Allow skipping EOF validation in row block processing

Because of this piece of code:

https://github.com/nissl-lab/npoi/blob/408ec5aaa9cff0e359c1e837074b161de18ed609/main/HSSF/Model/RecordOrderer.cs#L436-L438

We are having trouble reading XLS files generated by a 3rd party. This has been discussed for example here. So Excel itself and validators allow such invalid format and fix it during saving, but in POI and NPOI this validation kicks in and throws an error that really cannot be easily circumvented.

Would you accept a PR that would check for example a global static flag, like RecordOrderer.ValidateEofOnEndOfRowBlock which would otherwise default to true but would allow reading such files that do not fully follow the spec?

[SheetJSDev]

@tonyqus there are errors in the specs and errors in plenty of third party software, so it’s generally best to start with Excel’s behavior. Attached is a sample BIFF5 XLS file generated using SheetJS https://jsfiddle.net/bk3pjs74/

var ws = XLSX.utils.aoa_to_sheet([
  ["a","b","c"],
  [1,2,3]
]);
var wb = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(wb, ws, "Sheet1");
XLSX.writeFile(wb, "npoi776.xls", { bookType: "biff5" });

BIFF5 file: npoi776.xls

To see a BIFF8 version of this, the library has to be patched to remove the current Window2 write call:

$ git clone --depth=1 https://github.com/sheetjs/sheetjs
$ cd sheetjs
$ <xlsx.flow.js sed '/if.*write_Window2/d' > testlib.js
$ node -pe 'var XLSX = require("./testlib"); var ws = XLSX.utils.aoa_to_sheet([["a","b","c"],[1,2,3]]);var wb = XLSX.utils.book_new();XLSX.utils.book_append_sheet(wb, ws, "Sheet1");XLSX.writeFile(wb, "npoi776.biff8.xls", { bookType: "biff8" });'

BIFF8 file: npoi776.biff8.xls

Both files pass Microsoft’s Binary File Format Validator and open in Excel 2019 for Windows and for Mac. It’s reasonable to assume spec error.

PS: From our old test machine, the program files have the following checksums:

MD5 (BFFWrapper.dll) = ae7fca7869a62b88b3e595aafbd8c81d
MD5 (docValidation.dll) = ef0da1baf8dea3b635ae4be478f643b6
MD5 (pptValidation.dll) = 28171b2b28ea74e03bd1ae07f36d50fd
MD5 (xlsValidation.dll) = 79a2a96d28fb630509b2d88e6a6c8676
MD5 (BFFValidator.exe) = b643c993e358c87423f47c8e8e99aa6f

[tonyqus]

Can you create a PR for this? I think I can review the code. @lahma