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Allow Nc4Iosp to open CDF-5 files through netCDF-C in strict mode #1564

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Merged
lesserwhirls merged 1 commit into from
Jun 17, 2026
+10 −9
Merged

Allow Nc4Iosp to open CDF-5 files through netCDF-C in strict mode #1564

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19 changes: 10 additions & 9 deletions netcdf4/src/main/java/ucar/nc2/jni/netcdf/Nc4Iosp.java
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Original file line number Diff line number Diff line change
Expand Up @@ -196,12 +196,13 @@ public void setChunker(Nc4Chunking chunker) {
}

/**
* Checks whether {@code raf} is a valid file NetCDF-4 file. Actually, it checks whether it is a valid HDF-5 file of
* any type. Furthermore, it checks whether the NetCDF C library is available on the system. If both conditions are
* satisfied, this method returns {@code true}; otherwise it returns {@code false}.
* Checks whether {@code raf} is a HDF-5 or CDF-5 file. Furthermore, it checks whether the netCDF-C library
* is available on the system. If {@link NetcdfClibrary#isStrictRead()} is {@code true}, it strictly limits
* reading to files that are likely netCDF-4, not just any HDF-5 file. If {@code false}, it will attempt to
* read any HDF-5 or CDF-5 file through the netCDF-C library.
*
* @param raf a file on disk.
* @return {@code true} if {@code raf} is a valid HDF-5 file and the NetCDF C library is available.
* @return {@code true} if {@code raf} is a valid HDF-5 or CDF-5 file and the netCDF-C library is available.
* @throws IOException if an I/O error occurs.
*/
@Override
Expand All @@ -223,12 +224,12 @@ public boolean isValidFile(RandomAccessFile raf) throws IOException {
} else if (!isClibraryPresent()) {
log.debug("File appears to be valid but netCDF-C isn't installed: {}", raf.getLocation());
} else {
// file appears to be valid and netCDF-c is present
// file appears to be valid and netCDF-C is present
if (NetcdfClibrary.isStrictRead()) {
// strictly limit to reading files that are very likely netcdf4
validCheck2 = isLikelyNetcdf4(raf);
// strictly limit to reading files that are very likely netCDF-4 or CDF-5
validCheck2 = format == NCheader.NC_FORMAT_64BIT_DATA || isLikelyNetcdf4(raf);
} else {
// try to read all HDF5 files through the netCDF-C library
// try to read all HDF-5 and CDF-5 files through the netCDF-C library
validCheck2 = true;
}
}
Expand All @@ -253,7 +254,7 @@ public String getFileTypeId() {

@Override
public String getFileTypeVersion() {
// TODO this only works for files writtten by netcdf4 c library. what about plain hdf5?
// TODO this only works for files written by netcdf4 c library. what about plain hdf5?
return ncfile.getRootGroup().findAttributeString(CDM.NCPROPERTIES, "N/A");
}

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