Re: BUG #19704: ispell dictionary accepts trailing junk in numeric COMPOUNDFLAG

Thanks for reporting the bug,

I reproduced this and verified the bug locally. Attached patch adds a check
to ensure the entire token is consumed (skipping trailing whitespace) after
strtol(), matching the existing error-handling style in the same function.
With the patch applied, the example above correctly fails with invalid
affix flag "1x".

I tested this manually: the malformed case above now errors, a normal valid
case (COMPOUNDFLAG 1) still works as before, and the full regression suite
passes (240/240). I haven't added a dedicated regression test for this yet,
because I was not sure if my patch was correct or in the right direction.
I'd be happy to implement changes and regression tests suggested.

Regards,
Samriddha

On Sun, Sep 20, 2026 at 4:35 PM PG Bug reporting form <
noreply(at)postgresql(dot)org> wrote:

> The following bug has been logged on the website:
>
> Bug reference: 19704
> Logged by: Qifan Liu
> Email address: imchifan(at)163(dot)com
> PostgreSQL version: 18.6
> Operating system: Linux/amd64
> Description:
>
> Creating an ispell text-search dictionary from an affix file containing
> COMPOUNDFLAG 1x and FLAG num succeeds. PostgreSQL interprets the malformed
> compound flag as numeric flag 1. This can cause subtle text-search behavior
> in dictionaries installed from malformed affix files.
>
> Steps to reproduce
> ------------------
> Run as an operating-system user allowed to create files in PostgreSQL's
> tsearch_data directory.
>
> set -eu
> sd=$(pg_config --sharedir)/tsearch_data
> n=pg_numeric_compoundflag
> printf 'SET UTF-8\nCOMPOUNDFLAG 1x\nFLAG num\n' > "$sd/$n.affix"
> printf '2\nfoo/1\nbar/1\n' > "$sd/$n.dict"
> psql -X -v ON_ERROR_STOP=1 -At postgres <<SQL
> CREATE TEXT SEARCH DICTIONARY $n (
> TEMPLATE = ispell,
> DictFile = $n,
> AffFile = $n
> );
> SELECT coalesce(array_to_string(ts_lexize('$n', 'foo'), ','), 'NULL');
> SQL
>
> Actual result
> -------------
> Dictionary creation succeeds, and the malformed COMPOUNDFLAG value is
> treated as flag 1:
>
> CREATE TEXT SEARCH DICTIONARY
> foo
>
> Expected result
> ---------------
> Dictionary creation should fail with a configuration-file error because
> "1x"
> is not a valid numeric flag. PostgreSQL should not accept the prefix "1",
> discard the trailing "x", and subsequently lexize the entry as flag 1.
>
> Additional information
> ----------------------
> The issue was reproduced on PostgreSQL 20devel, PostgreSQL 18.6, and
> PostgreSQL 17.11.
> Inference: numeric flag conversion validates the converted prefix or range
> but does not verify that conversion consumed the entire token.
>
>
>
>
>