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# systemtap python module
# Copyright (C) 2016 Red Hat Inc.
#
# This file is part of systemtap, and is free software. You can
# redistribute it and/or modify it under the terms of the GNU General
# Public License (GPL); either version 2, or (at your option) any
# later version.
# Note that we'd like for this module to be the same between python 2
# and python 3, but the 'print' function has changed quite
# dramatically between the two versions. You'd think we could use the
# '__future__' module's 'print' function so we'd be able to use python
# 3's 'print' function style everywhere. However, this causes python 2
# scripts that get loaded to have to use python 3 print syntax, since
# the '__future__' module's print function "leaks" through to the
# python 2 script. There's probably a way to fix that, but we'll just
# punt and use 'sys.stdout.write()', which is a little less
# convenient, but works the same on both python 2 and python 3.
import cmd
import os.path
import sys
if sys.version_info[0] == 2:
import _HelperSDT
else:
from . import _HelperSDT
class _Breakpoint:
def __init__(self, index, filename, funcname, lineno, flags, key):
self.index = index
self.filename = filename
self.funcname = funcname
self.lineno = lineno
self.key = key
# Decode flags.
self.callp = False
self.returnp = False
if flags & 0x2:
self.callp = True
if flags & 0x1:
self.returnp = True
def dump(self, out=None):
if out is None:
out = sys.stdout
out.write("%s\n" % self.bpformat())
def bpformat(self):
if self.returnp:
disp = '%s.return:%d' % (self.funcname, self.lineno)
elif self.callp:
disp = '%s.call:%d' % (self.funcname, self.lineno)
else:
disp = '%s:%d' % (self.funcname, self.lineno)
return '%-4dbreakpoint at %s:%s %d' % (self.index, self.filename,
disp, self.key)
class _BreakpointList:
def __init__(self):
self._index = 1
self._bynumber = [] # breakpoints indexed by number
# N.B. To make sure we're inside the right function, and not
# just executing a 'def' statement, we need the function name
# for line number breakpoints.
#
# The 'by line' and 'by function' lists are indexed by a (file,
# function, lineno) tuple. The 'by function return' list is
# indexed by a (file, function) tuple.
self._byline = {}
self._byfunc = {}
self._byfuncret = {}
# Let's keep a cache of the os.path.abspath() results, to
# avoid looking up the same paths over and over again.
self._abspath_cache = {}
def _abspath(self, path):
if path in self._abspath_cache:
return self._abspath_cache[path]
abspath = os.path.abspath(path)
self._abspath_cache[path] = abspath
return abspath
def add(self, filename, funcname, lineno, flags, key):
# Ensure we've got a full absolute path here.
filename = self._abspath(filename)
# We get passed the full function name, like
# "class.method". When the breakpoint hits, we only see
# 'method'. So, cut the function name down to the last bit.
period = funcname.rfind('.')
if period >= 0:
funcname = funcname[period + 1:]
bp = _Breakpoint(self._index, filename, funcname, lineno,
flags, key)
self._index += 1
self._bynumber.append(bp)
if bp.returnp:
if (filename, funcname) in self._byfuncret:
self._byfuncret[filename, funcname].append(bp)
else:
self._byfuncret[filename, funcname] = [bp]
elif bp.callp:
if (filename, funcname, lineno) in self._byfunc:
self._byfunc[filename, funcname, lineno].append(bp)
else:
self._byfunc[filename, funcname, lineno] = [bp]
else:
if (filename, funcname, lineno) in self._byline:
self._byline[filename, funcname, lineno].append(bp)
else:
self._byline[filename, funcname, lineno] = [bp]
def dump(self, out=None):
if out is None:
out = sys.stdout
for bp in self._bynumber:
bp.dump(out)
def break_here(self, frame, event):
# Depending on how the script name was passed to python,
# relative or absolute, we might or might not get a full
# pathname here. So, we'll make sure we've got an absolute
# path.
filename = self._abspath(frame.f_code.co_filename)
funcname = frame.f_code.co_name
lineno = frame.f_lineno
if event == 'call':
if (filename, funcname, lineno) in self._byfunc:
return self._byfunc[filename, funcname, lineno]
elif event == 'line':
if (filename, funcname, lineno) in self._byline:
return self._byline[filename, funcname, lineno]
elif event == 'return':
if (filename, funcname) in self._byfuncret:
return self._byfuncret[filename, funcname]
return None
class Dispatcher(cmd.Cmd):
def __init__(self, pyfile):
# Note that using the cmd class here is overkill, but it would
# allow us to add more commands very easily.
cmd.Cmd.__init__(self)
self._bplist = _BreakpointList()
# Note that the filename of breakpoint info has the python
# major version present.
bpFileBase = '_stp_python%d_probes' % sys.version_info[0]
# Read the breakpoints from a file.
lines = []
if 'SYSTEMTAP_MODULE' in os.environ:
self.envModule = os.environ['SYSTEMTAP_MODULE']
bpFileName = "/proc/systemtap/%s/%s" % (self.envModule,
bpFileBase)
try:
bpFile = open(bpFileName)
except IOError:
sys.stderr.write("Error: the '%s' file could not be opened\n"
% bpFileName)
sys.exit(1)
else:
lines = bpFile.readlines()
bpFile.close()
else:
sys.stderr.write("Error: the 'SYSTEMTAP_MODULE' environment"
" variable does not exist\n")
sys.exit(1)
# Now handle each command
for line in lines:
line = line[:-1]
if len(line) > 0 and line[0] != '#':
self.onecmd(line)
def pytrace_dispatch(self, frame, event, arg):
if event == 'call':
bplist = self._bplist.break_here(frame, event)
if bplist:
for bp in bplist:
_HelperSDT.trace_callback(_HelperSDT.PyTrace_CALL,
frame, arg, self.envModule,
bp.key)
return self.pytrace_dispatch
elif event == 'line':
bplist = self._bplist.break_here(frame, event)
if bplist:
for bp in bplist:
_HelperSDT.trace_callback(_HelperSDT.PyTrace_LINE,
frame, arg, self.envModule,
bp.key)
return self.pytrace_dispatch
elif event == 'return':
bplist = self._bplist.break_here(frame, event)
if bplist:
for bp in bplist:
_HelperSDT.trace_callback(_HelperSDT.PyTrace_RETURN,
frame, arg, self.envModule,
bp.key)
return self.pytrace_dispatch
return self.pytrace_dispatch
#
# cmd class commands
#
def do_b(self, arg):
# Breakpoint command:
# b [ MODULE|FUNCTION@FILENAME:LINENO|FLAGS|KEY ]
if not arg:
self._bplist.dump()
return
# Parse argument.
# FIXME: 'module' needed?
# module = None
funcname = None
filename = None
lineno = None
flags = None
key = None
parts = arg.split('|')
if len(parts) != 4:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Wrong number of major parts (%d vs. 4)\n" %
len(parts))
return
# module = parts[0]
filename_arg = parts[1]
try:
flags = int(parts[2])
except:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Invalid flags value (%s)\n" % parts[2])
return
try:
key = int(parts[3])
except:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Invalid key value (%s)\n" % parts[3])
return
parts = filename_arg.split('@')
if len(parts) != 2:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Wrong number of filename parts (%d vs. 2)\n" %
len(parts))
return
funcname = parts[0]
lineno_arg = parts[1]
parts = lineno_arg.split(':')
if len(parts) != 2:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Wrong number of line number parts (%d vs. 2)\n" %
len(parts))
return
filename = parts[0]
try:
lineno = int(parts[1])
except:
sys.stderr.write("Invalid breakpoint format: %s\n" % arg)
sys.stderr.write("Invalid line number value (%s)\n" % parts[1])
return
# Actually add the breakpoint.
self._bplist.add(filename, funcname, lineno, flags, key)
def run():
# Now that we're attached, run the real python file.
mainpyfile = sys.argv[1]
if not os.path.exists(mainpyfile):
sys.stderr.write("Error: '%s' does not exist\n" % mainpyfile)
sys.exit(1)
del sys.argv[0] # Hide this module from the argument list
# Start tracing.
dispatcher = Dispatcher(mainpyfile)
sys.settrace(dispatcher.pytrace_dispatch)
# The script we're about to run has to run in __main__ namespace
# (or imports from __main__ will break).
#
# So we clear up the __main__ namespace and set several special
# variables (this gets rid of our globals).
import __main__
__main__.__dict__.clear()
__main__.__dict__.update({"__name__": "__main__",
"__file__": mainpyfile,
"__builtins__": __builtins__})
# Run the real file. When it finishes, remove tracing.
try:
# execfile(mainpyfile, __main__.__dict__, __main__.__dict__)
exec(compile(open(mainpyfile).read(), mainpyfile, 'exec'),
__main__.__dict__, __main__.__dict__)
finally:
sys.settrace(None)
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