef	void		(*FSISyncProc) P_((int));
typedef	int		(*FSIRemoveProc) P_((char *));
typedef	int		(*FSIRenameProc) P_((char *, char *));
typedef	int		(*FSIVersionProc) P_((char *, char *, char *, int, long *));
typedef	void		(*FSIAbilitiesProc) P_((I_ABILITIES *));
typedef	int		(*FSIExecuteProc) P_((char *, char *));
typedef	int		(*FSICopyProc) P_((char *, char *));
typedef	int		(*FSIBeginProc) P_((void));
typedef	int		(*FSICommitProc) P_((int));
typedef	int		(*FSIRollbackProc) P_((int));
typedef	int		(*FSIRecoverProc) P_((void));
typedef	GenericProc	(*FSIRegisterProc) P_((char *, GenericProc));
typedef	void		(*FSIInitConfigProc) P_((void));

typedef	int		(*FSI_RInitProc) P_((void));
typedef	void		(*FSI_RExitProc) P_((void));
typedef	int		(*FSI_RMakeProc) P_((char *, char *, long));
typedef	RFilePtr	(*FSI_ROpenProc) P_((char *, int, unsigned,
					     unsigned, long));
typedef	int		(*FSI_RUnlockProc) P_((RFilePtr));
typedef	int		(*FSI_RCloseProc) P_((RFilePtr));
typedef	unsigned	(*FSI_RReadProc) P_((RFilePtr, char *, long));
typedef	unsigned	(*FSI_RNextProc) P_((RFilePtr, char *));
typedef	unsigned	(*FSI_RPreviousProc) P_((RFilePtr, char *));
typedef	int		(*FSI_RStartProc) P_((RFilePtr, long, int));
typedef	int		(*FSI_RWriteProc) P_((RFilePtr, char *, unsigned,
					      long));
typedef	int		(*FSI_RDeleteProc) P_((RFilePtr, long));
typedef	int		(*FSI_RRewriteProc) P_((RFilePtr, char *, unsigned,
						long));
typedef	int		(*FSI_RRemoveProc) P_((char *));
typedef	int		(*FSI_RRenameProc) P_((char *, char *));
typedef	int		(*FSI_RCopyProc) P_((char *, char *));
typedef	int		(*FSI_RInfoProc) P_((RFilePtr, int, char *));

typedef	int		(*FSI_SMakeProc) P_((char *, char *));
typedef	SFilePtr	(*FSI_SOpenProc) P_((char *, int, unsigned, int,
					     unsigned, int, char *, int));
typedef	int		(*FSI_SCloseProc) P_((SFilePtr, int));
typedef	int		(*FSI_SReadProc) P_((SFilePtr, char *));
typedef	int		(*FSI_SWriteProc) P_((SFilePtr, char *, unsigned, int));
typedef	int		(*FSI_SRewriteProc) P_((SFilePtr, char *, unsigned));
typedef	int		(*FSI_SRemoveProc) P_((char *));
typedef	int		(*FSI_SRenameProc) P_((char *, char *));
typedef	int		(*FSI_SCopyProc) P_((char *, char *));
typedef	LargeFileOff_t	(*FSI_SSeekProc) P_((SFilePtr, LargeFileOff_t, int));
typedef	int		(*FSI_SInfoProc) P_((SFilePtr, int, char *));

typedef	struct _i_dispatch {
	/*  Indexed file functions  */
	FSIInitProc		p_init;
	FSIExitProc		p_exit;
	FSIMakeProc		p_make;
	FSIOpenProc		p_open;
	FSICloseProc		p_close;
	FSIReadProc		p_read;
	FSINextProc		p_next;
	FSIPreviousProc		p_previous;
	FSIStartProc		p_start;
	FSIWriteProc		p_write;
	FSIRewriteProc		p_rewrite;
	FSIDeleteProc		p_delete;
	FSIUnlockProc		p_unlock;
	FSIInfoProc		p_info;
	FSISyncProc		p_sync;
	FSIRemoveProc		p_remove;
	FSIRenameProc		p_rename;
	FSIVersionProc		p_version;
	FSIAbilitiesProc	p_abilities;
	FSIExecuteProc		p_execute;
	FSICopyProc		p_copy;
	FSIBeginProc		p_begin;
	FSICommitProc		p_commit;
	FSIRollbackProc		p_rollback;
	FSIRecoverProc		p_recover;

	/*  Setup functions  */
	FSIRegisterProc		p_register;
	FSIInitConfigProc	p_init_cfg;

	/*  Relative file functions  */
	FSI_RInitProc		pr_init;
	FSI_RExitProc		pr_exit;
	FSI_RMakeProc		pr_make;
	FSI_ROpenProc		pr_open;
	FSI_RUnlockProc		pr_unlock;
	FSI_RCloseProc		pr_close;
	FSI_RReadProc		pr_read;
	FSI_RNextProc		pr_next;
	FSI_RPreviousProc	pr_previous;
	FSI_RStartProc		pr_start;
	FSI_RWriteProc		pr_write;
	FSI_RDeleteProc		pr_delete;
	FSI_RRewriteProc	pr_rewrite;
	FSI_RRemoveProc		pr_remove;
	FSI_RRenameProc		pr_rename;
	FSI_RCopyProc		pr_copy;
	FSI_RInfoProc		pr_info;

	/*  Sequential file functions  */
	FSI_SMakeProc		ps_make;
	FSI_SOpenProc		ps_open;
	FSI_SCloseProc		ps_close;
	FSI_SReadProc		ps_read;
	FSI_SWriteProc		ps_write;
	FSI_SRewriteProc	ps_rewrite;
	FSI_SRemoveProc		ps_remove;
	FSI_SRenameProc		ps_rename;
	FSI_SCopyProc		ps_copy;
	FSI_SSeekProc		ps_seek;
	FSI_SInfoProc		ps_info;
} I_DISPATCH;

typedef	int		(*FSI_IGetDispatchTableProc) P_((I_DISPATCH **));


#else	/* INTERNAL_USE */

struct _AcuFile_ {
	long	notused;
};

typedef	struct _AcuFile_	*IFilePtr;
typedef	struct _AcuFile_	*RFilePtr;
typedef	struct _AcuFile_	*SFilePtr;

#endif	/* INTERNAL_USE */