use backtrace_symbols_fmt on FreeBSD to emulate glibc output

"'Tis better to emit than to parse"

Since FreeBSD has backtrace_symbols_fmt(3) and glibc does not,
we'll use the hard-coded glibc backtrace_symbols(3) format.
This saves us the trouble of maintaining separate parsers.

I consider the default glibc format superior, anyways, since the
important piece (%f - filename) is up front, since the %a
(address) is process-specific and not useful when viewed from a
different process.

1 files changed, 2 insertions, 7 deletions

diff --git a/Mwrap.xs b/Mwrap.xs
index 5541559..ceeb495 100644
--- a/Mwrap.xs
+++ b/Mwrap.xs
@@ -23,14 +23,9 @@ static SV *location_string(struct src_loc *l)
                 else
                         sv_setpvf(ret, "%s:%zu", l->f->fn, l->lineno);
         } else {
-                char **s = backtrace_symbols((void *)l->bt, (int)l->bt_len);
-
-                if (!s) {
-                        fprintf(stderr, "backtrace_symbols => NULL: %s\n",
-                                strerror(errno));
-                        return &PL_sv_undef;
-                }
+                char **s = bt_syms(l->bt, l->bt_len);
 
+                if (!s) return &PL_sv_undef;
                 ret = newSVpvn(s[0], strlen(s[0]));
                 free(s);
         }