Currently, if the `num` field of a varray is not a numeric type, such as
being placed in a wrapper, the array variant of assert_field_type will
fail the check.
HPET currently wraps num_timers in BqlCell<>. Although BqlCell<> is not
necessary from strictly speaking, it makes sense for vmstate to respect
BqlCell.
The failure of assert_field_type is because it cannot convert BqlCell<T>
into usize for use as the index. Use a constant 0 instead for the index,
by avoiding $(...)? and extracting the common parts of
assert_field_type! into an internal case.
Commit message based on a patch by Zhao Liu <zhao1.liu@intel.com>.
Link: https://lore.kernel.org/r/20250414144943.1112885-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When pass a varray to vmstate_struct, the `type` parameter should be the
type of the element in the varray, for example:
vmstate_struct!(HPETState, timers, [0 .. num_timers], VMSTATE_HPET_TIMER,
BqlRefCell<HPETTimer>).with_version_id(0)
But this breaks current type check, because it checks the type of
`field`, which is an array type (for the above example, type of timers
is [BqlRefCell<HPETTimer>; 32], not BqlRefCell<HPETTimer>).
But the current assert_field_type() can no longer be extended to include
new arguments, so a variant of it (a second macro containing the
`num = $num:ident` parameter) had to be added to handle array cases.
In this new macro, it not only checks the type of element, but also
checks whether the `num` (number of elements in varray) is out of range.
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250318130219.1799170-6-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new assertion that is similar to "const { assert!(...) }" but can be used
outside functions and with older versions of Rust. A similar macro is found in
Linux, whereas the "static_assertions" crate has a const_assert macro that
produces worse error messages.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Link: https://lore.kernel.org/r/20250321112523.1774131-2-peter.maydell@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It is a common convention in QEMU to return a positive value in case of
success, and a negated errno value in case of error. Unfortunately,
using errno portably in Rust is a bit complicated; on Unix the errno
values are supported natively by io::Error, but on Windows they are not;
so, use the libc crate.
This is a set of utility functions that are used by both chardev and
block layer bindings.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It is relatively common in the low-level qemu_api code to assert that
a field of a struct has a specific type; for example, it can be used
to ensure that the fields match what the qemu_api and C code expects
for safety.
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
