HDF5 version 1.8.20 released on 2017-11-28
================================================================================

INTRODUCTION
============

This document describes the differences between HDF5-1.8.19 and
HDF5-1.8.20, and contains information on the platforms tested and
known problems in HDF5-1.8.20.
For more details, see the files HISTORY-1_0-1_8_0_rc3.txt
and HISTORY-1_8.txt in the release_docs/ directory of the HDF5 source.

Links to the HDF5 1.8.20 source code, documentation, and additional materials
can be found on the HDF5 web page at:

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

The HDF5 1.8.20 release can be obtained from:

     https://support.hdfgroup.org/HDF5/release/obtain518.html

User documentation for 1.8.20 can be accessed directly at this location:

     https://support.hdfgroup.org/HDF5/doc1.8/

New features in the HDF5-1.8.x release series, including brief general
descriptions of some new and modified APIs, are described in the "What's New
in 1.8.0?" document:

     https://support.hdfgroup.org/HDF5/doc/ADGuide/WhatsNew180.html

All new and modified APIs are listed in detail in the "HDF5 Software Changes
from Release to Release" document, in the section "Release 1.8.20 (current
release) versus Release 1.8.19

     https://support.hdfgroup.org/HDF5/doc1.8/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, Languages, and Compilers
- Bug Fixes since HDF5-1.8.20
- Supported Platforms
- Supported Configuration Features Summary
- More Tested Platforms
- Known Problems


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

    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)


    C++ API
    -------
    - The following C++ API wrappers have been added to the C++ Library:

        // Creates a binary object description of this datatype.
        void DataType::encode() - C API H5Tencode()

        // Returns the decoded type from the binary object description.
        DataType::decode() - C API H5Tdecode()
        ArrayType::decode() - C API H5Tdecode()
        CompType::decode() - C API H5Tdecode()
        DataType::decode() - C API H5Tdecode()
        EnumType::decode() - C API H5Tdecode()
        FloatType::decode() - C API H5Tdecode()
        IntType::decode() - C API H5Tdecode()
        StrType::decode() - C API H5Tdecode()
        VarLenType::decode() - C API H5Tdecode()

        // Three overloaded functions to retrieve information about an object
        H5Location::getObjectInfo() - H5Oget_info()/H5Oget_info_by_name()

      (BMR - 2017/10/17, HDFFV-10175)

    - New constructors to open existing datatypes added in ArrayType,
      CompType, DataType, EnumType, FloatType, IntType, StrType, and
      VarLenType.

      (BMR - 2017/10/17, HDFFV-10175)

    - A document is added to the HDF5 C++ API Reference Manual to show the
      mapping from a C API to C++ wrappers.  It can be found from the main
      page of the C++ API Reference Manual.

      (BMR - 2017/10/17, HDFFV-10151)


    High-Level APIs
    ---------------
    - H5DOread_chunk

      Users wanted to read compressed data directly from a file without any
      processing by the HDF5 data transfer pipeline, just as they were able
      to write it directly to a file with H5DOwrite_chunk.

      New API function, corresponding to existing function H5DOwrite_chunk.
      H5DOread_chunk reads a raw data chunk directly from a chunked dataset
      in the file into the application buffer, bypassing the library’s internal
      data transfer pipeline, including filters.

      (VC - 2017/05/02, HDFFV-9934)


Support for New Platforms, Languages, and Compilers
===================================================

    - Added NAG compiler


Bug Fixes since HDF5-1.8.19
===========================

    Configuration
    -------------
    - 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)


    - Fixed Fortran linker flags when using the NAG Fortran compiler (autotools).

      (HDFFV-10037, MSB, 2017/10/21)

    - 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)


    Library
    -------
    - 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 H5Sencode bug when num points selected is >2^32

      Modified to fail if the 32 bit limit is exceeded when encoding either
      offsets or counts in the selection.

      (HDFFV-10323, VC, 2017/09/07)

    - 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, 2017/09/05)


    Tools
    -----
    - 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)

    - 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)


    C++ API
    -------
    - Marked the following functions deprecated because they were moved to
      class H5Object:
        H5Location::createAttribute()
        H5Location::openAttribute()
        H5Location::attrExists()
        H5Location::removeAttr()
        H5Location::renameAttr()
        H5Location::getNumAttrs()

      (BMR - 2017/10/17)


Supported Platforms
===================
The following platforms are supported and have been tested for this release.
They are built with the configure process unless specified otherwise.

    Linux 2.6.32-573.22.1.el6     GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (platypus/mayll)              Version 4.4.7 20120313
                                     Versions 4.9.3, 5.3.0, 6.2.0
                                  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 17.0.0.196 Build 20160721
                                  MPICH 3.1.4 compiled with GCC 4.9.3
                                  OpenMPI 2.0.1 compiled with GCC 4.9.3

    Linux 2.6.32-573.18.1.el6     gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)
    #1 SMP ppc64 GNU/Linux        g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)
    (ostrich)                     GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)
                                  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/jelly           Version 4.8.5 20150623 (Red Hat 4.8.5-4)
                                     Versions 4.9.3, 5.3.0, 6.2.0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 17.0.4.196 Build 20170411
                                  MPICH 3.1.4 compiled with GCC 4.9.3
                                  NAG Fortran Compiler Release 6.1(Tozai) Build 6116

    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 Mavericks 10.9.5     Apple LLVM version 6.0 (clang-600.0.57)
    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 LLVM version 6.1 (clang-602.0.53)
    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 LLVM version 7.3.0 (clang-703.0.29)
    64-bit                        gfortran GNU Fortran (GCC) 5.2.0
    (VM osx1011dev/osx1011test)   Intel icc/icpc/ifort version 16.0.2

    Mac OS Sierra 10.12.6         Apple LLVM version 8.1 (clang-802.0.42)
    64-bit                        gfortran GNU Fortran (GCC) 7.1.0
    (kite)                        Intel icc/icpc/ifort version 17.0.2


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
SunOS 5.11 32-bit                       n        y/y    n        y    y     y
SunOS 5.11 64-bit                       n        y/y    n        y    y     y
Windows 7                               y        y/y    n        y    y     y
Windows 7 x64                           y        y/y    n        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 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
Mac OS Sierra 10.12.6 64-bit            n        y/y    n        y    y     y
AIX 6.1 32- and 64-bit                  n        y/n    n        y    y     y
CentOS 6.7 Linux 2.6.32 x86_64 GNU      y        y/y    y        y    y     y
CentOS 6.7 Linux 2.6.32 x86_64 Intel    n        y/y    n        y    y     y
CentOS 6.7 Linux 2.6.32 x86_64 PGI      n        y/y    n        y    y     y
CentOS 7.1 Linux 3.10.0 x86_64 GNU      y        y/y    y        y    y     y
CentOS 7.1 Linux 3.10.0 x86_64 Intel    n        y/y    n        y    y     y
Linux 2.6.32-431.11.2.el6.ppc64         n        y/n    n        y    y     y

Platform                                 Shared  Shared    Shared    Thread-
                                         C libs  F90 libs  C++ libs  safe
SunOS 5.11 32-bit                          y       y         y         y
SunOS 5.11 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 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
Mac OS Sierra 10.12.6 64-bit               y       n         y         y
AIX 6.1 32- and 64-bit                     y       n         n         y
CentOS 6.7 Linux 2.6.32 x86_64 GNU         y       y         y         y
CentOS 6.7 Linux 2.6.32 x86_64 Intel       y       y         y         y
CentOS 6.7 Linux 2.6.32 x86_64 PGI         y       y         y         y
CentOS 7.1 Linux 3.10.0 x86_64 GNU         y       y         y         y
CentOS 7.1 Linux 3.10.0 x86_64 Intel       y       y         y         y
Linux 2.6.32-431.11.2.el6.ppc64            y       y         y         y

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     g95 (GCC 4.0.3 (g95 0.94!)
    #1 SMP x86_64 GNU/Linux
    (mayll)

    Debian8.4.0 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1 x86_64 GNU/Linux
                                  gcc (Debian 4.9.2-10) 4.9.2
                                  GNU Fortran (Debian 4.9.2-10) 4.9.2
                                  (cmake and autotools)

    Fedora24 4.7.2-201.fc24.x86_64 #1 SMP x86_64 x86_64 x86_64 GNU/Linux
                                  gcc (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)

    CentOS 7.2 3.10.0-327.28.2.el7.x86_64 #1 SMP x86_64 x86_64 x86_64 GNU/Linux
                                  gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)
                                  GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)
                                  (cmake and autotools)

    Ubuntu 16.04 4.4.0-38-generic #62-Ubuntu SMP x86_64 GNU/Linux
                                  gcc (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0
                                  GNU Fortran (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0
                                  (cmake and autotools)


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

    The dynamically loaded plugin test libraries require undefined references
    to HDF5 functions to be resolved at runtime in order to function properly.
    With autotools on CYGWIN this results in build errors, and we have not
    found a solution that satisfies both.  Therefore the dynamically loaded
    plugin tests have been disabled on CYGWIN.

    Mac OS X 10.13 added additional subdirectory structure in .libs for shared
    libraries.  Consequently "make check" will fail testing java and dynamically
    loaded plugin test libraries attempting to copy files from the previous
    locations in .libs directories.  This will be addressed in the next release
    when support for the Mac OS X 10.13 platform is added.

    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.
