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fam.h

/*
    Copyright (C) 1999-2003 Silicon Graphics, Inc.  All Rights Reserved.

    This program is free software; you can redistribute it and/or modify it
    under the terms of version 2.1 of the GNU Lesser General Public License
    as published by the Free Software Foundation.

    This program is distributed in the hope that it would be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  Further, any
    license provided herein, whether implied or otherwise, is limited to
    this program in accordance with the express provisions of the GNU Lesser
    General Public License.  Patent licenses, if any, provided herein do not
    apply to combinations of this program with other product or programs, or
    any other product whatsoever. This program is distributed without any
    warranty that the program is delivered free of the rightful claim of any
    third person by way of infringement or the like.  See the GNU Lesser
    General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write the Free Software Foundation, Inc., 59
    Temple Place - Suite 330, Boston MA 02111-1307, USA.
*/

#ifndef _FAM_
#define _FAM_
#ifdef __cplusplus
extern "C" {
#endif


/*****************************************************************************
*
*  MODULE:  Fam.h - File Alteration Monitor 
*
*   Fam allows applications to monitor files - receiving events when they
*   change.  The scheme is simple:  Applications register which
*   files/directories they are interested, and fam will notify the
*   application when any of these files are changed.
*
*****************************************************************************/

/* For NAME_MAX - maximum # of chars in a filename */
#include "limits.h"





/*****************************************************************************
*  DATA STRUCTURES
*
*
*  FAMConnection Structure:
*
*  The FAMConnection Data structure is created when opening a connection
*  to fam.  After that, it is passed into all fam procedures.  This
*  structure has all the information in it to talk to fam (Currently,
*  the only data inside this structure is a file descriptor for
*  the socket to fam).  
*****************************************************************************/

typedef struct FAMConnection {
    int fd;
    void *client;
} FAMConnection;


/*****************************************************************************
*  To access the fd inside this structure (so the application writer can
*  use select for fam events), the following macro is defined (this will 
*  allow us to change the implementation without users having to change 
*  their code):
*****************************************************************************/
#define FAMCONNECTION_GETFD(fc)      ((fc)->fd)





/*****************************************************************************
*  FAMRequest Structure:
*
*  Every time fam is called on to monitor a file, it passes back a
*  FAMRequest structure.  The main piece of data that this structure 
*  contans is a reqnum.  This reqnum is guaranteed to be unique.  When
*  cancelling or suspending a monitor request, you must pass this
*  data structure into FAMCancelMonitor or FAMSuspendMonitor to
*  make sure that you are cancelling/suspending the correct request
*  (You can monitor the same file/directory more than once).
*****************************************************************************/

typedef struct FAMRequest {
    int reqnum;
} FAMRequest;


/*****************************************************************************
*  Once again, to access the reqnum inside this structure, use the
*  following macro:
*****************************************************************************/
#define FAMREQUEST_GETREQNUM(fc)     ((fc)->reqnum)



/*****************************************************************************
*  FAMEvent Structure:
*
*  When a file/directory has been modified/deleted, fam will pass
*  a FAMEvent structure to the application (through the callback
*  in the FAMMonitorFile/Directory routines).  This structure will
*  describe what event happened to the file.  The different events
*  that can happen to a file are listed in the FAMCodes enum.
*****************************************************************************/
enum FAMCodes { FAMChanged=1, FAMDeleted=2, FAMStartExecuting=3, 
            FAMStopExecuting=4, FAMCreated=5, FAMMoved=6, 
            FAMAcknowledge=7, FAMExists=8, FAMEndExist=9 };

typedef struct  FAMEvent {
    FAMConnection* fc;         /* The fam connection that event occurred on */
    FAMRequest fr;             /* Corresponds to the FamRequest from monitor */
    char *hostname;            /* host and filename - pointer to which */
    char filename[PATH_MAX];   /* file changed */
    void *userdata;            /* userdata associated with this monitor req. */
    enum FAMCodes code;        /* What happened to file - see above */
} FAMEvent;





/*****************************************************************************
*  ERROR HANDLING
*
*  If an error occurs inside of libfam, a global named FAMErrno is set
*  to a non-zero value and the routine that the error occurred in will 
*  return an error value (usually NULL).  FAMErrlist is a global
*  string array (indexed by FAMErrno) that describes the last error 
*  that happened;
*
*  NOTE: currently FAMErrno and FamErrList are unused
*****************************************************************************/

extern int FAMErrno;
extern char *FamErrlist[];

/*
*[NOTE: Eventually, there will be a bunch of defines right here defining what
* errors can happen in using libfam ]
*/






/*****************************************************************************
*  PROCEDURES:
*
*  FAMOpen, FAMClose
*
*  The first step that an application has to do is open a connection to
*  fam.  This is done through the FAMOpen.  FAMOpen returns a FAMConnection
*  data structure which is passed to all fam procedures.  FAMClose closes
*  a fam connection.  
*
*  On error, FAMOpen will return NULL and FAMClose will return -1 (and
*  FAMErrno will be set to the value of the error).  
*****************************************************************************/

extern int FAMOpen(FAMConnection* fc);
extern int FAMOpen2(FAMConnection* fc, const char* appName);
extern int FAMClose(FAMConnection* fc);



/*****************************************************************************
*  FAMMonitorDirectory, FAMMonitorFile
*
*  These routines tell fam to start monitoring a file/directory.  The
*  parameters to this function are a FAMConnection (received from FAMOpen),
*  a filename and a user data ptr.  A FAMRequest structure is returned.
*  When the file/directory changes, a fam event structure will be 
*  generated.  The application can retrieve this structure by calling
*  FAMNextEvent (see description under FAMNextEvent).
*
*  The difference between these two routines is that FAMMonitorDirectory
*  monitors any changes that happens to the contents of the directory
*  (as well as the directory file itself) and FAMMonitorFile monitors
*  only what happens to a particular file.
*
*  On error FAMMonitorDirectory/File will return NULL (and FAMErrno will
*  be set to the value of the error).  
*****************************************************************************/

extern int FAMMonitorDirectory(FAMConnection *fc,
                         const char *filename,
                         FAMRequest* fr,
                         void* userData);
extern int FAMMonitorFile(FAMConnection *fc,
                    const char *filename, 
                    FAMRequest* fr,
                    void* userData);
extern int FAMMonitorCollection(FAMConnection *fc,
                        const char *filename, 
                        FAMRequest* fr,
                        void* userData,
                        int depth,
                        const char* mask);

extern int FAMMonitorDirectory2(FAMConnection *fc,
                        const char *filename,
                        FAMRequest* fr);
extern int FAMMonitorFile2(FAMConnection *fc,
                     const char *filename,
                     FAMRequest* fr);


/*****************************************************************************
*  FAMSuspendMonitor, FAMResumeMonitor
*
*  FAMSuspendMonitor enables applications to suspend
*  receive events about files/directories that are changing.  This can
*  be useful in situations when an application is stowed and does not
*  want to receive events until it is unstowed.  FAMResumeMonitor
*  signals fam to start monitoring the file/directory again.  
*
*  Both of these routines take a FAMConnection and a FAMRequest structure.
*  The FAMRequest Structure is returned from the FAMMonitorFile/Directory
*  routines.
*
*  On error, FAMResume/SuspendMonitor will return -1 (and the global
*  FAMErrno will be set to the value of the error).
*****************************************************************************/

int FAMSuspendMonitor(FAMConnection *fc, const FAMRequest *fr);
int FAMResumeMonitor(FAMConnection *fc, const FAMRequest *fr);






/*****************************************************************************
*  FAMCancelMonitor
*
*  When an application is done monitoring a file/directory, it should
*  call FAMCancelMonitor.  This routine will signal fam not to watch
*  this directory anymore. Once again, the FAMRequest structure is
*  returned from the FAMMonitorFile/Directory routines.
*
*  On error, FAMCancelMonitor will return -1 (and the global
*  FAMErrno will be set to the value of the error).  This routine will free
*  the FAMRequest structure that is passed in.
*****************************************************************************/

int FAMCancelMonitor(FAMConnection *fc, const FAMRequest *fr);




/*****************************************************************************
*  FAMNextEvent, FAMPending
*  
*  FAMNextEvent will get the next fam event (file/directory change).  If 
*  there are no fam events waiting, then FAMNextEvent will wait 
*  until a fam event has been received (from fam).
*
*  FAMPending will return the number of fam events that are waiting.
*  This routine always returns immediately to the caller.
*
*  Essentially, there are two ways to for applications to receive fam
*  events:
*
*  1.  The "Polling" approach - Just call FAMPending periodically;
*      like when the system is waiting for input.  If FAMPending returns
*      with a positive return value, then there are fam events waiting.
*      Call FAMNextEvent to receive the events.
*
*  2.  The "Select" approach - Use the fd returned from famOpen (in the
*      FAMConnection structure) as one of the fds that the application
*      selects on.  When select returns saying that data is on the fam
*      fd, call FAMNextEvent.
*
*  FAMNextEvent reads any information that is on the fam socket,
*  and returns it to the application (in the form of a FAMEvent).
*
*  On error, FAMNextEvent and FAMPendingEvent will return -1 (and the global
*  FAMErrno will be set to the value of the error).
*****************************************************************************/

int FAMNextEvent(FAMConnection *fc, FAMEvent *fe);
int FAMPending(FAMConnection* fc);




/*****************************************************************************
*  FAMDebugLevel
*  
*  This doesn't do anything.
*
*****************************************************************************/

#define FAM_DEBUG_OFF 0
#define FAM_DEBUG_ON  1
#define FAM_DEBUG_VERBOSE 2

int FAMDebugLevel(FAMConnection *fc, int debugLevel);

#ifdef __cplusplus
}
#endif
#endif  /* _FAM_ */

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