## Improvements to S3 Documentation
* Create a new document *quickstart_paths.md* that give a summary of the legal path formats used by netcdf-c. This includes both file paths and URL paths.
* Modify *nczarr.md* to remove most of the S3 related text.
* Move the S3 text from *nczarr.md* to a new document *cloud.md*.
* Add some S3-related text to the *byterange.md* document.
Hopefully, this will make it easier for users to find the information they want.
## Rebuild NCZarr Testing
In order to avoid problems with running make check in parallel, two changes were made:
1. The *nczarr_test* test system was rebuilt. Now, for each test.
any generated files are kept in a test-specific directory, isolated
from all other test executions.
2. Similarly, since the S3 test bucket is shared, any generated S3 objects
are isolated using a test-specific key path.
## Other S3 Related Changes
* Add code to ensure that files created on S3 are reclaimed at end of testing.
* Used the bash "trap" command to ensure S3 cleanup even if the test fails.
* Cleanup the S3 related configure.ac flag set since S3 is used in several places. So now one should use the option *--enable-s3* instead of *--enable-nczarr-s3*, although the latter is still kept as a deprecated alias for the former.
* Get some of the github actions yml to work with S3; required fixing various test scripts adding a secret to access the Unidata S3 bucket.
* Cleanup S3 portion of libnetcdf.settings.in and netcdf_meta.h.in and test_common.in.
* Merge partial S3 support into dhttp.c.
* Create an experimental s3 access library especially for use with Windows. It is enabled by using the options *--enable-s3-internal* (automake) or *-DENABLE_S3_INTERNAL=ON* (CMake). Also add a unit-test for it.
* Move some definitions from ncrc.h to ncs3sdk.h
## Other Changes
* Provide a default implementation of strlcpy and move this and similar defaults into *dmissing.c*.
## Overwriting
I think I solved the file overwrite problem by doing light name
mangling of the shared library names. With this change the probabilty
is very small that installing our filter wrappers in a directory will
overwrite code produced by others.
## Default Install Location
I have setup the --with-plugin-dir option default to install in
the following locations in order of preference
1. If HDF5_PLUGIN_PATH is defined (at build time remember), then the last directory in that path will be where the filter wrapper shared libraries will be installed.
2. Otherwise the default is "/usr/local/hdf5/lib/plugin" (on *nix*) or "%ALLUSERSPROFILE%\\hdf5\\lib\\plugin" for Windows or Mingw.
Currently, --with-plugin-dir is disabled by default.
I should note that even if I enable it by default, installing
netcdf-c will still not run "out of the box" because the hypothetical
naive user will not know which compressor libraries need to be
pre-installed before netcdf is installed. Nor will that user have any
way to find out what needs to be installed.
re: https://github.com/Unidata/netcdf-c/issues/2338
re: https://github.com/Unidata/netcdf-c/issues/2294
In issue https://github.com/Unidata/netcdf-c/issues/2338,
Ed Hartnett suggested a better way to install filters to a user
defined location -- for Automake, anyway.
This PR implements that suggestion. It turns out to be more
complicated than it appears, so there are fair number of changes;
mostly to shell scripts. Most of the change is in plugins/Makefile.am.
NOTE: this PR still does NOT address the use of HDF5_PLUGIN_PATH
as the default; this turns out to be complex when dealing with NCZarr.
So this will be addressed in a subsequent post 4.9.0 PR.
## Misc. Changes
1. Record the occurrences of incomplete codecs in libnczarr so that
they can be included in _Codecs attribute correctly. This allows
users to see what missing filters are referenced in the Zarr file.
Primarily affects libnczarr/zfilter.[ch]. Also required creating a
new no-effect filter: H5Zunknown.c.
2. Move the unknown filter test to a separate test file.
3. Incorporates PR https://github.com/Unidata/netcdf-c/pull/2343
