kiwix-search should report about missing ft index

[kelson42]

If a ZIM file is missing the ft index then kiwix-search should:

• return 1 (or any not null error code)
• print an error on STDERR reporting the missing of the index (and therefore the impossibility to run the search properly).

This should work with and without the --suggestion option. In case of --suggestion, as we have a fallback solution (based on native ZIM title list), the returned value should be 0, the error message should be printed on STDERR as a warning.

Requirement comes from #130 discussion

[julianharty]

Yay, thank you.

[arjun-369]

I'd like to resolve this issue. The code can be traced from kiwix-search.cpp to reader.cpp, that provides a method to check if a fulltext index exists within a .zim file.
The ZIM files from #130 aren't available.
Can you provide me with some ZIM files which can be used to test the code.

[kelson42]

I don't think we have one but You can build one pretty easily with mwoffliner

[arjun-369]

In the above image, the ZIM file "wikipedia_en_sociology_nopic_2021-03.zim" contains a fulltext index while the ZIM file "wikiquote_en_all_2021-04.zim" does not contain a fulltext index.

[kelson42]

@arjun-369 Seems you are on the right path, check that all the requirements of the ticket are fullfilled and open a PR please

[mgautierfr]

This should work with and without the --suggestion option. In case of --suggestion, as we have a fallback solution (based on native ZIM title list), the returned value should be 0, the error message should be printed on STDERR as a warning.

In kiwix-search tool, we always the kiwix-lib's Searcher to do the search (suggestion or not).
The Searcher always use the xapian database, the fallback is made by the Reader.

I've tried to change this #136 but you disagree about that (we probably had a discussion elsewhere to agree to drop it).

[mgautierfr]

I've missed read the @kelson42 comment. It was about the return code, not making the suggestion using the fallback.
So I agree.