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    SubjectRe: [PATCH] tools/lib/traceevent, perf tools: Handle %pU format correctly
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    On 2019/10/16 下午10:54, Steven Rostedt wrote:
    > On Wed, 16 Oct 2019 14:39:20 +0800
    > Qu Wenruo <wqu@suse.com> wrote:
    >
    >> +static void print_uuid_arg(struct trace_seq *s, void *data, int size,
    >> + struct tep_event *event, struct tep_print_arg *arg)
    >> +{
    >> + const char *fmt;
    >> + unsigned char *buf;
    >> +
    >> + fmt = "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x";
    >> + if (arg->type != TEP_PRINT_FIELD) {
    >> + trace_seq_printf(s, "ARG TYPE NOT FIELID but %d", arg->type);
    >> + return;
    >> + }
    >> +
    >> + if (!arg->field.field) {
    >> + arg->field.field = tep_find_any_field(event, arg->field.name);
    >> + if (!arg->field.field) {
    >> + do_warning("%s: field %s not found",
    >> + __func__, arg->field.name);
    >> + return;
    >> + }
    >> + }
    >> + buf = data + arg->field.field->offset;
    >
    > You also need to make sure the data field is not smaller than 16 bytes.
    >
    > if (arg->field.field->size < 16) {
    > trace_seq_puts(s, "INVALIDUUID");
    > return;
    > }
    >

    Oh, forgot that sanity check.

    >> +
    >> + trace_seq_printf(s, fmt, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5],
    >> + buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12],
    >> + buf[13], buf[14], buf[15]);
    >> +}
    >> +
    >
    > Hmm, I know print_mac_addr() does something similar as this, but this
    > is getting a bit extreme (too many arguments!). What about doing:
    >
    > for (i = 0; i < 4; i++)
    > trace_seq_printf(s, "%02x", buf++);
    >
    > for (i = 0; i < 3; i++)
    > trace_seq_printf(s, "-%02x%02x", buf[i * 2], buf[i * 2 + 1]);
    >
    > buf += 6;
    >
    > trace_seq_putc(s, '-');
    >
    > for (i = 0; i < 6; i++)
    > trace_seq_printf(s, "%02x", buf++);
    >
    >
    >
    > Hmm, not sure the above is better, but having that many arguments just
    > looks ugly to me.

    Indeed, I'll update the patchset to make it more sane.

    Thanks,
    Qu
    >
    > -- Steve
    >

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