Hi,

the attached patch improves the error handling for backtrace failing,
by printing the error number or the error string in addition to the
message. It also fixes a potential null pointer crash in gf_strerror.

Regtested on x86_64-pc-linux-gnu, Ok for trunk?

2015-09-01  Janne Blomqvist  <jb@gcc.gnu.org>

    PR libfortran/67414
    * io/write.c (gfc_itoa): Move to runtime/string.c.
    * libgfortran.h (show_backtrace): Make arg bool.
    (gfc_itoa): New prototype.
    * runtime/backtrace.c (struct mystate): Change type of try_simple
    field, add in_signal_handler field.
    (error_callback): Print out error number, or if not in a signal
    handler, the error message.
    (show_backtrace): Change type of arg, change initialization of
    struct mystate.
    (backtrace): Call show_backtrace with correct arg type.
    * runtime/compile_options.c (backtrace_handler): Call with correct
    arg type.
    * runtime/error.c (sys_abort): Likewise.
    (gf_strerror): Handle newlocale() failure.
    * runtime/string.c (gfc_itoa): Function moved here from
    io/write.c.


-- 
Janne Blomqvist