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Issue #10827: Changed the rules for 2-digit years. The time.asctime

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function will now format any year when time.accept2dyear is false and
will accept years >= 1000 otherwise.  The year range accepted by
time.mktime and time.strftime is still system dependent, but
time.mktime will now accept full range supported by the OS. Conversion
of 2-digit years to 4-digit is deprecated.
This commit is contained in:
Alexander Belopolsky 2011-01-07 19:59:19 +00:00
parent 696efdd03f
commit c64708ae48
4 changed files with 102 additions and 56 deletions
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47
Modules/timemodule.c
View file

@ -312,34 +312,42 @@ gettmarg(PyObject *args, struct tm *p)
&p->tm_wday, &p->tm_yday, &p->tm_isdst))
return 0;
/* XXX: Why 1900? If the goal is to interpret 2-digit years as those in
* 20th / 21st century according to the POSIX standard, we can just treat
* 0 <= y < 100 as special. Year 100 is probably too ambiguous and should
* be rejected, but years 101 through 1899 can be passed through.
/* If year is specified with less than 4 digits, its interpretation
* depends on the accept2dyear value.
*
* If accept2dyear is true (default), a backward compatibility behavior is
* invoked as follows:
*
* - for 2-digit year, century is guessed according to POSIX rules for
* %y strptime format: 21st century for y < 69, 20th century
* otherwise. A deprecation warning is issued when century
* information is guessed in this way.
*
* - for 3-digit or negative year, a ValueError exception is raised.
*
* If accept2dyear is false (set by the program or as a result of a
* non-empty value assigned to PYTHONY2K environment variable) all year
* values are interpreted as given.
*/
if (y < 1900) {
if (y < 1000) {
PyObject *accept = PyDict_GetItemString(moddict,
"accept2dyear");
int acceptval = accept != NULL && PyObject_IsTrue(accept);
if (acceptval == -1)
return 0;
if (acceptval) {
if (69 <= y && y <= 99)
y += 1900;
else if (0 <= y && y <= 68)
if (0 <= y && y < 69)
y += 2000;
else if (69 <= y && y < 100)
y += 1900;
else {
PyErr_SetString(PyExc_ValueError,
"year out of range");
return 0;
}
}
/* XXX: When accept2dyear is false, we don't have to reject y < 1900.
* Consider removing the following else-clause. */
else {
PyErr_SetString(PyExc_ValueError,
"year out of range");
return 0;
if (PyErr_WarnEx(PyExc_DeprecationWarning,
"Century info guessed for a 2-digit year.", 1) != 0)
return 0;
}
}
p->tm_year = y - 1900;
@ -462,6 +470,15 @@ time_strftime(PyObject *self, PyObject *args)
else if (!gettmarg(tup, &buf) || !checktm(&buf))
return NULL;
/* XXX: Reportedly, some systems have issues formating dates prior to year
* 1900. These systems should be identified and this check should be
* moved to appropriate system specific section below. */
if (buf.tm_year < 0) {
PyErr_Format(PyExc_ValueError, "year=%d is before 1900; "
"the strftime() method requires year >= 1900",
buf.tm_year + 1900);
}
/* Normalize tm_isdst just in case someone foolishly implements %Z
based on the assumption that tm_isdst falls within the range of
[-1, 1] */