[pywin32-bugs] [ pywin32-Bugs-762523 ] reading SQL dates before the epoch creates strange results

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Bugs item #762523, was opened at 2003-06-28 17:17
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Richard Laager (rlaager)
Assigned to: Nobody/Anonymous (nobody)
Summary: reading SQL dates before the epoch creates strange results

Initial Comment:
Insert* a date before 1970-01-01 00:00:00.000 GMT 
into a database and try reading it from Python using the 
odbc driver.

* This will probably require using something other than 
Python. I haven't tested inserting such dates, only 
reading them.

The bug probably exists because mktime returns -1 for 
dates that it can't represent. I whipped up the following 
untested patch which will turn all unrepresentable dates 
into the epoch. This is much better than returning 
random data from memory.

I don't know enough about the driver to suggest a 
better way to do this.

diff -ur win32-orig/src/odbc.cpp win32/src/odbc.cpp
--- win32-orig/src/odbc.cpp	1997-06-13 
10:37:06.000000000 -0500
+++ win32/src/odbc.cpp	2003-06-28 
17:00:06.000000000 -0500
@@ -427,7 +427,11 @@
   gt.tm_hour = dt->hour;
   gt.tm_min = dt->minute;
   gt.tm_sec = dt->second;
-  return dbiMakeDate(PyInt_FromLong(mktime(&gt)));
+  time_t t = mktime(&gt);
+  // Set dates outside of time_t's range to the epoch.
+  if (t == (time_t)-1)
+    t = 0;
+  return dbiMakeDate(PyInt_FromLong(t)));
 }
 
 static PyObject *rawCopy(const void *v, int sz)


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