Remove asserts on str probe names

`open_kprobes` is a dict of open kprobes. Its keys are strings for normal
probes and a tuple for perf buffers. Normal probes need unregistering on script
exit; perf buffers do not. `cleanup` currently looks for string keys
(specifically type `str`) when working out what to unregister, which is a bit
brittle -- in Python2 strings can be both native `str` and `unicode`, depending
what exactly was passed to `attach-*/detach_*` and whether `from __future__
import unicode_literals` is used (e.g. iovisor#623).

This diff makes the API more relaxed by casting the probe name to `str` to
match the expectations of `cleanup`. This works in py2 (with and without
unicode_literals) and py3.

src/python/bcc/__init__.py

@@ -364,7 +364,6 @@ def _del_kprobe(self, name):
  def attach_kprobe(self, event="", fn_name="", event_re="",
  pid=-1, cpu=0, group_fd=-1):
 
- assert isinstance(event, str), "event must be a string"
  # allow the caller to glob multiple functions together
  if event_re:
  for line in self._get_kprobe_functions(event_re):
@@ -375,6 +374,7 @@ def attach_kprobe(self, event="", fn_name="", event_re="",
  pass
  return
 
+ event = str(event)
  self._check_probe_quota(1)
  fn = self.load_func(fn_name, BPF.KPROBE)
  ev_name = "p_" + event.replace("+", "_").replace(".", "_")
@@ -389,7 +389,7 @@ def attach_kprobe(self, event="", fn_name="", event_re="",
  return self
 
  def detach_kprobe(self, event):
- assert isinstance(event, str), "event must be a string"
+ event = str(event)
  ev_name = "p_" + event.replace("+", "_").replace(".", "_")
  if ev_name not in self.open_kprobes:
  raise Exception("Kprobe %s is not attached" % event)
@@ -403,7 +403,6 @@ def detach_kprobe(self, event):
  def attach_kretprobe(self, event="", fn_name="", event_re="",
  pid=-1, cpu=0, group_fd=-1):
 
- assert isinstance(event, str), "event must be a string"
  # allow the caller to glob multiple functions together
  if event_re:
  for line in self._get_kprobe_functions(event_re):
@@ -414,6 +413,7 @@ def attach_kretprobe(self, event="", fn_name="", event_re="",
  pass
  return
 
+ event = str(event)
  self._check_probe_quota(1)
  fn = self.load_func(fn_name, BPF.KPROBE)
  ev_name = "r_" + event.replace("+", "_").replace(".", "_")
@@ -428,7 +428,7 @@ def attach_kretprobe(self, event="", fn_name="", event_re="",
  return self
 
  def detach_kretprobe(self, event):
- assert isinstance(event, str), "event must be a string"
+ event = str(event)
  ev_name = "r_" + event.replace("+", "_").replace(".", "_")
  if ev_name not in self.open_kprobes:
  raise Exception("Kretprobe %s is not attached" % event)
@@ -527,6 +527,7 @@ def attach_uprobe(self, name="", sym="", addr=None,
  BPF(text).attach_uprobe("/usr/bin/python", "main")
  """
 
+ name = str(name)
  (path, addr) = BPF._check_path_symbol(name, sym, addr)
 
  self._check_probe_quota(1)
@@ -549,6 +550,7 @@ def detach_uprobe(self, name="", sym="", addr=None):
  or binary 'name'.
  """
 
+ name = str(name)
  (path, addr) = BPF._check_path_symbol(name, sym, addr)
  ev_name = "p_%s_0x%x" % (self._probe_repl.sub("_", path), addr)
  if ev_name not in self.open_uprobes:
@@ -570,6 +572,7 @@ def attach_uretprobe(self, name="", sym="", addr=None,
  meaning of additional parameters.
  """
 
+ name = str(name)
  (path, addr) = BPF._check_path_symbol(name, sym, addr)
 
  self._check_probe_quota(1)
@@ -592,6 +595,7 @@ def detach_uretprobe(self, name="", sym="", addr=None):
  or binary 'name'.
  """
 
+ name = str(name)
  (path, addr) = BPF._check_path_symbol(name, sym, addr)
  ev_name = "r_%s_0x%x" % (self._probe_repl.sub("_", path), addr)
  if ev_name not in self.open_uprobes: