Bug#946695: foma: segfault on mis-use of "_"

[Kevin Ryde]

Package: foma
Version: 1:0.9.18+r243-6+b1
Severity: minor
File: /usr/bin/foma

Entering command

    regex x_y;

gets a segfault.  gdb says it's in fsm_count() due to deref of net==NULL.

If I'm not mistaken this is incorrect syntax, but it'd be good to get
some message instead of a segfault.

I struck this on trying to use "_" as part of a "def" regex name.  The
def succeeds, but using it is bad.  I suppose enough quoting could work
but better don't do that ...


-- System Information:
Versions of packages foma depends on:
ii  libc6         2.29-2
ii  libfoma0      1:0.9.18+r243-6+b1
ii  libreadline8  8.0-3
ii  libtinfo6     6.1+20190803-1
ii  zlib1g        1:1.2.11.dfsg-1+b1