[svn-r16815] Description:

    Added member function Attribute::getInMemDataSize(), which is a wrapper
    of several C calls, to simplify getting the attribute's data size in
    memory.  Used this new function in Attribute::read to get the fixed-len
    string attribute data.

    Added to tests in tattr.cpp.

Platforms tested:
    Linux/32 2.6 (jam)
    FreeBSD/64 6.3 (liberty)
    SunOS 5.10 (linew)

2 files changed, 70 insertions, 12 deletions

diff --git a/c++/src/H5Attribute.cpp b/c++/src/H5Attribute.cpp
index d80286b..a844b77 100644
--- a/c++/src/H5Attribute.cpp
+++ b/c++/src/H5Attribute.cpp
@@ -150,6 +150,50 @@ void Attribute::read( const DataType& mem_type, void *buf ) const
 }
 
 //--------------------------------------------------------------------------
+// Function:	Attribute::getInMemDataSize
+///\brief	Gets the size in memory of the attribute's data.
+///\exception	H5::AttributeIException
+// Programmer	Binh-Minh Ribler - 2000
+//--------------------------------------------------------------------------
+size_t Attribute::getInMemDataSize() const
+{
+    // Get the data type of this attribute
+    hid_t mem_type_id = H5Aget_type(id);
+    if (mem_type_id <= 0)
+    {
+	throw AttributeIException("Attribute::getDataSize", "H5Aget_type failed");
+    }
+
+    // Get the data type's size
+    hid_t native_type = H5Tget_native_type(mem_type_id, H5T_DIR_DEFAULT);
+    if (native_type < 0)
+    {
+	throw AttributeIException("Attribute::read", "H5Tget_native_type failed");
+    }
+    size_t type_size = H5Tget_size(native_type);
+    if (type_size == 0)
+    {
+	throw AttributeIException("Attribute::read", "H5Tget_size failed");
+    }
+
+    // Get number of elements of the attribute
+    hid_t space_id = H5Aget_space(id);
+    if (space_id < 0)
+    {
+	throw AttributeIException("Attribute::read", "H5Aget_space failed");
+    }
+    hssize_t num_elements = H5Sget_simple_extent_npoints(space_id);
+    if (num_elements < 0)
+    {
+	throw AttributeIException("Attribute::read", "H5Sget_simple_extent_npoints failed");
+    }
+
+    // Calculate and return the size of the data
+    size_t data_size = type_size * num_elements;
+    return(data_size);
+}
+
+//--------------------------------------------------------------------------
 // Function:	Attribute::read
 ///\brief	This is an overloaded member function, provided for convenience.
 ///		It reads a \a H5std_string from this attribute.
@@ -163,14 +207,8 @@ void Attribute::read( const DataType& mem_type, void *buf ) const
 //		space for the buffer.  Obtained the attribute size and
 //		allocated memory properly. - BMR
 //--------------------------------------------------------------------------
-void Attribute::read( const DataType& mem_type, H5std_string& strg ) const
+void Attribute::read(const DataType& mem_type, H5std_string& strg) const
 {
-    // Get the size of the attribute data.
-    hsize_t attr_size = H5Aget_storage_size(id);
-    if (attr_size <= 0)
-    {
-	throw AttributeIException("Attribute::read", "Unable to get attribute size before reading");
-    }
 
     // Check if this attribute has variable-len string or fixed-len string and
     // proceed appropriately.
@@ -183,20 +221,36 @@ void Attribute::read( const DataType& mem_type, H5std_string& strg ) const
     // Prepare and call C API to read attribute.
     char *strg_C;
     herr_t ret_value = 0;
+    size_t attr_size;
     if (!is_variable_len)	// only allocate for fixed-len string
     {
-	strg_C = new char [(size_t)attr_size+1];
-	if (strg_C == NULL)
+	// Get the size of the attribute's data
+	attr_size = getInMemDataSize();
+
+	if (attr_size > 0)
 	{
-	    throw AttributeIException("Attribute::read", "Unable to allocate buffer to read the attribute");
+	    strg_C = new char [(size_t)attr_size+1];
+	    if (strg_C == NULL)
+	    {
+		throw AttributeIException("Attribute::read",
+			"Unable to allocate buffer to read the attribute");
+	    }
+	    ret_value = H5Aread(id, mem_type.getId(), strg_C);
 	}
-	ret_value = H5Aread(id, mem_type.getId(), strg_C);
+	else
+	    HDstrcpy(strg_C, "");
     }
     else
     {
 	// no allocation for variable-len string; C library will
 	ret_value = H5Aread(id, mem_type.getId(), &strg_C);
     }
+    if( ret_value < 0 )
+    {
+	if (!is_variable_len)	// only de-allocate for fixed-len string
+	    delete []strg_C;
+	throw AttributeIException("Attribute::read", "H5Aread failed");
+    }
 
     if( ret_value < 0 )
     {
@@ -208,7 +262,8 @@ void Attribute::read( const DataType& mem_type, H5std_string& strg ) const
     // Get string from the C char* and release resource allocated locally
     if (!is_variable_len)
     {
-	strg_C[attr_size] = '\0';
+	if (strg_C != "")
+	    strg_C[attr_size] = '\0';
 	strg = strg_C;
 	delete []strg_C;
     }
diff --git a/c++/src/H5Attribute.h b/c++/src/H5Attribute.h
index 9cf91ba..00a08a5 100644
--- a/c++/src/H5Attribute.h
+++ b/c++/src/H5Attribute.h
@@ -40,6 +40,9 @@ class H5_DLLCPP Attribute : public AbstractDs, public IdComponent {
 	// Returns the amount of storage size required for this attribute.
 	hsize_t getStorageSize() const;
 
+	// Returns the in memory size of this attribute's data.
+	size_t getInMemDataSize() const;
+
 	// Reads data from this attribute.
 	void read( const DataType& mem_type, void *buf ) const;
 	void read( const DataType& mem_type, H5std_string& strg ) const;