from test.support import (TESTFN, import_module, unlink, requires, _2G, _4G, gc_collect, cpython_only) import unittest import os import re import itertools import socket import sys import weakref # Skip test if we can't import mmap. mmap = import_module('mmap') PAGESIZE = mmap.PAGESIZE class MmapTests(unittest.TestCase): def setUp(self): if os.path.exists(TESTFN): os.unlink(TESTFN) def tearDown(self): try: os.unlink(TESTFN) except OSError: pass def test_basic(self): # Test mmap module on Unix systems and Windows # Create a file to be mmap'ed. f = open(TESTFN, 'bw+') try: # Write 2 pages worth of data to the file f.write(b'\0'* PAGESIZE) f.write(b'foo') f.write(b'\0'* (PAGESIZE-3) ) f.flush() m = mmap.mmap(f.fileno(), 2 * PAGESIZE) finally: f.close() # Simple sanity checks tp = str(type(m)) # SF bug 128713: segfaulted on Linux self.assertEqual(m.find(b'foo'), PAGESIZE) self.assertEqual(len(m), 2*PAGESIZE) self.assertEqual(m[0], 0) self.assertEqual(m[0:3], b'\0\0\0') # Shouldn't crash on boundary (Issue #5292) self.assertRaises(IndexError, m.__getitem__, len(m)) self.assertRaises(IndexError, m.__setitem__, len(m), b'\0') # Modify the file's content m[0] = b'3'[0] m[PAGESIZE +3: PAGESIZE +3+3] = b'bar' # Check that the modification worked self.assertEqual(m[0], b'3'[0]) self.assertEqual(m[0:3], b'3\0\0') self.assertEqual(m[PAGESIZE-1 : PAGESIZE + 7], b'\0foobar\0') m.flush() # Test doing a regular expression match in an mmap'ed file match = re.search(b'[A-Za-z]+', m) if match is None: self.fail('regex match on mmap failed!') else: start, end = match.span(0) length = end - start self.assertEqual(start, PAGESIZE) self.assertEqual(end, PAGESIZE + 6) # test seeking around (try to overflow the seek implementation) m.seek(0,0) self.assertEqual(m.tell(), 0) m.seek(42,1) self.assertEqual(m.tell(), 42) m.seek(0,2) self.assertEqual(m.tell(), len(m)) # Try to seek to negative position... self.assertRaises(ValueError, m.seek, -1) # Try to seek beyond end of mmap... self.assertRaises(ValueError, m.seek, 1, 2) # Try to seek to negative position... self.assertRaises(ValueError, m.seek, -len(m)-1, 2) # Try resizing map try: m.resize(512) except SystemError: # resize() not supported # No messages are printed, since the output of this test suite # would then be different across platforms. pass else: # resize() is supported self.assertEqual(len(m), 512) # Check that we can no longer seek beyond the new size. self.assertRaises(ValueError, m.seek, 513, 0) # Check that the underlying file is truncated too # (bug #728515) f = open(TESTFN, 'rb') try: f.seek(0, 2) self.assertEqual(f.tell(), 512) finally: f.close() self.assertEqual(m.size(), 512) m.close() def test_access_parameter(self): # Test for "access" keyword parameter mapsize = 10 with open(TESTFN, "wb") as fp: fp.write(b"a"*mapsize) with open(TESTFN, "rb") as f: m = mmap.mmap(f.fileno(), mapsize, access=mmap.ACCESS_READ) self.assertEqual(m[:], b'a'*mapsize, "Readonly memory map data incorrect.") # Ensuring that readonly mmap can't be slice assigned try: m[:] = b'b'*mapsize except TypeError: pass else: self.fail("Able to write to readonly memory map") # Ensuring that readonly mmap can't be item assigned try: m[0] = b'b' except TypeError: pass else: self.fail("Able to write to readonly memory map") # Ensuring that readonly mmap can't be write() to try: m.seek(0,0) m.write(b'abc') except TypeError: pass else: self.fail("Able to write to readonly memory map") # Ensuring that readonly mmap can't be write_byte() to try: m.seek(0,0) m.write_byte(b'd') except TypeError: pass else: self.fail("Able to write to readonly memory map") # Ensuring that readonly mmap can't be resized try: m.resize(2*mapsize) except SystemError: # resize is not universally supported pass except TypeError: pass else: self.fail("Able to resize readonly memory map") with open(TESTFN, "rb") as fp: self.assertEqual(fp.read(), b'a'*mapsize, "Readonly memory map data file was modified") # Opening mmap with size too big with open(TESTFN, "r+b") as f: try: m = mmap.mmap(f.fileno(), mapsize+1) except ValueError: # we do not expect a ValueError on Windows # CAUTION: This also changes the size of the file on disk, and # later tests assume that the length hasn't changed. We need to # repair that. if sys.platform.startswith('win'): self.fail("Opening mmap with size+1 should work on Windows.") else: # we expect a ValueError on Unix, but not on Windows if not sys.platform.startswith('win'): self.fail("Opening mmap with size+1 should raise ValueError.") m.close() if sys.platform.startswith('win'): # Repair damage from the resizing test. with open(TESTFN, 'r+b') as f: f.truncate(mapsize) # Opening mmap with access=ACCESS_WRITE with open(TESTFN, "r+b") as f: m = mmap.mmap(f.fileno(), mapsize, access=mmap.ACCESS_WRITE) # Modifying write-through memory map m[:] = b'c'*mapsize self.assertEqual(m[:], b'c'*mapsize, "Write-through memory map memory not updated properly.") m.flush() m.close() with open(TESTFN, 'rb') as f: stuff = f.read() self.assertEqual(stuff, b'c'*mapsize, "Write-through memory map data file not updated properly.") # Opening mmap with access=ACCESS_COPY with open(TESTFN, "r+b") as f: m = mmap.mmap(f.fileno(), mapsize, access=mmap.ACCESS_COPY) # Modifying copy-on-write memory map m[:] = b'd'*mapsize self.assertEqual(m[:], b'd' * mapsize, "Copy-on-write memory map data not written correctly.") m.flush() with open(TESTFN, "rb") as fp: self.assertEqual(fp.read(), b'c'*mapsize, "Copy-on-write test data file should not be modified.") # Ensuring copy-on-write maps cannot be resized self.assertRaises(TypeError, m.resize, 2*mapsize) m.close() # Ensuring invalid access parameter raises exception with open(TESTFN, "r+b") as f: self.assertRaises(ValueError, mmap.mmap, f.fileno(), mapsize, access=4) if os.name == "posix": # Try incompatible flags, prot and access parameters. with open(TESTFN, "r+b") as f: self.assertRaises(ValueError, mmap.mmap, f.fileno(), mapsize, flags=mmap.MAP_PRIVATE, prot=mmap.PROT_READ, access=mmap.ACCESS_WRITE) # Try writing with PROT_EXEC and without PROT_WRITE prot = mmap.PROT_READ | getattr(mmap, 'PROT_EXEC', 0) with open(TESTFN, "r+b") as f: m = mmap.mmap(f.fileno(), mapsize, prot=prot) self.assertRaises(TypeError, m.write, b"abcdef") self.assertRaises(TypeError, m.write_byte, 0) m.close() def test_bad_file_desc(self): # Try opening a bad file descriptor... self.assertRaises(OSError, mmap.mmap, -2, 4096) def test_tougher_find(self): # Do a tougher .find() test. SF bug 515943 pointed out that, in 2.2, # searching for data with embedded \0 bytes didn't work. with open(TESTFN, 'wb+') as f: data = b'aabaac\x00deef\x00\x00aa\x00' n = len(data) f.write(data) f.flush() m = mmap.mmap(f.fileno(), n) for start in range(n+1): for finish in range(start, n+1): slice = data[start : finish] self.assertEqual(m.find(slice), data.find(slice)) self.assertEqual(m.find(slice + b'x'), -1) m.close() def test_find_end(self): # test the new 'end' parameter works as expected with open(TESTFN, 'wb+') as f: data = b'one two ones' n = len(data) f.write(data) f.flush() m = mmap.mmap(f.fileno(), n) self.assertEqual(m.find(b'one'), 0) self.assertEqual(m.find(b'ones'), 8) self.assertEqual(m.find(b'one', 0, -1), 0) self.assertEqual(m.find(b'one', 1), 8) self.assertEqual(m.find(b'one', 1, -1), 8) self.assertEqual(m.find(b'one', 1, -2), -1) self.assertEqual(m.find(bytearray(b'one')), 0) def test_rfind(self): # test the new 'end' parameter works as expected with open(TESTFN, 'wb+') as f: data = b'one two ones' n = len(data) f.write(data) f.flush() m = mmap.mmap(f.fileno(), n) self.assertEqual(m.rfind(b'one'), 8) self.assertEqual(m.rfind(b'one '), 0) self.assertEqual(m.rfind(b'one', 0, -1), 8) self.assertEqual(m.rfind(b'one', 0, -2), 0) self.assertEqual(m.rfind(b'one', 1, -1), 8) self.assertEqual(m.rfind(b'one', 1, -2), -1) self.assertEqual(m.rfind(bytearray(b'one')), 8) def test_double_close(self): # make sure a double close doesn't crash on Solaris (Bug# 665913) with open(TESTFN, 'wb+') as f: f.write(2**16 * b'a') # Arbitrary character with open(TESTFN, 'rb') as f: mf = mmap.mmap(f.fileno(), 2**16, access=mmap.ACCESS_READ) mf.close() mf.close() def test_entire_file(self): # test mapping of entire file by passing 0 for map length with open(TESTFN, "wb+") as f: f.write(2**16 * b'm') # Arbitrary character with open(TESTFN, "rb+") as f, \ mmap.mmap(f.fileno(), 0) as mf: self.assertEqual(len(mf), 2**16, "Map size should equal file size.") self.assertEqual(mf.read(2**16), 2**16 * b"m") def test_length_0_offset(self): # Issue #10916: test mapping of remainder of file by passing 0 for # map length with an offset doesn't cause a segfault. # NOTE: allocation granularity is currently 65536 under Win64, # and therefore the minimum offset alignment. with open(TESTFN, "wb") as f: f.write((65536 * 2) * b'm') # Arbitrary character with open(TESTFN, "rb") as f: with mmap.mmap(f.fileno(), 0, offset=65536, access=mmap.ACCESS_READ) as mf: self.assertRaises(IndexError, mf.__getitem__, 80000) def test_length_0_large_offset(self): # Issue #10959: test mapping of a file by passing 0 for # map length with a large offset doesn't cause a segfault. with open(TESTFN, "wb") as f: f.write(115699 * b'm') # Arbitrary character with open(TESTFN, "w+b") as f: self.assertRaises(ValueError, mmap.mmap, f.fileno(), 0, offset=2147418112) def test_move(self): # make move works everywhere (64-bit format problem earlier) with open(TESTFN, 'wb+') as f: f.write(b"ABCDEabcde") # Arbitrary character f.flush() mf = mmap.mmap(f.fileno(), 10) mf.move(5, 0, 5) self.assertEqual(mf[:], b"ABCDEABCDE", "Map move should have duplicated front 5") mf.close() # more excessive test data = b"0123456789" for dest in range(len(data)): for src in range(len(data)): for count in range(len(data) - max(dest, src)): expected = data[:dest] + data[src:src+count] + data[dest+count:] m = mmap.mmap(-1, len(data)) m[:] = data m.move(dest, src, count) self.assertEqual(m[:], expected) m.close() # segfault test (Issue 5387) m = mmap.mmap(-1, 100) offsets = [-100, -1, 0, 1, 100] for source, dest, size in itertools.product(offsets, offsets, offsets): try: m.move(source, dest, size) except ValueError: pass offsets = [(-1, -1, -1), (-1, -1, 0), (-1, 0, -1), (0, -1, -1), (-1, 0, 0), (0, -1, 0), (0, 0, -1)] for source, dest, size in offsets: self.assertRaises(ValueError, m.move, source, dest, size) m.close() m = mmap.mmap(-1, 1) # single byte self.assertRaises(ValueError, m.move, 0, 0, 2) self.assertRaises(ValueError, m.move, 1, 0, 1) self.assertRaises(ValueError, m.move, 0, 1, 1) m.move(0, 0, 1) m.move(0, 0, 0) def test_anonymous(self): # anonymous mmap.mmap(-1, PAGE) m = mmap.mmap(-1, PAGESIZE) for x in range(PAGESIZE): self.assertEqual(m[x], 0, "anonymously mmap'ed contents should be zero") for x in range(PAGESIZE): b = x & 0xff m[x] = b self.assertEqual(m[x], b) def test_read_all(self): m = mmap.mmap(-1, 16) self.addCleanup(m.close) # With no parameters, or None or a negative argument, reads all m.write(bytes(range(16))) m.seek(0) self.assertEqual(m.read(), bytes(range(16))) m.seek(8) self.assertEqual(m.read(), bytes(range(8, 16))) m.seek(16) self.assertEqual(m.read(), b'') m.seek(3) self.assertEqual(m.read(None), bytes(range(3, 16))) m.seek(4) self.assertEqual(m.read(-1), bytes(range(4, 16))) m.seek(5) self.assertEqual(m.read(-2), bytes(range(5, 16))) m.seek(9) self.assertEqual(m.read(-42), bytes(range(9, 16))) def test_read_invalid_arg(self): m = mmap.mmap(-1, 16) self.addCleanup(m.close) self.assertRaises(TypeError, m.read, 'foo') self.assertRaises(TypeError, m.read, 5.5) self.assertRaises(TypeError, m.read, [1, 2, 3]) def test_extended_getslice(self): # Test extended slicing by comparing with list slicing. s = bytes(reversed(range(256))) m = mmap.mmap(-1, len(s)) m[:] = s self.assertEqual(m[:], s) indices = (0, None, 1, 3, 19, 300, sys.maxsize, -1, -2, -31, -300) for start in indices: for stop in indices: # Skip step 0 (invalid) for step in indices[1:]: self.assertEqual(m[start:stop:step], s[start:stop:step]) def test_extended_set_del_slice(self): # Test extended slicing by comparing with list slicing. s = bytes(reversed(range(256))) m = mmap.mmap(-1, len(s)) indices = (0, None, 1, 3, 19, 300, sys.maxsize, -1, -2, -31, -300) for start in indices: for stop in indices: # Skip invalid step 0 for step in indices[1:]: m[:] = s self.assertEqual(m[:], s) L = list(s) # Make sure we have a slice of exactly the right length, # but with different data. data = L[start:stop:step] data = bytes(reversed(data)) L[start:stop:step] = data m[start:stop:step] = data self.assertEqual(m[:], bytes(L)) def make_mmap_file (self, f, halfsize): # Write 2 pages worth of data to the file f.write (b'\0' * halfsize) f.write (b'foo') f.write (b'\0' * (halfsize - 3)) f.flush () return mmap.mmap (f.fileno(), 0) def test_empty_file (self): f = open (TESTFN, 'w+b') f.close() with open(TESTFN, "rb") as f : self.assertRaisesRegex(ValueError, "cannot mmap an empty file", mmap.mmap, f.fileno(), 0, access=mmap.ACCESS_READ) def test_offset (self): f = open (TESTFN, 'w+b') try: # unlink TESTFN no matter what halfsize = mmap.ALLOCATIONGRANULARITY m = self.make_mmap_file (f, halfsize) m.close () f.close () mapsize = halfsize * 2 # Try invalid offset f = open(TESTFN, "r+b") for offset in [-2, -1, None]: try: m = mmap.mmap(f.fileno(), mapsize, offset=offset) self.assertEqual(0, 1) except (ValueError, TypeError, OverflowError): pass else: self.assertEqual(0, 0) f.close() # Try valid offset, hopefully 8192 works on all OSes f = open(TESTFN, "r+b") m = mmap.mmap(f.fileno(), mapsize - halfsize, offset=halfsize) self.assertEqual(m[0:3], b'foo') f.close() # Try resizing map try: m.resize(512) except SystemError: pass else: # resize() is supported self.assertEqual(len(m), 512) # Check that we can no longer seek beyond the new size. self.assertRaises(ValueError, m.seek, 513, 0) # Check that the content is not changed self.assertEqual(m[0:3], b'foo') # Check that the underlying file is truncated too f = open(TESTFN, 'rb') f.seek(0, 2) self.assertEqual(f.tell(), halfsize + 512) f.close() self.assertEqual(m.size(), halfsize + 512) m.close() finally: f.close() try: os.unlink(TESTFN) except OSError: pass def test_subclass(self): class anon_mmap(mmap.mmap): def __new__(klass, *args, **kwargs): return mmap.mmap.__new__(klass, -1, *args, **kwargs) anon_mmap(PAGESIZE) @unittest.skipUnless(hasattr(mmap, 'PROT_READ'), "needs mmap.PROT_READ") def test_prot_readonly(self): mapsize = 10 with open(TESTFN, "wb") as fp: fp.write(b"a"*mapsize) with open(TESTFN, "rb") as f: m = mmap.mmap(f.fileno(), mapsize, prot=mmap.PROT_READ) self.assertRaises(TypeError, m.write, "foo") def test_error(self): self.assertIs(mmap.error, OSError) def test_io_methods(self): data = b"0123456789" with open(TESTFN, "wb") as fp: fp.write(b"x"*len(data)) with open(TESTFN, "r+b") as f: m = mmap.mmap(f.fileno(), len(data)) # Test write_byte() for i in range(len(data)): self.assertEqual(m.tell(), i) m.write_byte(data[i]) self.assertEqual(m.tell(), i+1) self.assertRaises(ValueError, m.write_byte, b"x"[0]) self.assertEqual(m[:], data) # Test read_byte() m.seek(0) for i in range(len(data)): self.assertEqual(m.tell(), i) self.assertEqual(m.read_byte(), data[i]) self.assertEqual(m.tell(), i+1) self.assertRaises(ValueError, m.read_byte) # Test read() m.seek(3) self.assertEqual(m.read(3), b"345") self.assertEqual(m.tell(), 6) # Test write() m.seek(3) m.write(b"bar") self.assertEqual(m.tell(), 6) self.assertEqual(m[:], b"012bar6789") m.write(bytearray(b"baz")) self.assertEqual(m.tell(), 9) self.assertEqual(m[:], b"012barbaz9") self.assertRaises(ValueError, m.write, b"ba") def test_non_ascii_byte(self): for b in (129, 200, 255): # > 128 m = mmap.mmap(-1, 1) m.write_byte(b) self.assertEqual(m[0], b) m.seek(0) self.assertEqual(m.read_byte(), b) m.close() @unittest.skipUnless(os.name == 'nt', 'requires Windows') def test_tagname(self): data1 = b"0123456789" data2 = b"abcdefghij" assert len(data1) == len(data2) # Test same tag m1 = mmap.mmap(-1, len(data1), tagname="foo") m1[:] = data1 m2 = mmap.mmap(-1, len(data2), tagname="foo") m2[:] = data2 self.assertEqual(m1[:], data2) self.assertEqual(m2[:], data2) m2.close() m1.close() # Test different tag m1 = mmap.mmap(-1, len(data1), tagname="foo") m1[:] = data1 m2 = mmap.mmap(-1, len(data2), tagname="boo") m2[:] = data2 self.assertEqual(m1[:], data1) self.assertEqual(m2[:], data2) m2.close() m1.close() @cpython_only @unittest.skipUnless(os.name == 'nt', 'requires Windows') def test_sizeof(self): m1 = mmap.mmap(-1, 100) tagname = "foo" m2 = mmap.mmap(-1, 100, tagname=tagname) self.assertEqual(sys.getsizeof(m2), sys.getsizeof(m1) + len(tagname) + 1) @unittest.skipUnless(os.name == 'nt', 'requires Windows') def test_crasher_on_windows(self): # Should not crash (Issue 1733986) m = mmap.mmap(-1, 1000, tagname="foo") try: mmap.mmap(-1, 5000, tagname="foo")[:] # same tagname, but larger size except: pass m.close() # Should not crash (Issue 5385) with open(TESTFN, "wb") as fp: fp.write(b"x"*10) f = open(TESTFN, "r+b") m = mmap.mmap(f.fileno(), 0) f.close() try: m.resize(0) # will raise OSError except: pass try: m[:] except: pass m.close() @unittest.skipUnless(os.name == 'nt', 'requires Windows') def test_invalid_descriptor(self): # socket file descriptors are valid, but out of range # for _get_osfhandle, causing a crash when validating the # parameters to _get_osfhandle. s = socket.socket() try: with self.assertRaises(OSError): m = mmap.mmap(s.fileno(), 10) finally: s.close() def test_context_manager(self): with mmap.mmap(-1, 10) as m: self.assertFalse(m.closed) self.assertTrue(m.closed) def test_context_manager_exception(self): # Test that the OSError gets passed through with self.assertRaises(Exception) as exc: with mmap.mmap(-1, 10) as m: raise OSError self.assertIsInstance(exc.exception, OSError, "wrong exception raised in context manager") self.assertTrue(m.closed, "context manager failed") def test_weakref(self): # Check mmap objects are weakrefable mm = mmap.mmap(-1, 16) wr = weakref.ref(mm) self.assertIs(wr(), mm) del mm gc_collect() self.assertIs(wr(), None) def test_write_returning_the_number_of_bytes_written(self): mm = mmap.mmap(-1, 16) self.assertEqual(mm.write(b""), 0) self.assertEqual(mm.write(b"x"), 1) self.assertEqual(mm.write(b"yz"), 2) self.assertEqual(mm.write(b"python"), 6) @unittest.skipIf(os.name == 'nt', 'cannot resize anonymous mmaps on Windows') def test_resize_past_pos(self): m = mmap.mmap(-1, 8192) self.addCleanup(m.close) m.read(5000) try: m.resize(4096) except SystemError: self.skipTest("resizing not supported") self.assertEqual(m.read(14), b'') self.assertRaises(ValueError, m.read_byte) self.assertRaises(ValueError, m.write_byte, 42) self.assertRaises(ValueError, m.write, b'abc') def test_concat_repeat_exception(self): m = mmap.mmap(-1, 16) with self.assertRaises(TypeError): m + m with self.assertRaises(TypeError): m * 2 def test_flush_return_value(self): # mm.flush() should return None on success, raise an # exception on error under all platforms. mm = mmap.mmap(-1, 16) self.addCleanup(mm.close) mm.write(b'python') result = mm.flush() self.assertIsNone(result) if sys.platform.startswith('linux'): # 'offset' must be a multiple of mmap.PAGESIZE on Linux. # See bpo-34754 for details. self.assertRaises(OSError, mm.flush, 1, len(b'python')) @unittest.skipUnless(hasattr(mmap.mmap, 'madvise'), 'needs madvise') def test_madvise(self): size = 2 * PAGESIZE m = mmap.mmap(-1, size) with self.assertRaisesRegex(ValueError, "madvise start out of bounds"): m.madvise(mmap.MADV_NORMAL, size) with self.assertRaisesRegex(ValueError, "madvise start out of bounds"): m.madvise(mmap.MADV_NORMAL, -1) with self.assertRaisesRegex(ValueError, "madvise length invalid"): m.madvise(mmap.MADV_NORMAL, 0, -1) with self.assertRaisesRegex(OverflowError, "madvise length too large"): m.madvise(mmap.MADV_NORMAL, PAGESIZE, sys.maxsize) self.assertEqual(m.madvise(mmap.MADV_NORMAL), None) self.assertEqual(m.madvise(mmap.MADV_NORMAL, PAGESIZE), None) self.assertEqual(m.madvise(mmap.MADV_NORMAL, PAGESIZE, size), None) self.assertEqual(m.madvise(mmap.MADV_NORMAL, 0, 2), None) self.assertEqual(m.madvise(mmap.MADV_NORMAL, 0, size), None) class LargeMmapTests(unittest.TestCase): def setUp(self): unlink(TESTFN) def tearDown(self): unlink(TESTFN) def _make_test_file(self, num_zeroes, tail): if sys.platform[:3] == 'win' or sys.platform == 'darwin': requires('largefile', 'test requires %s bytes and a long time to run' % str(0x180000000)) f = open(TESTFN, 'w+b') try: f.seek(num_zeroes) f.write(tail) f.flush() except (OSError, OverflowError, ValueError): try: f.close() except (OSError, OverflowError): pass raise unittest.SkipTest("filesystem does not have largefile support") return f def test_large_offset(self): with self._make_test_file(0x14FFFFFFF, b" ") as f: with mmap.mmap(f.fileno(), 0, offset=0x140000000, access=mmap.ACCESS_READ) as m: self.assertEqual(m[0xFFFFFFF], 32) def test_large_filesize(self): with self._make_test_file(0x17FFFFFFF, b" ") as f: if sys.maxsize < 0x180000000: # On 32 bit platforms the file is larger than sys.maxsize so # mapping the whole file should fail -- Issue #16743 with self.assertRaises(OverflowError): mmap.mmap(f.fileno(), 0x180000000, access=mmap.ACCESS_READ) with self.assertRaises(ValueError): mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) with mmap.mmap(f.fileno(), 0x10000, access=mmap.ACCESS_READ) as m: self.assertEqual(m.size(), 0x180000000) # Issue 11277: mmap() with large (~4 GiB) sparse files crashes on OS X. def _test_around_boundary(self, boundary): tail = b' DEARdear ' start = boundary - len(tail) // 2 end = start + len(tail) with self._make_test_file(start, tail) as f: with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as m: self.assertEqual(m[start:end], tail) @unittest.skipUnless(sys.maxsize > _4G, "test cannot run on 32-bit systems") def test_around_2GB(self): self._test_around_boundary(_2G) @unittest.skipUnless(sys.maxsize > _4G, "test cannot run on 32-bit systems") def test_around_4GB(self): self._test_around_boundary(_4G) if __name__ == '__main__': unittest.main()