path: root/release_docs/RELEASE.txt

HDF5 version 1.10.5-snap1 currently under development
================================================================================


INTRODUCTION

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from Release to Release and New Features in the HDF5-1.10.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/HDF5+Application+Developer%27s+Guide

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 HDF5-1.10.3
- Supported Platforms
- Tested Configuration Features Summary
- More Tested Platforms
- Known Problems
- CMake vs. Autotools installations


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

    Configuration:
    -------------
    - Rework CMake command files to fix MPI testing.

      Added setup fixture to remove any test generated files and added DEPENDS
      to test properties to execute tests in order expected.

      (ADB - 2019/02/14, TILABS-111)

    - Disable SZIP or ZLIB options if TGZ files are not available.

      Changed the TGZ option for SZip and ZLib to disable the options
      if the source tar.gz files are not found.

      (ADB - 2019/02/05, HDFFV-10697)

    - Rework CMake versioning for OSX platforms.

      Changed the current_version and compatibility_version flags from optional
      with HDF5_BUILD_WITH_INSTALL_NAME to always setting the flags for OSX.

      (ADB - 2019/01/22, HDFFV-10685)

    - Rework CMake command files to eliminate developer CMP005 warning

      Use variables without quotes in if () statements.

      (ADB - 2019/01/18, TILABS-105)

    - Rework CMake configure files to eliminate developer CMP0075 warning

      Renamed varname to HDF5_REQUIRED_LIBRARIES as the contents were not
      required for configuration. Also moved check includes calls to top of
      files.

      (ADB - 2019/01/03, HDFFV-10546)

    - Keep stderr and stdout separate in tests

      Changed test handling of output capture. Tests now keep the stderr
      output separate from the stdout output. It is up to the test to decide
      which output to check against a reference. Also added the option
      to grep for a string in either output.

      (ADB - 2018/12/12, HDFFV-10632)

    - Add toolchain and cross-compile support

      Added info on using a toolchain file to INSTALL_CMAKE.txt. A
      toolchain file is also used in cross-compiling, which requires
      CMAKE_CROSSCOMPILING_EMULATOR to be set. To help with cross-compiling
      the fortran configure process, the HDF5UseFortran.cmake file macros
      were improved. Fixed a Fortran configure file issue that incorrectly
      used #cmakedefine instead of #define.

      (ADB - 2018/10/04, HDFFV-10594)

    - Add warning flags for Intel compilers

      Identified Intel compiler specific warnings flags that should be used
      instead of GNU flags.

      (ADB - 2018/10/04, TRILABS-21)

    - Add default rpath to targets

      Default rpaths should be set in shared executables and
      libraries to allow the use of loading dependent libraries
      without requiring LD_LIBRARY_PATH to be set. The default
      path should be relative using @rpath on osx and $ORIGIN
      on linux. Windows is not affected.

      (ADB - 2018/09/26, HDFFV-10594)

    - Incorrectly installed private header files were removed from
      CMake installs.

      The CMake build files incorrectly flagged the following header files
      as public and installed them. They are private and will no longer be
      installed.

        HDF5 library private package files (H5Xpkg.h)
        H5Edefin.h
        H5Einit.h
        H5Eterm.h
        H5LTparse.h
        h5diff.h
        h5tools_dump.h
        h5tools.h
        h5tools_ref.h
        h5tools_str.h
        h5tools_utils.h
        h5trav.h

      (DER - 2018/10/26, HDFFV-10614, 10609)

    - Autotools installs now install H5FDwindows.h

      This is simply to align the installed header files between the
      autotools and CMake. H5FDwindows.h has no functionality on
      non-Windows systems.

      (DER - 2018/10/26, HDFFV-10614)

    - Added a new option to enable/disable using pread/pwrite instead of
      read/write in the sec2, log, and core VFDs.

      This option is enabled by default when pread/pwrite are detected.

      Autotools:    --enable-preadwrite
      CMake:        HDF5_ENABLE_PREADWRITE

      (DER - 2019/02/03, HDFFV-10696)


    Library:
    --------
    - Added new chunk query functions

      The following public functions were added to discover information about
      the chunks in an HDF5 file.
        herr_t H5Dget_num_chunks(dset_id, fspace_id, *nchunks)
        herr_t H5Dget_chunk_info_by_coord(dset_id, *coord, *filter_mask, *addr, *size)
        herr_t H5Dget_chunk_info(dset_id, fspace_id, index, *coord, *filter_mask, *addr, *size)

      (BMR - 2018/11/07, HDFFV-10615)

    - Allow pre-generated H5Tinit.c and H5make_libsettings.c to be used.

      Rather than always running H5detect and generating H5Tinit.c and
      H5make_libsettings.c, supply a location for those files.

      (ADB - 2018/09/18, HDFFV-10332)

    - Several empty public header files where removed from the distribution

      The following files were empty placeholders. They are for internal
      packages that are unlikely to ever have public functionality and have
      thus been removed.

        H5Bpublic.h
        H5B2public.h
        H5FSpublic.h
        H5HFpublic.h
        H5HGpublic.h
        H5HLpublic.h

      They were only installed in CMake builds.

      (DER - 2018/10/26, HDFFV-10614)

    - Add ability to minimze dataset object headers.

      Creation of many, very small datasets resulted in extensive file bloat
      due to extra space in the dataset object headers -- this space is
      allocated by default to allow for the insertion of a small number of
      attributes within the object header and not require a continuation
      block, an unnecessary provision in the target use case.

      Inform the library to expect no attributes on created datasets, and to
      allocate the least space possible for the object headers.
      NOTE: A continuation block is created if attributes are added to a
      'minimized' dataset, which can reduce performance.
      NOTE: Some extra space is allocated for attributes essential to the
      correct behavior of the object header (store creation times, e.g.). This
      does not violate the design principle, as the space is calculated and
      allocated as needed at the time of dataset object header creation --
      unused space is not generated.
      New API calls:
      H5Fget_dset_no_attrs_hint
      H5Fset_dset_no_attrs_hint
      H5Pget_dset_no_attrs_hint
      H5Pset_dset_no_attrs_hint

      (JOS - 2019/01/04, TRILAB-45)

    - The sec2, log, and core VFDs can now use pread/pwrite instead of
      read/write.

      pread and pwrite do not change the file offset, a feature that was
      requested by a user working with a multi-threaded application.

      The option to configure this feature is described above.

      (DER - 2019/02/03, HDFFV-10696)


     Parallel Library:
    -----------------
    - All MPI-1 API calls have been replaced with MPI-2 equivalents.

      This was done to better support OpenMPI, as default builds no longer
      include MPI-1 support (as of OpenMPI 4.0).

      (DER - 2018/12/30, HDFFV-10566)

    - Changed the default behavior in parallel when reading the same dataset in its entirely
      (i.e. H5S_ALL dataset selection) which is being read by all the processes collectively.
      The dataset mush be contiguous, less than 2GB, and of an atomic datatype.
      The new behavior is the HDF5 library will use an MPI_Bcast to pass the data read from
      the disk by the root process to the remain processes in the MPI communicator associated
      with the HDF5 file.

      (MSB - 2019/01/02, HDFFV-10652)

    Fortran Library:
    ----------------
    - Added wrappers for dataset object header minimization calls.
      (see the note for TRILAB-45, above)

      New API calls:

      h5fget_dset_no_attrs_hint_f
      h5fset_dset_no_attrs_hint_f
      h5pget_dset_no_attrs_hint_f
      h5pset_dset_no_attrs_hint_f

      (DER - 2019/01/09, TRILAB-45)

    - Added new Fortran derived type, c_h5o_info_t, which is interoperable with
      C's h5o_info_t. This is needed for callback functions which
      pass C's h5o_info_t data type definition.

      (MSB, 2019/01/08, HDFFV-10443)

    - Added new Fortran API, H5gmtime, which converts (C) 'time_t' structure
      to Fortran DATE AND TIME storage format.

      (MSB, 2019/01/08, HDFFV-10443)

    - Added new Fortran 'fields' optional parameter to: h5ovisit_f, h5oget_info_by_name_f,
      h5oget_info, h5oget_info_by_idx and h5ovisit_by_name_f.

      (MSB, 2019/01/08, HDFFV-10443)

    C++ Library:
    ------------
    -

    Java Library:
    ----------------
    - Add new functions to java interface

      Added wrappers for:
      H5Fset_libver_bounds
      H5Fget_dset_no_attrs_hint/H5Fset_dset_no_attrs_hint
      H5Pget_dset_no_attrs_hint/H5Pset_dset_no_attrs_hint

      (ADB - 2019/01/07, HDFFV-10664)

    - Fix java unit tests when Time is a natural number

      Time substitution in java/test/junit.sh.in doesn't
      handle the case when Time is a natural number. Fixed
      the regular expression.

      (ADB - 2019/01/07, HDFFV-10674)

    - Duplicate the data read/write functions of Datasets for Attributes.

      Region references could not be displayed for attributes as they could
      for datasets. Datasets had overloaded read and write functions for different
      datatypes that were not available for attributes. After adding similar
      functions, attribute region references work normally.

      (ADB - 2018/12/12, HDFVIEW-4)


    Tools:
    ------
    - The h5repart -family-to-sec2 argument was changed to -family-to-single

      In order to better support other single-file VFDs which could work with
      h5repart, the -family-to-sec2 argument was renamed to -family-to-single.
      This is just a name change and the functionality of the argument has not
      changed.

      The -family-to-sec2 argument has been kept for backwards-compatibility.
      This argument should be considered deprecated.

      (DER - 2018/11/14, HDFFV-10633)

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

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

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

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

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

Bug Fixes since HDF5-1.10.3 release
==================================

    Library
    -------
    - Fix hangs with collective metadata reads during chunked dataset I/O

      In the parallel library, it was discovered that when a particular
      sequence of operations following a pattern of:

      "write to chunked dataset" -> "flush file" -> "read from dataset"

      occurred with collective metadata reads enabled, hangs could be
      observed due to certain MPI ranks not participating in the collective
      metadata reads.

      To fix the issue, collective metadata reads are now disabled during
      chunked dataset raw data I/O.

      (JTH - 2019/02/11, HDFFV-10563, HDFFV-10688)

    - Performance issue when closing an object

      The slow down is due to the search of the "tag_list" to find
      out the "corked" status of an object and "uncork" it if so.

      Improve porformance by skipping the search of the "tag_list"
      if there are no "corked" objects when closing an object.

      (VC - 2019/2/6)

    - Revert H5Oget_info* and H5Ovisit* functions

      In 1.10.3 new H5Oget_info*2 and H5Ovisit*2 functions were
      added for performance. Inadvertently, the original functions;
          H5Oget_info,
          H5Oget_info_by_name,
          H5Oget_info_by_idx,
          H5Ovisit,
          H5Ovisit_by_name
      were versioned to H5Oget_info*1 and H5Ovisit*1. This
      broke the API compatibility for a maintenance release. The
      original functions have been restored.

      (ADB - 2019/01/24, HDFFV-10686)

    - Fixed a potential invalid memory access and failure that could occur when
      decoding an unknown object header message (from a future version of the
      library).

      (NAF - 2019/01/07)

    - Deleting attributes in dense storage

      The library aborts with "infinite loop closing library" after
      attributes in dense storage are created and then deleted.

      When deleting the attribute nodes from the name index v2 B-tree,
      if an attribute is found in the intermediate B-tree nodes,
      which may be merged/redistributed in the process, we need to
      free the dynamically allocated spaces for the intermediate
      decoded attribute.

      (VC - 2018/12/26, HDFFV-10659)

    - Fixed an issue where the parallel filters tests would fail
      if zlib was not available on the system. Until support can
      be added in the tests for filters beyond gzip/zlib, the tests
      will be skipped if zlib is not available.

      (JTH - 2018/12/05)

    - A bug was discovered in the parallel library where an application
      would eventually consume all of the available MPI communicators
      when continually writing to a compressed dataset in parallel. This
      was due to internal copies of an HDF5 File Access Property List,
      which each contained a copy of the MPI communicator, not being
      closed at the end of each write operation. This problem was
      exacerbated by larger numbers of processors.

      (JTH - 2018/12/05, HDFFV-10629)

    - Allow H5detect and H5make_libsettings to take a file as an argument.

      Rather than only writing to stdout, add a command argument to name
      the file that H5detect and H5make_libsettings will use for output.
      Without an argument, stdout is still used, so backwards compatibility
      is maintained.

      (ADB - 2018/09/05, HDFFV-9059)

    - A bug was discovered in the parallel library where an application
      would hang if a collective read/write of a chunked dataset occurred
      when collective metadata reads were enabled and some of the ranks
      had no selection in the dataset's dataspace. The ranks which had no
      selection in the dataset's dataspace called H5D__chunk_addrmap() to
      retrieve the lowest chunk address in the dataset. This is because we
      require reads/writes to be performed in strictly non-decreasing order
      of chunk address in the file.

      When the chunk index used was a version 1 or 2 B-tree, these
      non-participating ranks would issue a collective MPI_Bcast() call
      that the participating ranks would not issue, causing the hang. Since
      the non-participating ranks are not actually reading/writing anything,
      the H5D__chunk_addrmap() call can be safely removed and the address used
      for the read/write can be set to an arbitrary number (0 was chosen).

      (JTH - 2018/08/25, HDFFV-10501)

    - There was missing protection against division by zero reported to
      The HDF Group as issue #CVE-2018-17233.

      Protection against division by zero was added to address the issue
      #CVE-2018-17233.  In addition, several similar occurrences in the same
      file were fixed as well.

      (BMR - 2018/12/23, HDFFV-10577)

    - There was missing protection against division by zero reported to
      The HDF Group as issue #CVE-2018-17434.

      Protection against division by zero was added to address the issue
      #CVE-2018-17434.

      (BMR - 2019/01/29, HDFFV-10586)

    - The issue CVE-2018-17437 was reported to The HDF Group

      Although CVE-2018-17437 reported a memory leak, the actual issue
      was invalid read. It was found that the attribute name length
      in an attribute message was corrupted, which caused the buffer
      pointer to be advanced too far and later caused an invalid read.

      A check was added to detect when the attribute name or its length
      was corrupted and report the potential of data corruption.

      (BMR - 2019/01/29, HDFFV-10588)

    - H5Ewalk did not stop when it was supposed to

      H5Ewalk was supposed to stop when the callback function stopped
      even though the errors in the stack were not all visited, but it
      did not.  This problem is now fixed.

      (BMR - 2019/01/29, HDFFV-10684)

    - Uninitialized bytes from a type conversion buffer could be written
      to disk in H5Dwrite calls where type conversion takes place
      and the type conversion buffer was created by the HDF5 library.

      When H5Dwrite is called and datatype conversion must be performed,
      the library will create a temporary buffer for type conversion if
      one is not provided by the user via H5Pset_buffer. This internal
      buffer is allocated via malloc and contains uninitialized data. In
      some datatype conversions (float to long double, possibly others),
      some of this uninitialized data could be written to disk.

      This was flagged by valgrind in the dtransform test and does not
      appear to be a common occurrence (it is flagged in one test out
      of the entire HDF5 test suite).

      Switching to calloc fixed the problem.

      (DER - 2019/02/03, HDFFV-10694)


    Java Library:
    ----------------
    - JNI native library dependencies

      The build for the hdf5_java native library used the wrong
      hdf5 target library for CMake builds. Correcting the hdf5_java
      library to build with the shared hdf5 library required testing
      paths to change also.

      (ADB - 2018/08/31, HDFFV-10568)
     - Java iterator callbacks

      Change global callback object to a small stack structure in order
      to fix a runtime crash. This crash was discovered when iterating
      through a file with nested group members. The global variable
      visit_callback is overwritten when recursion starts. When recursion
      completes, visit_callback will be pointing to the wrong callback method.

      (ADB - 2018/08/15, HDFFV-10536)

    - Java HDFLibraryException class

      Change parent class from Exception to RuntimeException.

      (ADB - 2018/07/30, HDFFV-10534)

    - JNI Read and Write

      Refactored variable-length functions, H5DreadVL and H5AreadVL,
      to correct dataset and attribute reads. New write functions,
      H5DwriteVL and H5AwriteVL, are under construction.

      (ADB - 2018/06/02, HDFFV-10519)

    Fortran
    --------
    - Added symbolic links libhdf5_hl_fortran.so to libhdf5hl_fortran.so and
      libhdf5_hl_fortran.a to libhdf5hl_fortran.a in hdf5/lib directory for
      autotools installs.  These were added to match the name of the files
      installed by cmake and the general pattern of hl lib files.  We will
      change the names of the installed lib files to the matching name in
      the next major release.

      (LRK - 2019/01/04, HDFFV-10596)

    - Made Fortran specific subroutines PRIVATE in generic procedures.

      Affected generic procedures were functions in H5A, H5D, H5P, H5R and H5T.

      (MSB, 2018/12/04, HDFFV-10511)

    - Fixed issue with Fortran not returning h5o_info_t field values
      meta_size%attr%index_size and  meta_size%attr%heap_size.

      (MSB, 2018/1/8, HDFFV-10443)


    Tools
    -----
    -

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

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

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

    F90 APIs
    --------
    -

    C++ APIs
    --------
    -

    Testing
    -------
    - Fixed a test failure in testpar/t_dset.c caused by
      the test trying to use the parallel filters feature
      on MPI-2 implementations.

      (JTH, 2019/2/7)

Bug Fixes since HDF5-1.10.2 release
==================================

    Library
    -------
    - Java HDF5LibraryException class

      The error minor and major values would be lost after the
      constructor executed.

      Created two local class variables to hold the values obtained during
      execution of the constructor. Refactored the class functions to retrieve
      the class values rather then calling the native functions.
      The native functions were renamed and called only during execution
      of the constructor.
      Added error checking to calling class constructors in JNI classes.

      (ADB - 2018/08/06, HDFFV-10544)

    - Added checks of the defined MPI_VERSION to guard against usage of
      MPI-3 functions in the Parallel Compression and "big Parallel I/O"
      features when HDF5 is built with MPI-2. Previously, the configure
      step would pass but the build itself would fail when it could not
      locate the MPI-3 functions used.

      As a result of these new checks, HDF5 can again be built with MPI-2,
      but the Parallel Compression feature will be disabled as it relies
      on the MPI-3 functions used.

      (JTH - 2018/08/02, HDFFV-10512)

    - User's patches: CVEs

      The following patches have been applied:

      CVE-2018-11202 - NULL pointer dereference was discovered in
                       H5S_hyper_make_spans in H5Shyper.c (HDFFV-10476)
        https://security-tracker.debian.org/tracker/CVE-2018-11202
        https://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2018-11202

      CVE-2018-11203 - A division by zero was discovered in
                       H5D__btree_decode_key in H5Dbtree.c (HDFFV-10477)
        https://security-tracker.debian.org/tracker/CVE-2018-11203
        https://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2018-11203

      CVE-2018-11204 - A NULL pointer dereference was discovered in
                       H5O__chunk_deserialize in H5Ocache.c (HDFFV-10478)
        https://security-tracker.debian.org/tracker/CVE-2018-11204
        https://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2018-11204

      CVE-2018-11206 - An out of bound read was discovered in
                       H5O_fill_new_decode and H5O_fill_old_decode in H5Ofill.c
                       (HDFFV-10480)
        https://security-tracker.debian.org/tracker/CVE-2018-11206
        https://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2018-11206

      CVE-2018-11207 - A division by zero was discovered in
                       H5D__chunk_init in H5Dchunk.c  (HDFFV-10481)
        https://security-tracker.debian.org/tracker/CVE-2018-11207
        https://cve.mitre.org/cgi-bin/cvename.cgi?name=3DCVE-2018-11207

      (BMR - 2018/7/22, PR#s: 1134 and 1139,
       HDFFV-10476, HDFFV-10477, HDFFV-10478, HDFFV-10480, HDFFV-10481)

    - H5Adelete

      H5Adelete failed when deleting the last "large" attribute that
      is stored densely via fractal heap/v2 b-tree.

      After removing the attribute, update the ainfo message.  If the
      number of attributes goes to zero, remove the message.

      (VC - 2018/07/20, HDFFV-9277)

    - A bug was discovered in the parallel library which caused partial
      parallel reads of filtered datasets to return incorrect data. The
      library used the incorrect dataspace for each chunk read, causing
      the selection used in each chunk to be wrong.

      The bug was not caught during testing because all of the current
      tests which do parallel reads of filtered data read all of the data
      using an H5S_ALL selection. Several tests were added which exercise
      partial parallel reads.

      (JTH - 2018/07/16, HDFFV-10467)

    - A bug was discovered in the parallel library which caused parallel
      writes of filtered datasets to trigger an assertion failure in the
      file free space manager.

      This occurred when the filter used caused chunks to repeatedly shrink
      and grow over the course of several dataset writes. The previous chunk
      information, such as the size of the chunk and the offset in the file,
      was being cached and not updated after each write, causing the next write
      to the chunk to retrieve the incorrect cached information and run into
      issues when reallocating space in the file for the chunk.

      (JTH - 2018/07/16, HDFFV-10509)

    - A bug was discovered in the parallel library which caused the
      H5D__mpio_array_gatherv() function to allocate too much memory.

      When the function is called with the 'allgather' parameter set
      to a non-true value, the function will receive data from all MPI
      ranks and gather it to the single rank specied by the 'root'
      parameter. However, the bug in the function caused memory for
      the received data to be allocated on all MPI ranks, not just the
      singular rank specified as the receiver. In some circumstances,
      this would cause an application to fail due to the large amounts
      of memory being allocated.

      (JTH - 2018/07/16, HDFFV-10467)

    - Error checks in h5stat and when decoding messages

      h5stat exited with seg fault/core dumped when
      errors are encountered in the internal library.

      Add error checks and --enable-error-stack option to h5stat.
      Add range checks when decoding messages: old fill value, old
      layout and refcount.

      (VC - 2018/07/11, HDFFV-10333)

    - 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)

    Configuration
    -------------
    - Applied patches to address Cywin build issues

      There were three issues for Cygwin builds:
      - Shared libs were not built.
      - The -std=c99 flag caused a SIG_SETMASK undeclared error.
      - Undefined errors when buildbing test shared libraries.

      Patches to address these issues were received and incorporated in this version.

      (LRK - 2018/07/18, HDFFV-10475)

    - Moved the location of gcc attribute.

      The gcc attribute(no_sanitize), named as the macro HDF_NO_UBSAN,
      was located after the function name. Builds with GCC 7 did not
      indicate any problem, but GCC 8 issued errors. Moved the
      attribute before the function name, as required.

      (ADB - 2018/05/22, HDFFV-10473)

    - Reworked java test suite into individual JUnit tests.

      Testing the whole suite of java unit tests in a single JUnit run
      made it difficult to determine actual failures when tests would fail.
      Running each file set of tests individually, allows individual failures
      to be diagnosed easier. A side benefit is that tests for optional components
      of the library can be disabled if not configured.

      (ADB - 2018/05/16, HDFFV-9739)

    - Converted CMake global commands ADD_DEFINITIONS and INCLUDE_DIRECTORIES
      to use target_* type commands. This change modernizes the CMake usage
      in the HDF5 library.

      In addition, there is the intention to convert to generator expressions,
      where possible. The exception is Fortran FLAGS on Windows Visual Studio.
      The HDF macros TARGET_C_PROPERTIES and TARGET_FORTRAN_PROPERTIES have
      been removed with this change in usage.

      The additional language (C++ and Fortran) checks have also been localized
      to only be checked when that language is enabled.

      (ADB - 2018/05/08)

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

    Fortran
    --------
    -

    Tools
    -----
    -

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

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

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

    F90 APIs
    --------
    -

    C++ APIs
    --------
    - Adding default arguments to existing functions

      Added the following items:
      + Two more property list arguments are added to H5Location::createDataSet:
        const DSetAccPropList& dapl = DSetAccPropList::DEFAULT
        const LinkCreatPropList& lcpl = LinkCreatPropList::DEFAULT

      + One more property list argument is added to H5Location::openDataSet:
        const DSetAccPropList& dapl = DSetAccPropList::DEFAULT

      (BMR - 2018/07/21, PR# 1146)

    - Improvement C++ documentation

      Replaced the table in main page of the C++ documentation from mht to htm format
      for portability.

      (BMR - 2018/07/17, PR# 1141)

    Testing
    -------

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

    Linux 2.6.32-696.16.1.el6.ppc64 gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
    #1 SMP ppc64 GNU/Linux        g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
    (ostrich)                     GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
                                  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 17.0.0.098 Build 20160721
                                  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 2015 w/ Intel Fortran 16 (cmake)

    Windows 7 x64                 Visual Studio 2013
                                  Visual Studio 2015 w/ Intel Fortran 16 (cmake)
                                  Visual Studio 2015 w/ Intel C, Fortran 2018 (cmake)
                                  Visual Studio 2015 w/ MSMPI 8 (cmake)

    Windows 10                    Visual Studio 2015 w/ Intel Fortran 18 (cmake)

    Windows 10 x64                Visual Studio 2015 w/ Intel Fortran 18 (cmake)
                                  Visual Studio 2017 w/ Intel Fortran 18 (cmake)

    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
    (osx1011dev/osx1011test)      Intel icc/icpc/ifort version 16.0.2

    Mac OS Sierra 10.12.6         Apple LLVM version 8.1.0 (clang/clang++-802.0.42)
    64-bit                        gfortran GNU Fortran (GCC) 7.1.0
    (swallow/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
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 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
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 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
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 4.9.3, 5.3.0, 6.2.0
                                  PGI C, Fortran, C++ for 64-bit target on
                                  x86-64;
                                     Version 17.10-0
                                  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

    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)
                                  GCC Version 7.1.0
                                  OpenMPI 3.0.0-GCC-7.2.0-2.29,
                                     3.1.0-GCC-7.2.0-2.29
                                  Intel(R) C (icc) and C++ (icpc) compilers
                                     Version 17.0.0.098 Build 20160721
                                  with NAG Fortran Compiler Release 6.1(Tozai)

    Linux 3.10.0-327.10.1.el7     MPICH 3.2 compiled with GCC 5.3.0
    #1 SMP x86_64 GNU/Linux
    (moohan)

    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.

    Three tests fail with OpenMPI 3.0.0/GCC-7.2.0-2.29:
        testphdf5 (ecdsetw, selnone, cchunk1, cchunk3, cchunk4, and actualio)
        t_shapesame (sscontig2)
        t_pflush1/fails on exit
    The first two tests fail attempting collective writes.

    CPP ptable test fails on VS2017 with Intel compiler, JIRA issue: HDFFV-10628.
    This test will pass with VS2015 with Intel compiler.

    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.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.