Miscellaneous bug and pyodbc compatibility fixes #13
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NamedTupleRow and MutableNamedTupleRow depend on _ColBufferList being populated, so without this change they do not work.
This is consistent with pyodbc.
I think out-of-the-box compatibility with pyodbc is a worthy goal. I understand not wanting a hard dependency on 'recordtype' but at least providing read-only named field access seems like an improvement.
I've run into memory corruption bugs with the following test program on
64-bit Linux, sizeof(wchar_t) == 4, sizeof(Py_UNICODE) == 4,
sizeof(SQLWCHAR) == 2.
from pypyodbc import connect
# Replace '...' with real values
conn_string = 'DRIVER={SQL Server};SERVER=...;PORT=1433;UID=...;PWD=...;TDS_Version=7.1;APP=...;DATABASE=...'
while True:
connect(conn_string, ansi=False)
For me this typically causes libc to abort() complaining of memory
corruption, double-free, etc. within a few tens of iterations with
cpython (and quicker with pypy).
The bug seems to be in the conversion from Python string to
SQLWCHAR * when calling SQLDriverConnectW. Given the sizes above,
pypyodbc sets wchar_pointer = ctypes.c_char_p, then passes a
UTF-16-encoded byte buffer to it. ctypes.c_char_p null-terminates the
string when converting to a C array - but it only adds a single NUL
byte. unixODBC expects that argument to be a UTF-16 array, terminated by
two NUL bytes.
This fix is a bit of a hack, but it does work.
It might be clearer to define something akin to c_char_p for these
arguments, I suppose.
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Ping? I've been running this branch for a while, and it still seems to work. :) |
| @@ -26,7 +26,7 @@ | |||
| paramstyle = 'qmark' | |||
| threadsafety = 1 | |||
| version = '1.3.0' | |||
| lowercase=True | |||
| lowercase = False | |||
There was a problem hiding this comment.
This probably will affect projects with lowercase names everywhere.
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This code makes more compatible with pyodbc, I will plan to make proper testing before. Thanks. |
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You should take a look at PR #14 – it contains all of these patches plus one extra fix from @batterseapower. |
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Here are some fixes and changes I needed to make to drop pypyodbc into a project which currently uses pyodbc. I think being compatible out-of-the-box is a good thing to aim for(?). I haven't run any of the test suites, I'm afraid, but it seems to work in my project!