[PATCH STABLE] do not crash on or store negative timestamps (issue2513)

[Adrian Buehlmann]

On 2010-11-23 02:34, Benjamin Pollack wrote:
> On Nov 22, 2010, at 5:48 PM, Adrian Buehlmann wrote:
>>> diff --git a/mercurial/util.py b/mercurial/util.py
>>> --- a/mercurial/util.py
>>> +++ b/mercurial/util.py
>>> @@ -1031,6 +1031,8 @@ def datestr(date=None, format='%a %b %d 
>>>         minutes = abs(tz) // 60
>>>         format = format.replace("%1", "%c%02d" % (sign, minutes // 60))
>>>         format = format.replace("%2", "%02d" % (minutes % 60))
>>> +    if t < 0:
>>> +        t = 0
>>>     s = time.strftime(format, time.gmtime(float(t) - tz))
>>>     return s
>>
>> Doesn't t=0 still lead to negative arguments for time.gmtime() for
>> timezones to the west of Greenwich (e.g. U.S.)?
> 
> Correct; I realized that in the channel after I'd already set the patch. Near as I can tell, what matters is not that t < 0, but rather that t < 43200, which is the greatest negative offset that I know of in a timezone. (50400 would be the greatest positive, but because it's ahead of GMT, I don't think we care.)
> 
> I'll do a second patch with this and with Nicolas' request for an argument to ValueError.

I found something interesting though, which could be somewhat of an
argument for having the patch like you sent it above. See this:

$ python
Python 2.6.5 (r265:79096, Mar 19 2010, 21:48:26) [MSC v.1500 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import time
>>> time.gmtime(0)
time.struct_time(tm_year=1970, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0,
tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=0)
>>> time.gmtime(-1)
time.struct_time(tm_year=1969, tm_mon=12, tm_mday=31, tm_hour=23,
tm_min=59, tm_sec=59, tm_wday=3, tm_yday=365, tm_isdst=
0)
>>> time.gmtime(-43200)
time.struct_time(tm_year=1969, tm_mon=12, tm_mday=31, tm_hour=12,
tm_min=0, tm_sec=0, tm_wday=3, tm_yday=365, tm_isdst=0)
>>> time.gmtime(-43201)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: (22, 'Invalid argument')


In other words, time.gmtime(-1) doesn't crash neither does
time.gmtime(-43200).

It needs to be -43201 or smaller to crash (which is not what I'd expect
from reading the msdn page I linked).