/*
 *	Copyright 1996, University Corporation for Atmospheric Research
 *      See netcdf/COPYRIGHT file for copying and redistribution conditions.
 */
/* $Id: v1hpg.c,v 1.70 2010/05/26 21:43:34 dmh Exp $ */

#include "ncconfig.h"
#include "nc.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "rnd.h"
#include "ncx.h"

/*
 * This module defines the external representation
 * of the "header" of a netcdf version one file and
 * the version two variant that uses 64-bit file
 * offsets instead of the 32-bit file offsets in version
 * one files.
 * For each of the components of the NC structure,
 * There are (static) ncx_len_XXX(), v1h_put_XXX()
 * and v1h_get_XXX() functions. These define the
 * external representation of the components.
 * The exported entry points for the whole NC structure
 * are built up from these.
 */


/*
 * "magic number" at beginning of file: 0x43444601 (big endian)
 * assert(sizeof(ncmagic) % X_ALIGN == 0);
 */
static const schar ncmagic[] = {'C', 'D', 'F', 0x02};
static const schar ncmagic1[] = {'C', 'D', 'F', 0x01};


/*
 * v1hs == "Version 1 Header Stream"
 *
 * The netcdf file version 1 header is
 * of unknown and potentially unlimited size.
 * So, we don't know how much to get() on
 * the initial read. We build a stream, 'v1hs'
 * on top of ncio to do the header get.
 */
typedef struct v1hs {
        ncio *nciop;
        off_t offset;	/* argument to nciop->get() */
        size_t extent;	/* argument to nciop->get() */
        int flags;	/* set to RGN_WRITE for write */
        int version;    /* format variant: NC_FORMAT_CLASSIC or NC_FORMAT_64BIT */
        void *base;	/* beginning of current buffer */
        void *pos;	/* current position in buffer */
        void *end;	/* end of current buffer = base + extent */
} v1hs;


/*
 * Release the stream, invalidate buffer
 */
static int
rel_v1hs(v1hs *gsp)
{
        int status;
        if(gsp->offset == OFF_NONE || gsp->base == NULL)
                return ENOERR;
        status = gsp->nciop->rel(gsp->nciop, gsp->offset,
                         gsp->flags == RGN_WRITE ? RGN_MODIFIED : 0);
        gsp->end = NULL;
        gsp->pos = NULL;
        gsp->base = NULL;
        return status;
}


/*
 * Release the current chunk and get the next one.
 * Also used for initialization when gsp->base == NULL.
 */
static int
fault_v1hs(v1hs *gsp, size_t extent)
{
        int status;

        if(gsp->base != NULL)
        {
                const ptrdiff_t incr = (char *)gsp->pos - (char *)gsp->base;
                status = rel_v1hs(gsp);
                if(status)
                        return status;
                gsp->offset += incr;
        }

        if(extent > gsp->extent)
                gsp->extent = extent;

        status = gsp->nciop->get(gsp->nciop,
                        gsp->offset, gsp->extent,
                        gsp->flags, &gsp->base);
        if(status)
                return status;

        gsp->pos = gsp->base;
        gsp->end = (char *)gsp->base + gsp->extent;

        return ENOERR;
}


/*
 * Ensure that 'nextread' bytes are available.
 */
static int
check_v1hs(v1hs *gsp, size_t nextread)
{

#if 0 /* DEBUG */
fprintf(stderr, "nextread %lu, remaining %lu\n",
        (unsigned long)nextread,
        (unsigned long)((char *)gsp->end - (char *)gsp->pos));
#endif

        if((char *)gsp->pos + nextread <= (char *)gsp->end)
                return ENOERR;
        return fault_v1hs(gsp, nextread);
}

/* End v1hs */

/* Write a size_t to the header */
static int
v1h_put_size_t(v1hs *psp, const size_t *sp)
{
        int status = check_v1hs(psp, X_SIZEOF_SIZE_T);
        if(status != ENOERR)
                return status;
        return ncx_put_size_t(&psp->pos, sp);
}


/* Read a size_t from the header */
static int
v1h_get_size_t(v1hs *gsp, size_t *sp)
{
        int status = check_v1hs(gsp, X_SIZEOF_SIZE_T);
        if(status != ENOERR)
                return status;
        return ncx_get_size_t((const void **)(&gsp->pos), sp);
}


/* Begin nc_type */

#define X_SIZEOF_NC_TYPE X_SIZEOF_INT

/* Write a nc_type to the header */
static int
v1h_put_nc_type(v1hs *psp, const nc_type *typep)
{
        const int itype = (int) *typep;
        int status = check_v1hs(psp, X_SIZEOF_INT);
        if(status != ENOERR)
                return status;
        status =  ncx_put_int_int(psp->pos, &itype);
        psp->pos = (void *)((char *)psp->pos + X_SIZEOF_INT);
        return status;
}


/* Read a nc_type from the header */
static int
v1h_get_nc_type(v1hs *gsp, nc_type *typep)
{
        int type = 0;
        int status = check_v1hs(gsp, X_SIZEOF_INT);
        if(status != ENOERR)
                return status;
        status =  ncx_get_int_int(gsp->pos, &type);
        gsp->pos = (void *)((char *)gsp->pos + X_SIZEOF_INT);
        if(status != ENOERR)
                return status;

        assert(type == NC_BYTE
                || type == NC_CHAR
                || type == NC_SHORT
                || type == NC_INT
                || type == NC_FLOAT
                || type == NC_DOUBLE);

        /* else */
        *typep = (nc_type) type;

        return ENOERR;
}

/* End nc_type */
/* Begin NCtype (internal tags) */

#define X_SIZEOF_NCTYPE X_SIZEOF_INT

/* Write a NCtype to the header */
static int
v1h_put_NCtype(v1hs *psp, NCtype type)
{
        const int itype = (int) type;
        int status = check_v1hs(psp, X_SIZEOF_INT);
        if(status != ENOERR)
                return status;
        status = ncx_put_int_int(psp->pos, &itype);
        psp->pos = (void *)((char *)psp->pos + X_SIZEOF_INT);
        return status;
}

/* Read a NCtype from the header */
static int
v1h_get_NCtype(v1hs *gsp, NCtype *typep)
{
        int type = 0;
        int status = check_v1hs(gsp, X_SIZEOF_INT);
        if(status != ENOERR)
                return status;
        status =  ncx_get_int_int(gsp->pos, &type);
        gsp->pos = (void *)((char *)gsp->pos + X_SIZEOF_INT);
        if(status != ENOERR)
                return status;
        /* else */
        *typep = (NCtype) type;
        return ENOERR;
}

/* End NCtype */
/* Begin NC_string */

/*
 * How much space will the xdr'd string take.
 * Formerly
NC_xlen_string(cdfstr)
 */
static size_t
ncx_len_NC_string(const NC_string *ncstrp)
{
        size_t sz = X_SIZEOF_SIZE_T; /* nchars */

        assert(ncstrp != NULL);

        if(ncstrp->nchars != 0)
        {
#if 0
                assert(ncstrp->nchars % X_ALIGN == 0);
                sz += ncstrp->nchars;
#else
                sz += _RNDUP(ncstrp->nchars, X_ALIGN);
#endif
        }
        return sz;
}


/* Write a NC_string to the header */
static int
v1h_put_NC_string(v1hs *psp, const NC_string *ncstrp)
{
        int status;

#if 0
        assert(ncstrp->nchars % X_ALIGN == 0);
#endif

        status = v1h_put_size_t(psp, &ncstrp->nchars);
        if(status != ENOERR)
                return status;
        status = check_v1hs(psp, _RNDUP(ncstrp->nchars, X_ALIGN));
        if(status != ENOERR)
                return status;
        status = ncx_pad_putn_text(&psp->pos, ncstrp->nchars, ncstrp->cp);
        if(status != ENOERR)
                return status;

        return ENOERR;
}


/* Read a NC_string from the header */
static int
v1h_get_NC_string(v1hs *gsp, NC_string **ncstrpp)
{
        int status;
        size_t nchars = 0;
        NC_string *ncstrp;

        status = v1h_get_size_t(gsp, &nchars);
        if(status != ENOERR)
                return status;

        ncstrp = new_NC_string(nchars, NULL);
        if(ncstrp == NULL)
        {
                return NC_ENOMEM;
        }


#if 0
/* assert(ncstrp->nchars == nchars || ncstrp->nchars - nchars < X_ALIGN); */
        assert(ncstrp->nchars % X_ALIGN == 0);
        status = check_v1hs(gsp, ncstrp->nchars);
#else

        status = check_v1hs(gsp, _RNDUP(ncstrp->nchars, X_ALIGN));
#endif
        if(status != ENOERR)
                goto unwind_alloc;

        status = ncx_pad_getn_text((const void **)(&gsp->pos),
                 nchars, ncstrp->cp);
        if(status != ENOERR)
                goto unwind_alloc;

        *ncstrpp = ncstrp;

        return ENOERR;

unwind_alloc:
        free_NC_string(ncstrp);
        return status;

}

/* End NC_string */
/* Begin NC_dim */

/*
 * How much space will the xdr'd dim take.
 * Formerly
NC_xlen_dim(dpp)
 */
static size_t
ncx_len_NC_dim(const NC_dim *dimp)
{
        size_t sz;

        assert(dimp != NULL);

        sz = ncx_len_NC_string(dimp->name);
        sz += X_SIZEOF_SIZE_T;

        return(sz);
}


/* Write a NC_dim to the header */
static int
v1h_put_NC_dim(v1hs *psp, const NC_dim *dimp)
{
        int status;

        status = v1h_put_NC_string(psp, dimp->name);
        if(status != ENOERR)
                return status;

        status = v1h_put_size_t(psp, &dimp->size);
        if(status != ENOERR)
                return status;

        return ENOERR;
}

/* Read a NC_dim from the header */
static int
v1h_get_NC_dim(v1hs *gsp, NC_dim **dimpp)
{
        int status;
        NC_string *ncstrp;
        NC_dim *dimp;

        status = v1h_get_NC_string(gsp, &ncstrp);
        if(status != ENOERR)
                return status;

        dimp = new_x_NC_dim(ncstrp);
        if(dimp == NULL)
        {
                status = NC_ENOMEM;
                goto unwind_name;
        }

        status = v1h_get_size_t(gsp, &dimp->size);
        if(status != ENOERR)
        {
                free_NC_dim(dimp); /* frees name */
                return status;
        }

        *dimpp = dimp;

        return ENOERR;

unwind_name:
        free_NC_string(ncstrp);
        return status;
}


/* How much space in the header is required for this NC_dimarray? */
static size_t
ncx_len_NC_dimarray(const NC_dimarray *ncap)
{
        size_t xlen = X_SIZEOF_NCTYPE;	/* type */
        xlen += X_SIZEOF_SIZE_T;	/* count */
        if(ncap == NULL)
                return xlen;
        /* else */
        {
                const NC_dim **dpp = (const NC_dim **)ncap->value;
                const NC_dim *const *const end = &dpp[ncap->nelems];
                for(  /*NADA*/; dpp < end; dpp++)
                {
                        xlen += ncx_len_NC_dim(*dpp);
                }
        }
        return xlen;
}


/* Write a NC_dimarray to the header */
static int
v1h_put_NC_dimarray(v1hs *psp, const NC_dimarray *ncap)
{
        int status;

        assert(psp != NULL);

        if(ncap == NULL
#if 1
                /* Backward:
                 * This clause is for 'byte for byte'
                 * backward compatibility.
                 * Strickly speaking, it is 'bug for bug'.
                 */
                || ncap->nelems == 0
#endif
                )
        {
                /*
                 * Handle empty netcdf
                 */
                const size_t nosz = 0;

                status = v1h_put_NCtype(psp, NC_UNSPECIFIED);
                if(status != ENOERR)
                        return status;
                status = v1h_put_size_t(psp, &nosz);
                if(status != ENOERR)
                        return status;
                return ENOERR;
        }
        /* else */

        status = v1h_put_NCtype(psp, NC_DIMENSION);
        if(status != ENOERR)
                return status;
        status = v1h_put_size_t(psp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        {
                const NC_dim **dpp = (const NC_dim **)ncap->value;
                const NC_dim *const *const end = &dpp[ncap->nelems];
                for( /*NADA*/; dpp < end; dpp++)
                {
                        status = v1h_put_NC_dim(psp, *dpp);
                        if(status)
                                return status;
                }
        }
        return ENOERR;
}


/* Read a NC_dimarray from the header */
static int
v1h_get_NC_dimarray(v1hs *gsp, NC_dimarray *ncap)
{
        int status;
        NCtype type = NC_UNSPECIFIED;

        assert(gsp != NULL && gsp->pos != NULL);
        assert(ncap != NULL);
        assert(ncap->value == NULL);

        status = v1h_get_NCtype(gsp, &type);
        if(status != ENOERR)
                return status;

        status = v1h_get_size_t(gsp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        if(ncap->nelems == 0)
                return ENOERR;
        /* else */
        if(type != NC_DIMENSION)
                return EINVAL;

        ncap->value = (NC_dim **) malloc(ncap->nelems * sizeof(NC_dim *));
        if(ncap->value == NULL)
                return NC_ENOMEM;
        ncap->nalloc = ncap->nelems;

        {
                NC_dim **dpp = ncap->value;
                NC_dim *const *const end = &dpp[ncap->nelems];
                for( /*NADA*/; dpp < end; dpp++)
                {
                        status = v1h_get_NC_dim(gsp, dpp);
                        if(status)
                        {
                                ncap->nelems = (size_t)(dpp - ncap->value);
                                free_NC_dimarrayV(ncap);
                                return status;
                        }
                }
        }

        return ENOERR;
}


/* End NC_dim */
/* Begin NC_attr */


/*
 * How much space will 'attrp' take in external representation?
 * Formerly
NC_xlen_attr(app)
 */
static size_t
ncx_len_NC_attr(const NC_attr *attrp)
{
        size_t sz;

        assert(attrp != NULL);

        sz = ncx_len_NC_string(attrp->name);
        sz += X_SIZEOF_NC_TYPE; /* type */
        sz += X_SIZEOF_SIZE_T; /* nelems */
        sz += attrp->xsz;

        return(sz);
}


#undef MIN
#define MIN(mm,nn) (((mm) < (nn)) ? (mm) : (nn))

/*
 * Put the values of an attribute
 * The loop is necessary since attrp->nelems
 * could potentially be quite large.
 */
static int
v1h_put_NC_attrV(v1hs *psp, const NC_attr *attrp)
{
        int status;
        const size_t perchunk =  psp->extent;
        size_t remaining = attrp->xsz;
        void *value = attrp->xvalue;
        size_t nbytes;

        assert(psp->extent % X_ALIGN == 0);

        do {
                nbytes = MIN(perchunk, remaining);

                status = check_v1hs(psp, nbytes);
                if(status != ENOERR)
                        return status;

                (void) memcpy(psp->pos, value, nbytes);

                psp->pos = (void *)((char *)psp->pos + nbytes);
                value = (void *)((char *)value + nbytes);
                remaining -= nbytes;

        } while(remaining != 0);

        return ENOERR;
}

/* Write a NC_attr to the header */
static int
v1h_put_NC_attr(v1hs *psp, const NC_attr *attrp)
{
        int status;

        status = v1h_put_NC_string(psp, attrp->name);
        if(status != ENOERR)
                return status;

        status = v1h_put_nc_type(psp, &attrp->type);
        if(status != ENOERR)
                return status;

        status = v1h_put_size_t(psp, &attrp->nelems);
        if(status != ENOERR)
                return status;

        status = v1h_put_NC_attrV(psp, attrp);
        if(status != ENOERR)
                return status;

        return ENOERR;
}


/*
 * Get the values of an attribute
 * The loop is necessary since attrp->nelems
 * could potentially be quite large.
 */
static int
v1h_get_NC_attrV(v1hs *gsp, NC_attr *attrp)
{
        int status;
        const size_t perchunk =  gsp->extent;
        size_t remaining = attrp->xsz;
        void *value = attrp->xvalue;
        size_t nget;

        do {
                nget = MIN(perchunk, remaining);

                status = check_v1hs(gsp, nget);
                if(status != ENOERR)
                        return status;

                (void) memcpy(value, gsp->pos, nget);

                gsp->pos = (void *)((char *)gsp->pos + nget);
                value = (void *)((char *)value + nget);
                remaining -= nget;

        } while(remaining != 0);

        return ENOERR;
}


/* Read a NC_attr from the header */
static int
v1h_get_NC_attr(v1hs *gsp, NC_attr **attrpp)
{
        NC_string *strp;
        int status;
        nc_type type;
        size_t nelems;
        NC_attr *attrp;

        status = v1h_get_NC_string(gsp, &strp);
        if(status != ENOERR)
                return status;

        status = v1h_get_nc_type(gsp, &type);
        if(status != ENOERR)
                goto unwind_name;

        status = v1h_get_size_t(gsp, &nelems);
        if(status != ENOERR)
                goto unwind_name;

        attrp = new_x_NC_attr(strp, type, nelems);
        if(attrp == NULL)
        {
                status = NC_ENOMEM;
                goto unwind_name;
        }

        status = v1h_get_NC_attrV(gsp, attrp);
        if(status != ENOERR)
        {
                free_NC_attr(attrp); /* frees strp */
                return status;
        }

        *attrpp = attrp;

        return ENOERR;

unwind_name:
        free_NC_string(strp);
        return status;
}


/* How much space in the header is required for this NC_attrarray? */
static size_t
ncx_len_NC_attrarray(const NC_attrarray *ncap)
{
        size_t xlen = X_SIZEOF_NCTYPE;	/* type */
        xlen += X_SIZEOF_SIZE_T;	/* count */
        if(ncap == NULL)
                return xlen;
        /* else */
        {
                const NC_attr **app = (const NC_attr **)ncap->value;
                const NC_attr *const *const end = &app[ncap->nelems];
                for( /*NADA*/; app < end; app++)
                {
                        xlen += ncx_len_NC_attr(*app);
                }
        }
        return xlen;
}


/* Write a NC_attrarray to the header */
static int
v1h_put_NC_attrarray(v1hs *psp, const NC_attrarray *ncap)
{
        int status;

        assert(psp != NULL);

        if(ncap == NULL
#if 1
                /* Backward:
                 * This clause is for 'byte for byte'
                 * backward compatibility.
                 * Strickly speaking, it is 'bug for bug'.
                 */
                || ncap->nelems == 0
#endif
                )
        {
                /*
                 * Handle empty netcdf
                 */
                const size_t nosz = 0;

                status = v1h_put_NCtype(psp, NC_UNSPECIFIED);
                if(status != ENOERR)
                        return status;
                status = v1h_put_size_t(psp, &nosz);
                if(status != ENOERR)
                        return status;
                return ENOERR;
        }
        /* else */

        status = v1h_put_NCtype(psp, NC_ATTRIBUTE);
        if(status != ENOERR)
                return status;
        status = v1h_put_size_t(psp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        {
                const NC_attr **app = (const NC_attr **)ncap->value;
                const NC_attr *const *const end = &app[ncap->nelems];
                for( /*NADA*/; app < end; app++)
                {
                        status = v1h_put_NC_attr(psp, *app);
                        if(status)
                                return status;
                }
        }
        return ENOERR;
}


/* Read a NC_attrarray from the header */
static int
v1h_get_NC_attrarray(v1hs *gsp, NC_attrarray *ncap)
{
        int status;
        NCtype type = NC_UNSPECIFIED;

        assert(gsp != NULL && gsp->pos != NULL);
        assert(ncap != NULL);
        assert(ncap->value == NULL);

        status = v1h_get_NCtype(gsp, &type);
        if(status != ENOERR)
                return status;
        status = v1h_get_size_t(gsp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        if(ncap->nelems == 0)
                return ENOERR;
        /* else */
        if(type != NC_ATTRIBUTE)
                return EINVAL;

        ncap->value = (NC_attr **) malloc(ncap->nelems * sizeof(NC_attr *));
        if(ncap->value == NULL)
                return NC_ENOMEM;
        ncap->nalloc = ncap->nelems;

        {
                NC_attr **app = ncap->value;
                NC_attr *const *const end = &app[ncap->nelems];
                for( /*NADA*/; app < end; app++)
                {
                        status = v1h_get_NC_attr(gsp, app);
                        if(status)
                        {
                                ncap->nelems = (size_t)(app - ncap->value);
                                free_NC_attrarrayV(ncap);
                                return status;
                        }
                }
        }

        return ENOERR;
}

/* End NC_attr */
/* Begin NC_var */

/*
 * How much space will the xdr'd var take.
 * Formerly
NC_xlen_var(vpp)
 */
static size_t
ncx_len_NC_var(const NC_var *varp, size_t sizeof_off_t)
{
        size_t sz;

        assert(varp != NULL);
        assert(sizeof_off_t != 0);

        sz = ncx_len_NC_string(varp->name);
        sz += X_SIZEOF_SIZE_T; /* ndims */
        sz += ncx_len_int(varp->ndims); /* dimids */
        sz += ncx_len_NC_attrarray(&varp->attrs);
        sz += X_SIZEOF_NC_TYPE; /* type */
        sz += X_SIZEOF_SIZE_T; /* len */
        sz += sizeof_off_t; /* begin */

        return(sz);
}


/* Write a NC_var to the header */
static int
v1h_put_NC_var(v1hs *psp, const NC_var *varp)
{
        int status;

        status = v1h_put_NC_string(psp, varp->name);
        if(status != ENOERR)
                return status;

        status = v1h_put_size_t(psp, &varp->ndims);
        if(status != ENOERR)
                return status;

        status = check_v1hs(psp, ncx_len_int(varp->ndims));
        if(status != ENOERR)
                return status;
        status = ncx_putn_int_int(&psp->pos,
                        varp->ndims, varp->dimids);
        if(status != ENOERR)
                return status;

        status = v1h_put_NC_attrarray(psp, &varp->attrs);
        if(status != ENOERR)
                return status;

        status = v1h_put_nc_type(psp, &varp->type);
        if(status != ENOERR)
                return status;

        status = v1h_put_size_t(psp, &varp->len);
        if(status != ENOERR)
                return status;

        status = check_v1hs(psp, psp->version == 1 ? 4 : 8);
        if(status != ENOERR)
                 return status;
        status = ncx_put_off_t(&psp->pos, &varp->begin, psp->version == 1 ? 4 : 8);
        if(status != ENOERR)
                return status;

        return ENOERR;
}


/* Read a NC_var from the header */
static int
v1h_get_NC_var(v1hs *gsp, NC_var **varpp)
{
        NC_string *strp;
        int status;
        size_t ndims;
        NC_var *varp;

        status = v1h_get_NC_string(gsp, &strp);
        if(status != ENOERR)
                return status;

        status = v1h_get_size_t(gsp, &ndims);
        if(status != ENOERR)
                goto unwind_name;

        varp = new_x_NC_var(strp, ndims);
        if(varp == NULL)
        {
                status = NC_ENOMEM;
                goto unwind_name;
        }

        status = check_v1hs(gsp, ncx_len_int(ndims));
        if(status != ENOERR)
                goto unwind_alloc;
        status = ncx_getn_int_int((const void **)(&gsp->pos),
                        ndims, varp->dimids);
        if(status != ENOERR)
                goto unwind_alloc;

        status = v1h_get_NC_attrarray(gsp, &varp->attrs);
        if(status != ENOERR)
                goto unwind_alloc;

        status = v1h_get_nc_type(gsp, &varp->type);
        if(status != ENOERR)
                 goto unwind_alloc;

        status = v1h_get_size_t(gsp, &varp->len);
        if(status != ENOERR)
                 goto unwind_alloc;

        status = check_v1hs(gsp, gsp->version == 1 ? 4 : 8);
        if(status != ENOERR)
                 goto unwind_alloc;
        status = ncx_get_off_t((const void **)&gsp->pos,
                               &varp->begin, gsp->version == 1 ? 4 : 8);
        if(status != ENOERR)
                 goto unwind_alloc;

        *varpp = varp;
        return ENOERR;

unwind_alloc:
        free_NC_var(varp); /* frees name */
        return status;

unwind_name:
        free_NC_string(strp);
        return status;
}


/* How much space in the header is required for this NC_vararray? */
static size_t
ncx_len_NC_vararray(const NC_vararray *ncap, size_t sizeof_off_t)
{
        size_t xlen = X_SIZEOF_NCTYPE;	/* type */
        xlen += X_SIZEOF_SIZE_T;	/* count */
        if(ncap == NULL)
                return xlen;
        /* else */
        {
                const NC_var **vpp = (const NC_var **)ncap->value;
                const NC_var *const *const end = &vpp[ncap->nelems];
                for( /*NADA*/; vpp < end; vpp++)
                {
                        xlen += ncx_len_NC_var(*vpp, sizeof_off_t);
                }
        }
        return xlen;
}


/* Write a NC_vararray to the header */
static int
v1h_put_NC_vararray(v1hs *psp, const NC_vararray *ncap)
{
        int status;

        assert(psp != NULL);

        if(ncap == NULL
#if 1
                /* Backward:
                 * This clause is for 'byte for byte'
                 * backward compatibility.
                 * Strickly speaking, it is 'bug for bug'.
                 */
                || ncap->nelems == 0
#endif
                )
        {
                /*
                 * Handle empty netcdf
                 */
                const size_t nosz = 0;

                status = v1h_put_NCtype(psp, NC_UNSPECIFIED);
                if(status != ENOERR)
                        return status;
                status = v1h_put_size_t(psp, &nosz);
                if(status != ENOERR)
                        return status;
                return ENOERR;
        }
        /* else */

        status = v1h_put_NCtype(psp, NC_VARIABLE);
        if(status != ENOERR)
                return status;
        status = v1h_put_size_t(psp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        {
                const NC_var **vpp = (const NC_var **)ncap->value;
                const NC_var *const *const end = &vpp[ncap->nelems];
                for( /*NADA*/; vpp < end; vpp++)
                {
                        status = v1h_put_NC_var(psp, *vpp);
                        if(status)
                                return status;
                }
        }
        return ENOERR;
}


/* Read a NC_vararray from the header */
static int
v1h_get_NC_vararray(v1hs *gsp, NC_vararray *ncap)
{
        int status;
        NCtype type = NC_UNSPECIFIED;

        assert(gsp != NULL && gsp->pos != NULL);
        assert(ncap != NULL);
        assert(ncap->value == NULL);

        status = v1h_get_NCtype(gsp, &type);
        if(status != ENOERR)
                return status;

        status = v1h_get_size_t(gsp, &ncap->nelems);
        if(status != ENOERR)
                return status;

        if(ncap->nelems == 0)
                return ENOERR;
        /* else */
        if(type != NC_VARIABLE)
                return EINVAL;

        ncap->value = (NC_var **) malloc(ncap->nelems * sizeof(NC_var *));
        if(ncap->value == NULL)
                return NC_ENOMEM;
        ncap->nalloc = ncap->nelems;

        {
                NC_var **vpp = ncap->value;
                NC_var *const *const end = &vpp[ncap->nelems];
                for( /*NADA*/; vpp < end; vpp++)
                {
                        status = v1h_get_NC_var(gsp, vpp);
                        if(status)
                        {
                                ncap->nelems = (size_t)(vpp - ncap->value);
                                free_NC_vararrayV(ncap);
                                return status;
                        }
                }
        }

        return ENOERR;
}


/* End NC_var */
/* Begin NC */

/*
 * Recompute the shapes of all variables
 * Sets ncp->begin_var to start of first variable.
 * Sets ncp->begin_rec to start of first record variable.
 * Returns -1 on error. The only possible error is a reference
 * to a non existent dimension, which could occur for a corrupted
 * netcdf file.
 */
static int
NC_computeshapes(NC *ncp)
{
        NC_var **vpp = (NC_var **)ncp->vars.value;
        NC_var *const *const end = &vpp[ncp->vars.nelems];
        NC_var *first_var = NULL;	/* first "non-record" var */
        NC_var *first_rec = NULL;	/* first "record" var */
        int status;

        ncp->begin_var = (off_t) ncp->xsz;
        ncp->begin_rec = (off_t) ncp->xsz;
        ncp->recsize = 0;

        if(ncp->vars.nelems == 0)
                return(0);

        for( /*NADA*/; vpp < end; vpp++)
        {
                status = NC_var_shape(*vpp, &ncp->dims);
                if(status != ENOERR)
                        return(status);

                if(IS_RECVAR(*vpp))
                {
                        if(first_rec == NULL)
                                first_rec = *vpp;
                        ncp->recsize += (*vpp)->len;
                }
                else
                {
                        if(first_var == NULL)
                                first_var = *vpp;
                        /*
                         * Overwritten each time thru.
                         * Usually overwritten in first_rec != NULL clause below.
                         */
                        ncp->begin_rec = (*vpp)->begin + (off_t)(*vpp)->len;
                }
        }

        if(first_rec != NULL)
        {
                assert(ncp->begin_rec <= first_rec->begin);
                ncp->begin_rec = first_rec->begin;
                /*
                 * for special case of exactly one record variable, pack value
                 */
                if(ncp->recsize == first_rec->len)
                        ncp->recsize = *first_rec->dsizes * first_rec->xsz;
        }

        if(first_var != NULL)
        {
                ncp->begin_var = first_var->begin;
        }
        else
        {
                ncp->begin_var = ncp->begin_rec;
        }

        assert(ncp->begin_var > 0);
        assert(ncp->xsz <= (size_t)ncp->begin_var);
        assert(ncp->begin_rec > 0);
        assert(ncp->begin_var <= ncp->begin_rec);

        return(ENOERR);
}

/* How much space in the header is required for the NC data structure? */
size_t
ncx_len_NC(const NC *ncp, size_t sizeof_off_t)
{
        size_t xlen = sizeof(ncmagic);

        assert(ncp != NULL);

        xlen += X_SIZEOF_SIZE_T; /* numrecs */
        xlen += ncx_len_NC_dimarray(&ncp->dims);
        xlen += ncx_len_NC_attrarray(&ncp->attrs);
        xlen += ncx_len_NC_vararray(&ncp->vars, sizeof_off_t);

        return xlen;
}


/* Write the file header */
int
ncx_put_NC(const NC *ncp, void **xpp, off_t offset, size_t extent)
{
        int status = ENOERR;
        v1hs ps; /* the get stream */

        assert(ncp != NULL);

        /* Initialize stream ps */

        ps.nciop = ncp->nciop;
        ps.flags = RGN_WRITE;

        if (ncp->flags & NC_64BIT_OFFSET)
          ps.version = 2;
        else
          ps.version = 1;

        if(xpp == NULL)
        {
                /*
                 * Come up with a reasonable stream read size.
                 */
                extent = ncp->xsz;
                if(extent <= MIN_NC_XSZ)
                {
                        /* first time read */
                        extent = ncp->chunk;
                        /* Protection for when ncp->chunk is huge;
                         * no need to read hugely. */
                        if(extent > 4096)
                                extent = 4096;
                }
                else if(extent > ncp->chunk)
                {
                        extent = ncp->chunk;
                }

                ps.offset = 0;
                ps.extent = extent;
                ps.base = NULL;
                ps.pos = ps.base;

                status = fault_v1hs(&ps, extent);
                if(status)
                        return status;
        }
        else
        {
                ps.offset = offset;
                ps.extent = extent;
                ps.base = *xpp;
                ps.pos = ps.base;
                ps.end = (char *)ps.base + ps.extent;
        }

        if (ps.version == 2)
          status = ncx_putn_schar_schar(&ps.pos, sizeof(ncmagic), ncmagic);
        else
          status = ncx_putn_schar_schar(&ps.pos, sizeof(ncmagic1), ncmagic1);
        if(status != ENOERR)
                goto release;

        {
        const size_t nrecs = NC_get_numrecs(ncp);
        status = ncx_put_size_t(&ps.pos, &nrecs);
        if(status != ENOERR)
                goto release;
        }

        assert((char *)ps.pos < (char *)ps.end);

        status = v1h_put_NC_dimarray(&ps, &ncp->dims);
        if(status != ENOERR)
                goto release;

        status = v1h_put_NC_attrarray(&ps, &ncp->attrs);
        if(status != ENOERR)
                goto release;

        status = v1h_put_NC_vararray(&ps, &ncp->vars);
        if(status != ENOERR)
                goto release;

release:
        (void) rel_v1hs(&ps);

        return status;
}


/* Make the in-memory NC structure from reading the file header */
int
nc_get_NC(NC *ncp)
{
        int status;
        v1hs gs; /* the get stream */

        assert(ncp != NULL);

        /* Initialize stream gs */

        gs.nciop = ncp->nciop;
        gs.offset = 0; /* beginning of file */
        gs.extent = 0;
        gs.flags = 0;
        gs.version = 0;
        gs.base = NULL;
        gs.pos = gs.base;

        {
                /*
                 * Come up with a reasonable stream read size.
                 */
                off_t filesize;
                size_t extent = MIN_NC_XSZ;

                extent = ncp->xsz;
                if(extent <= MIN_NC_XSZ)
                {
                        status = ncio_filesize(ncp->nciop, &filesize);
                        if(status)
                            return status;
                        if(filesize < sizeof(ncmagic)) { /* too small, not netcdf */

                            status = NC_ENOTNC;
                            return status;
                        }
                        /* first time read */
                        extent = ncp->chunk;
                        /* Protection for when ncp->chunk is huge;
                         * no need to read hugely. */
                        if(extent > 4096)
                                extent = 4096;
                        if(extent > filesize)
                          extent = (size_t)filesize;
                }
                else if(extent > ncp->chunk)
                {
                        extent = ncp->chunk;
                }

                /*
                 * Invalidate the I/O buffers to force a read of the header
                 * region.
                 */
                status = gs.nciop->sync(gs.nciop);
                if(status)
                        return status;

                status = fault_v1hs(&gs, extent);
                if(status)
                        return status;
        }

        /* get the header from the stream gs */

        {
                /* Get & check magic number */
                schar magic[sizeof(ncmagic)];
                (void) memset(magic, 0, sizeof(magic));

                status = ncx_getn_schar_schar(
                        (const void **)(&gs.pos), sizeof(magic), magic);
                if(status != ENOERR)
                        goto unwind_get;

                if(memcmp(magic, ncmagic, sizeof(ncmagic)-1) != 0)
                {
                        status = NC_ENOTNC;
                        goto unwind_get;
                }
                /* Check version number in last byte of magic */
                if (magic[sizeof(ncmagic)-1] == 0x1) {
                  gs.version = 1;
                } else if (magic[sizeof(ncmagic)-1] == 0x2) {
                  gs.version = 2;
                  fSet(ncp->flags, NC_64BIT_OFFSET);
                  /* Now we support version 2 file access on non-LFS systems -- rkr */
#if 0
                  if (sizeof(off_t) != 8) {
                    fprintf(stderr, "NETCDF WARNING: Version 2 file on 32-bit system.\n");
                  }
#endif
                } else {
                        status = NC_ENOTNC;
                        goto unwind_get;
                }
        }

        {
        size_t nrecs = 0;
        status = ncx_get_size_t((const void **)(&gs.pos), &nrecs);
        if(status != ENOERR)
                goto unwind_get;
        NC_set_numrecs(ncp, nrecs);
        }

        assert((char *)gs.pos < (char *)gs.end);

        status = v1h_get_NC_dimarray(&gs, &ncp->dims);
        if(status != ENOERR)
                goto unwind_get;

        status = v1h_get_NC_attrarray(&gs, &ncp->attrs);
        if(status != ENOERR)
                goto unwind_get;

        status = v1h_get_NC_vararray(&gs, &ncp->vars);
        if(status != ENOERR)
                goto unwind_get;

        ncp->xsz = ncx_len_NC(ncp, (gs.version == 1) ? 4 : 8);

        status = NC_computeshapes(ncp);
        if(status != ENOERR)
                goto unwind_get;

unwind_get:
        (void) rel_v1hs(&gs);
        return status;
}
