netcdf-c/libdispatch/daux.c

/*
Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
See COPYRIGHT for license information.
*/

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
 * access to either file, you may request a copy from help@hdfgroup.org.     *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "config.h"
#include "netcdf.h"
#include "netcdf_aux.h"
#include "ncoffsets.h"
#include "nclog.h"
#include "ncrc.h"
#include "netcdf_filter.h"

struct NCAUX_FIELD {
    char* name;
    nc_type fieldtype;
    size_t ndims;
    int dimsizes[NC_MAX_VAR_DIMS];
    size_t size;
    size_t offset;
    size_t alignment;
};

struct NCAUX_CMPD {
    int ncid;
    int mode;
    char* name;
    size_t nfields;
    struct NCAUX_FIELD* fields;
    size_t size;
    size_t offset; /* cumulative as fields are added */
    size_t alignment;
};

static int computefieldinfo(struct NCAUX_CMPD* cmpd);

static int filterspec_cvt(const char* txt, size_t* nparamsp, unsigned int* params);

/**************************************************/
/*
This code is a variant of the H5detect.c code from HDF5.
Author: D. Heimbigner 10/7/2008
*/

EXTERNL int
ncaux_begin_compound(int ncid, const char *name, int alignmode, void** tagp)
{
#ifdef USE_NETCDF4
    int status = NC_NOERR;
    struct NCAUX_CMPD* cmpd = NULL;

    if(tagp) *tagp = NULL;

    cmpd = (struct NCAUX_CMPD*)calloc(1,sizeof(struct NCAUX_CMPD));
    if(cmpd == NULL) {status = NC_ENOMEM; goto fail;}
    cmpd->ncid = ncid;
    cmpd->mode = alignmode;
    cmpd->nfields = 0;
    cmpd->name = strdup(name);
    if(cmpd->name == NULL) {status = NC_ENOMEM; goto fail;}

    if(tagp) {
      *tagp = (void*)cmpd;
    } else { /* Error, free cmpd to avoid memory leak. */
      free(cmpd);
    }
    return status;

fail:
    ncaux_abort_compound((void*)cmpd);
    return status;
#else
    return NC_ENOTBUILT;
#endif
}

EXTERNL int
ncaux_abort_compound(void* tag)
{
#ifdef USE_NETCDF4
    int i;
    struct NCAUX_CMPD* cmpd = (struct NCAUX_CMPD*)tag;
    if(cmpd == NULL) goto done;
    if(cmpd->name) free(cmpd->name);
    for(i=0;i<cmpd->nfields;i++) {
	struct NCAUX_FIELD* field = &cmpd->fields[i];
	if(field->name) free(field->name);
    }
    if(cmpd->fields) free(cmpd->fields);
    free(cmpd);

done:
    return NC_NOERR;
#else
    return NC_ENOTBUILT;
#endif
}

EXTERNL int
ncaux_add_field(void* tag,  const char *name, nc_type field_type,
			   int ndims, const int* dimsizes)
{
#ifdef USE_NETCDF4
    int i;
    int status = NC_NOERR;
    struct NCAUX_CMPD* cmpd = (struct NCAUX_CMPD*)tag;
    struct NCAUX_FIELD* newfields = NULL;
    struct NCAUX_FIELD* field = NULL;

    if(cmpd == NULL) goto done;
    if(ndims < 0) {status = NC_EINVAL; goto done;}
    for(i=0;i<ndims;i++) {
	if(dimsizes[i] <= 0) {status = NC_EINVAL; goto done;}
    }
    if(cmpd->fields == NULL) {
        newfields = (struct NCAUX_FIELD*)calloc(1,sizeof(struct NCAUX_FIELD));
    } else {
        newfields = (struct NCAUX_FIELD*)realloc(cmpd->fields,cmpd->nfields+1*sizeof(struct NCAUX_FIELD));
    }
    if(cmpd->fields == NULL) {status = NC_ENOMEM; goto done;}
    cmpd->fields = newfields;
    field = &cmpd->fields[cmpd->nfields+1];
    field->name = strdup(name);
    field->fieldtype = field_type;
    if(field->name == NULL) {status = NC_ENOMEM; goto done;}
    field->ndims = (size_t)ndims;
    memcpy(field->dimsizes,dimsizes,sizeof(int)*field->ndims);
    cmpd->nfields++;

done:
    if(newfields)
      free(newfields);
    return status;
#else
    return NC_ENOTBUILT;
#endif
}

EXTERNL int
ncaux_end_compound(void* tag, nc_type* idp)
{
#ifdef USE_NETCDF4
    int i;
    int status = NC_NOERR;
    struct NCAUX_CMPD* cmpd = (struct NCAUX_CMPD*)tag;

    if(cmpd == NULL) {status = NC_EINVAL; goto done;}

    /* Compute field and compound info */
    status = computefieldinfo(cmpd);
    if(status != NC_NOERR) goto done;

    status = nc_def_compound(cmpd->ncid, cmpd->size, cmpd->name, idp);
    if(status != NC_NOERR) goto done;

    for(i=0;i<cmpd->nfields;i++) {
	struct NCAUX_FIELD* field = &cmpd->fields[i];
	if(field->ndims > 0) {
            status = nc_insert_compound(cmpd->ncid, *idp, field->name,
					field->offset, field->fieldtype);
	} else {
            status = nc_insert_array_compound(cmpd->ncid, *idp, field->name,
					field->offset, field->fieldtype,
					(int)field->ndims,field->dimsizes);
	}
        if(status != NC_NOERR) goto done;
    }

done:
    return status;
#else
    return NC_ENOTBUILT;
#endif
}

/**************************************************/

/**
 @param ncclass - type class for which alignment is requested; excludes ENUM|COMPOUND
*/

int
ncaux_class_alignment(int ncclass, size_t* alignp)
{
    int stat = NC_NOERR;
    size_t align = 0;
    if(ncclass <= NC_MAX_ATOMIC_TYPE || ncclass == NC_VLEN || ncclass == NC_OPAQUE) {
        stat = NC_class_alignment(ncclass,&align);
    } else {
        nclog(NCLOGERR,"ncaux_class_alignment: class %d; alignment cannot be determermined",ncclass);
    }
    if(alignp) *alignp = align;
    if(align == 0) stat = NC_EINVAL;
    return stat;
}


#ifdef USE_NETCDF4
/* Find first primitive field of a possibly nested sequence of compounds */
static nc_type
findfirstfield(int ncid, nc_type xtype)
{
    int status = NC_NOERR;
    nc_type fieldtype = xtype;
    if(xtype <= NC_MAX_ATOMIC_TYPE) goto done;

    status = nc_inq_compound_fieldtype(ncid, xtype, 0, &fieldtype);
    if(status != NC_NOERR) goto done;
    fieldtype = findfirstfield(ncid,fieldtype);

done:
    return (status == NC_NOERR?fieldtype:NC_NAT);
}

static size_t
getpadding(size_t offset, size_t alignment)
{
    size_t rem = (alignment==0?0:(offset % alignment));
    size_t pad = (rem==0?0:(alignment - rem));
    return pad;
}

static size_t
dimproduct(size_t ndims, int* dimsizes)
{
    int i;
    size_t product = 1;
    for(i=0;i<ndims;i++) product *= (size_t)dimsizes[i];
    return product;
}

static int
computefieldinfo(struct NCAUX_CMPD* cmpd)
{
    int i;
    int status = NC_NOERR;
    size_t offset = 0;
    size_t totaldimsize;

    /* Assign the sizes for the fields */
    for(i=0;i<cmpd->nfields;i++) {
	struct NCAUX_FIELD* field = &cmpd->fields[i];
	status = nc_inq_type(cmpd->ncid,field->fieldtype,NULL,&field->size);
        if(status != NC_NOERR) goto done;
	totaldimsize = dimproduct(field->ndims,field->dimsizes);
	field->size *= totaldimsize;
    }

    for(offset=0,i=0;i<cmpd->nfields;i++) {
        struct NCAUX_FIELD* field = &cmpd->fields[i];
	int alignment = 0;
	nc_type firsttype = findfirstfield(cmpd->ncid,field->fieldtype);

        /* only support 'c' alignment for now*/
	switch (field->fieldtype) {
	case NC_OPAQUE:
	    field->alignment = 1;
	    break;
	case NC_ENUM:
	    status = ncaux_type_alignment(firsttype,cmpd->ncid,&field->alignment);
	    break;
	case NC_VLEN: /*fall thru*/
	case NC_COMPOUND:
            status = ncaux_type_alignment(firsttype,cmpd->ncid,&field->alignment);
	    break;
	default:
            status = ncaux_type_alignment(field->fieldtype,cmpd->ncid,&field->alignment);
	    break;

	}
        offset += getpadding(offset,alignment);
        field->offset = offset;
        offset += field->size;
    }
    cmpd->size = offset;
    cmpd->alignment = cmpd->fields[0].alignment;

done:
    return status;
}

#endif /*USE_NETCDF4*/


/**************************************************/
/* Forward */

#define NUMCHAR "0123456789"
#define LPAREN '('
#define RPAREN ')'
#define LBRACK '['
#define RBRACK ']'

static int gettype(const int q0, const int q1, int* unsignedp);

/* Look at q0 and q1) to determine type */
static int
gettype(const int q0, const int q1, int* isunsignedp)
{
    int type = 0;
    int isunsigned = 0;
    char typechar;
    
    isunsigned = (q0 == 'u' || q0 == 'U');
    if(q1 == '\0')
	typechar = q0; /* we were given only a single char */
    else if(isunsigned)
	typechar = q1; /* we have something like Ux as the tag */
    else
	typechar = q1; /* look at last char for tag */
    switch (typechar) {
    case 'f': case 'F': case '.': type = 'f'; break; /* float */
    case 'd': case 'D': type = 'd'; break; /* double */
    case 'b': case 'B': type = 'b'; break; /* byte */
    case 's': case 'S': type = 's'; break; /* short */
    case 'l': case 'L': type = 'l'; break; /* long long */
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9': type = 'i'; break;
    case 'u': case 'U': type = 'i'; isunsigned = 1; break; /* unsigned int */
    case '\0': type = 'i'; break;
    default: break;
    }
    if(isunsignedp) *isunsignedp = isunsigned;
    return type;
}

#ifdef WORDS_BIGENDIAN
/* Byte swap an 8-byte integer in place */
static void
byteswap8(unsigned char* mem)
{
    unsigned char c;
    c = mem[0];
    mem[0] = mem[7];
    mem[7] = c;
    c = mem[1];
    mem[1] = mem[6];
    mem[6] = c;
    c = mem[2];
    mem[2] = mem[5];
    mem[5] = c;
    c = mem[3];
    mem[3] = mem[4];
    mem[4] = c;
}

/* Byte swap an 8-byte integer in place */
static void
byteswap4(unsigned char* mem)
{
    unsigned char c;
    c = mem[0];
    mem[0] = mem[3];
    mem[3] = c;
    c = mem[1];
    mem[1] = mem[2];
    mem[2] = c;
}
#endif

/**************************************************/
/* Moved here from netcdf_filter.h */

/*
This function implements the 8-byte conversion algorithms for HDF5
Before calling *nc_def_var_filter* (unless *NC_parsefilterspec* was used),
the client must call this function with the decode argument set to 0.
Inside the filter code, this function should be called with the decode
argument set to 1.

* @params mem8 is a pointer to the 8-byte value either to fix.
* @params decode is 1 if the function should apply the 8-byte decoding algorithm
          else apply the encoding algorithm.
*/

void
ncaux_h5filterspec_fix8(unsigned char* mem8, int decode)
{
#ifdef WORDS_BIGENDIAN
    if(decode) { /* Apply inverse of the encode case */
	byteswap4(mem8); /* step 1: byte-swap each piece */
	byteswap4(mem8+4);
	byteswap8(mem8); /* step 2: convert to little endian format */
    } else { /* encode */
	byteswap8(mem8); /* step 1: convert to little endian format */
	byteswap4(mem8); /* step 2: byte-swap each piece */
	byteswap4(mem8+4);
    }
#else /* Little endian */
    /* No action is necessary */
#endif	    
}

/*
Parse a filter spec string into a NC_FILTER_SPEC*
Note that this differs from the usual case in that the
function is called once to get both the number of parameters
and the parameters themselves (hence the unsigned int** paramsp).

@param txt - a string containing the spec as a sequence of
              constants separated by commas, where first constant
	      is the filter id and the rest are parameters.
@param idp - store the parsed filter id here
@param nparamsp - store the number of parameters here
@param paramsp - store the vector of parameters here; caller frees.
@return NC_NOERR if parse succeeded
@return NC_EINVAL otherwise
*/

EXTERNL int
ncaux_h5filterspec_parse(const char* txt, unsigned int* idp, size_t* nparamsp, unsigned int** paramsp)
{
    int i,stat = NC_NOERR;
    char* p;
    char* sdata0 = NULL; /* what to free */
    char* sdata = NULL; /* sdata0 with leading prefix skipped */
    size_t nparams; /* no. of comma delimited params */
    size_t nactual; /* actual number of unsigned int's */
    const char* sid = NULL;
    unsigned int filterid = 0;
    unsigned int* params = NULL;
    size_t len;
    
    if(txt == NULL)
        {stat = NC_EINVAL; goto done;}
    len = strlen(txt);
    if(len == 0)
        {stat = NC_EINVAL; goto done;}

    if((sdata0 = (char*)calloc(1,len+1+1))==NULL)
	{stat = NC_ENOMEM; goto done;}	
    memcpy(sdata0,txt,len);
    sdata = sdata0;

    /* Count number of parameters + id and delimit */
    p=sdata;
    for(nparams=0;;nparams++) {
        char* q = strchr(p,',');
	if(q == NULL) break;
	*q++ = '\0';
	p = q;
    }
    nparams++; /* for final piece */

    if(nparams == 0)
	{stat = NC_EINVAL; goto done;} /* no id and no parameters */

    p = sdata;

    /* Extract the filter id */
    sid = p;
    if((sscanf(sid,"%u",&filterid)) != 1) {stat = NC_EINVAL; goto done;}
    nparams--;

    /* skip past the filter id */
    p = p + strlen(p) + 1;

    /* Allocate the max needed space (assume all params are 64 bit) */
    if((params = (unsigned int*)calloc(sizeof(unsigned int),(nparams)*2))==NULL)
	{stat = NC_ENOMEM; goto done;}

    /* walk and capture */
    for(nactual=0,i=0;i<nparams;i++) { /* step thru param strings */
	size_t count = 0;
	len = strlen(p);
	/* skip leading white space */
	while(strchr(" 	",*p) != NULL) {p++; len--;}
	if((stat = filterspec_cvt(p,&count,params+nactual))) goto done;
	nactual += count;
        p = p + strlen(p) + 1; /* move to next param string */
    }
    /* Now return results */
    if(idp) *idp = filterid;
    if(nparamsp) *nparamsp = nactual;
    if(paramsp) {*paramsp = params; params = NULL;}
done:
    nullfree(params);
    nullfree(sdata0);
    return stat;
}

/*
Parse a filter parameter string into a sequence of unsigned ints.

@param txt - a string containing the parameter string.
@param nuiparamsp - store the number of unsigned ints here
@param uiparamsp - store the vector of unsigned ints here; caller frees.
@return NC_NOERR if parse succeeded
@return NC_EINVAL otherwise
*/

EXTERNL int
ncaux_h5filterspec_parse_parameter(const char* txt, size_t* nuiparamsp, unsigned int* uiparams)
{
    int stat = NC_NOERR;
    char* p;
    char* sdata0 = NULL; /* what to free */
    char* sdata = NULL; /* sdata0 with leading prefix skipped */
    size_t nuiparams = 0;
    size_t len;
    
    if(txt == NULL)
        {stat = NC_EINVAL; goto done;}
    len = strlen(txt);
    if(len == 0)
        {stat = NC_EINVAL; goto done;}

    if((sdata0 = (char*)calloc(1,len+1+1))==NULL)
	{stat = NC_ENOMEM; goto done;}	
    memcpy(sdata0,txt,len);
    sdata = sdata0;

    p = sdata;

    nuiparams = 0;
    len = strlen(p);
    /* skip leading white space */
    while(strchr(" 	",*p) != NULL) {p++; len--;}
    if((stat = filterspec_cvt(p,&nuiparams,uiparams))) goto done;
    /* Now return results */
    if(nuiparamsp) *nuiparamsp = nuiparams;
done:
    nullfree(sdata0);
    return stat;
}

/*
Parse a string containing multiple '|' separated filter specs.
Use a vector of NC_Filterspec structs to return results.
@param txt0 - a string containing the list of filter specs.
@param formatp - store any leading format integer here
@param nspecsp - # of parsed specs
@param specsp - pointer to hold vector of parsed specs. Caller frees
@return NC_NOERR if parse succeeded
@return NC_EINVAL if bad parameters or parse failed
*/

EXTERNL int
ncaux_h5filterspec_parselist(const char* txt0, int* formatp, size_t* nspecsp, NC_H5_Filterspec*** vectorp)
{
    int stat = NC_NOERR;
    int format = 0;
    size_t len = 0;
    size_t nspecs = 0;
    NC_H5_Filterspec** vector = NULL;
    char* spec = NULL; /* without prefix */
    char* p = NULL;
    char* q = NULL;

    if(txt0  == NULL) return NC_EINVAL;
    /* Duplicate txt0 so we can modify it */
    len = strlen(txt0);
    if((spec = calloc(1,len+1+1)) == NULL) {stat = NC_ENOMEM; goto done;}
    memcpy(spec,txt0,len); /* Note double ending nul */

    /* See if there is a prefix '[format]' tag */
    if(spec[0] == LBRACK) {
	p = spec + 1;
	q = strchr(p,RBRACK);
	if(q == NULL) {stat = NC_EINVAL; goto done;}
	*q++ = '\0'; /* delimit tag */
	if(sscanf(p,"%d",&format) != 1) {stat = NC_EINVAL; goto done;}
	spec = q; /* skip tag wrt later processing */
    }

    /* pass 1: count number of specs */
    p = spec;
    nspecs = 0;
    while(*p) {
	q = strchr(p,'|');
	if(q == NULL) q = p + strlen(p); /* fake it */
	nspecs++;
	p = q + 1;
    }
    if(nspecs >  0) {
	int count = 0;
	if((vector = (NC_H5_Filterspec**)calloc(sizeof(NC_H5_Filterspec*),nspecs)) == NULL)
	    {stat = NC_ENOMEM; goto done;}
	/* pass 2: parse */
	p = spec;
	for(count=0;count<nspecs;count++) {
	    NC_H5_Filterspec* spec = (NC_H5_Filterspec*)calloc(1,sizeof(NC_H5_Filterspec));
	    if(spec == NULL) {stat = NC_ENOMEM; goto done;}
	    vector[count] = spec;
	    q = strchr(p,'|');
	    if(q == NULL) q = p + strlen(p); /* fake it */
	    *q = '\0';
	    if((stat=ncaux_h5filterspec_parse(p,&spec->filterid,&spec->nparams,&spec->params))) goto done;
	    p = q+1; /* ok because of double nul */
	}
    }
    if(formatp) *formatp = format;
    if(nspecsp) *nspecsp = nspecs;
    if(vectorp) {*vectorp = vector; vector = NULL;}
done:
    nullfree(spec);
    if(vector) {
	int i;
        for(i=0;i<nspecs;i++)
	    ncaux_h5filterspec_free(vector[i]);
	nullfree(vector);
    }
    return stat;
}

/*
Parse a string containing multiple '|' separated filter specs.
Use a vector of NC_Filterspec structs to return results.
@param txt0 - a string containing the list of filter specs.
@param formatp - store any leading format integer here
@param nspecsp - # of parsed specs
@param specsp - pointer to hold vector of parsed specs. Caller frees
@return NC_NOERR if parse succeeded
@return NC_EINVAL if bad parameters or parse failed
*/

EXTERNL void
ncaux_h5filterspec_free(NC_H5_Filterspec* f)
{
    if(f) nullfree(f->params);
    nullfree(f);
}


/*
Convert a parameter string to one or two unsigned ints/
@param txt - (in) string constant
@param nparamsp - (out) # of unsigned ints produced
@param params - (out) produced unsigned ints
@return NC_NOERR if parse succeeded
@return NC_EINVAL if bad parameters or parse failed
*/

static int
filterspec_cvt(const char* txt, size_t* nparamsp, unsigned int* params)
{
    int stat = NC_NOERR;
    size_t nparams = 0; /*actual count*/
    unsigned long long val64u;
    unsigned int val32u;
    double vald;
    float valf;
    unsigned int *vector;
    unsigned char mem[8];
    int isunsigned = 0;
    int isnegative = 0;
    int type = 0;
    const char* q;
    const char* p = txt;
    size_t len = strlen(p);
    int sstat;

    /* skip leading white space */
    while(strchr(" 	",*p) != NULL) {p++; len--;}
    /* Get leading sign character, if any */
    if(*p == '-') isnegative = 1;
    /* Get trailing type tag characters */
    switch (len) {
    case 0: stat = NC_EINVAL; goto done; /* empty parameter */
    case 1: case 2:
        q = (p + len) - 1; /* point to last char */
        type = gettype(*q,'\0',&isunsigned);
        break;
    default: /* > 2 => we might have a two letter tag */
        q = (p + len) - 2;
        type = gettype(*q,*(q+1),&isunsigned);
        break;
    }
    /* Now parse */
    switch (type) {
    case 'b': case 's': case 'i':
         /* special case for a positive integer;for back compatibility.*/
        if(!isnegative)
	     sstat = sscanf(p,"%u",&val32u);
        else
	    sstat = sscanf(p,"%d",(int*)&val32u);
        if(sstat != 1) {stat = NC_EINVAL; goto done;}
        switch(type) {
        case 'b': val32u = (val32u & 0xFF); break;
        case 's': val32u = (val32u & 0xFFFF); break;
        }
        params[nparams++] = val32u;
        break;
    case 'f':
        sstat = sscanf(p,"%lf",&vald);
        if(sstat != 1) {stat = NC_EINVAL; goto done;}
        valf = (float)vald;
        params[nparams++] = *(unsigned int*)&valf;
        break;
    /* The following are 8-byte values, so we must swap pieces if this
    is a little endian machine */        
    case 'd':
        sstat = sscanf(p,"%lf",&vald);
        if(sstat != 1) {stat = NC_EINVAL; goto done;};
        memcpy(mem,&vald,sizeof(mem));
        ncaux_h5filterspec_fix8(mem,0);
        vector = (unsigned int*)mem;
        params[nparams++] = vector[0];
        params[nparams++] = vector[1];
        break;
    case 'l': /* long long */
        if(isunsigned)
            sstat = sscanf(p,"%llu",&val64u);
        else
            sstat = sscanf(p,"%lld",(long long*)&val64u);
        if(sstat != 1) {stat = NC_EINVAL; goto done;};
        memcpy(mem,&val64u,sizeof(mem));
        ncaux_h5filterspec_fix8(mem,0);
        vector = (unsigned int*)&mem;
        params[nparams++] = vector[0];
        params[nparams++] = vector[1];
        break;
    default:
        {stat = NC_EINVAL; goto done;};
    }
    *nparamsp = nparams;

done:
    return stat;
}
    
#if 0
/*
Parse a filter spec string into a NC_H5_Filterspec*
@param txt - a string containing the spec as a sequence of
              constants separated by commas.
@param specp - store the parsed filter here -- caller frees
@return NC_NOERR if parse succeeded
@return NC_EINVAL otherwise
*/

EXTERNL int
ncaux_filter_parsespec(const char* txt, NC_H5_Filterspec** h5specp)
{
    int stat = NC_NOERR;
    NC_Filterspec* spec = NULL;
    NC_H5_Filterspec* h5spec = NULL;
    size_t len;
    
    if(txt == NULL) 
	{stat = NC_EINVAL; goto done;}
    len = strlen(txt);
    if(len == 0) {stat = NC_EINVAL; goto done;}

    /* Parse as strings */
    if((stat = ncaux_filterspec_parse(txt,&spec))) goto done;
    /* walk and convert */
    if((stat = ncaux_filterspec_cvt(spec,&h5spec))) goto done;
    /* Now return results */
    if(h5specp != NULL) {*h5specp = h5spec; h5spec = NULL;}

done:
    ncaux_filterspec_free(spec);
    if(h5spec) nullfree(h5spec->params);
    nullfree(h5spec);
    return stat;
}

/*
Parse a string containing multiple '|' separated filter specs.

@param spec0 - a string containing the list of filter specs.
@param nspecsp - # of parsed specs
@param specsp - pointer to hold vector of parsed specs. Caller frees
@return NC_NOERR if parse succeeded
@return NC_EINVAL if bad parameters or parse failed
*/

EXTERNL int
ncaux_filter_parselist(const char* txt0, size_t* nspecsp, NC_H5_Filterspec*** vectorp)
{
    int stat = NC_NOERR;
    size_t len = 0;
    size_t nspecs = 0;
    NC_H5_Filterspec** vector = NULL;
    char* spec0 = NULL; /* with prefix */
    char* spec = NULL; /* without prefix */
    char* p = NULL;
    char* q = NULL;

    if(txt0  == NULL) return NC_EINVAL;
    /* Duplicate txt0 so we can modify it */
    len = strlen(txt0);
    if((spec = calloc(1,len+1+1)) == NULL) return NC_ENOMEM;
    memcpy(spec,txt0,len); /* Note double ending nul */
    spec0 = spec; /* Save for later free */

    /* See if there is a prefix '[format]' tag; ignore it */
    if(spec[0] == LBRACK) {
	spec = q; /* skip tag wrt later processing */
    }
    /* pass 1: count number of specs */
    p = spec;
    nspecs = 0;
    while(*p) {
	q = strchr(p,'|');
	if(q == NULL) q = p + strlen(p); /* fake it */
	nspecs++;
	p = q + 1;
    }
    if(nspecs >  0) {
	int count = 0;
	if((vector = (NC_H5_Filterspec**)malloc(sizeof(NC_H5_Filterspec*)*nspecs)) == NULL)
	    {stat = NC_ENOMEM; goto done;}
	/* pass 2: parse */
	p = spec;
	for(count=0;count<nspecs;count++) {
	    NC_H5_Filterspec* aspec = NULL;
	    q = strchr(p,'|');
	    if(q == NULL) q = p + strlen(p); /* fake it */
	    *q = '\0';
	    if(ncaux_filter_parsespec(p,&aspec))
	        {stat = NC_EINVAL; goto done;}
	    vector[count] = aspec; aspec = NULL;
	    p = q+1; /* ok because of double nul */
	}
    }
    if(nspecsp) *nspecsp = nspecs;
    if(vectorp) *vectorp = (nspecs == 0 ? NULL : vector);
    vector = NULL;
done:
    nullfree(spec0);
    if(vector != NULL) {
	int k;
	for(k=0;k<nspecs;k++) {
	    NC_H5_Filterspec* nfs = vector[k];
	    if(nfs->params) free(nfs->params);
	    nullfree(nfs);
	}
	free(vector);
    }
    return stat;
}
#endif

/**************************************************/
/* Wrappers to export selected functions from libnetcdf */

EXTERNL int
ncaux_readfile(const char* filename, size_t* sizep, void** contentp)
{
    int stat = NC_NOERR;
    NCbytes* content = ncbytesnew();
    stat = NC_readfile(filename,content);
    if(stat == NC_NOERR && sizep)
        *sizep = ncbyteslength(content);
    if(stat == NC_NOERR && contentp)
        *contentp = ncbytesextract(content);
    ncbytesfree(content);
    return stat;        
}

EXTERNL int
ncaux_writefile(const char* filename, size_t size, void* content)
{
    return NC_writefile(filename,size,content);
}

/**************************************************/
/**
Reclaim the output tree of data from a call
to e.g. nc_get_vara or the input to e.g. nc_put_vara.
This recursively walks the top-level instances to
reclaim any nested data such as vlen or strings or such.

This function is just a wrapper around nc_reclaim_data.

@param ncid file ncid
@param xtype type id
@param memory to reclaim
@param count number of instances of the type in memory
@return error code
*/

EXTERNL int
ncaux_reclaim_data(int ncid, int xtype, void* memory, size_t count)
{
    /* Defer to the internal version */
    return nc_reclaim_data(ncid, xtype, memory, count);
}

/*
This function is just a wrapper around nc_reclaim_data_all.
@param ncid file ncid
@param xtype type id
@param memory to reclaim
@param count number of instances of the type in memory
@return error code
*/

EXTERNL int
ncaux_reclaim_data_all(int ncid, int xtype, void* memory, size_t count)
{
    /* Defer to the internal version */
    return nc_reclaim_data_all(ncid, xtype, memory, count);
}

/**
 @param ncid - only needed for a compound type
 @param xtype - type for which alignment is requested
*/
int
ncaux_type_alignment(int xtype, int ncid, size_t* alignp)
{
    /* Defer to the internal version */
    return NC_type_alignment(ncid, xtype, alignp);
}