ncdf4a13/libsrc/ncio.h

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/*
 *      Copyright 1996, University Corporation for Atmospheric Research
 *      See netcdf/COPYRIGHT file for copying and redistribution conditions.
 */
/* $Id: ncio.h,v 1.27 2006/01/03 04:56:28 russ Exp $ */

#ifndef _NCIO_H_
#define _NCIO_H_

#include <stddef.h>     /* size_t */
#include <sys/types.h>  /* off_t */
#include "netcdf.h"

typedef struct ncio ncio;       /* forward reference */

/*
 * A value which is an invalid off_t
 */
#define OFF_NONE  ((off_t)(-1))

/*
 * Flags used by the region layer,
 *  'rflags' argument to ncio.rel() and ncio.get().
 */
#define RGN_NOLOCK      0x1     /* Don't lock region.
                                 * Used when contention control handled
                                 * elsewhere.
                                 */
#define RGN_NOWAIT      0x2     /* return immediate if can't lock, else wait */

#define RGN_WRITE       0x4     /* we intend to modify, else read only */

#define RGN_MODIFIED    0x8     /* we did modify, else, discard */


/*
 * The next four typedefs define the signatures
 * of function pointers in struct ncio below.
 * They are not used outside of this file and ncio.h,
 * They just make some casts in the ncio.c more readable.
 */
        /*
         * Indicate that you are done with the region which begins
         * at offset. Only reasonable flag value is RGN_MODIFIED.
         */
typedef int ncio_relfunc(ncio *const nciop,
                 off_t offset, int rflags);

        /*
         * Request that the region (offset, extent)
         * be made available through *vpp.
         */
typedef int ncio_getfunc(ncio *const nciop,
                        off_t offset, size_t extent,
                        int rflags,
                        void **const vpp);

        /*
         * Like memmove(), safely move possibly overlapping data.
         * Only reasonable flag value is RGN_NOLOCK.
         */
typedef int ncio_movefunc(ncio *const nciop, off_t to, off_t from,
                        size_t nbytes, int rflags);

        /*
         * Write out any dirty buffers to disk and
         * ensure that next read will get data from disk.
         */
typedef int ncio_syncfunc(ncio *const nciop);

        /*
         * Don't call this. 
         * Internal function called at close to
         * free up anything hanging off pvt;
         */
typedef void ncio_freefunc(void *const pvt);

/* Get around cplusplus "const xxx in class ncio without constructor" error */
#if defined(__cplusplus)
#define NCIO_CONST
#else
#define NCIO_CONST const
#endif

/*
 * netcdf i/o abstraction
 */
struct ncio {
        /*
         * A copy of the ioflags argument passed in to ncio_open()
         * or ncio_create().
         */
        int ioflags;

        /*
         * The file descriptor of the netcdf file.
         * This gets handed to the user as the netcdf id.
         */
        NCIO_CONST int fd;

        /* member functions do the work */

        ncio_relfunc *NCIO_CONST rel;

        ncio_getfunc *NCIO_CONST get;

        ncio_movefunc *NCIO_CONST move;

        ncio_syncfunc *NCIO_CONST sync;

        ncio_freefunc *NCIO_CONST free; /* Implementation private */

        /*
         * A copy of the 'path' argument passed in to ncio_open()
         * or ncio_create(). Used by ncabort() to remove (unlink)
         * the file and by error messages.
         */
        const char *path;

        /* implementation private stuff */
        void *NCIO_CONST pvt;
};

#undef NCIO_CONST

extern int
ncio_create(const char *path, int ioflags,
        size_t initialsz,
        off_t igeto, size_t igetsz, size_t *sizehintp,
        ncio **nciopp, void **const igetvpp);

extern int
ncio_open(const char *path,
        int ioflags,
        off_t igeto, size_t igetsz, size_t *sizehintp,
        ncio **nciopp, void **const igetvpp);

extern int 
ncio_close(ncio *nciop, int doUnlink);

extern int
ncio_filesize(ncio *nciop, off_t *filesizep);

extern int
ncio_pad_length(ncio *nciop, off_t length);

#endif /* _NCIO_H_ */

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