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#
# Author: Zoltan Varga (vargaz@gmail.com)
# License: MIT/X11
#
#
# This is a mono support mode for a python-enabled gdb:
# http://sourceware.org/gdb/wiki/PythonGdb
# Usage:
# - copy/symlink this file, plus mono-gdbinit to the directory where the mono
# executable lives.
# - run mono under gdb, or attach to a mono process using gdb
# - Type 'xdb' in gdb to load/reload the debugging info emitted by the runtime.
# - The debug info is emitted to a file called xdb.s in the current working directory.
# When attaching to a mono process, make sure you are in the same directory.
#
from __future__ import print_function
import os
class StringPrinter:
"Print a C# string"
def __init__(self, val):
self.val = val
def to_string(self):
if int(self.val.cast (gdb.lookup_type ("guint64"))) == 0:
return "null"
obj = self.val.cast (gdb.lookup_type ("MonoString").pointer ()).dereference ()
len = obj ['length']
chars = obj ['chars']
i = 0
res = ['"']
while i < len:
val = (chars.cast(gdb.lookup_type ("gint64")) + (i * 2)).cast(gdb.lookup_type ("gunichar2").pointer ()).dereference ()
if val >= 256:
c = "\u%X".format (val)
else:
c = chr (val)
res.append (c)
i = i + 1
res.append ('"')
return ''.join (res)
def stringify_class_name(ns, name):
if ns == "System":
if name == "Byte":
return "byte"
if name == "String":
return "string"
if ns == "":
return name
else:
return "{0}.{1}".format (ns, name)
class ArrayPrinter:
"Print a C# array"
def __init__(self, val, class_ns, class_name):
self.val = val
self.class_ns = class_ns
self.class_name = class_name
def to_string(self):
obj = self.val.cast (gdb.lookup_type ("MonoArray").pointer ()).dereference ()
length = obj ['max_length']
return "{0} [{1}]".format (stringify_class_name (self.class_ns, self.class_name [0:len (self.class_name) - 2]), int (length))
class ObjectPrinter:
"Print a C# object"
def __init__(self, val):
if str(val.type)[-1] == "&":
self.val = val.address.cast (gdb.lookup_type ("MonoObject").pointer ())
else:
self.val = val.cast (gdb.lookup_type ("MonoObject").pointer ())
class _iterator:
def __init__(self,obj):
self.obj = obj
self.iter = self.obj.type.fields ().__iter__ ()
pass
def __iter__(self):
return self
def next(self):
field = self.iter.next ()
try:
if str(self.obj [field.name].type) == "object":
# Avoid recursion
return (field.name, self.obj [field.name].cast (gdb.lookup_type ("void").pointer ()))
else:
return (field.name, self.obj [field.name])
except:
# Superclass
return (field.name, self.obj.cast (gdb.lookup_type ("{0}".format (field.name))))
def children(self):
# FIXME: It would be easier if gdb.Value would support iteration itself
# It would also be better if we could return None
if int(self.val.cast (gdb.lookup_type ("guint64"))) == 0:
return {}.__iter__ ()
try:
obj = self.val.dereference ()
class_ns = obj ['vtable'].dereference ()['klass'].dereference ()['name_space'].string ()
class_name = obj ['vtable'].dereference ()['klass'].dereference ()['name'].string ()
if class_name [-2:len(class_name)] == "[]":
return {}.__iter__ ()
gdb_type = gdb.lookup_type ("struct {0}_{1}".format (class_ns.replace (".", "_"), class_name))
return self._iterator(obj.cast (gdb_type))
except:
print (sys.exc_info ()[0])
print (sys.exc_info ()[1])
return {}.__iter__ ()
def to_string(self):
if int(self.val.cast (gdb.lookup_type ("guint64"))) == 0:
return "null"
try:
obj = self.val.dereference ()
class_ns = obj ['vtable'].dereference ()['klass'].dereference ()['name_space'].string ()
class_name = obj ['vtable'].dereference ()['klass'].dereference ()['name'].string ()
if class_ns == "System" and class_name == "String":
return StringPrinter (self.val).to_string ()
if class_name [-2:len(class_name)] == "[]":
return ArrayPrinter (self.val,class_ns,class_name).to_string ()
if class_ns != "":
try:
gdb_type = gdb.lookup_type ("struct {0}.{1}".format (class_ns, class_name))
except:
# Maybe there is no debug info for that type
return "{0}.{1}".format (class_ns, class_name)
#return obj.cast (gdb_type)
return "{0}.{1}".format (class_ns, class_name)
return class_name
except:
print (sys.exc_info ()[0])
print (sys.exc_info ()[1])
# FIXME: This can happen because we don't have liveness information
return self.val.cast (gdb.lookup_type ("guint64"))
class MonoMethodPrinter:
"Print a MonoMethod structure"
def __init__(self, val):
self.val = val
def to_string(self):
if int(self.val.cast (gdb.lookup_type ("guint64"))) == 0:
return "0x0"
val = self.val.dereference ()
klass = val ["klass"].dereference ()
class_name = stringify_class_name (klass ["name_space"].string (), klass ["name"].string ())
return "\"{0}:{1} ()\"".format (class_name, val ["name"].string ())
# This returns more info but requires calling into the inferior
#return "\"{0}\"".format (gdb.parse_and_eval ("mono_method_full_name ({0}, 1)".format (str (int (self.val.cast (gdb.lookup_type ("guint64")))))).string ())
class MonoClassPrinter:
"Print a MonoClass structure"
def __init__(self, val):
self.val = val
def to_string(self):
if int(self.val.cast (gdb.lookup_type ("guint64"))) == 0:
return "0x0"
klass = self.val.dereference ()
class_name = stringify_class_name (klass ["name_space"].string (), klass ["name"].string ())
return "\"{0}\"".format (class_name)
# This returns more info but requires calling into the inferior
#return "\"{0}\"".format (gdb.parse_and_eval ("mono_type_full_name (&((MonoClass*){0})->byval_arg)".format (str (int ((self.val).cast (gdb.lookup_type ("guint64")))))))
def lookup_pretty_printer(val):
t = str (val.type)
if t == "object":
return ObjectPrinter (val)
if t[0:5] == "class" and t[-1] == "&":
return ObjectPrinter (val)
if t == "string":
return StringPrinter (val)
if t == "MonoMethod *":
return MonoMethodPrinter (val)
if t == "MonoClass *":
return MonoClassPrinter (val)
return None
def register_csharp_printers(obj):
"Register C# pretty-printers with objfile Obj."
if obj == None:
obj = gdb
obj.pretty_printers.append (lookup_pretty_printer)
register_csharp_printers (gdb.current_objfile())
class MonoSupport(object):
def __init__(self):
self.s_size = 0
def run_hook(self):
if os.access ("xdb.s", os.F_OK):
os.remove ("xdb.s")
gdb.execute ("set environment MONO_XDEBUG gdb")
def stop_hook(self):
# Called when the program is stopped
# Need to recompile+reload the xdb.s file if needed
# FIXME: Need to detect half-written files created when the child is
# interrupted while executing the xdb.s writing code
# FIXME: Handle appdomain unload
if os.access ("xdb.s", os.F_OK):
new_size = os.stat ("xdb.s").st_size
if new_size > self.s_size:
sofile = "xdb.so"
gdb.execute ("shell as -o xdb.o xdb.s && ld -shared -o {} xdb.o".format (sofile))
# FIXME: This prints messages which couldn't be turned off
gdb.execute ("add-symbol-file {} 0".format (sofile))
self.s_size = new_size
class RunHook (gdb.Command):
def __init__ (self):
super (RunHook, self).__init__ ("hook-run", gdb.COMMAND_NONE,
gdb.COMPLETE_COMMAND, pre_hook_of="run")
def invoke(self, arg, from_tty):
mono_support.run_hook ()
print ("Mono support loaded.")
mono_support = MonoSupport ()
# This depends on the changes in gdb-python.diff to work
#RunHook ()
# Register our hooks
# This currently cannot be done from python code
exec_file = gdb.current_objfile ().filename
# FIXME: Is there a way to detect symbolic links ?
if os.stat (exec_file).st_size != os.lstat (exec_file).st_size:
exec_file = os.readlink (exec_file)
exec_dir = os.path.dirname (exec_file)
gdb.execute ("source {0}/{1}-gdbinit".format (exec_dir, os.path.basename (exec_file)))
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