ucalls: use replace error handler (iovisor#1888)

Prevents the following error when tracing a java program that contains
non-ascii method name:

Traceback (most recent call last):
  File "/usr/share/bcc/tools/lib/ucalls", line 305, in <module>
    data = get_data()   # [(function, (num calls, latency in ns))]
  File "/usr/share/bcc/tools/lib/ucalls", line 266, in get_data
    bpf["counts"].items()))
  File "/usr/share/bcc/tools/lib/ucalls", line 264, in <lambda>
    kv[0].method.decode(),
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc4 in position 11: ordinal not in range(128)

Signed-off-by: Jerome Marchand <[email protected]>

tools/lib/ucalls.py

@@ -255,13 +255,15 @@
 def get_data():
  # Will be empty when no language was specified for tracing
  if args.latency:
- data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
- kv[0].method.decode(),
+ data = list(map(lambda kv: (kv[0].clazz.decode('utf-8', 'replace') \
+ + "." + \
+ kv[0].method.decode('utf-8', 'replace'),
  (kv[1].num_calls, kv[1].total_ns)),
  bpf["times"].items()))
  else:
- data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
- kv[0].method.decode(),
+ data = list(map(lambda kv: (kv[0].clazz.decode('utf-8', 'replace') \
+ + "." + \
+ kv[0].method.decode('utf-8', 'replace'),
  (kv[1].value, 0)),
  bpf["counts"].items()))