fbsd-nat: Return nullptr rather than failing ::thread_name.

ptrace on FreeBSD cannot be used against running processes and instead
fails with EBUSY.  This meant that 'info threads' would fail if any of
the threads were running (for example when using schedule-multiple=on
in gdb.base/fork-running-state.exp).  Instead of throwing errors, just
return nullptr as no thread name is better than causing info threads to
fail completely.

diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
index 89c9ae6a9b7a25c8eb29202a6dd9501deaa4e613..cea3ce7d3840ec159e05086a9a7cb3df14d413f2 100644 (file)
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -819,9 +819,9 @@ fbsd_nat_target::thread_name (struct thread_info *thr)
      if a name has not been set explicitly.  Return a NULL name in
      that case.  */
   if (!fbsd_fetch_kinfo_proc (pid, &kp))
-    perror_with_name (_("Failed to fetch process information"));
+    return nullptr;
   if (ptrace (PT_LWPINFO, lwp, (caddr_t) &pl, sizeof pl) == -1)
-    perror_with_name (("ptrace (PT_LWPINFO)"));
+    return nullptr;
   if (strcmp (kp.ki_comm, pl.pl_tdname) == 0)
     return NULL;
   xsnprintf (buf, sizeof buf, "%s", pl.pl_tdname);