Bruno Haible <[EMAIL PROTECTED]> wrote: > Jim Meyering wrote: >> When I build a coreutils snapshot with -D_FORTIFY_SOURCE=2 on a >> relatively recent fedora-based system, seq always aborts like this: >> >> $ ./seq 1 >> *** %n in writable segment detected *** >> 1zsh: abort ./seq 1 >> [Exit 134 (ABRT)] >> >> That is due to the fact that vasnprintf writes %n into a format >> string that is subsequently used by snprintf. > > Use of %n is valid in ISO C99 and in POSIX.
As you know I don't dispute its validity. However, vasnprintf.c should resort to incurring the expense of that portability kludge only when necessary. How about if it does that only when a configure-time test has detected that snprintf's return value is not conforming? Then, vasnprintf.c will be more efficient, and won't use the offending %n, on the vast majority of systems that have an snprintf implementation with a conforming return value.
