re: issue https://github.com/Unidata/netcdf-c/issues/1251
Assume that you have the URL to a remote dataset
which is a normal netcdf-3 or netcdf-4 file.
This PR allows the netcdf-c to read that dataset's
contents as a netcdf file using HTTP byte ranges
if the remote server supports byte-range access.
Originally, this PR was set up to access Amazon S3 objects,
but it can also access other remote datasets such as those
provided by a Thredds server via the HTTPServer access protocol.
It may also work for other kinds of servers.
Note that this is not intended as a true production
capability because, as is known, this kind of access to
can be quite slow. In addition, the byte-range IO drivers
do not currently do any sort of optimization or caching.
An additional goal here is to gain some experience with
the Amazon S3 REST protocol.
This architecture and its use documented in
the file docs/byterange.dox.
There are currently two test cases:
1. nc_test/tst_s3raw.c - this does a simple open, check format, close cycle
for a remote netcdf-3 file and a remote netcdf-4 file.
2. nc_test/test_s3raw.sh - this uses ncdump to investigate some remote
datasets.
This PR also incorporates significantly changed model inference code
(see the superceded PR https://github.com/Unidata/netcdf-c/pull/1259).
1. It centralizes the code that infers the dispatcher.
2. It adds support for byte-range URLs
Other changes:
1. NC_HDF5_finalize was not being properly called by nc_finalize().
2. Fix minor bug in ncgen3.l
3. fix memory leak in nc4info.c
4. add code to walk the .daprc triples and to replace protocol=
fragment tag with a more general mode= tag.
Final Note:
Th inference code is still way too complicated. We need to move
to the validfile() model used by netcdf Java, where each
dispatcher is asked if it can process the file. This decentralizes
the inference code. This will be done after all the major new
dispatchers (PIO, Zarr, etc) have been implemented.
https://github.com/Unidata/netcdf-c/issues/1168https://github.com/Unidata/netcdf-c/issues/1163https://github.com/Unidata/netcdf-c/issues/1162
This PR partially fixes memory leaks in the netcdf-c library,
in the ncdump utility, and in some test cases.
The netcdf-c library now runs memory clean with the assumption
that the --disable-utilities option is used. The primary remaining
problem is ncgen. Once that is fixed, I believe the netcdf-c library
will run memory clean with no limitations.
Notes
-----------
1. Memory checking was performed using gcc -fsanitize=address.
Valgrind-based testing has yet to be performed.
2. The pnetcdf, hdf4, and examples code has not been tested.
Misc. Non-leak changes
1. Make tst_diskless2 only run when netcdf4 is enabled (issue 1162)
2. Fix CmakeLists.txt to turn off logging if ENABLE_NETCDF_4 is OFF
3. Isolated all my debug scripts into a single top-level directory
called debug
4. Fix some USE_NETCDF4 dependencies in nc_test and nc_test4 Makefile.am
re: https://github.com/Unidata/netcdf-c/issues/1154
Inadvertently, the behavior of NC_DISKLESS with nc_create() was
changed in release 4.6.1. Previously, the NC_WRITE flag needed
to be explicitly used with NC_DISKLESS in order to cause the
created file to be persisted to disk.
Additional analyis indicated that the current NC_DISKLESS
implementation was seriously flawed.
This PR attempts to clean up and regularize the situation with
respect to NC_DISKLESS control. One important aspect of diskless
operation is that there are two different notions of write.
1. The file is read-write vs read-only when using the netcdf API.
2. The file is persisted or not to disk at nc_close().
Previously, these two were conflated. The rules now are
as follows.
1. NC_DISKLESS + NC_WRITE means that the file is read/write using the netcdf API
2. NC_DISKLESS + NC_PERSIST means that the file is persisted to a disk file at nc_close.
3. NC_DISKLESS + NC_PERSIST + NC_WRITE means both 1 and 2.
The NC_PERSIST flag is new and takes over the obsolete NC_MPIPOSIX flag.
NC_MPIPOSIX is still defined, but is now an alias for the NC_MPIIO flag.
It is also now the case that for netcdf-4, NC_DISKLESS is independent
of NC_INMEMORY and in fact it is an error to specify both flags
simultaneously.
Finally, the MMAP code was fixed to use NC_PERSIST as well.
Also marked MMAP as deprecated.
Also added a test case to test various combinations of NC_DISKLESS,
NC_PERSIST, and NC_WRITE.
This PR affects a number of files and especially test cases
that used NC_DISKLESS.
Misc. Unrelated fixes
1. fixed some warnings in ncdump/dumplib.c
re: https://github.com/Unidata/netcdf-c/issues/972
The current szip plugin code in the HDF5 library has some
unexpected behaviors that require some changes to how
nc_inq_var_szip is implemented and to the corresponding tests:
nc_test4/{test_szip,tst_vars3}.
Specifically, the following can happen:
1. The number of parameters provided by the user will be two,
but the number of parameters returned by nc_inq_var_filter
will be four because the HDF5 code (H5Zszip) will add two
extra parameters for internal use. It turns out that the two
parameters provided when calling nc_def_var_filter correspond
to the first two parameters of the four parameters returned
by nc_inq_var_filter.
2. The nc_inq_var_szip values corresponding to the ones provided
by the caller may be different than those provided by
nc_def_var_filter. The value of the options_mask argument is
known to add additional flag bits, and the pixels_per_block
parameter may be modified.
re: github issue https://github.com/Unidata/netcdf-c/issues/1111
One of the less common use cases for the in-memory feature is
apparently failing with HDF5-1.10.x. The fix is complicated and
requires significant changes to libhdf5/nc4memcb.c. The current
setup is detailed in the file docs/inmeminternal.dox.
Additionally, it was discovered that the program
nc_test/tst_inmemory.c, which is invoked by
nc_test/run_inmemory.sh, actually was failing because of the
above problem. But the failure is not detected since the script
does not return non-zero value.
Other Changes:
1. Fix nc_test_tst_inmemory to return errors correctly.
2. Make ncdap_tests/findtestserver.c and dap4_tests/findtestserver4.c
be generated from ncdap_test/findtestserver.c.in.
3. Make LOG() print output to stderr instead of stdout to
avoid contaminating e.g. ncdump output.
4. Modify the handling of NC_INMEMORY and NC_DISKLESS flags
to properly handle that NC_DISKLESS => NC_INMEMORY. This
affects a number of code pieces, especially memio.c.
stored in the _NCProperties attribute to allow two things:
1. capture of additional library dependencies (over and above
hdf5)
2. Recognition of non-netcdf libraries that create netcdf-4 format
files.
To this end, the _NCProperties format has been extended to be
and arbitrary set of key=value pairs separated by commas.
This new format has version = 2, and uses commas as the pair separator.
Thus the general form is:
_NCProperties = "version=2,key1=value,key2=value2..." ;
This new version is accompanied by a new ./configure option of the form
--with-ncproperties="key1=value1,key2=value2..."
that specifies pairs to add to the _NCProperties attribute for all
files created with that netcdf library.
At this point, what is missing is some programmatic way to
specify either all the pairs or additional pairs
to the _NCProperties attribute. Not sure of the best way
to do this.
Builders using non-netcdf libraries can specify
whatever they want in the key value pairs (as long
as the version=2 is specified first).
By convention, the primary library is expected to be the
the first pair after the leading version=2 pair, but this
is convention only and is neither required nor enforced.
Related changes:
1. Fixed the tests that check _NCProperties to properly operate with version=2.
2. When reading a version 1 _NCProperties attribute, convert it to look
like a version 2 attribute.
2. Added some version 2 tests to ncdump/tst_fileinfo.c and
ncdump/tst_fileinfo.sh
Misc Changes:
1. Fix minor problem in ncdap_test/testurl.sh where a parameter to
buildurl needed to be quoted.
2. Minor fix to ncgen to swap switches -H and -h to be consistent
with other utilities.
3. Document the -M flag in nccopy usage() and the nccopy man page.
4. Modify a test case to use the nccopy -M flag.
