/**

 * @file

 *

 * Infer as much as possible from the omode + path.

 * Rewrite the path to a canonical form.

 *

 * Copyright 2018 University Corporation for Atmospheric

 * Research/Unidata. See COPYRIGHT file for more info.

*/

#include "config.h"

#include <stddef.h>

#include <stdlib.h>

#include <string.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef HAVE_SYS_TYPES_H

#include <sys/types.h>

#endif

#ifndef _WIN32

#ifdef USE_HDF5

#include <hdf5.h>

#endif /* USE_HDF5 */

#endif /* _WIN32 */

#ifdef HAVE_SYS_XATTR_H

#include <sys/xattr.h>

#endif

#include "ncdispatch.h"

#include "ncpathmgr.h"

#include "netcdf_mem.h"

#include "fbits.h"

#include "ncbytes.h"

#include "nclist.h"

#include "nclog.h"

#include "nchttp.h"

#include "ncutil.h"

#ifdef NETCDF_ENABLE_S3

#include "ncs3sdk.h"

#endif

#ifndef nulldup

 #define nulldup(x) ((x)?strdup(x):(x))

#endif

#undef DEBUG

/* If Defined, then use only stdio for all magic number io;

   otherwise use stdio or mpio as required.

 */

#undef USE_STDIO

/**

Sort info for open/read/close of

file when searching for magic numbers

*/

struct MagicFile {

    const char* path;

    struct NCURI* uri;

    int omode;

    NCmodel* model;

    long long filelen;

    int use_parallel;

    int iss3;

    void* parameters; /* !NULL if inmemory && !diskless */

    FILE* fp;

#ifdef USE_PARALLEL

    MPI_File fh;

#endif

    char* curlurl; /* url to use with CURLOPT_SET_URL */

    NC_HTTP_STATE* state;

#ifdef NETCDF_ENABLE_S3

    NCS3INFO s3;

    void* s3client;

    char* errmsg;

#endif

};

/** @internal Magic number for HDF5 files. To be consistent with

 * H5Fis_hdf5, use the complete HDF5 magic number */

static char HDF5_SIGNATURE[MAGIC_NUMBER_LEN] = "\211HDF\r\n\032\n";

#define modelcomplete(model) ((model)->impl != 0)

#ifdef DEBUG

static void dbgflush(void)

{

    fflush(stdout);

    fflush(stderr);

}

static void

fail(int err)

{

    return;

}

static int

check(int err)

{

    if(err != NC_NOERR)

  fail(err);

    return err;

}

#else

#define check(err) (err)

#endif

/*

Define a table of "mode=" string values

from which the implementation can be inferred.

Note that only cases that can currently

take URLs are included.

*/

static struct FORMATMODES {

    const char* tag;

    const int impl; /* NC_FORMATX_XXX value */

    const int format; /* NC_FORMAT_XXX value */

} formatmodes[] = {

{"dap2",NC_FORMATX_DAP2,NC_FORMAT_CLASSIC},

{"dap4",NC_FORMATX_DAP4,NC_FORMAT_NETCDF4},

{"netcdf-3",NC_FORMATX_NC3,0}, /* Might be e.g. cdf5 */

{"classic",NC_FORMATX_NC3,0}, /* ditto */

{"netcdf-4",NC_FORMATX_NC4,NC_FORMAT_NETCDF4},

{"enhanced",NC_FORMATX_NC4,NC_FORMAT_NETCDF4},

{"udf0",NC_FORMATX_UDF0,0},

{"udf1",NC_FORMATX_UDF1,0},

{"udf2",NC_FORMATX_UDF2,0},

{"udf3",NC_FORMATX_UDF3,0},

{"udf4",NC_FORMATX_UDF4,0},

{"udf5",NC_FORMATX_UDF5,0},

{"udf6",NC_FORMATX_UDF6,0},

{"udf7",NC_FORMATX_UDF7,0},

{"udf8",NC_FORMATX_UDF8,0},

{"udf9",NC_FORMATX_UDF9,0},

{"nczarr",NC_FORMATX_NCZARR,NC_FORMAT_NETCDF4},

{"zarr",NC_FORMATX_NCZARR,NC_FORMAT_NETCDF4},

{"bytes",NC_FORMATX_NC4,NC_FORMAT_NETCDF4}, /* temporary until 3 vs 4 is determined */

{NULL,0},

};

/* Replace top-level name with defkey=defvalue */

static const struct MACRODEF {

    char* name;

    char* defkey;

    char* defvalues[4];

} macrodefs[] = {

{"zarr","mode",{"nczarr","zarr",NULL}},

{"dap2","mode",{"dap2",NULL}},

{"dap4","mode",{"dap4",NULL}},

{"s3","mode",{"s3","nczarr",NULL}},

{"bytes","mode",{"bytes",NULL}},

{"xarray","mode",{"zarr", NULL}},

{"noxarray","mode",{"nczarr", "noxarray", NULL}},

{"zarr","mode",{"nczarr","zarr", NULL}},

{"gs3","mode",{"gs3","nczarr",NULL}}, /* Google S3 API */

{NULL,NULL,{NULL}}

};

/*

Mode inferences: if mode contains key value, then add the inferred value;

Warning: be careful how this list is constructed to avoid infinite inferences.

In order to (mostly) avoid that consequence, any attempt to

infer a value that is already present will be ignored.

This effectively means that the inference graph

must be a DAG and may not have cycles.

You have been warned.

*/

static const struct MODEINFER {

    char* key;

    char* inference;

} modeinferences[] = {

{"zarr","nczarr"},

{"xarray","zarr"},

{"noxarray","nczarr"},

{"noxarray","zarr"},

{NULL,NULL}

};

/* Mode negations: if mode contains key, then remove all occurrences of the inference and repeat */

static const struct MODEINFER modenegations[] = {

{"bytes","nczarr"}, /* bytes negates (nc)zarr */

{"bytes","zarr"},

{"noxarray","xarray"},

{NULL,NULL}

};

/* Map FORMATX to readability to get magic number */

static struct Readable {

    int impl;

    int readable;

} readable[] = {

{NC_FORMATX_NC3,1},

{NC_FORMATX_NC_HDF5,1},

{NC_FORMATX_NC_HDF4,1},

{NC_FORMATX_PNETCDF,1},

{NC_FORMATX_DAP2,0},

{NC_FORMATX_DAP4,0},

{NC_FORMATX_UDF0,1},

{NC_FORMATX_UDF1,1},

{NC_FORMATX_UDF2,1},

{NC_FORMATX_UDF3,1},

{NC_FORMATX_UDF4,1},

{NC_FORMATX_UDF5,1},

{NC_FORMATX_UDF6,1},

{NC_FORMATX_UDF7,1},

{NC_FORMATX_UDF8,1},

{NC_FORMATX_UDF9,1},

{NC_FORMATX_NCZARR,0}, /* eventually make readable */

{0,0},

};

/* Define the known URL protocols and their interpretation */

static struct NCPROTOCOLLIST {

    const char* protocol;

    const char* substitute;

    const char* fragments; /* arbitrary fragment arguments */

} ncprotolist[] = {

    {"http",NULL,NULL},

    {"https",NULL,NULL},

    {"file",NULL,NULL},

    {"dods","http","mode=dap2"},

    {"dap4","http","mode=dap4"},

    {"s3","s3","mode=s3"},

    {"gs3","gs3","mode=gs3"},

    {NULL,NULL,NULL} /* Terminate search */

};

/* Forward */

static int NC_omodeinfer(int useparallel, int omode, NCmodel*);

static int check_file_type(const char *path, int omode, int use_parallel, void *parameters, NCmodel* model, NCURI* uri);

static int processuri(const char* path, NCURI** urip, NClist* fraglist);

static int processmacros(NClist* fraglistp, NClist* expanded);

static char* envvlist2string(NClist* pairs, const char*);

static void set_default_mode(int* cmodep);

static int parseonchar(const char* s, int ch, NClist* segments);

static int mergelist(NClist** valuesp);

static int openmagic(struct MagicFile* file);

static int readmagic(struct MagicFile* file, size_t pos, char* magic);

static int closemagic(struct MagicFile* file);

static int NC_interpret_magic_number(char* magic, NCmodel* model);

#ifdef DEBUG

static void printmagic(const char* tag, char* magic,struct MagicFile*);

static void printlist(NClist* list, const char* tag);

#endif

static int isreadable(NCURI*,NCmodel*);

static char* list2string(NClist*);

static int parsepair(const char* pair, char** keyp, char** valuep);

static NClist* parsemode(const char* modeval);

static const char* getmodekey(const NClist* envv);

static int replacemode(NClist* envv, const char* newval);

static void infernext(NClist* current, NClist* next);

static int negateone(const char* mode, NClist* modes);

static void cleanstringlist(NClist* strs, int caseinsensitive);

static int isdaoscontainer(const char* path);

/*

If the path looks like a URL, then parse it, reformat it.

*/

static int

processuri(const char* path, NCURI** urip, NClist* fraglenv)

{

    int stat = NC_NOERR;

    int found = 0;

    NClist* tmp = NULL;

    struct NCPROTOCOLLIST* protolist;

    NCURI* uri = NULL;

    size_t pathlen = strlen(path);

    char* str = NULL;

    const NClist* ufrags;

    size_t i;

    if(path == NULL || pathlen == 0) {stat = NC_EURL; goto done;}

    /* Defaults */

    if(urip) *urip = NULL;

    ncuriparse(path,&uri);

    if(uri == NULL) goto done; /* not url */

    /* Look up the protocol */

    for(found=0,protolist=ncprotolist;protolist->protocol;protolist++) {

        if(strcmp(uri->protocol,protolist->protocol) == 0) {

      found = 1;

      break;

  }

    }

    if(!found)

  {stat = NC_EINVAL; goto done;} /* unrecognized URL form */

    /* process the corresponding fragments for that protocol */

    if(protolist->fragments != NULL) {

  tmp = nclistnew();

  if((stat = parseonchar(protolist->fragments,'&',tmp))) goto done;

  for(i=0;i<nclistlength(tmp);i++) {

      char* key=NULL;

          char* value=NULL;

      if((stat = parsepair(nclistget(tmp,i),&key,&value))) goto done;

      if(value == NULL) value = strdup("");

      nclistpush(fraglenv,key);

          nclistpush(fraglenv,value);

  }

  nclistfreeall(tmp); tmp = NULL;

    }

    /* Substitute the protocol in any case */

    if(protolist->substitute) ncurisetprotocol(uri,protolist->substitute);

    /* capture the fragments of the url */

    ufrags = (const NClist*)ncurifragmentparams(uri);

    for(i=0;i<nclistlength(ufrags);i+=2) {

  const char* key = nclistget(ufrags,i);

  const char* value = nclistget(ufrags,i+1);

        nclistpush(fraglenv,nulldup(key));

  value = (value==NULL?"":value);

  nclistpush(fraglenv,strdup(value));

    }

    if(urip) {

  *urip = uri;

  uri = NULL;

    }

done:

    nclistfreeall(tmp);

    nullfree(str);

    if(uri != NULL) ncurifree(uri);

    return check(stat);

}

/* Split a key=value pair */

static int

parsepair(const char* pair, char** keyp, char** valuep)

{

    const char* p;

    char* key = NULL;

    char* value = NULL;

    if(pair == NULL)

        return NC_EINVAL; /* empty pair */

    if(pair[0] == '\0' || pair[0] == '=')

        return NC_EINVAL; /* no key */

    p = strchr(pair,'=');

    if(p == NULL) {

  value = NULL;

  key = strdup(pair);

    } else {

  ptrdiff_t len = (p-pair);

  if((key = malloc((size_t)len+1))==NULL) return NC_ENOMEM;

  memcpy(key,pair,(size_t)len);

  key[len] = '\0';

  if(p[1] == '\0')

      value = NULL;

  else

      value = strdup(p+1);

    }

    if(keyp) {*keyp = key; key = NULL;};

    if(valuep) {*valuep = value; value = NULL;};

    nullfree(key);

    nullfree(value);

    return NC_NOERR;

}

#if 0

static int

parseurlmode(const char* modestr, NClist* list)

{

    int stat = NC_NOERR;

    const char* p = NULL;

    const char* endp = NULL;

    if(modestr == NULL || *modestr == '\0') goto done;

    /* Split modestr at the commas or EOL */

    p = modestr;

    for(;;) {

  char* s;

  ptrdiff_t slen;

  endp = strchr(p,',');

  if(endp == NULL) endp = p + strlen(p);

  slen = (endp - p);

  if((s = malloc(slen+1)) == NULL) {stat = NC_ENOMEM; goto done;}

  memcpy(s,p,slen);

  s[slen] = '\0';

  nclistpush(list,s);

  if(*endp == '\0') break;

  p = endp+1;

    }

done:

    return check(stat);

}

#endif

/* Split a string at a given char */

static int

parseonchar(const char* s, int ch, NClist* segments)

{

    int stat = NC_NOERR;

    const char* p = NULL;

    const char* endp = NULL;

    if(s == NULL || *s == '\0') goto done;

    p = s;

    for(;;) {

  char* q;

  ptrdiff_t slen;

  endp = strchr(p,ch);

  if(endp == NULL) endp = p + strlen(p);

  slen = (endp - p);

  if((q = malloc((size_t)slen+1)) == NULL) {stat = NC_ENOMEM; goto done;}

  memcpy(q,p,(size_t)slen);

  q[slen] = '\0';

  nclistpush(segments,q);

  if(*endp == '\0') break;

  p = endp+1;

    }

done:

    return check(stat);

}

/* Convert a key,value envv pairlist into a delimited string*/

static char*

envvlist2string(NClist* envv, const char* delim)

{

    size_t i;

    NCbytes* buf = NULL;

    char* result = NULL;

    if(envv == NULL || nclistlength(envv) == 0) return NULL;

    buf = ncbytesnew();

    for(i=0;i<nclistlength(envv);i+=2) {

  const char* key = nclistget(envv,i);

  const char* val = nclistget(envv,i+1);

  if(key == NULL || strlen(key) == 0) continue;

  assert(val != NULL);

  if(i > 0) ncbytescat(buf,"&");

  ncbytescat(buf,key);

  if(val != NULL && val[0] != '\0') {

      ncbytescat(buf,"=");

      ncbytescat(buf,val);

  }

    }

    result = ncbytesextract(buf);

    ncbytesfree(buf);

    return result;

}

/* Given a mode= argument, fill in the impl */

static int

processmodearg(const char* arg, NCmodel* model)

{

    int stat = NC_NOERR;

    struct FORMATMODES* format = formatmodes;

    for(;format->tag;format++) {

  if(strcmp(format->tag,arg)==0) {

            model->impl = format->impl;

      if(format->format != 0) model->format = format->format;

  }

    }

    return check(stat);

}

/* Given an envv fragment list, do macro replacement */

static int

processmacros(NClist* fraglenv, NClist* expanded)

{

    size_t i;

    int stat = NC_NOERR;

    const struct MACRODEF* macros = NULL;

    for(i=0;i<nclistlength(fraglenv);i+=2) {

  int found = 0;

  char* key = nclistget(fraglenv,i);

  char* value = nclistget(fraglenv,i+1);

  if(strlen(value) == 0) { /* must be a singleton  */

            for(macros=macrodefs;macros->name;macros++) {

                if(strcmp(macros->name,key)==0) {

        char* const * p;

        nclistpush(expanded,strdup(macros->defkey));

        for(p=macros->defvalues;*p;p++) 

      nclistpush(expanded,strdup(*p));

        found = 1;        

        break;

          }

      }

  }

  if(!found) {/* pass thru */

      nclistpush(expanded,strdup(key));

          nclistpush(expanded,strdup(value));

  }

    }

    return check(stat);

}

/* Process mode flag inferences */

static int

processinferences(NClist* fraglenv)

{

    int stat = NC_NOERR;

    const char* modeval = NULL;

    NClist* newmodes = nclistnew();

    NClist* currentmodes = NULL;

    NClist* nextmodes = nclistnew();

    size_t i;

    char* newmodeval = NULL;

    /* Get "mode" entry */

    if((modeval = getmodekey(fraglenv))==NULL) goto done;

    /* Get the mode as list */

    currentmodes = parsemode(modeval);

#ifdef DEBUG

    printlist(currentmodes,"processinferences: initial mode list");

#endif

    /* Do what amounts to breadth first inferencing down the inference DAG. */

    for(;;) {

        NClist* tmp = NULL;

        /* Compute the next set of inferred modes */

#ifdef DEBUG

printlist(currentmodes,"processinferences: current mode list");

#endif

        infernext(currentmodes,nextmodes);

#ifdef DEBUG

printlist(nextmodes,"processinferences: next mode list");

#endif

        /* move current modes into list of newmodes */

        for(i=0;i<nclistlength(currentmodes);i++) {

      nclistpush(newmodes,nclistget(currentmodes,i));

  }

        nclistsetlength(currentmodes,0); /* clear current mode list */

        if(nclistlength(nextmodes) == 0) break; /* nothing more to do */

#ifdef DEBUG

printlist(newmodes,"processinferences: new mode list");

#endif

  /* Swap current and next */

        tmp = currentmodes;

  currentmodes = nextmodes;

  nextmodes = tmp;

        tmp = NULL;

    }

    /* cleanup any unused elements in currentmodes */

    nclistclearall(currentmodes);

    /* Ensure no duplicates */

    cleanstringlist(newmodes,1);

#ifdef DEBUG

    printlist(newmodes,"processinferences: final inferred mode list");

#endif

   /* Remove negative inferences */

   for(i=0;i<nclistlength(newmodes);i++) {

  const char* mode = nclistget(newmodes,i);

  negateone(mode,newmodes);

    }

    /* Store new mode value */

    if((newmodeval = list2string(newmodes))== NULL)

  {stat = NC_ENOMEM; goto done;}        

    if((stat=replacemode(fraglenv,newmodeval))) goto done;

    modeval = NULL;

done:

    nullfree(newmodeval);

    nclistfreeall(newmodes);

    nclistfreeall(currentmodes);

    nclistfreeall(nextmodes);

    return check(stat);

}

static int

negateone(const char* mode, NClist* newmodes)

{

    const struct MODEINFER* tests = modenegations;

    int changed = 0;

    for(;tests->key;tests++) {

  if(strcasecmp(tests->key,mode)==0) {

      /* Find and remove all instances of the inference value */

      for(size_t i = nclistlength(newmodes); i-- > 0;) {

    char* candidate = nclistget(newmodes,i);

    if(strcasecmp(candidate,tests->inference)==0) {

        nclistremove(newmodes,i);

        nullfree(candidate);

              changed = 1;

    }

      }

        }

    }

    return changed;

}

static void

infernext(NClist* current, NClist* next)

{

    size_t i;

    for(i=0;i<nclistlength(current);i++) {

        const struct MODEINFER* tests = NULL;

  const char* cur = nclistget(current,i);

        for(tests=modeinferences;tests->key;tests++) {

      if(strcasecmp(tests->key,cur)==0) {

          /* Append the inferred mode unless dup */

    if(!nclistmatch(next,tests->inference,1))

              nclistpush(next,strdup(tests->inference));

      }

        }

    }

}

/*

Given a list of strings, remove nulls and duplicates

*/

static int

mergelist(NClist** valuesp)

{

    size_t i,j;

    int stat = NC_NOERR;

    NClist* values = *valuesp;

    NClist* allvalues = nclistnew();

    NClist* newvalues = nclistnew();

    char* value = NULL;

    for(i=0;i<nclistlength(values);i++) {

  char* val1 = nclistget(values,i);

  /* split on commas and put pieces into allvalues */

  if((stat=parseonchar(val1,',',allvalues))) goto done;

    }

    /* Remove duplicates and "" */

    while(nclistlength(allvalues) > 0) {

  value = nclistremove(allvalues,0);

  if(strlen(value) == 0) {

      nullfree(value); value = NULL;

  } else {

      for(j=0;j<nclistlength(newvalues);j++) {

          char* candidate = nclistget(newvalues,j);

          if(strcasecmp(candidate,value)==0)

              {nullfree(value); value = NULL; break;}

       }

  }

  if(value != NULL) {nclistpush(newvalues,value); value = NULL;}

    }

    /* Make sure to have at least 1 value */

    if(nclistlength(newvalues)==0) nclistpush(newvalues,strdup(""));

    *valuesp = values; values = NULL;

done:

    nclistfree(allvalues);

    nclistfreeall(values);

    nclistfreeall(newvalues);

    return check(stat);

}

static int

lcontains(NClist* l, const char* key0)

{

    size_t i;

    for(i=0;i<nclistlength(l);i++) {

        const char* key1 = nclistget(l,i);

  if(strcasecmp(key0,key1)==0) return 1;

    }

    return 0;

}

/* Warning values should not use nclistfreeall */

static void

collectvaluesbykey(NClist* fraglenv, const char* key, NClist* values)

{

    size_t i;

    /* collect all the values with the same key (including this one) */

    for(i=0;i<nclistlength(fraglenv);i+=2) {

        const char* key2 = nclistget(fraglenv,i);

        if(strcasecmp(key,key2)==0) {

      const char* value2 = nclistget(fraglenv,i+1);

      nclistpush(values,value2); value2 = NULL;

  }

    }

}

/* Warning allkeys should not use nclistfreeall */

static void

collectallkeys(NClist* fraglenv, NClist* allkeys)

{

    size_t i;

    /* collect all the distinct keys */

    for(i=0;i<nclistlength(fraglenv);i+=2) {

  char* key = nclistget(fraglenv,i);

  if(!lcontains(allkeys,key)) {

      nclistpush(allkeys,key);

  }

    }

}

/* Given a fragment envv list, coalesce duplicate keys and remove duplicate values*/

static int

cleanfragments(NClist* fraglenv, NClist* newlist)

{

    size_t i;

    int stat = NC_NOERR;

    NClist* tmp = NULL;

    NClist* allkeys = NULL;

    NCbytes* buf = NULL;

    char* key = NULL;

    char* value = NULL;

    buf = ncbytesnew();

    allkeys = nclistnew();

    tmp = nclistnew();

    /* collect all unique keys */

    collectallkeys(fraglenv,allkeys);

    /* Collect all values for same key across all fragment pairs */

    for(i=0;i<nclistlength(allkeys);i++) {

  key = nclistget(allkeys,i);

  collectvaluesbykey(fraglenv,key,tmp);

  /* merge the key values, remove duplicate */

  if((stat=mergelist(&tmp))) goto done;

        /* Construct key,value pair and insert into newlist */

  key = strdup(key);

  nclistpush(newlist,key);

  value = list2string(tmp);

  nclistpush(newlist,value);

  nclistclear(tmp);

    }

done:

    nclistfree(allkeys);

    nclistfree(tmp);

    ncbytesfree(buf);

    return check(stat);

}

/* process non-mode fragment keys in case they hold significance; currently not */

static int

processfragmentkeys(const char* key, const char* value, NCmodel* model)

{

    return NC_NOERR;

}

/*

Infer from the mode + useparallel

only call if iscreate or file is not easily readable.

*/

static int

NC_omodeinfer(int useparallel, int cmode, NCmodel* model)

{

    int stat = NC_NOERR;

    /* If no format flags are set, then use default */

    if(!fIsSet(cmode,NC_FORMAT_ALL))

  set_default_mode(&cmode);

    /* Process the cmode; may override some already set flags. The

     * user-defined formats must be checked first. They may choose to

     * use some of the other flags, like NC_NETCDF4, so we must first

     * check NC_UDF0-NC_UDF9 before checking for any other flag. */

    int udf_found = 0;

    /* Lookup table for all UDF mode flags. This replaces the previous bit-shift

     * calculation which was fragile due to non-sequential bit positions

     * (bits 16, 19-25 to avoid conflicts with NC_NOATTCREORD and NC_NODIMSCALE_ATTACH). */

    static const int udf_flags[NC_MAX_UDF_FORMATS] = {

        NC_UDF0, NC_UDF1, NC_UDF2, NC_UDF3, NC_UDF4,

        NC_UDF5, NC_UDF6, NC_UDF7, NC_UDF8, NC_UDF9

    };

    /* Check if any UDF format flag is set in the mode */

    for(int i = 0; i < NC_MAX_UDF_FORMATS; i++) {

        if(fIsSet(cmode, udf_flags[i])) {

            /* Convert array index to format constant (handles gap in numbering) */

            int formatx = (i <= 1) ? (NC_FORMATX_UDF0 + i) : (NC_FORMATX_UDF2 + i - 2);

            model->impl = formatx;

            udf_found = 1;

            break;

        }

    }

    if(udf_found)

    {

        if(fIsSet(cmode,NC_64BIT_OFFSET)) 

        {

            model->format = NC_FORMAT_64BIT_OFFSET;

        }

        else if(fIsSet(cmode,NC_64BIT_DATA))

        {

            model->format = NC_FORMAT_64BIT_DATA;

        }

        else if(fIsSet(cmode,NC_NETCDF4))

        {

            if(fIsSet(cmode,NC_CLASSIC_MODEL))

                model->format = NC_FORMAT_NETCDF4_CLASSIC;

            else

                model->format = NC_FORMAT_NETCDF4;

        }

        if(! model->format)

            model->format = NC_FORMAT_CLASSIC;

  goto done;

    }

    if(fIsSet(cmode,NC_64BIT_OFFSET)) {

  model->impl = NC_FORMATX_NC3;

  model->format = NC_FORMAT_64BIT_OFFSET;

        goto done;

    }

    if(fIsSet(cmode,NC_64BIT_DATA)) {

  model->impl = NC_FORMATX_NC3;

  model->format = NC_FORMAT_64BIT_DATA;

        goto done;

    }

    if(fIsSet(cmode,NC_NETCDF4)) {

  model->impl = NC_FORMATX_NC4;

        if(fIsSet(cmode,NC_CLASSIC_MODEL))

      model->format = NC_FORMAT_NETCDF4_CLASSIC;

  else

      model->format = NC_FORMAT_NETCDF4;

        goto done;

    }

    /* Default to classic model */

    model->format = NC_FORMAT_CLASSIC;

    model->impl = NC_FORMATX_NC3;

done:

    /* Apply parallel flag */

    if(useparallel) {

        if(model->impl == NC_FORMATX_NC3)

      model->impl = NC_FORMATX_PNETCDF;

    }

    return check(stat);

}

/*

If the mode flags do not necessarily specify the

format, then default it by adding in appropriate flags.

*/

static void

set_default_mode(int* modep)

{

    int mode = *modep;

    int dfaltformat;

    dfaltformat = nc_get_default_format();

    switch (dfaltformat) {

    case NC_FORMAT_64BIT_OFFSET: mode |= NC_64BIT_OFFSET; break;

    case NC_FORMAT_64BIT_DATA: mode |= NC_64BIT_DATA; break;

    case NC_FORMAT_NETCDF4: mode |= NC_NETCDF4; break;

    case NC_FORMAT_NETCDF4_CLASSIC: mode |= (NC_NETCDF4|NC_CLASSIC_MODEL); break;

    case NC_FORMAT_CLASSIC: /* fall thru */

    default: break; /* default to classic */

    }

    *modep = mode; /* final result */

}

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

/*

   Infer model for this dataset using some

   combination of cmode, path, and reading the dataset.

   See the documentation in docs/internal.dox.

@param path

@param omode

@param iscreate

@param useparallel

@param params

@param model

@param newpathp

*/

int

NC_infermodel(const char* path, int* omodep, int iscreate, int useparallel, void* params, NCmodel* model, char** newpathp)

{

    size_t i;

    int stat = NC_NOERR;

    NCURI* uri = NULL;

    int omode = *omodep;

    NClist* fraglenv = nclistnew();

    NClist* modeargs = nclistnew();

    char* sfrag = NULL;

    const char* modeval = NULL;

    char* abspath = NULL;

    NClist* tmp = NULL;

    /* Phase 1:

       1. convert special protocols to http|https

       2. begin collecting fragments

    */

    if((stat = processuri(path, &uri, fraglenv))) goto done;

    if(uri != NULL) {

#ifdef DEBUG

  printlist(fraglenv,"processuri");

#endif

        /* Phase 2: Expand macros and add to fraglenv */

  nclistfreeall(tmp);

  tmp = nclistnew();

        if((stat = processmacros(fraglenv,tmp))) goto done;

  nclistfreeall(fraglenv);

  fraglenv = tmp; tmp = NULL;

#ifdef DEBUG

  printlist(fraglenv,"processmacros");

#endif

  /* Cleanup the fragment list */

  nclistfreeall(tmp);

  tmp = nclistnew();

        if((stat = cleanfragments(fraglenv,tmp))) goto done;

  nclistfreeall(fraglenv);

  fraglenv = tmp; tmp = NULL;

        /* Phase 2a: Expand mode inferences and add to fraglenv */

        if((stat = processinferences(fraglenv))) goto done;

#ifdef DEBUG

  printlist(fraglenv,"processinferences");

#endif

        /* Phase 3: coalesce duplicate fragment keys and remove duplicate values */

  nclistfreeall(tmp);

  tmp = nclistnew();

        if((stat = cleanfragments(fraglenv,tmp))) goto done;

  nclistfreeall(fraglenv);

  fraglenv = tmp; tmp = NULL;

#ifdef DEBUG

  printlist(fraglenv,"cleanfragments");

#endif

        /* Phase 4: Rebuild the url fragment and rebuilt the url */

        sfrag = envvlist2string(fraglenv,"&");

        nclistfreeall(fraglenv); fraglenv = NULL;

#ifdef DEBUG

  fprintf(stderr,"frag final: %s\n",sfrag);

#endif

        ncurisetfragments(uri,sfrag);

        nullfree(sfrag); sfrag = NULL;