Python 2.6.2 (r262:71605, Apr 14 2009, 22:40:02) [MSC v.1500 32 bit 
(Intel)] on win32
IDLE 2.6.2      
>>> import zipfile
>>> new = zipfile.ZipFile('C:\\x', 'w', zipfile.ZIP_DEFLATED)
>>> zi = zipfile.ZipInfo('test',(1,2,3,4,5,6))
>>> new.writestr(zi,'fgh')

Warning (from warnings module):
  File "H:\programs\python\lib\zipfile.py", line 1105
    self.fp.write(zinfo.FileHeader())
DeprecationWarning: struct integer overflow masking is deprecated

Warning (from warnings module):
  File "H:\programs\python\lib\zipfile.py", line 1105
    self.fp.write(zinfo.FileHeader())
DeprecationWarning: 'H' format requires 0 <= number <= 65535
>>>

This code is broken in 2.7alpha4 - it doesn't add file at all.

Traceback (most recent call last):
  File "test.py", line 5, in <module>
    new.writestr(zi,'fgh')
  File "C:\~env\Python27\lib\zipfile.py", line 1099, in writestr
    self.fp.write(zinfo.FileHeader())
  File "C:\~env\Python27\lib\zipfile.py", line 342, in FileHeader
    len(filename), len(extra))
struct.error: ushort format requires 0 <= number <= USHRT_MAX

Making the stage test needed, since we need to get the test into the test suite as a unit test.

This is not a bug in the code, but in the application. You are passing a date before 1980; this is not supported in zipfiles. Try passing 1980 instead of 1.

I think the error message could be better, though; it should probably be a ValueError.

Reducing the priority to normal.

[Martin]
> I think the error message could be better, though; it should probably be a ValueError.

Do you mean a ValueError at the level of the struct module, or the zipfile module.

I'd quite like to change all the exceptions raised by the struct module to ValueError or TypeError (as appropriate);  I'm not sure what the point of struct.error is supposed to be.  I've resisted making this change up until now for backwards compatibility reasons, but perhaps it could be considered for 3.2 (but not for 2.7).

Retitled to reflect that the error message should be enhanced.

Attached a patch for 2.7 that raises ValueError for timestamps before 1980, documents that 1980 or later is required, and adds some tests.

New changeset 649ac338203f by Senthil Kumaran in branch '2.7':
Fix closes Issue6090 - Raise a ValueError, instead of failing with unrelated
http://hg.python.org/cpython/rev/649ac338203f

New changeset 12f3e86e9041 by Senthil Kumaran in branch '3.2':
3.2 - Fix closes Issue6090 - Raise a ValueError, instead of failing with unrelated
http://hg.python.org/cpython/rev/12f3e86e9041

New changeset 55318658e1be by Senthil Kumaran in branch 'default':
default - Fix closes Issue6090 - Raise a ValueError, instead of failing with unrelated
http://hg.python.org/cpython/rev/55318658e1be

Fixed in all active branches. Thanks for the patch, Petri. 
Mark, for this issue, raising ValueError from zipfile was seemingly a  right thing to do, the previous error from struct for a side effect of sending a value lower than 1980.

One ongoing weakness I see with this situation is that it's difficult to code a suitable work-around if a user wants to zip files that have a date < 1980 (e.g. to zip it with a datestamp of 1-Jan-1980).
https://stackoverflow.com/q/45703747/60075

I am trying to create a zip file with Python 3.5.2 zipfile, on Linux. Some of the files I'm trying to add have timestamps of 1-Jan-1970 (embedded system without a real-time clock module). So zipfile gives an exception:

ValueError: ZIP does not support timestamps before 1980

My goal then is to implement a work-around to add these files to the zip file with a timestamp of 1-Jan-1980. However, I am finding it difficult to find a suitable work-around.

At first I thought I can do this:

def zinfo_from_file(fullname, arcname):
    st = os.stat(fullname)
    mtime = time.localtime(st.st_mtime)
    date_time = mtime[0:6]
    if date_time[0] < 1980:
        date_time = (1980, 1, 1, 0, 0, 0)
    zinfo = zipfile.ZipInfo(arcname, date_time)
    return zinfo

...
zinfo = zinfo_from_file(fullname, arcname)
chunksize=512
with open(fullname, 'rb') as src, myzipfile.open(zinfo, 'w') as dest:
    while True:
        data = src.read(chunksize)
        if not data:
            break
        dest.write(data)
...

However, it turns out that myzipfile.open(zinfo, 'w') is not supported until Python 3.6. (I'm using Yocto to build embedded Linux, which currently only supports Python 3.5.x.)

I guess I could try doing myzipfile.writestr(...), although then it appears that I have to load the entire file data into memory.