In qCompress, we've been calculating postive len values out of them,
only to fail at random points later, possibly running into UB. Fail
early instead.
In qUncompress, we've been catching negative values, and reported them
indiscriminately as "invalid data". Use a better warning message
instead.
By rights, nbytes ≥ 0 would be a precondition of both functions (which
we would Q_ASSERT() on), but seeing we're picking this back into LTS
branches, I found it prudent to use a non-fatal way to signal the
precondition violation.
If and when we keep these functions for Qt 7, it will be as an
overload that takes QByteArrayView, in which case nbytes ≥ 0 enters as
a hard precondition via the QByteArrayView constructor, so there
appears to be no need to pre-program a Q_ASSERT() for Qt 7.0.
Pick-to: 6.4 6.3 6.2
Task-number: QTBUG-104972
Task-number: QTBUG-106542
Change-Id: I6a1b25fe12d31e3d4c845033cad320832976f83c
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
bbd1f576f7