[igt-dev] [PATCH i-g-t v2] igt_eld: add igt_is_igt

[Ser, Simon]

On Thu, 2019-09-12 at 18:44 +0300, Simon Ser wrote:
> This function parses the monitor name from an ELD blob and checks
> whether it
> comes from an IGT EDID.
> 
> v2: replace a bunch of random numbers with constants (Chris, Andi)

And of course the commit message is still wrong…

> Signed-off-by: Simon Ser <simon.ser at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Andi Shyti <andi.shyti at intel.com>
> ---
> 
> Hrm, indeed, you're right, constants make the code much better.
> 
>  lib/igt_eld.c | 29 +++++++++++++++++++++++++++++
>  lib/igt_eld.h |  1 +
>  2 files changed, 30 insertions(+)
> 
> diff --git a/lib/igt_eld.c b/lib/igt_eld.c
> index 16c4ac06c6f6..d565a4c04773 100644
> --- a/lib/igt_eld.c
> +++ b/lib/igt_eld.c
> @@ -262,3 +262,32 @@ bool eld_has_igt(void)
>  	struct eld_entry eld;
>  	return eld_get_igt(&eld);
>  }
> +
> +#define ELD_MAX_SIZE 256
> +#define MONITOR_NAME_OFFSET 20
> +#define MONITOR_NAME_MAX_SIZE 16
> +
> +/** eld_is_igt: check whether the ELD blob comes from an IGT EDID */
> +bool eld_is_igt(const char *eld, size_t eld_size)
> +{
> +	char name[MONITOR_NAME_MAX_SIZE + 1];
> +	int name_size;
> +
> +	igt_assert_f(eld_size >= MONITOR_NAME_OFFSET &&
> +		     eld_size <= ELD_MAX_SIZE,
> +		     "Invalid ELD size: %zu\n", eld_size);
> +
> +	name_size = eld[4] & 0x1F;
> +	igt_assert_f(name_size <= MONITOR_NAME_MAX_SIZE &&
> +		     MONITOR_NAME_OFFSET + name_size <= eld_size,
> +		     "Invalid monitor name size in ELD: %d\n",
> name_size);
> +	if (name_size == 0) {
> +		igt_debug("ELD doesn't contain a monitor name\n");
> +		return false;
> +	}
> +
> +	memcpy(name, &eld[MONITOR_NAME_OFFSET], name_size);
> +	name[name_size] = '\0';
> +	igt_debug("Checking ELD with monitor name: %s\n", name);
> +	return strcmp(name, "IGT") == 0;
> +}
> diff --git a/lib/igt_eld.h b/lib/igt_eld.h
> index 7c4489f054f1..36f000abe3f9 100644
> --- a/lib/igt_eld.h
> +++ b/lib/igt_eld.h
> @@ -51,5 +51,6 @@ struct eld_entry {
> 
>  bool eld_get_igt(struct eld_entry *eld);
>  bool eld_has_igt(void);
> +bool eld_is_igt(const char *eld, size_t eld_size);
> 
>  #endif
> --
> 2.23.0
> 
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