Lib/test/test_mmap.py

   1
   2 import mmap
   3 import string, os, re, sys
   4
   5 PAGESIZE = mmap.PAGESIZE
   6
   7 def test_both():
   8     "Test mmap module on Unix systems and Windows"
   9
  10     # Create an mmap'ed file
  11     f = open('foo', 'w+')
  12
  13     # Write 2 pages worth of data to the file
  14     f.write('\0'* PAGESIZE)
  15     f.write('foo')
  16     f.write('\0'* (PAGESIZE-3) )
  17
  18     m = mmap.mmap(f.fileno(), 2 * PAGESIZE)
  19     f.close()
  20
  21     # Simple sanity checks
  22     print '  Position of foo:', string.find(m, 'foo') / float(PAGESIZE), 'pages'
  23     assert string.find(m, 'foo') == PAGESIZE
  24
  25     print '  Length of file:', len(m) / float(PAGESIZE), 'pages'
  26     assert len(m) == 2*PAGESIZE
  27
  28     print '  Contents of byte 0:', repr(m[0])
  29     assert m[0] == '\0'
  30     print '  Contents of first 3 bytes:', repr(m[0:3])
  31     assert m[0:3] == '\0\0\0'
  32
  33     # Modify the file's content
  34     print "\n  Modifying file's content..."
  35     m[0] = '3'
  36     m[PAGESIZE +3: PAGESIZE +3+3]='bar'
  37
  38     # Check that the modification worked
  39     print '  Contents of byte 0:', repr(m[0])
  40     assert m[0] == '3'
  41     print '  Contents of first 3 bytes:', repr(m[0:3])
  42     assert m[0:3] == '3\0\0'
  43     print '  Contents of second page:',  m[PAGESIZE-1 : PAGESIZE + 7]
  44     assert m[PAGESIZE-1 : PAGESIZE + 7] == '\0foobar\0'
  45
  46     m.flush()
  47
  48     # Test doing a regular expression match in an mmap'ed file
  49     match=re.search('[A-Za-z]+', m)
  50     if match == None:
  51         print '  ERROR: regex match on mmap failed!'
  52     else:
  53         start, end = match.span(0)
  54         length = end - start
  55
  56         print '  Regex match on mmap (page start, length of match):',
  57         print start / float(PAGESIZE), length
  58
  59         assert start == PAGESIZE
  60         assert end == PAGESIZE + 6
  61
  62     print ' Test passed'
  63
  64 test_both()
  65