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gh-137928: Centralize size validation in multiprocessing.heap #137929

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gh-137928: Centralize size validation in multiprocessing.heap #137929

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8c3baf0
gh-137928: Centralize size validation in multiprocessing.heap
acabelloj Aug 18, 2025
204d264
gh-137928: Move size validation helper to module level in multiproces…
acabelloj Aug 21, 2025
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27 changes: 19 additions & 8 deletions Lib/multiprocessing/heap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,12 @@

__all__ = ['BufferWrapper']

#
# Module constants
#

_MAXSIZE = sys.maxsize

#
# Inheritable class which wraps an mmap, and from which blocks can be allocated
#
Expand Down Expand Up @@ -108,6 +114,17 @@ def rebuild_arena(size, dupfd):

reduction.register(Arena, reduce_arena)

#
# Validation helpers
#

def _validate_size(size):
"""Validate requested size; raise ValueError if < 0, OverflowError if >= _MAXSIZE."""
if size < 0:
raise ValueError("Size {0:n} out of range".format(size))
if _MAXSIZE <= size:
raise OverflowError("Size {0:n} too large".format(size))

#
# Class allowing allocation of chunks of memory from arenas
#
Expand Down Expand Up @@ -295,10 +312,7 @@ def free(self, block):

def malloc(self, size):
# return a block of right size (possibly rounded up)
if size < 0:
raise ValueError("Size {0:n} out of range".format(size))
if sys.maxsize <= size:
raise OverflowError("Size {0:n} too large".format(size))
_validate_size(size)
if os.getpid() != self._lastpid:
self.__init__() # reinitialize after fork
with self._lock:
Expand All @@ -324,10 +338,7 @@ class BufferWrapper(object):
_heap = Heap()

def __init__(self, size):
if size < 0:
raise ValueError("Size {0:n} out of range".format(size))
if sys.maxsize <= size:
raise OverflowError("Size {0:n} too large".format(size))
_validate_size(size)
block = BufferWrapper._heap.malloc(size)
self._state = (block, size)
util.Finalize(self, BufferWrapper._heap.free, args=(block,))
Expand Down
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