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If on Windows, we require the 'largefile' resource. If not on Windows, we use a test that actually writes a byte beyond the 2BG limit -- seeking alone is not sufficient, since on some systems (e.g. Linux with glibc 2.2) the sytem call interface supports large seek offsets but not all filesystem implementations do. Note that on Windows, we do not use the write test: on Win2K, that test can take a minute trying to zero all those blocks on disk, and on Windows our code always supports large seek offsets (but again, not all filesystems do). This may mean that on Win95, or on certain other backward filesystems, test_largefile will *fail*.
140 lines
4 KiB
Python
140 lines
4 KiB
Python
#!python
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#----------------------------------------------------------------------
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# test largefile support on system where this makes sense
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#
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#XXX how to only run this when support is there
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#XXX how to only optionally run this, it will take along time
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#----------------------------------------------------------------------
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import test_support
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import os, struct, stat, sys
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# On Windows this test comsumes large resources; It takes a long time to build
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# the >2GB file and takes >2GB of disk space therefore the resource must be
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# enabled to run this test. If not, nothing after this line stanza will be
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# executed.
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if sys.platform[:3] == 'win':
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test_support.requires(
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'largefile',
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'test requires %s bytes and a long time to run' % str(size))
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else:
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# Only run if the current filesystem supports large files.
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# (Skip this test on Windows, since we now always support large files.)
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f = open(test_support.TESTFN, 'wb')
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try:
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# 2**31 == 2147483648
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f.seek(2147483649L)
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# Seeking is not enough of a test: you must write and flush, too!
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f.write("x")
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f.flush()
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except (IOError, OverflowError):
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f.close()
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os.unlink(test_support.TESTFN)
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raise test_support.TestSkipped, \
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"filesystem does not have largefile support"
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else:
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f.close()
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# create >2GB file (2GB = 2147483648 bytes)
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size = 2500000000L
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name = test_support.TESTFN
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def expect(got_this, expect_this):
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if test_support.verbose:
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print '%r =?= %r ...' % (got_this, expect_this),
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if got_this != expect_this:
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if test_support.verbose:
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print 'no'
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raise test_support.TestFailed, 'got %r, but expected %r' %\
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(got_this, expect_this)
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else:
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if test_support.verbose:
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print 'yes'
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# test that each file function works as expected for a large (i.e. >2GB, do
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# we have to check >4GB) files
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if test_support.verbose:
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print 'create large file via seek (may be sparse file) ...'
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f = open(name, 'wb')
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f.write('z')
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f.seek(0)
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f.seek(size)
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f.write('a')
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f.flush()
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if test_support.verbose:
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print 'check file size with os.fstat'
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expect(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
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f.close()
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if test_support.verbose:
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print 'check file size with os.stat'
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expect(os.stat(name)[stat.ST_SIZE], size+1)
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if test_support.verbose:
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print 'play around with seek() and read() with the built largefile'
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f = open(name, 'rb')
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expect(f.tell(), 0)
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expect(f.read(1), 'z')
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expect(f.tell(), 1)
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f.seek(0)
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expect(f.tell(), 0)
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f.seek(0, 0)
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expect(f.tell(), 0)
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f.seek(42)
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expect(f.tell(), 42)
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f.seek(42, 0)
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expect(f.tell(), 42)
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f.seek(42, 1)
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expect(f.tell(), 84)
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f.seek(0, 1)
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expect(f.tell(), 84)
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f.seek(0, 2) # seek from the end
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expect(f.tell(), size + 1 + 0)
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f.seek(-10, 2)
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expect(f.tell(), size + 1 - 10)
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f.seek(-size-1, 2)
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expect(f.tell(), 0)
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f.seek(size)
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expect(f.tell(), size)
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expect(f.read(1), 'a') # the 'a' that was written at the end of the file above
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f.seek(-size-1, 1)
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expect(f.read(1), 'z')
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expect(f.tell(), 1)
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f.close()
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if test_support.verbose:
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print 'play around with os.lseek() with the built largefile'
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f = open(name, 'rb')
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expect(os.lseek(f.fileno(), 0, 0), 0)
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expect(os.lseek(f.fileno(), 42, 0), 42)
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expect(os.lseek(f.fileno(), 42, 1), 84)
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expect(os.lseek(f.fileno(), 0, 1), 84)
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expect(os.lseek(f.fileno(), 0, 2), size+1+0)
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expect(os.lseek(f.fileno(), -10, 2), size+1-10)
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expect(os.lseek(f.fileno(), -size-1, 2), 0)
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expect(os.lseek(f.fileno(), size, 0), size)
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expect(f.read(1), 'a') # the 'a' that was written at the end of the file above
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f.close()
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# XXX add tests for truncate if it exists
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# XXX has truncate ever worked on Windows? specifically on WinNT I get:
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# "IOError: [Errno 13] Permission denied"
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##try:
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## newsize = size - 10
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## f.seek(newsize)
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## f.truncate()
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## expect(f.tell(), newsize)
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## newsize = newsize - 1
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## f.seek(0)
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## f.truncate(newsize)
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## expect(f.tell(), newsize)
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##except AttributeError:
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## pass
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os.unlink(name)
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