1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.
# Pretty-printers for SpiderMonkey's JS::Value.
import struct
import gdb
import gdb.types
import mozilla.prettyprinters
from mozilla.prettyprinters import pretty_printer
# Forget any printers from previous loads of this module.
mozilla.prettyprinters.clear_module_printers(__name__)
# See Value.h [SMDOC] JS::Value Boxing Formats for details on the JS::Value boxing
# formats handled below.
class Box(object):
def __init__(self, asBits, jtc):
self.asBits = asBits
self.jtc = jtc
# Value::asBits is uint64_t, but somehow the sign bit can be botched
# here, even though Python integers are arbitrary precision.
if self.asBits < 0:
self.asBits = self.asBits + (1 << 64)
# Return this value's type tag.
def tag(self):
raise NotImplementedError
# Return this value as a 32-bit integer, double, or address.
def as_uint32(self):
raise NotImplementedError
def as_double(self):
packed = struct.pack("q", self.asBits)
(unpacked,) = struct.unpack("d", packed)
return unpacked
def as_address(self):
raise NotImplementedError
class Punbox(Box):
# Packed non-number boxing --- the format used on x86_64. It would be nice to
# simply call Value::toInt32, etc. here, but the debugger is likely to see many
# Values, and doing several inferior calls for each one seems like a bad idea.
FULL_WIDTH = 64
TAG_SHIFT = 47
PAYLOAD_MASK = (1 << TAG_SHIFT) - 1
TAG_MASK = (1 << (FULL_WIDTH - TAG_SHIFT)) - 1
TAG_MAX_DOUBLE = 0x1FFF0
TAG_TYPE_MASK = 0x0000F
def tag(self):
tag = self.asBits >> Punbox.TAG_SHIFT
if tag <= Punbox.TAG_MAX_DOUBLE:
return self.jtc.DOUBLE
else:
return tag & Punbox.TAG_TYPE_MASK
def as_uint32(self):
return int(self.asBits & ((1 << 32) - 1))
def as_address(self):
return gdb.Value(self.asBits & Punbox.PAYLOAD_MASK)
class Nunbox(Box):
TAG_SHIFT = 32
TAG_CLEAR = 0xFFFF0000
PAYLOAD_MASK = 0xFFFFFFFF
TAG_TYPE_MASK = 0x0000000F
def tag(self):
tag = self.asBits >> Nunbox.TAG_SHIFT
if tag < Nunbox.TAG_CLEAR:
return self.jtc.DOUBLE
return tag & Nunbox.TAG_TYPE_MASK
def as_uint32(self):
return int(self.asBits & Nunbox.PAYLOAD_MASK)
def as_address(self):
return gdb.Value(self.asBits & Nunbox.PAYLOAD_MASK)
class JSValueTypeCache(object):
# Cache information about the Value type for this objfile.
def __init__(self, cache):
# Capture the tag values.
d = gdb.types.make_enum_dict(gdb.lookup_type("JSValueType"))
# The enum keys are prefixed when building with some compilers (clang at
# a minimum), so use a helper function to handle either key format.
def get(key):
val = d.get(key)
if val is not None:
return val
return d["JSValueType::" + key]
self.DOUBLE = get("JSVAL_TYPE_DOUBLE")
self.INT32 = get("JSVAL_TYPE_INT32")
self.UNDEFINED = get("JSVAL_TYPE_UNDEFINED")
self.BOOLEAN = get("JSVAL_TYPE_BOOLEAN")
self.MAGIC = get("JSVAL_TYPE_MAGIC")
self.STRING = get("JSVAL_TYPE_STRING")
self.SYMBOL = get("JSVAL_TYPE_SYMBOL")
self.BIGINT = get("JSVAL_TYPE_BIGINT")
self.NULL = get("JSVAL_TYPE_NULL")
self.OBJECT = get("JSVAL_TYPE_OBJECT")
# Let self.magic_names be an array whose i'th element is the name of
# the i'th magic value.
d = gdb.types.make_enum_dict(gdb.lookup_type("JSWhyMagic"))
self.magic_names = list(range(max(d.values()) + 1))
for (k, v) in d.items():
self.magic_names[v] = k
# Choose an unboxing scheme for this architecture.
self.boxer = Punbox if cache.void_ptr_t.sizeof == 8 else Nunbox
@pretty_printer("JS::Value")
class JSValue(object):
def __init__(self, value, cache):
# Save the generic typecache, and create our own, if we haven't already.
self.cache = cache
if not cache.mod_JS_Value:
cache.mod_JS_Value = JSValueTypeCache(cache)
self.jtc = cache.mod_JS_Value
self.value = value
self.box = self.jtc.boxer(value["asBits_"], self.jtc)
def to_string(self):
tag = self.box.tag()
if tag == self.jtc.UNDEFINED:
return "$JS::UndefinedValue()"
if tag == self.jtc.NULL:
return "$JS::NullValue()"
if tag == self.jtc.BOOLEAN:
return "$JS::BooleanValue(%s)" % str(self.box.as_uint32() != 0).lower()
if tag == self.jtc.MAGIC:
value = self.box.as_uint32()
if 0 <= value and value < len(self.jtc.magic_names):
return "$JS::MagicValue(%s)" % (self.jtc.magic_names[value],)
else:
return "$JS::MagicValue(%d)" % (value,)
if tag == self.jtc.INT32:
value = self.box.as_uint32()
signbit = 1 << 31
value = (value ^ signbit) - signbit
return "$JS::Int32Value(%s)" % value
if tag == self.jtc.DOUBLE:
return "$JS::DoubleValue(%s)" % self.box.as_double()
if tag == self.jtc.STRING:
value = self.box.as_address().cast(self.cache.JSString_ptr_t)
elif tag == self.jtc.OBJECT:
value = self.box.as_address().cast(self.cache.JSObject_ptr_t)
elif tag == self.jtc.SYMBOL:
value = self.box.as_address().cast(self.cache.JSSymbol_ptr_t)
elif tag == self.jtc.BIGINT:
return "$JS::BigIntValue()"
else:
value = "unrecognized!"
return "$JS::Value(%s)" % (value,)
def is_undefined(self):
return self.box.tag() == self.jtc.UNDEFINED
def get_string(self):
assert self.box.tag() == self.jtc.STRING
return self.box.as_address().cast(self.cache.JSString_ptr_t)
def get_private(self):
assert self.box.tag() == self.jtc.DOUBLE
return self.box.asBits
|
