bug? mmap doesn't like 0-length files

Cameron Simpson cs at zip.com.au
Tue Nov 23 03:59:29 CET 2010


On 22Nov2010 20:33, Neal Becker <ndbecker2 at gmail.com> wrote:
|  mmap.mmap (f.fileno(), 0, prot=mmap.PROT_READ)
| error: [Errno 22] Invalid argument
| 
| According to http://docs.python.org/library/mmap.html, mmap on _windows_ 
| doesn't accept 0-length file.  But this was tested on linux.  Is this a bug?  
| 
| I don't see anything in linux man-page about the underlying C mmap function 
| not accepting 0-length files.

On a local Gentoo Linux box mmap(2) says in the ERRORS section:

  EINVAL We don't like addr, length, or offset (e.g., they are too
         large, or not aligned on a page boundary).

  EINVAL (since Linux 2.6.12) length was 0.

  EINVAL flags contained neither MAP_PRIVATE or MAP_SHARED, or contained both
         of these values.

Sure looks like a length of 0 is disliked.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

Carpe Daemon - Seize the Background Process
        - Paul Tomblin <ab401 at freenet2.carleton.ca>



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