nc4dim.c

/*

This file is part of netcdf-4, a netCDF-like interface for HDF5, or a
HDF5 backend for netCDF, depending on your point of view.

This file handles the nc4 dimension functions.

Copyright 2003-5, University Corporation for Atmospheric Research. See
the COPYRIGHT file for copying and redistribution conditions.

$Id: nc4dim.c,v 1.41 2010/05/25 17:54:23 dmh Exp $
*/

#include "nc4internal.h"
#include "nc4dispatch.h"

/* Netcdf-4 files might have more than one unlimited dimension, but
   return the first one anyway. */
/* Note that this code is inconsistent with nc_inq */
int 
NC4_inq_unlimdim(int ncid, int *unlimdimidp)
{
   NC *nc;
   NC_GRP_INFO_T *grp, *g;
   NC_HDF5_FILE_INFO_T *h5;
   NC_DIM_INFO_T *dim;
   int found = 0;
   int retval;
 
   LOG((2, "%s: called", __func__));

   if ((retval = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))
      return retval;
   assert(h5);

   /* According to netcdf-3 manual, return -1 if there is no unlimited
      dimension. */
   *unlimdimidp = -1;
   for (g = grp; g && !found; g = g->parent)
   {
      for (dim = g->dim; dim; dim = dim->l.next)
      {
	 if (dim->unlimited)
	 {
	    *unlimdimidp = dim->dimid;
	    found++;
	    break;
	 }
      }
   }

   return NC_NOERR;
}

/* Dimensions are defined in attributes attached to the appropriate
   group in the data file. */
int
NC4_def_dim(int ncid, const char *name, size_t len, int *idp)
{
   NC *nc;
   NC_GRP_INFO_T *grp;
   NC_HDF5_FILE_INFO_T *h5;
   NC_DIM_INFO_T *dim;
   char norm_name[NC_MAX_NAME + 1];
   int retval = NC_NOERR;
   uint32_t nn_hash;

   LOG((2, "%s: ncid 0x%x name %s len %d", __func__, ncid, name, 
	(int)len));

   /* Find our global metadata structure. */
   if ((retval = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))
      return retval;

   assert(h5 && nc /*& grp*/);

   /* If the file is read-only, return an error. */
   if (h5->no_write)
     return NC_EPERM;

   /* Check some stuff if strict nc3 rules are in effect. */
   if (h5->cmode & NC_CLASSIC_MODEL)
   {
      /* Only one limited dimenson for strict nc3. */
      if (len == NC_UNLIMITED)
	 for (dim = grp->dim; dim; dim = dim->l.next)
	    if (dim->unlimited)
	       return NC_EUNLIMIT;

      /* Must be in define mode for stict nc3. */
      if (!(h5->flags & NC_INDEF))
	 return NC_ENOTINDEFINE;
   }   

   /* If it's not in define mode, enter define mode. */
   if (!(h5->flags & NC_INDEF))
      if ((retval = NC4_redef(ncid)))
	 return retval;

   /* Make sure this is a valid netcdf name. */
   if ((retval = nc4_check_name(name, norm_name)))
      return retval;

   /* For classic model: dim length has to fit in a 32-bit unsigned
    * int, as permitted for 64-bit offset format. */
   if (h5->cmode & NC_CLASSIC_MODEL)
      if(len > X_UINT_MAX) /* Backward compat */
	 return NC_EDIMSIZE;

   nn_hash = hash_fast(norm_name, strlen(norm_name));

   /* Make sure the name is not already in use. */
   for (dim = grp->dim; dim; dim = dim->l.next)
      if (nn_hash == dim->hash && !strncmp(dim->name, norm_name, NC_MAX_NAME))
	 return NC_ENAMEINUSE;

   /* Add a dimension to the list. The ID must come from the file
    * information, since dimids are visible in more than one group. */
   nc4_dim_list_add(&grp->dim, &dim);
   dim->dimid = grp->nc4_info->next_dimid++;

   /* Initialize the metadata for this dimension. */
   if (!(dim->name = strdup(norm_name)))
      return NC_ENOMEM;
   dim->len = len;
   if (len == NC_UNLIMITED)
      dim->unlimited = NC_TRUE;

   dim->hash = nn_hash;
   
   /* Pass back the dimid. */
   if (idp)
      *idp = dim->dimid;

   return retval;
}

/* Given dim name, find its id. */
int
NC4_inq_dimid(int ncid, const char *name, int *idp)
{
   NC *nc;
   NC_GRP_INFO_T *grp, *g;
   NC_HDF5_FILE_INFO_T *h5;
   NC_DIM_INFO_T *dim;
   char norm_name[NC_MAX_NAME + 1];
   int finished = 0;
   int retval;
   uint32_t shash;
   
   LOG((2, "%s: ncid 0x%x name %s", __func__, ncid, name));

   /* Find metadata for this file. */
   if ((retval = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))
      return retval;

   assert(h5);
   assert(nc && grp);

   /* Normalize name. */
   if ((retval = nc4_normalize_name(name, norm_name)))
      return retval;

   shash = hash_fast(norm_name, strlen(norm_name));

   /* Go through each dim and check for a name match. */
   for (g = grp; g && !finished; g = g->parent)
      for (dim = g->dim; dim; dim = dim->l.next)
	 if (dim->hash == shash && !strncmp(dim->name, norm_name, NC_MAX_NAME))
	 {
	    if (idp)
	       *idp = dim->dimid;
	    return NC_NOERR;
	 }

   return NC_EBADDIM;
}

/* Find out name and len of a dim. For an unlimited dimension, the
   length is the largest length so far written. If the name of lenp
   pointers are NULL, they will be ignored. */
int
NC4_inq_dim(int ncid, int dimid, char *name, size_t *lenp)
{
   NC *nc;
   NC_HDF5_FILE_INFO_T *h5;
   NC_GRP_INFO_T *grp, *dim_grp;
   NC_DIM_INFO_T *dim;
   int ret = NC_NOERR;

   LOG((2, "%s: ncid 0x%x dimid %d", __func__, ncid, dimid));

   /* Find our global metadata structure. */
   if ((ret = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))
      return ret;
   
   assert(h5);
   assert(nc && grp);

   /* Find the dimension and its home group. */
   if ((ret = nc4_find_dim(grp, dimid, &dim, &dim_grp)))
      return ret;
   assert(dim);

   /* Return the dimension name, if the caller wants it. */
   if (name && dim->name) 
      strcpy(name, dim->name);	    
   
   /* Return the dimension length, if the caller wants it. */
   if (lenp)
   {
      if (dim->unlimited)
      {
	 /* Since this is an unlimited dimension, go to the file
	    and see how many records there are. Take the max number
	    of records from all the vars that share this
	    dimension. */
	 *lenp = 0;
	 if ((ret = nc4_find_dim_len(dim_grp, dimid, &lenp)))
	    return ret;
      }
      else
      {
	 if (dim->too_long)
	 {
	    ret = NC_EDIMSIZE;
	    *lenp = NC_MAX_UINT;
	 }
	 else
	    *lenp = dim->len;
      }
   }

   return ret;
}

/* Rename a dimension, for those who like to prevaricate. */
int
NC4_rename_dim(int ncid, int dimid, const char *name)
{
   NC *nc;
   NC_GRP_INFO_T *grp;
   NC_HDF5_FILE_INFO_T *h5;
   NC_DIM_INFO_T *dim, *tmp_dim;
   char norm_name[NC_MAX_NAME + 1];
   int retval;

   if (!name)
      return NC_EINVAL;

   LOG((2, "%s: ncid 0x%x dimid %d name %s", __func__, ncid, 
	dimid, name));

   /* Find info for this file and group, and set pointer to each. */
   if ((retval = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))      
      return retval;

   assert(nc);
   assert(h5 && grp);
   
   /* Trying to write to a read-only file? No way, Jose! */
   if (h5->no_write)
      return NC_EPERM;

   /* Make sure this is a valid netcdf name. */
   if ((retval = nc4_check_name(name, norm_name)))
      return retval;

   /* Check if name is in use, and retain a pointer to the correct dim */
   tmp_dim = NULL;
   for (dim = grp->dim; dim; dim = dim->l.next)
   {
      if (!strncmp(dim->name, norm_name, NC_MAX_NAME))
	 return NC_ENAMEINUSE;
      if (dim->dimid == dimid)
	 tmp_dim = dim;
   }
   if (!tmp_dim)
      return NC_EBADDIM;
   dim = tmp_dim;

   /* Check for renaming dimension w/o variable */
   if (dim->hdf_dimscaleid)
   {
      /* Sanity check */
      assert(!dim->coord_var);

      /* Close the HDF5 dataset */
      if (H5Dclose(dim->hdf_dimscaleid) < 0) 
         return NC_EHDFERR;
      dim->hdf_dimscaleid = 0;
            
      /* Now delete the dataset (it will be recreated later, if necessary) */
      if (H5Gunlink(grp->hdf_grpid, dim->name) < 0)
         return NC_EDIMMETA;
   }

   /* Give the dimension its new name in metadata. UTF8 normalization
    * has been done. */
   if(dim->name)
      free(dim->name);
   if (!(dim->name = malloc((strlen(norm_name) + 1) * sizeof(char))))
      return NC_ENOMEM;
   strcpy(dim->name, norm_name);

   dim->hash = hash_fast(norm_name, strlen(norm_name));
   
   /* Check if dimension was a coordinate variable, but names are different now */
   if (dim->coord_var && strcmp(dim->name, dim->coord_var->name))
   {
      /* Break up the coordinate variable */
      if ((retval = nc4_break_coord_var(grp, dim->coord_var, dim)))
         return retval;
   }

   /* Check if dimension should become a coordinate variable */
   if (!dim->coord_var)
   {
      NC_VAR_INFO_T *var;

      /* Attempt to find a variable with the same name as the dimension in
       * the current group. */
      if ((retval = nc4_find_var(grp, dim->name, &var)))
         return retval;

      /* Check if we found a variable and the variable has the dimension in
       * index 0. */
      if (var && var->dim[0] == dim)
      {
          /* Sanity check */
          assert(var->dimids[0] == dim->dimid);

          /* Reform the coordinate variable */
          if ((retval = nc4_reform_coord_var(grp, var, dim)))
             return retval;
      }
   }

   return NC_NOERR;
}

/* Returns an array of unlimited dimension ids.The user can get the
   number of unlimited dimensions by first calling this with NULL for
   the second pointer.
*/
int 
NC4_inq_unlimdims(int ncid, int *nunlimdimsp, int *unlimdimidsp) 
{
  NC_DIM_INFO_T *dim;
  NC_GRP_INFO_T *grp;
  NC *nc;
  NC_HDF5_FILE_INFO_T *h5;
  int num_unlim = 0;
  int retval;

  LOG((2, "%s: ncid 0x%x", __func__, ncid));

  /* Find info for this file and group, and set pointer to each. */
  if ((retval = nc4_find_nc_grp_h5(ncid, &nc, &grp, &h5)))
    return retval;
  
   /* Get our dim info. */
   assert(h5);
   {
      for (dim=grp->dim; dim; dim=dim->l.next)
      {
	 if (dim->unlimited)
	 {
	    if (unlimdimidsp)
	       unlimdimidsp[num_unlim] = dim->dimid;
	    num_unlim++;
	 }
      }
   }

   /* Give the number if the user wants it. */
   if (nunlimdimsp)
      *nunlimdimsp = num_unlim;

   return NC_NOERR;
}