[Bug libfortran/46267] New: strerror() is not necessarily thread-safe

["jb at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46267

           Summary: strerror() is not necessarily thread-safe
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jb@gcc.gnu.org


In libgfortran/io/unix.c (get_oserror) strerror() is called. However, according
to POSIX

http://www.opengroup.org/onlinepubs/9699919799/functions/strerror.html

"The strerror() function need not be thread-safe."

Possible solutions

- On some targets such as Solaris 9 strerror() is thread-safe.

- On Windows there is apparently a thread-safe strerror_s() function.

- POSIX has the thread-safe strerror_r() function. Unfortunately it suffers
from a few issues.
   1) The interface is a bit cumbersome, the caller must allocate a buffer for
the message and pass it in
   2) glibc has also another strerror_r() function with an incompatible
interface. Thus one needs to do some macro trickery to use the POSIX version,
or then use the GNU version on glibc targets.
  In short, it's a trainwreck. See e.g.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6223913  and
https://www.securecoding.cert.org/confluence/display/seccode/CON33-C.+Avoid+race+conditions+when+using+library+functions

- POSIX 2008 has the strerror_l() function which is thread-safe and has a
similar interface as strerror(). Using this, if available, is perhaps the
simplest solution and should at least fix the issue on platforms which have
this function.