Maxim Yanchenko added the comment:
> You got lucky, since the offset must be a multiple of the page size.
That's why our header is exactly the page size :)
> Here's what POSIX says
Then it's just another discrepancy between POSIX and Linux, as I received
ENOMEM instead of EINVAL (RHEL6 on 2.6.
Charles-François Natali added the comment:
> The condition contradicts the exception text:
Why?
The offset is zero-based, so 0 <= offset < size is a valid check.
> First of all, it doesn't fail (at least on Linux), I tested it before
> posting.
Hmmm.
You got lucky, since the offset must be a
Maxim Yanchenko added the comment:
tried on newer Linux - crashes with my patch.
So I'll be thinking about a workaround, probably a fix for NumPy to avoid using
mmap in such cases but still provide uniform interface to avoid making special
conditional handling in all my scripts.
Therefore, I'm
Maxim Yanchenko added the comment:
Well, "n+1" is clearly outside the file, wile "n" is within and therefore valid.
Also, if your position is to forbid zero-size mmapping completely, then the
checks inside "if (map_size == 0) {" don't make any sense, especially as they
may or may fail.
>From
Antoine Pitrou added the comment:
I don't think it makes sense to accept mmap'ing empty contents when at offset
"n" but not at offset "n + 1". Either we remove the check entirely and let
people deal with the consequences, or we keep the check as-is.
--
nosy: +neologix
stage: committed
Maxim Yanchenko added the comment:
First of all, it doesn't fail (at least on Linux), I tested it before posting.
And the latest, it's not like I'm just stalking around and reading Python
sources for fun. It's a real and pretty valid case, I hit it while upgrading
our production code to pytho
Antoine Pitrou added the comment:
Well, you have to understand what this code does: it tries to prevent
non-meaningful offsets. If the offset is equal to the file size, mapping from
that offset would not map anything in the file (and the system call may
actually fail).
--
nosy: +pitr
New submission from Maxim Yanchenko :
The condition contradicts the exception text:
if (offset >= st.st_size) {
PyErr_SetString(PyExc_ValueError,
"mmap offset is greater than file size");
return NULL;
}
The co
