Hi Jeremy. I have seen issues that point to a problem with the HDF5 C++ APIs
and the microsoft RTL std::string type.
See my post
http://hdf-forum.184993.n3.nabble.com/Access-violation-writing-string-attributes-using-VC-2005-HDF5-1-8-5-tp1785421p1785421.html
for problems when writing string attributes using the c_str() pointer
returned from a string object (at a time when this should be valid).
Also, I've not posted this one, but in my code I have a temporary workaround
macro as below to avoid similar problems with variable length string
attribute types:
#define TLF_MAX_ATTRIBUTE_STRLEN 250 //until we sort out variable length
attrs.
//some macros and inlines to boilerplate writing attributes
#define TMS_HDF_VLSTR_VAR(varname) H5::StrType
varname(0,H5T_VARIABLE)//CAUTION: causes AV when writing attr
#define TMS_HDF_STR_VAR(varname) H5::StrType varname(0,
TLF_MAX_ATTRIBUTE_STRLEN)
I've not had the time to bottom these out, but I suspect a problem with
dangling pointers somewhere in the HDF5 / USOFT RTL layers.
What I would recommend is to use a C string: below is code I've used to read
string attribute VALUES (not quite the same as what you are trying to do,
but it should give you a clue) - use the hid of the attribute object and the
underlying C APIs, which do seem to work:
//similar inlines for reading attributes, which must exist.
inline void readAttr(hid_t objId, const H5::AtomType & localVar, const char
* attName, void * pResult)
{
hid_t attr_id = H5Aopen(objId, attName, H5P_DEFAULT);
if (attr_id < 0) throw(std::string("Attribute not found: ") + attName);
herr_t stat = H5Aread(attr_id, localVar.getId(), pResult);
H5Aclose(attr_id);
if (stat < 0) throw(std::string("Failed to read attribute: ") +
attName);
}
...
inline void readAttrStr(hid_t objId, const char * attName, std::string &
result)
{
TMS_HDF_STR_VAR(localVar);
char tmp[TLF_MAX_ATTRIBUTE_STRLEN];
readAttr(objId, localVar, attName, tmp);
result = const_cast<const char*>(tmp);
}
If using the C APIs and c strings avoids your bad pointer crash, then I
suspect you're seeing the same underlying problem that I saw. Don't forget
to close any temporay hids, the C api doesn't look after that for you, and
leaking hids causes performance problems.
Steve
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