On Sun, 5 Jul 2009, Alexander Best wrote:

i'm wondering why mmap and munmap behave differently when it comes to a length
argument of zero. allocating memory with mmap for a zero length file returns a
valid pointer to the mapped region.

munmap however isn't able to remove a mapping with no length.

wouldn't it be better to either forbid this in mmap or to allow it in munmap?

POSIX has an opinion:

http://www.opengroup.org/onlinepubs/9699919799/functions/mmap.html

"If len is zero, mmap() shall fail and no mapping shall be established."

http://www.opengroup.org/onlinepubs/9699919799/functions/munmap.html

"The munmap() function shall fail if:
...
[EINVAL]
    The len argument is 0."


--

Nate Eldredge
neldre...@math.ucsd.edu
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