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SubjectRe: [PATCH] hcidump: add support for time64 based libc
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On Jan 10, 2020, at 12:49 PM, Arnd Bergmann <arnd@arndb.de> wrote:

> diff --git a/monitor/hcidump.c b/monitor/hcidump.c
> index 8b6f846d3..6d2330287 100644
> --- a/monitor/hcidump.c
> +++ b/monitor/hcidump.c
> @@ -107,6 +107,36 @@ static int open_hci_dev(uint16_t index)
> return fd;
> }
>
> +static struct timeval hci_tstamp_read(void *data)
> +{
> + struct timeval tv;
> +
> + /*
> + * On 64-bit architectures, the data matches the timeval
> + * format. Note that on sparc64 this is different from
> + * all others.
> + */
> + if (sizeof(long) == 8) {
> + memcpy(&tv, data, sizeof(tv));
> + }
> +
> + /*
> + * On 32-bit architectures, the timeval definition may
> + * use 32-bit or 64-bit members depending on the C
> + * library and architecture.
> + * The cmsg data however always contains a pair of
> + * 32-bit values. Interpret as unsigned to make it work
> + * past y2038.
> + */
> + if (sizeof(long) == 4) {
> + unsigned int *stamp = data;
> + tv.tv_sec = stamp[0];
> + tv.tv_usec = stamp[1];
> + }
> +
> + return tv;
> +}

Should it be something more like

if (sizeof(long) == 8) {
/*
* On 64-bit architectures, the data matches the timeval
* format. Note that on sparc64 this is different from
* all others.
*/
memcpy(&tv, data, sizeof(tv));
} else if (sizeof(long) == 4) {
/*
* On 32-bit architectures, the timeval definition may
* use 32-bit or 64-bit members depending on the C
* library and architecture.
* The cmsg data however always contains a pair of
* 32-bit values. Interpret as unsigned to make it work
* past y2038.
*/
unsigned int *stamp = data;
tv.tv_sec = stamp[0];
tv.tv_usec = stamp[1];
} else {
abort(); /* or some other "sorry, we're not ready for 128-bit or weird architectures yet" failure */
}

return tv;

> static void device_callback(int fd, uint32_t events, void *user_data)
> {
> struct hcidump_data *data = user_data;
> @@ -150,7 +180,7 @@ static void device_callback(int fd, uint32_t events, void *user_data)
> memcpy(&dir, CMSG_DATA(cmsg), sizeof(dir));
> break;
> case HCI_CMSG_TSTAMP:
> - memcpy(&ctv, CMSG_DATA(cmsg), sizeof(ctv));
> + ctv = hci_tstamp_read(CMSG_DATA(cmsg));
> tv = &ctv;
> break;
> }

And libpcap's Linux BT code should do the same thing, changing its memcpy() call?

If you want, you can submit a pull request, or I can make the change.

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