valgrind warning

[Ben Pfaff]

I'm getting a new valgrind warning in fn_interp_vars():

==27225== Invalid read of size 1
==27225==    at 0x80D3DA8: fn_interp_vars (filename.c:97)
==27225==    by 0x80B5760: configure_driver_line (output.c:769)
==27225==    by 0x80B5C9C: outp_read_devices (output.c:332)
==27225==    by 0x80C5DAE: main (main.c:98)
==27225==  Address 0x46C1C6C is 0 bytes after a block of size 76 alloc'd
==27225==    at 0x401D41A: malloc (vg_replace_malloc.c:149)
==27225==    by 0x80E52F1: xmalloc (xmalloc.c:49)
==27225==    by 0x80D3D3A: fn_interp_vars (filename.c:85)
==27225==    by 0x80B5760: configure_driver_line (output.c:769)
==27225==    by 0x80B5C9C: outp_read_devices (output.c:332)
==27225==    by 0x80C5DAE: main (main.c:98)

Because of the location of the warning, I suspect it's
fn_interp_vars(), not the caller.
-- 
"Sanity is not statistical."
--George Orwell