dfile.c

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#include "config.h"
#include <stdlib.h>
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
 
#ifdef HAVE_UNISTD_H
#include <unistd.h> /* lseek() */
#endif
 
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
 
#include "ncdispatch.h"
#include "netcdf_mem.h"
#include "ncpathmgr.h"
#include "fbits.h"
 
#undef DEBUG
 
#ifndef nulldup
 #define nulldup(s) ((s)?strdup(s):NULL)
#endif
 
 
/* User-defined formats - expanded from 2 to 10 slots.
 * These arrays store dispatch tables and magic numbers for up to 10 custom formats.
 * Array-based design replaces the previous individual UDF0/UDF1 global variables. */
NC_Dispatch *UDF_dispatch_tables[NC_MAX_UDF_FORMATS] = {NULL};
char UDF_magic_numbers[NC_MAX_UDF_FORMATS][NC_MAX_MAGIC_NUMBER_LEN + 1] = {{0}};
 
static int udf_mode_to_index(int mode_flag) {
    int count = 0;
    int index = -1;
    
    /* Count how many UDF flags are set and remember the index */
    if (fIsSet(mode_flag, NC_UDF0)) { count++; index = 0; }
    if (fIsSet(mode_flag, NC_UDF1)) { count++; index = 1; }
    if (fIsSet(mode_flag, NC_UDF2)) { count++; index = 2; }
    if (fIsSet(mode_flag, NC_UDF3)) { count++; index = 3; }
    if (fIsSet(mode_flag, NC_UDF4)) { count++; index = 4; }
    if (fIsSet(mode_flag, NC_UDF5)) { count++; index = 5; }
    if (fIsSet(mode_flag, NC_UDF6)) { count++; index = 6; }
    if (fIsSet(mode_flag, NC_UDF7)) { count++; index = 7; }
    if (fIsSet(mode_flag, NC_UDF8)) { count++; index = 8; }
    if (fIsSet(mode_flag, NC_UDF9)) { count++; index = 9; }
    
    /* Only one UDF flag should be set at a time */
    if (count != 1)
        return -1;
    
    return index;
}
 
static int udf_formatx_to_index(int formatx) {
    /* UDF0 and UDF1 are sequential (8, 9) */
    if (formatx >= NC_FORMATX_UDF0 && formatx <= NC_FORMATX_UDF1)
        return formatx - NC_FORMATX_UDF0;
    /* UDF2-UDF9 start at 11 (skipping NCZARR at 10) */
    if (formatx >= NC_FORMATX_UDF2 && formatx <= NC_FORMATX_UDF9)
        return formatx - NC_FORMATX_UDF2 + 2;
    return -1;
}
 
/**************************************************/
 
 
int
nc_def_user_format(int mode_flag, NC_Dispatch *dispatch_table, char *magic_number)
{
    int udf_index;
 
    /* Check inputs. */
    if (!dispatch_table)
        return NC_EINVAL;
    if (magic_number && strlen(magic_number) > NC_MAX_MAGIC_NUMBER_LEN)
        return NC_EINVAL;
 
    /* Check the version of the dispatch table provided. */
    if (dispatch_table->dispatch_version != NC_DISPATCH_VERSION)
        return NC_EINVAL;
    /* user defined magic numbers not allowed with netcdf3 modes */ 
    if (magic_number && (fIsSet(mode_flag, NC_64BIT_OFFSET) ||
                         fIsSet(mode_flag, NC_64BIT_DATA) ||
                        (fIsSet(mode_flag, NC_CLASSIC_MODEL) &&
                        !fIsSet(mode_flag, NC_NETCDF4))))
        return NC_EINVAL;
 
    /* Get the UDF index from the mode flag. */
    udf_index = udf_mode_to_index(mode_flag);
    if (udf_index < 0 || udf_index >= NC_MAX_UDF_FORMATS)
        return NC_EINVAL;
 
    /* Retain a pointer to the dispatch_table and a copy of the magic
     * number, if one was provided. */
    UDF_dispatch_tables[udf_index] = dispatch_table;
    if (magic_number) {
        strncpy(UDF_magic_numbers[udf_index], magic_number, NC_MAX_MAGIC_NUMBER_LEN);
        /* Ensure null-termination since strncpy doesn't guarantee it if source >= max length */
        UDF_magic_numbers[udf_index][NC_MAX_MAGIC_NUMBER_LEN] = '\0';
    }
 
    return NC_NOERR;
}
 
int
nc_inq_user_format(int mode_flag, NC_Dispatch **dispatch_table, char *magic_number)
{
    int udf_index;
 
    /* Get the UDF index from the mode flag. */
    udf_index = udf_mode_to_index(mode_flag);
    if (udf_index < 0 || udf_index >= NC_MAX_UDF_FORMATS)
        return NC_EINVAL;
 
    /* Return the dispatch table and magic number. */
    if (dispatch_table)
        *dispatch_table = UDF_dispatch_tables[udf_index];
    if (magic_number)
        strncpy(magic_number, UDF_magic_numbers[udf_index], NC_MAX_MAGIC_NUMBER_LEN);
 
    return NC_NOERR;
}
 
int
nc_create(const char *path, int cmode, int *ncidp)
{
    return nc__create(path,cmode,NC_SIZEHINT_DEFAULT,NULL,ncidp);
}
 
int
nc__create(const char *path, int cmode, size_t initialsz,
           size_t *chunksizehintp, int *ncidp)
{
    return NC_create(path, cmode, initialsz, 0,
                     chunksizehintp, 0, NULL, ncidp);
}
 
int
nc_create_mem(const char* path, int mode, size_t initialsize, int* ncidp)
{
    if(mode & NC_MMAP) return NC_EINVAL;
    mode |= NC_INMEMORY; /* Specifically, do not set NC_DISKLESS */
    return NC_create(path, mode, initialsize, 0, NULL, 0, NULL, ncidp);
}
 
int
nc__create_mp(const char *path, int cmode, size_t initialsz,
              int basepe, size_t *chunksizehintp, int *ncidp)
{
    return NC_create(path, cmode, initialsz, basepe,
                     chunksizehintp, 0, NULL, ncidp);
}
 
int
nc_open(const char *path, int omode, int *ncidp)
{
    return NC_open(path, omode, 0, NULL, 0, NULL, ncidp);
}
 
int
nc__open(const char *path, int omode,
         size_t *chunksizehintp, int *ncidp)
{
    /* this API is for non-parallel access.
     * Note nc_open_par() also calls NC_open().
     */
    return NC_open(path, omode, 0, chunksizehintp, 0, NULL, ncidp);
}
 
int
nc_open_mem(const char* path, int omode, size_t size, void* memory, int* ncidp)
{
    NC_memio meminfo;
 
    /* Sanity checks */
    if(memory == NULL || size < MAGIC_NUMBER_LEN || path == NULL)
        return NC_EINVAL;
    if(omode & (NC_WRITE|NC_MMAP))
        return NC_EINVAL;
    omode |= (NC_INMEMORY); /* Note: NC_INMEMORY and NC_DISKLESS are mutually exclusive*/
    meminfo.size = size;
    meminfo.memory = memory;
    meminfo.flags = NC_MEMIO_LOCKED;
    return NC_open(path, omode, 0, NULL, 0, &meminfo, ncidp);
}
 
int
nc_open_memio(const char* path, int omode, NC_memio* params, int* ncidp)
{
    /* Sanity checks */
    if(path == NULL || params == NULL)
        return NC_EINVAL;
    if(params->memory == NULL || params->size < MAGIC_NUMBER_LEN)
        return NC_EINVAL;
 
    if(omode & NC_MMAP)
        return NC_EINVAL;
    omode |= (NC_INMEMORY);
    return NC_open(path, omode, 0, NULL, 0, params, ncidp);
}
 
int
nc__open_mp(const char *path, int omode, int basepe,
            size_t *chunksizehintp, int *ncidp)
{
    return NC_open(path, omode, basepe, chunksizehintp, 0, NULL, ncidp);
}
 
int
nc_inq_path(int ncid, size_t *pathlen, char *path)
{
    NC* ncp;
    int stat = NC_NOERR;
    if ((stat = NC_check_id(ncid, &ncp)))
        return stat;
    if(ncp->path == NULL) {
        if(pathlen) *pathlen = 0;
        if(path) path[0] = '\0';
    } else {
        if (pathlen) *pathlen = strlen(ncp->path);
        if (path) strcpy(path, ncp->path);
    }
    return stat;
}
 
int
nc_redef(int ncid)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->redef(ncid);
}
 
int
nc_enddef(int ncid)
{
    int status = NC_NOERR;
    NC *ncp;
    status = NC_check_id(ncid, &ncp);
    if(status != NC_NOERR) return status;
    return ncp->dispatch->_enddef(ncid,0,1,0,1);
}
 
int
nc__enddef(int ncid, size_t h_minfree, size_t v_align, size_t v_minfree,
           size_t r_align)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->_enddef(ncid,h_minfree,v_align,v_minfree,r_align);
}
 
int
nc_sync(int ncid)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->sync(ncid);
}
 
int
nc_abort(int ncid)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
 
    stat = ncp->dispatch->abort(ncid);
    del_from_NCList(ncp);
    free_NC(ncp);
    return stat;
}
 
int
nc_close(int ncid)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
 
    stat = ncp->dispatch->close(ncid,NULL);
    /* Remove from the nc list */
    if (!stat)
    {
        del_from_NCList(ncp);
        free_NC(ncp);
    }
    return stat;
}
 
int
nc_close_memio(int ncid, NC_memio* memio)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
 
    stat = ncp->dispatch->close(ncid,memio);
    /* Remove from the nc list */
    if (!stat)
    {
        del_from_NCList(ncp);
        free_NC(ncp);
    }
    return stat;
}
 
int
nc_set_fill(int ncid, int fillmode, int *old_modep)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->set_fill(ncid,fillmode,old_modep);
}
 
int
nc_inq_base_pe(int ncid, int *pe)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    if (pe) *pe = 0;
    return NC_NOERR;
}
 
int
nc_set_base_pe(int ncid, int pe)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return NC_NOERR;
}
 
int
nc_inq_format(int ncid, int *formatp)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->inq_format(ncid,formatp);
}
 
int
nc_inq_format_extended(int ncid, int *formatp, int *modep)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->inq_format_extended(ncid,formatp,modep);
}
 
int
nc_inq(int ncid, int *ndimsp, int *nvarsp, int *nattsp, int *unlimdimidp)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->inq(ncid,ndimsp,nvarsp,nattsp,unlimdimidp);
}
 
int
nc_inq_nvars(int ncid, int *nvarsp)
{
    NC* ncp;
    int stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) return stat;
    return ncp->dispatch->inq(ncid, NULL, nvarsp, NULL, NULL);
}
 
int
nc_inq_type(int ncid, nc_type xtype, char *name, size_t *size)
{
    NC* ncp;
    int stat;
 
    /* Do a quick triage on xtype */
    if(xtype <= NC_NAT) return NC_EBADTYPE;
    /* For compatibility, we need to allow inq about
       atomic types, even if ncid is ill-defined */
    if(xtype <= ATOMICTYPEMAX4) {
        if(name) strncpy(name,NC_atomictypename(xtype),NC_MAX_NAME);
        if(size) *size = NC_atomictypelen(xtype);
        return NC_NOERR;
    }
    /* Apparently asking about a user defined type, so we need
       a valid ncid */
    stat = NC_check_id(ncid, &ncp);
    if(stat != NC_NOERR) /* bad ncid */
        return NC_EBADTYPE;
    /* have good ncid */
    return ncp->dispatch->inq_type(ncid,xtype,name,size);
}
 
static int
check_create_mode(int mode)
{
    int mode_format;
    int use_mmap = 0;
    int inmemory = 0;
    int diskless = 0;
 
    /* This is a clever check to see if more than one format bit is
     * set. */
    mode_format = (mode & NC_NETCDF4) | (mode & NC_64BIT_OFFSET) |
        (mode & NC_CDF5);
    if (mode_format && (mode_format & (mode_format - 1)))
        return NC_EINVAL;
 
    use_mmap = ((mode & NC_MMAP) == NC_MMAP);
    inmemory = ((mode & NC_INMEMORY) == NC_INMEMORY);
    diskless = ((mode & NC_DISKLESS) == NC_DISKLESS);
 
    /* NC_INMEMORY and NC_DISKLESS and NC_MMAP are all mutually exclusive */
    if(diskless && inmemory) return NC_EDISKLESS;
    if(diskless && use_mmap) return NC_EDISKLESS;
    if(inmemory && use_mmap) return NC_EINMEMORY;
 
    /* mmap is not allowed for netcdf-4 */
    if(use_mmap && (mode & NC_NETCDF4)) return NC_EINVAL;
 
#ifndef USE_NETCDF4
    /* If the user asks for a netCDF-4 file, and the library was built
     * without netCDF-4, then return an error.*/
    if (mode & NC_NETCDF4)
        return NC_ENOTBUILT;
#endif /* USE_NETCDF4 undefined */
 
    /* Well I guess there is some sanity in the world after all. */
    return NC_NOERR;
}
 
int
NC_create(const char *path0, int cmode, size_t initialsz,
          int basepe, size_t *chunksizehintp, int useparallel,
          void* parameters, int *ncidp)
{
    int stat = NC_NOERR;
    NC* ncp = NULL;
    const NC_Dispatch* dispatcher = NULL;
    char* path = NULL;
    NCmodel model;
    char* newpath = NULL;
 
    TRACE(nc_create);
    if(path0 == NULL)
        {stat = NC_EINVAL; goto done;}
 
    /* Check mode flag for sanity. */
    if ((stat = check_create_mode(cmode))) goto done;
 
    /* Initialize the library. The available dispatch tables
     * will depend on how netCDF was built
     * (with/without netCDF-4, DAP, CDMREMOTE). */
    if(!NC_initialized) {
        if ((stat = nc_initialize())) goto done;
    }
 
    {
        /* Skip past any leading whitespace in path */
        const unsigned char* p;
        for(p=(const unsigned char*)path0;*p;p++) {if(*p > ' ') break;}
        path = nulldup((const char*)p);
    }
 
    memset(&model,0,sizeof(model));
    newpath = NULL;
    if((stat = NC_infermodel(path,&cmode,1,useparallel,NULL,&model,&newpath))) goto done;
    if(newpath) {
        nullfree(path);
        path = newpath;
        newpath = NULL;
    }
 
    assert(model.format != 0 && model.impl != 0);
 
    /* Now, check for NC_ENOTBUILT cases limited to create (so e.g. HDF4 is not listed) */
#ifndef USE_HDF5
    if (model.impl == NC_FORMATX_NC4)
    {stat = NC_ENOTBUILT; goto done;}
#endif
#ifndef USE_PNETCDF
    if (model.impl == NC_FORMATX_PNETCDF)
    {stat = NC_ENOTBUILT; goto done;}
#endif
#ifndef NETCDF_ENABLE_CDF5
    if (model.impl == NC_FORMATX_NC3 && (cmode & NC_64BIT_DATA))
    {stat = NC_ENOTBUILT; goto done;}
#endif
 
    /* Figure out what dispatcher to use */
    switch (model.impl) {
#ifdef USE_HDF5
    case NC_FORMATX_NC4:
        dispatcher = HDF5_dispatch_table;
        break;
#endif
#ifdef USE_PNETCDF
    case NC_FORMATX_PNETCDF:
        dispatcher = NCP_dispatch_table;
        break;
#endif
#ifdef USE_NETCDF4
    case NC_FORMATX_UDF0:
    case NC_FORMATX_UDF1:
    case NC_FORMATX_UDF2:
    case NC_FORMATX_UDF3:
    case NC_FORMATX_UDF4:
    case NC_FORMATX_UDF5:
    case NC_FORMATX_UDF6:
    case NC_FORMATX_UDF7:
    case NC_FORMATX_UDF8:
    case NC_FORMATX_UDF9:
        {
            /* Convert format constant to array index and validate */
            int udf_index = udf_formatx_to_index(model.impl);
            if (udf_index < 0 || udf_index >= NC_MAX_UDF_FORMATS) {
                stat = NC_EINVAL;
                goto done;
            }
            /* Get the dispatch table for this UDF slot */
            dispatcher = UDF_dispatch_tables[udf_index];
            /* Ensure the UDF format has been registered via nc_def_user_format() */
            if (!dispatcher) {
                stat = NC_ENOTBUILT;
                goto done;
            }
        }
        break;
#endif /* USE_NETCDF4 */
#ifdef NETCDF_ENABLE_NCZARR
    case NC_FORMATX_NCZARR:
        dispatcher = NCZ_dispatch_table;
    break;
#endif
    case NC_FORMATX_NC3:
        dispatcher = NC3_dispatch_table;
        break;
    default:
        {stat = NC_ENOTNC; goto done;}
    }
 
    /* Create the NC* instance and insert its dispatcher and model */
    if((stat = new_NC(dispatcher,path,cmode,&ncp))) goto done;
 
    /* Add to list of known open files and define ext_ncid */
    add_to_NCList(ncp);
 
    /* Assume create will fill in remaining ncp fields */
    if ((stat = dispatcher->create(ncp->path, cmode, initialsz, basepe, chunksizehintp,
                                   parameters, dispatcher, ncp->ext_ncid))) {
        del_from_NCList(ncp); /* oh well */
        free_NC(ncp);
    } else {
        if(ncidp)*ncidp = ncp->ext_ncid;
    }
done:
    nullfree(path);
    nullfree(newpath);
    return stat;
}
 
int
NC_open(const char *path0, int omode, int basepe, size_t *chunksizehintp,
        int useparallel, void* parameters, int *ncidp)
{
    int stat = NC_NOERR;
    NC* ncp = NULL;
    const NC_Dispatch* dispatcher = NULL;
    int inmemory = 0;
    int diskless = 0;
    int use_mmap = 0;
    char* path = NULL;
    NCmodel model;
    char* newpath = NULL;
 
    TRACE(nc_open);
    if(!NC_initialized) {
        stat = nc_initialize();
        if(stat) goto done;
    }
 
    /* Check inputs. */
    if (!path0)
        {stat = NC_EINVAL; goto done;}
 
    /* Capture the inmemory related flags */
    use_mmap = ((omode & NC_MMAP) == NC_MMAP);
    diskless = ((omode & NC_DISKLESS) == NC_DISKLESS);
    inmemory = ((omode & NC_INMEMORY) == NC_INMEMORY);
 
    /* NC_INMEMORY and NC_DISKLESS and NC_MMAP are all mutually exclusive */
    if(diskless && inmemory) {stat = NC_EDISKLESS; goto done;}
    if(diskless && use_mmap) {stat = NC_EDISKLESS; goto done;}
    if(inmemory && use_mmap) {stat = NC_EINMEMORY; goto done;}
 
    /* mmap is not allowed for netcdf-4 */
    if(use_mmap && (omode & NC_NETCDF4)) {stat = NC_EINVAL; goto done;}
 
    /* Attempt to do file path conversion: note that this will do
       nothing if path is a 'file:...' url, so it will need to be
       repeated in protocol code (e.g. libdap2, libdap4, etc).
    */
 
    {
        /* Skip past any leading whitespace in path */
        const char* p;
        for(p=(const char*)path0;*p;p++) {if(*p < 0 || *p > ' ') break;}
        path = nulldup(p);
    }
 
    memset(&model,0,sizeof(model));
    /* Infer model implementation and format, possibly by reading the file */
    if((stat = NC_infermodel(path,&omode,0,useparallel,parameters,&model,&newpath)))
        goto done;
    if(newpath) {
        nullfree(path);
        path = newpath;
    newpath = NULL;
    }
 
    /* Still no implementation, give up */
    if(model.impl == 0) {
#ifdef DEBUG
        fprintf(stderr,"implementation == 0\n");
#endif
        {stat = NC_ENOTNC; goto done;}
    }
 
    /* Suppress unsupported formats */
#if 0
    /* (should be more compact, table-driven, way to do this) */
    {
    int hdf5built = 0;
    int hdf4built = 0;
    int cdf5built = 0;
    int udf0built = 0;
    int udf1built = 0;
    int nczarrbuilt = 0;
#ifdef USE_NETCDF4
        hdf5built = 1;
#endif
#ifdef USE_HDF4
        hdf4built = 1;
#endif
#ifdef NETCDF_ENABLE_CDF5
        cdf5built = 1;
#endif
#ifdef NETCDF_ENABLE_NCZARR
    nczarrbuilt = 1;
#endif
        /* Check which UDF formats are built (i.e., have been registered).
         * A UDF format is considered "built" if its dispatch table is non-NULL. */
        int udfbuilt[NC_MAX_UDF_FORMATS] = {0};
        for(int i = 0; i < NC_MAX_UDF_FORMATS; i++) {
            if(UDF_dispatch_tables[i] != NULL)
                udfbuilt[i] = 1;
        }
 
        if(!hdf5built && model.impl == NC_FORMATX_NC4)
        {stat = NC_ENOTBUILT; goto done;}
        if(!hdf4built && model.impl == NC_FORMATX_NC_HDF4)
        {stat = NC_ENOTBUILT; goto done;}
        if(!cdf5built && model.impl == NC_FORMATX_NC3 && model.format == NC_FORMAT_CDF5)
        {stat = NC_ENOTBUILT; goto done;}
    if(!nczarrbuilt && model.impl == NC_FORMATX_NCZARR)
        {stat = NC_ENOTBUILT; goto done;}
        /* Check all UDF formats - ensure the requested format has been registered */
        for(int i = 0; i < NC_MAX_UDF_FORMATS; i++) {
            /* Convert array index to format constant (handles gap: UDF0=8, UDF1=9, UDF2=11...) */
            int formatx = (i <= 1) ? (NC_FORMATX_UDF0 + i) : (NC_FORMATX_UDF2 + i - 2);
            if(!udfbuilt[i] && model.impl == formatx)
                {stat = NC_ENOTBUILT; goto done;}
        }
    }
#else
    {
    unsigned built = 0 /* leave off the trailing semicolon so we can build constant */
        | (1<<NC_FORMATX_NC3) /* NC3 always supported */
#ifdef USE_HDF5
        | (1<<NC_FORMATX_NC_HDF5)
#endif
#ifdef USE_HDF4
        | (1<<NC_FORMATX_NC_HDF4)
#endif
#ifdef NETCDF_ENABLE_NCZARR
        | (1<<NC_FORMATX_NCZARR)
#endif
#ifdef NETCDF_ENABLE_DAP
        | (1<<NC_FORMATX_DAP2)
#endif
#ifdef NETCDF_ENABLE_DAP4
        | (1<<NC_FORMATX_DAP4)
#endif
#ifdef USE_PNETCDF
        | (1<<NC_FORMATX_PNETCDF)
#endif
        ; /* end of the built flags */
        /* Add UDF formats to built flags - set bit for each registered UDF format.
         * Use unsigned literal (1U) to avoid integer overflow for higher bit positions. */
        for(int i = 0; i < NC_MAX_UDF_FORMATS; i++) {
            if(UDF_dispatch_tables[i] != NULL) {
                /* Convert array index to format constant */
                int formatx = (i <= 1) ? (NC_FORMATX_UDF0 + i) : (NC_FORMATX_UDF2 + i - 2);
                built |= (1U << formatx);
            }
        }
    /* Verify the requested format is available */
    if((built & (1U << model.impl)) == 0)
            {stat = NC_ENOTBUILT; goto done;}
#ifndef NETCDF_ENABLE_CDF5
    /* Special case because there is no separate CDF5 dispatcher */
        if(model.impl == NC_FORMATX_NC3 && (omode & NC_64BIT_DATA))
            {stat = NC_ENOTBUILT; goto done;}
#endif
    }
#endif
    /* Figure out what dispatcher to use */
    if (!dispatcher) {
        switch (model.impl) {
#ifdef NETCDF_ENABLE_DAP
        case NC_FORMATX_DAP2:
            dispatcher = NCD2_dispatch_table;
            break;
#endif
#ifdef NETCDF_ENABLE_DAP4
        case NC_FORMATX_DAP4:
            dispatcher = NCD4_dispatch_table;
            break;
#endif
#ifdef NETCDF_ENABLE_NCZARR
    case NC_FORMATX_NCZARR:
        dispatcher = NCZ_dispatch_table;
        break;
#endif
#ifdef USE_PNETCDF
        case NC_FORMATX_PNETCDF:
            dispatcher = NCP_dispatch_table;
            break;
#endif
#ifdef USE_HDF5
        case NC_FORMATX_NC4:
            dispatcher = HDF5_dispatch_table;
            break;
#endif
#ifdef USE_HDF4
        case NC_FORMATX_NC_HDF4:
            dispatcher = HDF4_dispatch_table;
            break;
#endif
#ifdef USE_NETCDF4
        case NC_FORMATX_UDF0:
        case NC_FORMATX_UDF1:
        case NC_FORMATX_UDF2:
        case NC_FORMATX_UDF3:
        case NC_FORMATX_UDF4:
        case NC_FORMATX_UDF5:
        case NC_FORMATX_UDF6:
        case NC_FORMATX_UDF7:
        case NC_FORMATX_UDF8:
        case NC_FORMATX_UDF9:
            {
                /* Convert format constant to array index and validate */
                int udf_index = udf_formatx_to_index(model.impl);
                if (udf_index < 0 || udf_index >= NC_MAX_UDF_FORMATS) {
                    stat = NC_EINVAL;
                    goto done;
                }
                /* Get the dispatch table for this UDF slot */
                dispatcher = UDF_dispatch_tables[udf_index];
                /* Ensure the UDF format has been registered via nc_def_user_format() */
                if (!dispatcher) {
                    stat = NC_ENOTBUILT;
                    goto done;
                }
            }
            break;
#endif /* USE_NETCDF4 */
        case NC_FORMATX_NC3:
            dispatcher = NC3_dispatch_table;
            break;
        default:
            stat = NC_ENOTNC;
        goto done;
        }
    }
 
 
    /* If we can't figure out what dispatch table to use, give up. */
    if (!dispatcher) {stat = NC_ENOTNC; goto done;}
 
    /* Create the NC* instance and insert its dispatcher */
    if((stat = new_NC(dispatcher,path,omode,&ncp))) goto done;
 
    /* Add to list of known open files. This assigns an ext_ncid. */
    add_to_NCList(ncp);
 
    /* Assume open will fill in remaining ncp fields */
    stat = dispatcher->open(ncp->path, omode, basepe, chunksizehintp,
                            parameters, dispatcher, ncp->ext_ncid);
    if(stat == NC_NOERR) {
        if(ncidp) *ncidp = ncp->ext_ncid;
    } else {
        del_from_NCList(ncp);
        free_NC(ncp);
    }
 
done:
    nullfree(path);
    nullfree(newpath);
    return stat;
}
 
/*Provide an internal function for generating pseudo file descriptors
  for systems that are not file based (e.g. dap, memio).
*/
 
static int pseudofd = 0;
 
int
nc__pseudofd(void)
{
    if(pseudofd == 0)  {
#ifdef HAVE_GETRLIMIT
        int maxfd = 32767; /* default */
        struct rlimit rl;
        if(getrlimit(RLIMIT_NOFILE,&rl) == 0) {
            if(rl.rlim_max != RLIM_INFINITY)
                maxfd = (int)rl.rlim_max;
            if(rl.rlim_cur != RLIM_INFINITY)
                maxfd = (int)rl.rlim_cur;
        }
        pseudofd = maxfd+1;
#endif
    }
    return pseudofd++;
}