Re: [PATCH v3 05/19] cutils: Fix wraparound parsing in qemu_strtoui

[Hanna Czenczek <hreitz@redhat.com>]

On 22.05.23 21:04, Eric Blake wrote:
> While we were matching 32-bit strtol in qemu_strtoi, our use of a
> 64-bit parse was leaking through for some inaccurate answers in
> qemu_strtoui in comparison to a 32-bit strtoul (see the unit test for
> examples).  The comment for that function even described what we have
> to do for a correct parse, but didn't implement it correctly: since
> strtoull checks for overflow against the wrong values and then
> negates, we have to temporarily undo negation before checking for
> overflow against our desired value.
>
> Our int wrappers would be a lot easier to write if libc had a
> guaranteed 32-bit parser even on platforms with 64-bit long.
>
> Whether we parse C2x binary strings like "0b1000" is currently up to
> what libc does; our unit tests intentionally don't cover that at the
> moment, though.
>
> Fixes: 473a2a331e ("cutils: add qemu_strtoi & qemu_strtoui parsers for int/unsigned int types", v2.12.0)
> Signed-off-by: Eric Blake <eblake@redhat.com>
> CC: qemu-stable@nongnu.org
> ---
>
> v3: rewrite with better comments in code and commit message [Hanna];
> fix additional problems with wraparound, cc qemu-stable although this
> has been long-standing enough to be low priority, R-b dropped
> ---
>   tests/unit/test-cutils.c | 20 +++++++++-----------
>   util/cutils.c            | 25 +++++++++++++++++++------
>   2 files changed, 28 insertions(+), 17 deletions(-)

Reviewed-by: Hanna Czenczek <hreitz@redhat.com>