[svn-r9461] Purpose:

Changed functionality of H5Pget_data_transform

Description:
H5Pget_data_transform no longer allocates memory for the transform string...it
is the user's responsbility to do so.

Solution:
Made H5Pget_data_transform be more in line with other functions that do
similiar things:

User now has to allocate memory for the string themselves and specify how much
of the string should be copied into the buffer.  There is also support for
querying the length of the transform string.

Platforms tested:
sol + eirene + copper

Misc. update:

3 files changed, 41 insertions, 19 deletions

diff --git a/src/H5Pdxpl.c b/src/H5Pdxpl.c
index 430c025..5941a19 100644
--- a/src/H5Pdxpl.c
+++ b/src/H5Pdxpl.c
@@ -85,40 +85,65 @@ done:
  *
  * Purpose:
  *              Gets data transform expression. 
- *
  * 
  * Return:      Returns a non-negative value if successful; otherwise returns a negative value. 
  * 
+ * Comments:
+ *  If `expression' is non-NULL then write up to `size' bytes into that
+ *  buffer and always return the length of the transform name.
+ *  Otherwise `size' is ignored and the function does not store the expression,
+ *  just returning the number of characters required to store the expression.
+ *  If an error occurs then the buffer pointed to by `expression' (NULL or non-NULL)
+ *  is unchanged and the function returns a negative value.
+ *  If a zero is returned for the name's length, then there is no name
+ *  associated with the ID.
  * 
  * Programmer:	Leon Arber
  *              August 27, 2004
  * 
  * Modifications:
- *
+ *		October 20, 2004 LA: Changed API to use size and return ssize_t
  *-------------------------------------------------------------------------
  */
-herr_t H5Pget_data_transform(hid_t plist_id, char** expression)
+ssize_t H5Pget_data_transform(hid_t plist_id, char* expression /*out*/, size_t size)
 {
     H5P_genplist_t *plist;      /* Property list pointer */
     H5Z_data_xform_t *data_xform_prop=NULL;    /* New data xform property */
-    herr_t ret_value=SUCCEED;   /* return value */
+    ssize_t 	ret_value;   /* return value */
+
+    size_t	len;
+    char*	pexp;
 
   
     FUNC_ENTER_API(H5Pget_data_transform, FAIL);
 
-    /* Check arguments */
-    if (expression == NULL)
-	HGOTO_ERROR (H5E_ARGS, H5E_BADVALUE, FAIL, "expression cannot be NULL");
- 
     /* Get the plist structure */
     if(NULL == (plist = H5P_object_verify(plist_id,H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
 
     if(H5P_get(plist, H5D_XFER_XFORM_NAME, &data_xform_prop)<0)
-        HGOTO_ERROR (H5E_PLIST, H5E_CANTSET, FAIL, "Error setting data transform expression");
+        HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Error getting data transform expression");
 
+    if(NULL == data_xform_prop)
+        HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Cannot get a data transform that has not been set");
+    
     /* Get the data transform string */
-    *expression = H5Z_xform_extract_xform_str(data_xform_prop); 
+    pexp = H5Z_xform_extract_xform_str(data_xform_prop); 
+
+    if(!pexp)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "Failed to retrieve transform expression");
+    
+    len = HDstrlen(pexp);
+    if(expression)
+    {
+	/* sanity check */
+	if(size > len)
+	    size = len;
+	
+	HDstrncpy(expression, pexp, size);
+    }
+    
+    ret_value = (ssize_t)len;
     
 done:
     if(ret_value<0) {
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index bd9518e..6df6d0a 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -198,7 +198,7 @@ H5_DLL H5D_layout_t H5Pget_layout(hid_t plist_id);
 H5_DLL herr_t H5Pset_chunk(hid_t plist_id, int ndims, const hsize_t dim[]);
 H5_DLL int H5Pget_chunk(hid_t plist_id, int max_ndims, hsize_t dim[]/*out*/);
 H5_DLL herr_t H5Pset_data_transform(hid_t plist_id, const char* expression);
-H5_DLL herr_t H5Pget_data_transform(hid_t plist_id, char** expression);
+H5_DLL ssize_t H5Pget_data_transform(hid_t plist_id, char* expression /*out*/, size_t size);
 H5_DLL herr_t H5Pset_external(hid_t plist_id, const char *name, off_t offset,
           hsize_t size);
 H5_DLL int H5Pget_external_count(hid_t plist_id);
diff --git a/src/H5Ztrans.c b/src/H5Ztrans.c
index 51ce454..437d79e 100644
--- a/src/H5Ztrans.c
+++ b/src/H5Ztrans.c
@@ -1005,11 +1005,9 @@ done:
 static    herr_t
 H5Z_xform_eval_full(H5Z_node *tree, const size_t array_size,  const hid_t array_type, H5Z_result* res)
 {
-
     H5Z_result resl, resr;
     herr_t ret_value = SUCCEED;
 
-
     FUNC_ENTER_NOAPI(H5Z_xform_eval_full, FAIL);
 
     /* check args */
@@ -1048,6 +1046,7 @@ H5Z_xform_eval_full(H5Z_node *tree, const size_t array_size,  const hid_t array_
 	 * 2.  Figure out what type of data we're going to be manipulating
 	 * 3.  Do the operation on the data. */
 
+	
 	switch (tree->type) {
 	    case H5Z_XFORM_PLUS:  
 		H5Z_XFORM_TYPE_OP(resl, resr, array_type, +=, array_size)
@@ -1390,7 +1389,7 @@ H5Z_xform_create(const char *expr)
     
      /* we generate the parse tree right here and store a poitner to its root in the property. */
     if((data_xform_prop->parse_root = H5Z_xform_parse(expr, data_xform_prop->dat_val_pointers))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "unable to allocate memory for data transform parse tree")
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "unable to generate parse tree from expression")
 
     /* Assign return value */
     ret_value=data_xform_prop;
@@ -1590,18 +1589,16 @@ H5Z_xform_extract_xform_str(const H5Z_data_xform_t *data_xform_prop)
 {
     char* ret_value;
 
-    FUNC_ENTER_NOAPI(H5Z_xform_extract_xform_str, NULL)
+    FUNC_ENTER_NOAPI_NOFUNC(H5Z_xform_extract_xform_str)
 
     /* There should be no way that these can be NULL since the function
      * that calls this one checks to make sure they aren't before
      * pasing them */
     assert(exp);
     assert(data_xform_prop);
+  
+    ret_value = data_xform_prop->xform_exp;
 
-    if( (ret_value = H5MM_strdup(data_xform_prop->xform_exp)) == NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "unable to allocate memory for data transform string")
-
-done:
     FUNC_LEAVE_NOAPI(ret_value)  
 } /* H5Z_xform_extract_xform_str() */