path: root/release_docs/RELEASE.txt

HDF5 version 1.10.2-snap10 currently under development
================================================================================


INTRODUCTION

This document describes the differences between HDF5-1.10.1 and HDF5 1.10.2, and
contains information on the platforms tested and known problems in HDF5-1.10.1.
For more details check the HISTORY*.txt files in the HDF5 source.


Links to HDF5 1.10.1 source code, documentation, and additional materials can be found on The HDF5 web page at:

     https://support.hdfgroup.org/HDF5/

The HDF5 1.10.1 release can be obtained from:

     https://support.hdfgroup.org/HDF5/release/obtain5.html

User documentation for the snapshot can be accessed directly at this location:

     https://support.hdfgroup.org/HDF5/doc/

New features in the HDF5-1.10.x release series, including brief general
descriptions of some new and modified APIs, are described in the "New Features
in HDF5 1.10" document:

https://support.hdfgroup.org/HDF5/docNewFeatures/index.html

All new and modified APIs are listed in detail in the "HDF5 Software Changes
from Release to Release" document, in the section "Release 1.10.1 (current
release) versus Release 1.10.0

     https://support.hdfgroup.org/HDF5/doc/ADGuide/Changes.html

If you have any questions or comments, please send them to the HDF Help Desk:

    help@hdfgroup.org


CONTENTS

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.10.1
- Supported Platforms
- Tested Configuration Features Summary
- More Tested Platforms
- Known Problems


New Features
============

    Configuration:
    -------------
    - CMake

      Change minimum version to 3.10.

      This change removes the need to support a copy of the FindMPI.cmake module,
      which has been removed, along with its subfolder in the config/cmake_ext_mod
      location.

      (ADB - 2018/03/09)

    - CMake

      Add pkg-config file generation

      Added pkg-config file generation for the C, C++, HL, and HL C++ libraries.
      In addition, builds on linux will create h5cXXX scripts that use the pkg-config
      files. This is a limited implementation of a script like autotools h5cc.

      (ADB - 2018/03/08, HDFFV-4359)

    - CMake

      Refactor use of CMAKE_BUILD_TYPE for new variable, which understands
      the type of generator in use.

      Added new configuration macros to use new HDF_BUILD_TYPE variable. This
      variable is set correctly for the type of generator being used for the build.

      (ADB - 2018/01/08, HDFFV-10385, HDFFV-10296)

    - Removed version-specific gcc/gfortran flags for version 4.0 (inclusive)
      and earlier.

      The config/gnu-flags file, which is sourced as a part of the configure
      process, adds version-specific flags for use when building HDF5. Most of
      these flags control warnings and do not affect the final product.

      Flags for older versions of the compiler were consolidated into the
      common flags section. Moving these flags simplifies maintenance of
      the file.

      The upshot of this is that building with ancient versions of gcc
      (<= 4.0) will possibly no longer work without hand-hacking the file
      to remove the flags not understood by that version of the compiler.
      Nothing should change when building with gcc >= 4.1.

      (HDFFV-9937, DER, 2017/05/31)

    - -fno-omit-frame-pointer was added when building with debugging symbols
      enabled.

      Debugging symbols can be enabled independently of the overall build
      mode in both the autotools and CMake. This allows (limited) debugging
      of optimized code. Since many debuggers rely on the frame pointer,
      we've disabled this optimization when debugging symbols are requested
      (e.g.: via building with --enable-symbols).

      (HDFFV-10226, DER, 2017/05/31)

    Library:
    --------
    - Add prefix option to VDS files.

      Currently, VDS source files must be in the active directory to be
      found by the virtual file. Adding the option of a prefix to be set
      on the virtual file, using a data access property list (DAPL),
      allows the source files to located at an absolute or relative path
      to the virtual file.
      Private utility functions in H5D and H5L packages merged into single
      function in H5F package.

      New public APIs:
            herr_t H5Pset_virtual_prefix(hid_t dapl_id, const char* prefix);
            ssize_t H5Pget_virtual_prefix(hid_t dapl_id, char* prefix /*out*/, size_t size);
      The prefix can also be set with an environment variable, HDF5_VDS_PREFIX.

      (ADB - 2017/12/12, HDFFV-9724, HDFFV-10361)

    - H5FDdriver_query() API call added to the C library.

      This new library call allows the user to query a virtual file driver
      (VFD) for the feature flags it supports (listed in H5FDpublic.h).
      This can be useful to determine if a VFD supports SWMR, for example.

      Note that some VFDs have feature flags that may only be present
      after a file has been created or opened (e.g.: the core VFD will
      have the H5FD_FEAT_POSIX_COMPAT_HANDLE flag set if the backing
      store is switched on). Since the new API call queries a generic VFD
      unassociated with a file, these flags will never be returned.

      (HDFFV-10215, DER, 2017/05/31)


    - H5FD_FEAT_DEFAULT_VFD_COMPATIBLE VFD feature flag added to the C library.

      This new feature flag indicates that the VFD is compatible with the
      default VFD. VFDs that set this flag create single files that follow
      the canonical HDF5 file format.

      (HDFFV-10214, DER, 2017/05/31)

    - The H5I_REFERENCE value in the H5I_type_t enum (defined in H5Ipublic.h)
      has been marked as deprectated.

      This ID type value is not used in the C library. i.e.: There are no
      hid_t values that are of ID type H5I_REFERENCE.

      This enum value will be removed in a future major version of the library.
      The code will remain unchanged in the HDF5 1.10.x branches.

      (HDFFV-10252, DER, 2017/04/05)


    Parallel Library:
    -----------------
    - Optimize parallel open/location of the HDF5 super-block

      Previous releases of PHDF5 required all parallel ranks to
      search for the HDF5 superblock signature when opening the
      file. As this is accomplished more or less as a synchronous
      operation, a large number of processes can experience a
      slowdown in the file open due to filesystem contention.

      As a first step in improving the startup/file-open performance,
      we allow MPI rank 0 of the associated MPI communicator to locate
      the base offset of the super-block and then broadcast that result
      to the remaining ranks in the parallel group.  Note that this
      approach is utilized ONLY during file opens which employ the MPIO
      file driver in HDF5 by previously having called H5Pset_fapl_mpio().

      HDF5 parallel file operations which do not employ multiple ranks
      e.g. specifiying MPI_COMM_SELF (whose MPI_Comm_size == 1)
      as opposed to MPI_COMM_WORLD, will not be affected by this
      optimization.  Conversely, parallel file operations on subgroups
      of MPI_COMM_WORLD are allowed to be run in parallel with each
      subgroup operating as an independant collection of processes.

      (RAW - 2017/10/10, HDFFV-10294)


    - Large MPI-IO transfers

      Previous releases of PHDF5 would fail when attempting to
      read or write greater than 2GB of data in a single IO operation.
      This issue stems principally from an MPI API whose definitions
      utilize 32 bit integers to describe the number of data elements
      and datatype that MPI should use to effect a data transfer.
      Historically, HDF5 has invoked MPI-IO with the number of
      elements in a contiguous buffer represented as the length
      of that buffer in bytes.

      Resolving the issue and thus enabling larger MPI-IO transfers
      is accomplished first, by detecting when a user IO request would
      exceed the 2GB limit as described above.  Once a transfer request
      is identified as requiring special handling, PHDF5 now creates a
      derived datatype consisting of a vector of fixed sized blocks
      which is in turn wrapped within a single MPI_Type_struct to
      contain the vector and any remaining data.   The newly created
      datatype is then used in place of MPI_BYTE and can be used to
      fulfill the original user request without encountering API
      errors.

      (RAW - 2017/09/10, HDFFV-8839)

    Fortran Library:
    ----------------
    -

    C++ Library:
    ------------
    - The following wrappers are added:

      + H5Lcreate_soft:
        // Creates a soft link from link_name to target_name.
        void link(const char *target_name, const char *link_name,...)
        void link(const H5std_string& target_name,...)

      + H5Lcreate_hard:
        // Creates a hard link from new_name to curr_name.
        void link(const char *curr_name, const Group& new_loc,...)
        void link(const H5std_string& curr_name, const Group& new_loc,...)

        // Creates a hard link from new_name to curr_name in same location.
        void link(const char *curr_name, const hid_t same_loc,...)
        void link(const H5std_string& curr_name, const hid_t same_loc,...)

        Note: previous version of H5Location::link will be deprecated.

      + H5Lcopy:
        // Copy an object from a group of file to another.
        void copyLink(const char *src_name, const Group& dst,...)
        void copyLink(const H5std_string& src_name, const Group& dst,...)

        // Copy an object from a group of file to the same location.
        void copyLink(const char *src_name, const char *dst_name,...)
        void copyLink(const H5std_string& src_name,...)

      + H5Lmove:
        // Rename an object in a group or file to a new location.
        void moveLink(const char* src_name, const Group& dst,...)
        void moveLink(const H5std_string& src_name, const Group& dst,...)

        // Rename an object in a group or file to the same location.
        void moveLink(const char* src_name, const char* dst_name,...)
        void moveLink(const H5std_string& src_name,...)

        Note: previous version H5Location::move will be deprecated.

      + H5Ldelete:
        // Removes the specified link from this location.
        void unlink(const char *link_name,
            const LinkAccPropList& lapl = LinkAccPropList::DEFAULT)
        void unlink(const H5std_string& link_name,
            const LinkAccPropList& lapl = LinkAccPropList::DEFAULT)

    - Added class LinkCreatPropList

    - Added overloaded functions H5Location::createGroup to take a link
      creation property list
        Group createGroup(const char* name, const LinkCreatPropList& lcpl)
        Group createGroup(const H5std_string& name, const LinkCreatPropList& lcpl)
    - Added wrapper for H5Lget_info() to H5Location
        // Returns the information of the named link.
        H5L_info_t getLinkInfo(const H5std_string& link_name,...)

      (BMR - 2018/03/11, HDFFV-10149)


    Java Library:
    ----------------
    - Wrappers added for the following APIs:
      H5Pset_evict_on_close
      H5Pget_evict_on_close
      H5Pset_chunk_opts
      H5Pget_chunk_opts
      H5Pset_efile_prefix
      H5Pget_efile_prefix
      H5Pset_virtual_prefix
      H5Pget_virtual_prefix

      (ADB - 2017/12/20)

    - The H5I_REFERENCE value in the H5I_type_t enum (defined in H5Ipublic.h)
      has been marked as deprectated.

      JNI code which refers to this value will be removed in a future
      major version of the library. The code will remain unchanged in the
      1.10.x branches.

      See the C library section, above, for further information.

      (HDFFV-10252, DER, 2017/04/05)


    Tools:
    ------
    - h5diff

      h5diff has new option enable-error-stack.

      Updated h5diff with the --enable-error-stack argument, which
      enables the display of the hdf5 error stack. This completes the
      improvement to the main tools; h5copy, h5diff, h5dump, h5ls and
      h5repack.

      (ADB - 2017/08/30, HDFFV-9774)

    High-Level APIs:
    ---------------
    -

    C Packet Table API
    ------------------
    -

    Internal header file
    --------------------
    -

    Documentation
    -------------
    -

Support for new platforms, languages and compilers.
=======================================
    -

Bug Fixes since HDF5-1.10.1 release
==================================

    Library
    -------
    - H5Pset_evict_on_close in H5Pfapl.c

      Changed the minor error number from H5E_CANTSET to H5E_UNSUPPORTED for
      parallel library.
             (ADB - 2018/03/6, HDFFV-10414)

    - Utility function can not handle lowercase Windows drive letters

      Added call to toupper function for drive letter.

      (ADB - 2017/12/18, HDFFV-10307)

    - Fix H5Sencode() bug when the number of elements selected is > 2^32

      H5Sencode() incorrectly encodes dataspace selection with number of
      elements exceeding 2^32.  When decoding such selection via H5Sdecode(),
      the number of elements in the decoded dataspace is not the same as
      what is encoded.  This problem exists for H5S_SEL_HYPER and
      H5S_SEL_POINTS encoding.

      The cause of the problem is because the library uses 32 bits to
      encode counts and block offsets for the selection.
      The solution is to use the original 32 bit encodings if possible,
      but use a different way to encode selection > 32 bits when needed.
      See details in the RFC: H5Sencode/H5Secode Format Change.

      (VC - 2017/11/28, HDFFV-9947)

    - H5Pset_evict_on_close in H5Pfapl.c

      Changed the minor error number from H5E_CANTSET to H5E_UNSUPPORTED for
      parallel library.
             (ADB - 2018/03/6, HDFFV-10414)

    - Utility function can not handle lowercase Windows drive letters

      Added call to toupper function for drive letter.

      (ADB - 2017/12/18, HDFFV-10307)

    - filter plugin handling in H5PL.c and H5Z.c

      It was discovered that the dynamic loading process used by
      filter plugins had issues with library dependencies.

      CMake build process changed to use LINK INTERFACE keywords, which
      allowed HDF5 C library to make dependent libraries private. The
      filter plugin libraries no longer require dependent libraries
      (such as szip or zlib) to be available.
             (ADB - 2017/11/16, HDFFV-10328)

    - Fix rare object header corruption bug

      In certain cases, such as when converting large attributes to dense
      storage, an error could occur which would either fail an assertion or
      cause file corruption. Fixed and added test.

      (NAF - 2017/11/14, HDFFV-10274)

    - H5Zfilter_avail in H5Z.c

      The public function checked for plugins, while the private
      function did not.

      Modified H5Zfilter_avail and private function, H5Z_filter_avail.
      Moved check for plugin from public to private function. Updated
      H5P__set_filter due to change in H5Z_filter_avail. Updated tests.

      (ADB - 2017/10/10, HDFFV-10297, HDFFV-10319)

    - Fix H5HL_offset_into()

      (1) Fix H5HL_offset_into() to return error when offset exceeds heap data
          block size.
      (2) Fix other places in the library that call this routine to detect
          error routine.

      (HDFFV-10216, VC, 2017/08/30)

    - Fixes for paged aggregation

      Skip test in test/fheap.c when:
      (1) multi/split drivers and
      (2) persisting free-space or using paged aggregation strategy

      (VC, 2017/07/10)

    - Fixes for paged aggregation

      Changes made based on RFC review comments:
      (1) Add maximum value for file space page size
      (2) Drop check for page end metadata threshold
      (3) Remove "can_shrink" and "shrink" callbacks for small section class

      (VC, 2017/06/09)

    - Fix for infinite loop in H5VM_power2up().

      The function H5VM_power2up() returns the next power of 2
      for n. When n exceeds 2^63, it overflows and becomes 0 causing
      the infinite looping.

      The fix ensures that the function checks for n >= 2^63
      and returns 0.

      (HDFFV-10217, VC, 2017/07/10)

    - Fix for H5Ocopy doesn't work with open identifiers

      Changes made so that raw data for dataset objects are copied from
      cached info when possible instead of flushing objects to file and
      read them back in again.

      (HDFFV-7853, VC, 2017/07/05)

    - Refactored the testpar/t_bigio.c test to include ALARM macros

      Changed the test to include the ALARM_ON and ALARM_OFF macros which
      are intended to prevent nightly test hangs that have been observed
      with this particular parallel test example.  The code was also modified to
      simplify status reporting (only from MPI rank 0) and additional
      status checking added.

      (RAW - 2017/11/08, HDFFV-10301)

    - An uninitialized struct could cause a memory access error when using
      variable-length or reference types in a compressed, chunked dataset.

      A struct containing a callback function pointer and a pointer to some
      associated data was used before initialization. This could cause a
      memory access error and system crash. This could only occur under
      unusual conditions when using variable-lenth and reference types in
      a compressed, chunked dataset.

      On recent versions of Visual Studio, when built in debug mode, the
      debug heap will complain and cause a crash if the code in question
      is executed (this will cause the objcopy test to fail).

      (DER - 2017/11/21, HDFFV-10330)

    - Fix for collective metadata writes on file close

      It was discovered that metadata was being written twice as part of
      the parallel file close behavior, once independently and once
      collectively.

      A fix for this error was included as part of the parallel compression
      feature but remained undocumented here.

      (RAW - 2017/12/01, HDFFV-10272)

    - If an HDF5 file contains a filter pipeline message with a 'number of
      filters' field that exceeds the maximum number of allowed filters,
      the error handling code will attempt to dereference a NULL pointer.

      This issue was reported to The HDF Group as issue #CVE-2017-17505.

      NOTE: The HDF5 C library cannot produce such a file. This condition
            should only occur in a corrupt (or deliberately altered) file
            or a file created by third-party software.

      This problem arose because the error handling code assumed that
      the 'number of filters' field implied that a dynamic array of that
      size had already been created and that the cleanup code should
      iterate over that array and clean up each element's resources. If
      an error occurred before the array has been allocated, this will
      not be true.

      This has been changed so that the number of filters is set to
      zero on errors. Additionally, the filter array traversal in the
      error handling code now requires that the filter array not be NULL.

      (DER - 2018/02/06, HDFFV-10354)

    - If an HDF5 file contains a filter pipeline message which contains
      a 'number of filters' field that exceeds the actual number of
      filters in the message, the HDF5 C library will read off the end of
      the read buffer.

      This issue was reported to The HDF Group as issue #CVE-2017-17506.

      NOTE: The HDF5 C library cannot produce such a file. This condition
            should only occur in a corrupt (or deliberately altered) file
            or a file created by third-party software.

      The problem was fixed by passing the buffer size with the buffer
      and ensuring that the pointer cannot be incremented off the end
      of the buffer. A mismatch between the number of filters declared
      and the actual number of filters will now invoke normal HDF5
      error handling.

      (DER - 2018/02/26, HDFFV-10355)

    - If an HDF5 file contains a malformed compound datatype with a
      suitably large offset, the type conversion code can run off
      the end of the type conversion buffer, causing a segmentation
      fault.

      This issue was reported to The HDF Group as issue #CVE-2017-17507.

      NOTE: The HDF5 C library cannot produce such a file. This condition
            should only occur in a corrupt (or deliberately altered) file
            or a file created by third-party software.

      THE HDF GROUP WILL NOT FIX THIS BUG AT THIS TIME

      Fixing this problem would involve updating the publicly visible
      H5T_conv_t function pointer typedef and versioning the API calls
      which use it. We normally only modify the public API during
      major releases, so this bug will not be fixed at this time.

      (DER - 2018/02/26, HDFFV-10356)

    - If an HDF5 file contains a malformed compound type which contains
      a member of size zero, a division by zero error will occur while
      processing the type.

      This issue was reported to The HDF Group as issue #CVE-2017-17508.

      NOTE: The HDF5 C library cannot produce such a file. This condition
            should only occur in a corrupt (or deliberately altered) file
            or a file created by third-party software.

      Checking for zero before dividing fixes the problem. Instead of the
      division by zero, the normal HDF5 error handling is invoked.

      (DER - 2018/02/26, HDFFV-10357)

    - If an HDF5 file contains a malformed symbol table node that declares
      it contains more symbols than it actually contains, the library
      can run off the end of the metadata cache buffer while processing
      the symbol table node.

      This issue was reported to The HDF Group as issue #CVE-2017-17509.

      NOTE: The HDF5 C library cannot produce such a file. This condition
            should only occur in a corrupt (or deliberately altered) file
            or a file created by third-party software.

      Performing bounds checks on the buffer while processing fixes the
      problem. Instead of the segmentation fault, the normal HDF5 error
      handling is invoked.

      (DER - 2018/03/12, HDFFV-10358)

    Configuration
    -------------
    - CMake

      Update CMake commands configuration.

      A number of improvements were made to the CMake commands. Most
      changes simplify usage or eliminate unused constructs. Also,
      some changes support better cross-platform support.

      (ADB - 2018/02/01, HDFFV-10398)

    - CMake

      Correct usage of CMAKE_BUILD_TYPE variable.

      The use of the CMAKE_BUILD_TYPE is incorrect for multi-config
      generators (Visual Studio and XCode) and is optional for single
      config generators. Created a new macro to check
        GLOBAL PROPERTY -> GENERATOR_IS_MULTI_CONFIG
      Created two new HDF variable, HDF_BUILD_TYPE and HDF_CFG_BUILD_TYPE.
      Defaults for these variables is "Release".

      (ADB - 2018/01/10, HDFFV-10385)

    - CMake

      Add replacement of fortran flags if using static CRT.

      Added TARGET_STATIC_CRT_FLAGS call to HDFUseFortran.cmake file in
      config/cmake_ext_mod folder.

      (ADB - 2018/01/08, HDFFV-10334)

    - CMake

      The hdf5 library used shared szip and zlib, which needlessly required
      applications to link with the same szip and zlib libraries.

      Changed the target_link_libraries commands to use the static libs.
      Removed improper link duplication of szip and zlib.
      Adjusted the link dependencies and the link interface values of
      the target_link_libraries commands.

      (ADB - 2017/11/14, HDFFV-10329)

    - CMake MPI

      CMake implementation for MPI was problematic and would create incorrect
      MPI library references in the hdf5 libraries.

      Reworked the CMake MPI code to properly create CMake targets. Also merged
      the latest CMake FindMPI.cmake changes to the local copy. This is necessary
      until HDF changes the CMake minimum to 3.9 or greater.

      (ADB - 2017/11/02, HDFFV-10321)

    - Corrected FORTRAN_HAVE_C_LONG_DOUBLE processing in the autotools.

      A bug in the autotools Fortran processing code always set the
      FORTRAN_HAVE_C_LONG_DOUBLE variable to be true regardless of
      whether or not a C long double type was present.

      This would cause compilation failures on platforms where a C
      long double type was not available and the Fortran wrappers
      were being built.

      (HDFFV-10247, DER, 2017/07/05)

    - The deprecated --enable-production and --enable-debug configure options
      failed to emit errors when passed an empty string
      (e.g.: --enable-debug="").

      Due to the way we checked for these options being set, it was possible
      to avoid the error message and continue configuration if an empty string
      was passed to the option.

      Any use of --enable-production or --enable-debug will now halt the
      configuration step and emit a helpful error message
      (use --enable-build-mode=debug|production instead).

      (HDFFV-10248, DER, 2017/07/05)

    - CMake

      Too many commands for POST_BUILD step caused command line to be
      too big on windows.

      Changed foreach of copy command to use a custom command with the
      use of the HDFTEST_COPY_FILE macro.

      (ADB - 2017/07/12, HDFFV-10254)

    - cmake test execution environment

      The parallel HDF5 test: 't_pread' assumed the use of autotools
      and the directory structure associated with that testing approach.
      Modified the test code to check whether the 'h5jam' utility can be
      found in the same directory as the test executable (which is
      preferred directory structure utilized by cmake) and if found
      will invoke the tool directly rather than utilizing a relative path.

      (RAW - 2017/11/03, HDFFV-10318)

    Performance
    -------------
    -

    Fortran
    --------
    - Fixed compilation errors when using Intel 18 Fortran compilers
      (MSB - 2017/11/3, HDFFV-10322)

    Tools
    -----
    - h5repack

      h5repack changes the chunk parameters when a change of layout is not
      specified and a filter is applied.

      HDFFV-10297, HDFFV-10319 reworked code for h5repack and h5diff code
      in the tools library. The check for an existing layout was incorrectly
      placed into an if block and not executed. The check was moved into
      the normal path of the function.

      (ADB - 2018/02/21, HDFFV-10412)

    - h5dump

      the tools library will hide the error stack during file open.

      While this is preferable almost always, there are reasons to enable
      display of the error stack when a tool will not open a file. Adding an
      optional argument to the --enable-error-stack will provide this use case.
      As an optional argument it will not affect the operation of the
      --enable-error-stack. h5dump is the only tool to implement this change.

      (ADB - 2018/02/15, HDFFV-10384)

    - h5dump

      h5dump would output an indented blank line in the filters section.

      h5dump overused the h5tools_simple_prefix function, which is a
      function intended to account for the data index (x,y,z) option.
      Removed the function call for header information.

      (ADB - 2018/01/25, HDFFV-10396)

    - h5repack

      h5repack incorrectly searched internal object table for name.

      h5repack would search the table of objects for a name, if the
      name did not match it tried to determine if the name without a
      leading slash would match. The logic was flawed! The table
      stored names(paths) without a leading slash and did a strstr
      of the table path to the name.
      The assumption was that if there was a difference of one then
      it was a match, however "pressure" would match "/pressure" as
      well as "/pressure1", "/pressure2", etc. Changed logic to remove
      any leading slash and then do a full compare of the name.

      (ADB - 2018/01/18, HDFFV-10393)

    - h5repack

      h5repack failed to handle more then 9 chars for int conversion.

      User defined filter parameter conversions would fail for integers
      larger then 9 characters. Increased local variable array for storing
      the current command line parameter to prevent buffer overflows.

      (ADB - 2018/01/17, HDFFV-10392)

    - h5diff

      h5diff seg faulted if comparing VL strings against fixed strings.

      Reworked solution for HDFFV-8625 and HDFFV-8639. Implemented the check
      for string objects of same type in the diff_can_type function by
      adding an if(tclass1 == H5T_STRING) block. This if block moves the
      same check that was added for attributes to this function, which is
      used by all object types. This function also handles complex type
      structures.
      Also added a new test file in h5diffgenttest for testing this issue
      and removed the temporary files used in the test scripts.

      (ADB - 2018/01/04, HDFFV-8745)

    - h5repack

      h5repack failed to copy a dataset with existing filter.

      Reworked code for h5repack and h5diff code in tools library. Added
      improved error handling, cleanup of resources and checks of calls.
      Modified H5Zfilter_avail and private function, H5Z_filter_avail.
      Moved check for plugin from public to private function. Updated
      H5P__set_filter due to change in H5Z_filter_avail. Updated tests.
      Note, h5repack output display has changed to clarify the individual
      steps of the repack process. The output indicates if an operation
      applies to all objects. Lines with notation and no information
      have been removed.

      (ADB - 2017/10/10, HDFFV-10297, HDFFV-10319)

    - h5repack

      h5repack always set the User Defined filter flag to H5Z_FLAG_MANDATORY.

      Added another parameter to the 'UD=' option to set the flag by default
      to '0' or H5Z_FLAG_MANDATORY, the other choice is '1' or H5Z_FLAG_OPTIONAL.

      (ADB - 2017/08/31, HDFFV-10269)

    - h5ls

      h5ls generated error on stack when it encountered a H5S_NULL
      dataspace.

      Adding checks for H5S_NULL before calling H5Sis_simple (located
      in the h5tools_dump_mem function) fixed the issue.

      (ADB - 2017/08/17, HDFFV-10188)

    - h5repack

      Add tests to h5repack.sh.in to verify options added for paged
      aggregation work as expected.

      (VC, 2017/08/03)

    - h5dump

      h5dump segfaulted on output of XML file.

      Function that escape'd strings used the full buffer length
      instead of just the length of the replacement string in a
      strncpy call. Using the correct length fixed the issue.

      (ADB - 2017/08/01, HDFFV-10256)

    - h5diff

      h5diff segfaulted on compare of a  NULL variable length string.

      Improved h5diff compare of strings by adding a check for
      NULL strings and setting the lengths to zero.

      (ADB - 2017/07/25, HDFFV-10246)

    - h5import

      h5import crashed trying to import data from a subset of a dataset.

      Improved h5import by adding the SUBSET keyword. h5import understands
      to use the Count times the Block as the size of the dimensions.
      Added INPUT_B_ORDER keyword to old-style configuration files.
      The import from h5dump function expects the binary files to use native
      types (FILE '-b' option) in the binary file.

      (ADB - 2017/06/15, HDFFV-10219)

    - h5repack

      h5repack did not maintain the creation order flag of the root
      group.

      Improved h5repack by reading the creation order and applying the
      flag to the new root group. Also added arguments to set the
      order and index direction, which applies to the traversing of the
      original file, on the command line.

      (ADB - 2017/05/26, HDFFV-8611)

    - h5diff

      h5diff failed to account for strpad type and null terminators
      of char strings. Also, h5diff failed to account for string length
      differences and would give a different result depending on file
      order in the command line.

      Improved h5diff compare of strings and arrays by adding a check for
      string lengths and if the strpad was null filled.

      (ADB - 2017/05/18, HDFFV-9055, HDFFV-10128)

    High-Level APIs:
    ------
    - Fixed a bug in the H5DOwrite_chunk() API call where overwriting a chunk
      with no filters caused an assert to trip (with assertions enabled /
      debug builds) or additional chunks to be inserted instead of overwriting
      the data (without assertions enabled / production builds).

      (HDFFV-10187, DER, 2017/05/11)

    Fortran High-Level APIs:
    ------
    -

    Documentation
    -------------
    -

    F90 APIs
    --------
    -

    C++ APIs
    --------
    - Removal of memory leaks

      A private function was inadvertently called, causing memory leaks.  This
      is now fixed.

      (BMR - 2018/03/12 - User's reported in email)

    Testing
    -------
    - Memory for three variables in testphdf5's coll_write_test was malloced 
      but not freed, leaking memory when running the test.  The variables' 
      memory is now freed.

      (LRK - 2018/03/12, HDFFV-10397)

Supported Platforms
===================

    Linux 2.6.32-573.18.1.el6.ppc64 gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)
    #1 SMP ppc64 GNU/Linux        g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)
    (ostrich)                     GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)
                                  IBM XL C/C++ V13.1
                                  IBM XL Fortran V15.1

    Linux 3.10.0-327.10.1.el7   GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (kituo/moohan)                  Version 4.8.5 20150623 (Red Hat 4.8.5-4)
                                    Version 4.9.3, Version 5.2.0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 15.0.3.187 Build 20150407
                                  MPICH 3.1.4 compiled with GCC 4.9.3

    SunOS 5.11 32- and 64-bit     Sun C 5.12 SunOS_sparc
    (emu)                         Sun Fortran 95 8.6 SunOS_sparc
                                  Sun C++ 5.12 SunOS_sparc

    Windows 7                     Visual Studio 2012 w/ Intel Fortran 15 (cmake)
                                  Visual Studio 2013 w/ Intel Fortran 15 (cmake)
                                  Visual Studio 2015 w/ Intel Fortran 16 (cmake)

    Windows 7 x64                 Visual Studio 2012 w/ Intel Fortran 15 (cmake)
                                  Visual Studio 2013 w/ Intel Fortran 15 (cmake)
                                  Visual Studio 2015 w/ Intel Fortran 16 (cmake)
                                  Visual Studio 2015 w/ Intel C, Fortran 2017 (cmake)
                                  Visual Studio 2015 w/ MSMPI 8 (cmake)
                                  Cygwin(CYGWIN_NT-6.1 2.8.0(0.309/5/3)
                                      gcc and gfortran compilers (GCC 5.4.0)
                                      (cmake and autotools)

    Windows 10                    Visual Studio 2015 w/ Intel Fortran 16 (cmake)
                                  Cygwin(CYGWIN_NT-6.1 2.8.0(0.309/5/3)
                                      gcc and gfortran compilers (GCC 5.4.0)
                                      (cmake and autotools)

    Windows 10 x64                Visual Studio 2015 w/ Intel Fortran 16 (cmake)

    Mac OS X Mt. Lion 10.8.5      Apple clang/clang++ version 5.1 from Xcode 5.1
    64-bit                        gfortran GNU Fortran (GCC) 4.8.2
    (swallow/kite)                Intel icc/icpc/ifort version 15.0.3

    Mac OS X Mavericks 10.9.5     Apple clang/clang++ version 6.0 from Xcode 6.2
    64-bit                        gfortran GNU Fortran (GCC) 4.9.2
    (wren/quail)                  Intel icc/icpc/ifort version 15.0.3

    Mac OS X Yosemite 10.10.5     Apple clang/clang++ version 6.1 from Xcode 7.0
    64-bit                        gfortran GNU Fortran (GCC) 4.9.2
    (osx1010dev/osx1010test)      Intel icc/icpc/ifort version 15.0.3

    Mac OS X El Capitan 10.11.6   Apple clang/clang++ version 7.3.0 from Xcode 7.3
    64-bit                        gfortran GNU Fortran (GCC) 5.2.0
    (osx1010dev/osx1010test)      Intel icc/icpc/ifort version 16.0.2


Tested Configuration Features Summary
=====================================

    In the tables below
          y   = tested
          n   = not tested in this release
          C   = Cluster
          W   = Workstation
          x   = not working in this release
          dna = does not apply
          ( ) = footnote appears below second table
          <blank> = testing incomplete on this feature or platform

Platform                              C         F90/   F90      C++  zlib  SZIP
                                      parallel  F2003  parallel
Solaris2.11 32-bit                      n        y/y    n        y    y     y
Solaris2.11 64-bit                      n        y/n    n        y    y     y
Windows 7                               y        y/y    n        y    y     y
Windows 7 x64                           y        y/y    y        y    y     y
Windows 7 Cygwin                        n        y/n    n        y    y     y
Windows 7 x64 Cygwin                    n        y/n    n        y    y     y
Windows 10                              y        y/y    n        y    y     y
Windows 10 x64                          y        y/y    n        y    y     y
Mac OS X Mountain Lion 10.8.5 64-bit    n        y/y    n        y    y     y
Mac OS X Mavericks 10.9.5 64-bit        n        y/y    n        y    y     y
Mac OS X Yosemite 10.10.5 64-bit        n        y/y    n        y    y     y
Mac OS X El Capitan 10.11.6 64-bit      n        y/y    n        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 PGI      n        y/y    n        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 GNU      y        y/y    y        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 Intel    n        y/y    n        y    y     y
Linux 2.6.32-573.18.1.el6.ppc64         n        y/y    n        y    y     y


Platform                                 Shared  Shared    Shared    Thread-
                                         C libs  F90 libs  C++ libs  safe
Solaris2.11 32-bit                         y       y         y         y
Solaris2.11 64-bit                         y       y         y         y
Windows 7                                  y       y         y         y
Windows 7 x64                              y       y         y         y
Windows 7 Cygwin                           n       n         n         y
Windows 7 x64 Cygwin                       n       n         n         y
Windows 10                                 y       y         y         y
Windows 10 x64                             y       y         y         y
Mac OS X Mountain Lion 10.8.5 64-bit       y       n         y         y
Mac OS X Mavericks 10.9.5 64-bit           y       n         y         y
Mac OS X Yosemite 10.10.5 64-bit           y       n         y         y
Mac OS X El Capitan 10.11.6 64-bit         y       n         y         y
CentOS 7.2 Linux 2.6.32 x86_64 PGI         y       y         y         n
CentOS 7.2 Linux 2.6.32 x86_64 GNU         y       y         y         y
CentOS 7.2 Linux 2.6.32 x86_64 Intel       y       y         y         n
Linux 2.6.32-573.18.1.el6.ppc64            y       y         y         n

Compiler versions for each platform are listed in the preceding
"Supported Platforms" table.


More Tested Platforms
=====================
The following platforms are not supported but have been tested for this release.

    Linux 2.6.32-573.22.1.el6    GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (mayll/platypus)                 Version 4.4.7 20120313
                                     Version 4.8.4
                                  PGI C, Fortran, C++ for 64-bit target on
                                  x86-64;
                                      Version 16.10-0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 15.0.3.187 (Build 20150407)
                                  MPICH 3.1.4 compiled with GCC 4.9.3

    Linux 3.10.0-327.18.2.el7     GNU C (gcc) and C++ (g++) compilers
    #1 SMP x86_64 GNU/Linux          Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly)                       with NAG Fortran Compiler Release 6.1(Tozai)
                                  Intel(R) C (icc) and C++ (icpc) compilers
                                     Version 15.0.3.187 (Build 20150407)
                                  with NAG Fortran Compiler Release 6.1(Tozai)

    Linux 2.6.32-573.18.1.el6.ppc64  MPICH mpich 3.1.4 compiled with
    #1 SMP ppc64 GNU/Linux           IBM XL C/C++ for Linux, V13.1
    (ostrich)                        and IBM XL Fortran for Linux, V15.1

    Debian 8.4 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1 x86_64 GNU/Linux
                                  gcc, g++ (Debian 4.9.2-10) 4.9.2
                                  GNU Fortran (Debian 4.9.2-10) 4.9.2
                                  (cmake and autotools)

    Fedora 24  4.7.2-201.fc24.x86_64 #1 SMP x86_64 x86_64 x86_64 GNU/Linux
                                  gcc, g++ (GCC) 6.1.1 20160621
                                      (Red Hat 6.1.1-3)
                                  GNU Fortran (GCC) 6.1.1 20160621
                                      (Red Hat 6.1.1-3)
                                  (cmake and autotools)

    Ubuntu 16.04.1 4.4.0-38-generic #57-Ubuntu SMP x86_64 GNU/Linux
                                  gcc, g++ (Ubuntu 5.4.0-6ubuntu1~16.04.2)
                                      5.4.0 20160609
                                  GNU Fortran (Ubuntu 5.4.0-6ubuntu1~16.04.2)
                                      5.4.0 20160609
                                  (cmake and autotools)


Known Problems
==============

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.