Hi
Quick bit of background. I'm a Valgrind maintainer and recently I've
been working on getting Valgrind to work more like the underlying OS /
libc implementations of memalign, posix_memalign and aligned_alloc.
There are several issues with the manpage for memalign and aligned alloc.
quote:
The obsolete function memalign() allocates size bytes and
returns a
pointer to the allocated memory. The memory address will be a
multiple
of alignment, which must be a power of two.
endquote:
The power if two requirement is false for glibc which silently bumps up
the alignment to the next power of two.
quote:
The function aligned_alloc() is the same as memalign(), except
for the
added restriction that size should be a multiple of alignment.
endquote:
This is also false for glibc. In the glibc implementation weak aliases
are used so memalign and aligned_alloc call the same function.
quote:
ERRORS
EINVAL The alignment argument was not a power of two, or was not
a mul-
tiple of sizeof(void *).
endquote:
Both of the above only apply to posix_memalign and not to either
memalign or aligned_alloc.
There is a missing EINVAL description. If the alignment is so large that
the allocation will not be possible to satisfy then the call will fail
and set errno to EINVAL.
Regards
Paul
