Le 30/04/2019 à 22:09, Alistair Francis a écrit :
> Fix this warning with GCC 9 on Fedora 30:
> hw/usb/dev-mtp.c:1715:36: error: taking address of packed member of ‘struct
> <anonymous>’ may result in an unaligned pointer value
> [-Werror=address-of-packed-member]
> 1715 | dataset->filename);
> | ~~~~~~~^~~~~~~~~~
>
> Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
> ---
> hw/usb/dev-mtp.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
> index 99548b012d..6de85d99e6 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -1711,9 +1711,22 @@ static void usb_mtp_write_metadata(MTPState *s,
> uint64_t dlen)
> assert(!s->write_pending);
> assert(p != NULL);
>
> +/*
> + * We are about to access a packed struct. We are confident that the pointer
> + * address won't be unalligned, so we ignore GCC warnings.
> + */
> +#if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && QEMU_GNUC_PREREQ(9, 0)
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
> +#endif
> +
> filename = utf16_to_str(MIN(dataset->length, filename_chars),
> dataset->filename);
>
> +#if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && QEMU_GNUC_PREREQ(9, 0)
> +#pragma GCC diagnostic pop
> +#endif
> +
> if (strchr(filename, '/')) {
> usb_mtp_queue_result(s, RES_PARAMETER_NOT_SUPPORTED, d->trans,
> 0, 0, 0, 0);
>
You should move and use PRAGMA_DISABLE_PACKED_WARNING and
PRAGMA_REENABLE_PACKED_WARNING from linux-user/qemu.h.
It has laready been very well tested :)
Thanks,
Laurent
