imports e.g. test_support must do so using an absolute package name
such as "import test.test_support" or "from test import test_support".
This also updates the README in Lib/test, and gets rid of the
duplicate data dirctory in Lib/test/data (replaced by
Lib/email/test/data).
Now Tim and Jack can have at it. :)
and (b) stop trying to prevent file growth.
Beef up the file.truncate() docs.
Change test_largefile.py to stop assuming that f.truncate() moves the
file pointer to the truncation point, and to verify instead that it leaves
the file position alone. Remove the test for what happens when a
specified size exceeds the original file size (it's ill-defined, according
to the Single Unix Spec).
dropping MS's inadequate _chsize() function. This was inspired by
SF patch 498109 ("fileobject truncate support for win32"), which I
rejected.
libstdtypes.tex: Someone who knows should update the availability
blurb. For example, if it's available on Linux, it would be good to
say so.
test_largefile: Uncommented the file.truncate() tests, and reworked to
do more. The old comment about "permission errors" in the truncation
tests under Windows was almost certainly due to that the file wasn't open
for *write* access at this point, so of course MS wouldn't let you
truncate it. I'd be appalled if a Unixish system did.
CAUTION: Someone should run this test on Linux (etc) too. The
truncation part was commented out before. Note that test_largefile isn't
run by default.
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*.
1. That seeking beyond the end of a file increases the size of a file.
2. That files so extended are magically filled with null bytes.
I find no support for either in the C std, and #2 in particular turns out
not to be true on Win32 (you apparently see whatever trash happened to be
on disk). Left #1 intact, but changed the test to check only bytes it
explicitly wrote. Also fiddled the "expected" vs "got" failure reports
to consistently use repr (%r) -- they weren't readable otherwise.
Curious: the MS docs say stati64 etc are supported even on Win95, but
Win95 doesn't support a filesystem that allows partitions > 2 Gb.
test_largefile: This was opening its test file in text mode. I have no
idea how that worked under Win64, but it sure needs binary mode on Win98.
BTW, on Win98 test_largefile runs quickly (under a second).
catch IOError as well as OverflowError. I found that on Tru64 Unix
this was raised; probably because the OS (or libc) doesn't support
large files but the architecture is 64 bits!
Barry Warsaw
Tim Peters
Martin v. Löwis
Guido van Rossum
Fred Drake
Trent Mick