Issue #15167 (as part of #13959): imp.get_magic() is no implemented in
Lib/imp.py.
diff --git a/Lib/imp.py b/Lib/imp.py
index dab8312..58d1c97 100644
--- a/Lib/imp.py
+++ b/Lib/imp.py
@@ -10,12 +10,12 @@
load_dynamic, get_frozen_object, is_frozen_package,
init_builtin, init_frozen, is_builtin, is_frozen,
_fix_co_filename, extension_suffixes)
-# Could move out of _imp, but not worth the code
-from _imp import get_magic
+# Directly exposed by this module
from importlib._bootstrap import new_module
from importlib._bootstrap import cache_from_source
+
from importlib import _bootstrap
from importlib import machinery
import os
@@ -37,6 +37,11 @@
IMP_HOOK = 9
+def get_magic():
+ """Return the magic number for .pyc or .pyo files."""
+ return _bootstrap._MAGIC_BYTES
+
+
def get_tag():
"""Return the magic tag for .pyc or .pyo files."""
return sys.implementation.cache_tag
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 35c6e50..618dd26 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -300,6 +300,96 @@
# Finder/loader utility code ##################################################
+"""Magic word to reject .pyc files generated by other Python versions.
+It should change for each incompatible change to the bytecode.
+
+The value of CR and LF is incorporated so if you ever read or write
+a .pyc file in text mode the magic number will be wrong; also, the
+Apple MPW compiler swaps their values, botching string constants.
+
+The magic numbers must be spaced apart at least 2 values, as the
+-U interpeter flag will cause MAGIC+1 being used. They have been
+odd numbers for some time now.
+
+There were a variety of old schemes for setting the magic number.
+The current working scheme is to increment the previous value by
+10.
+
+Starting with the adoption of PEP 3147 in Python 3.2, every bump in magic
+number also includes a new "magic tag", i.e. a human readable string used
+to represent the magic number in __pycache__ directories. When you change
+the magic number, you must also set a new unique magic tag. Generally this
+can be named after the Python major version of the magic number bump, but
+it can really be anything, as long as it's different than anything else
+that's come before. The tags are included in the following table, starting
+with Python 3.2a0.
+
+Known values:
+ Python 1.5: 20121
+ Python 1.5.1: 20121
+ Python 1.5.2: 20121
+ Python 1.6: 50428
+ Python 2.0: 50823
+ Python 2.0.1: 50823
+ Python 2.1: 60202
+ Python 2.1.1: 60202
+ Python 2.1.2: 60202
+ Python 2.2: 60717
+ Python 2.3a0: 62011
+ Python 2.3a0: 62021
+ Python 2.3a0: 62011 (!)
+ Python 2.4a0: 62041
+ Python 2.4a3: 62051
+ Python 2.4b1: 62061
+ Python 2.5a0: 62071
+ Python 2.5a0: 62081 (ast-branch)
+ Python 2.5a0: 62091 (with)
+ Python 2.5a0: 62092 (changed WITH_CLEANUP opcode)
+ Python 2.5b3: 62101 (fix wrong code: for x, in ...)
+ Python 2.5b3: 62111 (fix wrong code: x += yield)
+ Python 2.5c1: 62121 (fix wrong lnotab with for loops and
+ storing constants that should have been removed)
+ Python 2.5c2: 62131 (fix wrong code: for x, in ... in listcomp/genexp)
+ Python 2.6a0: 62151 (peephole optimizations and STORE_MAP opcode)
+ Python 2.6a1: 62161 (WITH_CLEANUP optimization)
+ Python 3000: 3000
+ 3010 (removed UNARY_CONVERT)
+ 3020 (added BUILD_SET)
+ 3030 (added keyword-only parameters)
+ 3040 (added signature annotations)
+ 3050 (print becomes a function)
+ 3060 (PEP 3115 metaclass syntax)
+ 3061 (string literals become unicode)
+ 3071 (PEP 3109 raise changes)
+ 3081 (PEP 3137 make __file__ and __name__ unicode)
+ 3091 (kill str8 interning)
+ 3101 (merge from 2.6a0, see 62151)
+ 3103 (__file__ points to source file)
+ Python 3.0a4: 3111 (WITH_CLEANUP optimization).
+ Python 3.0a5: 3131 (lexical exception stacking, including POP_EXCEPT)
+ Python 3.1a0: 3141 (optimize list, set and dict comprehensions:
+ change LIST_APPEND and SET_ADD, add MAP_ADD)
+ Python 3.1a0: 3151 (optimize conditional branches:
+ introduce POP_JUMP_IF_FALSE and POP_JUMP_IF_TRUE)
+ Python 3.2a0: 3160 (add SETUP_WITH)
+ tag: cpython-32
+ Python 3.2a1: 3170 (add DUP_TOP_TWO, remove DUP_TOPX and ROT_FOUR)
+ tag: cpython-32
+ Python 3.2a2 3180 (add DELETE_DEREF)
+ Python 3.3a0 3190 __class__ super closure changed
+ Python 3.3a0 3200 (__qualname__ added)
+ 3210 (added size modulo 2**32 to the pyc header)
+ Python 3.3a1 3220 (changed PEP 380 implementation)
+ Python 3.3a4 3230 (revert changes to implicit __class__ closure)
+
+MAGIC must change whenever the bytecode emitted by the compiler may no
+longer be understood by older implementations of the eval loop (usually
+due to the addition of new opcodes).
+
+"""
+_RAW_MAGIC_NUMBER = 3230 | ord('\r') << 16 | ord('\n') << 24
+_MAGIC_BYTES = bytes(_RAW_MAGIC_NUMBER >> n & 0xff for n in range(0, 25, 8))
+
_PYCACHE = '__pycache__'
SOURCE_SUFFIXES = ['.py'] # _setup() adds .pyw as needed.
@@ -611,7 +701,7 @@
magic = data[:4]
raw_timestamp = data[4:8]
raw_size = data[8:12]
- if magic != _MAGIC_NUMBER:
+ if magic != _MAGIC_BYTES:
msg = 'bad magic number in {!r}: {!r}'.format(fullname, magic)
raise ImportError(msg, name=fullname, path=bytecode_path)
elif len(raw_timestamp) != 4:
@@ -768,7 +858,7 @@
_verbose_message('code object from {}', source_path)
if (not sys.dont_write_bytecode and bytecode_path is not None and
source_mtime is not None):
- data = bytearray(_MAGIC_NUMBER)
+ data = bytearray(_MAGIC_BYTES)
data.extend(_w_long(source_mtime))
data.extend(_w_long(len(source_bytes)))
data.extend(marshal.dumps(code_object))
@@ -1427,8 +1517,6 @@
return _handle_fromlist(module, fromlist, _gcd_import)
-_MAGIC_NUMBER = None # Set in _setup()
-
def _setup(sys_module, _imp_module):
"""Setup importlib by importing needed built-in modules and injecting them
@@ -1488,7 +1576,6 @@
setattr(self_module, 'path_separators', set(path_separators))
# Constants
setattr(self_module, '_relax_case', _make_relax_case())
- setattr(self_module, '_MAGIC_NUMBER', _imp_module.get_magic())
if builtin_os == 'nt':
SOURCE_SUFFIXES.append('.pyw')