This new Python code should be equivalent in behavior to the if
statement at line 312 of parsers.c. Without this, the pure-python
parsers improperly ignore truncated revlogs as created in
test-verify.t.
requires ctypes
Why is posixfile a class?
Because the implementation needs to use the Python library call os.fdopen [1],
which sets the 'name' attribute on the Python file object it creates to the
mostly meaningless string '<fdopen>', since file descriptors don't have a name.
But users of posixfile depend on the name attribute [2] being set to a proper
value, like Python's built-in 'open' function sets it on file objects.
Python file's name attribute is read-only, so we can't just assign to it after
the file object has alrady been created.
To solve this problem, we save the name of the file on a wrapper object,
and delegate the file function calls to the wrapped (private) file object
using __getattr__.
[1] http://docs.python.org/library/os.html#os.fdopen
[2] http://docs.python.org/library/stdtypes.html#file.name
In Python lists are implemented as arrays with overallocation. As a
result, list.insert(0, ...) is O(n), whereas list.append() has an
amortised running time of O(1). Reversing the internal representation
of the list should cause a slight speedup for pure Python builds.
The posixfile_nt class has been superseded by posixfile in osutils.c,
which works on Windows NT and above. All other systems get the regular
python file class which is assigned to posixfile in posix.py (for POSIX)
and in the pure python version of osutils.py (for Win 9x or Windows NT
in pure mode).
