cpython/Lib/test/test_mmap.py

from test.test_support import TESTFN, run_unittest
import mmap
import unittest
import os, re

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('foo'), PAGESIZE)

        self.assertEqual(len(m), 2*PAGESIZE)

        self.assertEqual(m[0], b'\0')
        self.assertEqual(m[0:3], b'\0\0\0')

        # Modify the file's content
        m[0] = b'3'
        m[PAGESIZE +3: PAGESIZE +3+3] = b'bar'

        # Check that the modification worked
        self.assertEqual(m[0], b'3')
        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('[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)
            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
        open(TESTFN, "wb").write(b"a"*mapsize)
        f = open(TESTFN, "rb")
        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")
        del m, f
        self.assertEqual(open(TESTFN, "rb").read(), b'a'*mapsize,
               "Readonly memory map data file was modified")

        # Opening mmap with size too big
        import sys
        f = open(TESTFN, "r+b")
        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()
        f.close()
        if sys.platform.startswith('win'):
            # Repair damage from the resizing test.
            f = open(TESTFN, 'r+b')
            f.truncate(mapsize)
            f.close()

        # Opening mmap with access=ACCESS_WRITE
        f = open(TESTFN, "r+b")
        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()
        f.close()
        f = open(TESTFN, 'rb')
        stuff = f.read()
        f.close()
        self.assertEqual(stuff, b'c'*mapsize,
               "Write-through memory map data file not updated properly.")

        # Opening mmap with access=ACCESS_COPY
        f = open(TESTFN, "r+b")
        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()
        self.assertEqual(open(TESTFN, "rb").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)
        del m, f

        # Ensuring invalid access parameter raises exception
        f = open(TESTFN, "r+b")
        self.assertRaises(ValueError, mmap.mmap, f.fileno(), mapsize, access=4)
        f.close()

        if os.name == "posix":
            # Try incompatible flags, prot and access parameters.
            f = open(TESTFN, "r+b")
            self.assertRaises(ValueError, mmap.mmap, f.fileno(), mapsize,
                              flags=mmap.MAP_PRIVATE,
                              prot=mmap.PROT_READ, access=mmap.ACCESS_WRITE)
            f.close()

    def test_bad_file_desc(self):
        # Try opening a bad file descriptor...
        self.assertRaises(mmap.error, 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.
        f = open(TESTFN, 'wb+')

        data = b'aabaac\x00deef\x00\x00aa\x00'
        n = len(data)
        f.write(data)
        f.flush()
        m = mmap.mmap(f.fileno(), n)
        f.close()

        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_double_close(self):
        # make sure a double close doesn't crash on Solaris (Bug# 665913)
        f = open(TESTFN, 'wb+')

        f.write(2**16 * b'a') # Arbitrary character
        f.close()

        f = open(TESTFN)
        mf = mmap.mmap(f.fileno(), 2**16, access=mmap.ACCESS_READ)
        mf.close()
        mf.close()
        f.close()

    def test_entire_file(self):
        # test mapping of entire file by passing 0 for map length
        if hasattr(os, "stat"):
            f = open(TESTFN, "wb+")

            f.write(2**16 * b'm') # Arbitrary character
            f.close()

            f = open(TESTFN, "rb+")
            mf = mmap.mmap(f.fileno(), 0)
            self.assertEqual(len(mf), 2**16, "Map size should equal file size.")
            self.assertEqual(mf.read(2**16), 2**16 * b"m")
            mf.close()
            f.close()

    def test_move(self):
        # make move works everywhere (64-bit format problem earlier)
        f = open(TESTFN, 'wb+')

        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()
        f.close()

    def test_anonymous(self):
        # anonymous mmap.mmap(-1, PAGE)
        m = mmap.mmap(-1, PAGESIZE)
        for x in range(PAGESIZE):
            self.assertEqual(m[x], b'\0', "anonymously mmap'ed contents should be zero")

        b = bytes(1)
        for x in range(PAGESIZE):
            b[0] = x & 255
            m[x] = b
            self.assertEqual(m[x], b)

    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, -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, -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.assertEquals(m[:], bytes(L))

def test_main():
    run_unittest(MmapTests)

if __name__ == '__main__':
    test_main()