ACK: [PATCH v2] DMI: Fix the way to load SMBIOS 3.x tables via sysfs

[Alex Hung]

On 2018-08-22 07:41 PM, songgebird at gmail.com wrote:
> From: Ge Song <ge.song at hxt-semitech.com>
> 
> In SMBIOS 3.x specs, the meaning of "Structure table maximum size"
> field in SMBIOS Entry Point Structure is "Maximum size of SMBIOS
> Structure Table, pointed to by the Structure Table Address, in bytes.
> The actual size is guaranteed to be less or equal to the maximum size."
> 
> Thus we cannot assume the whole size of SMBIOS segment equals to the
> value of entry->struct_table_length.
> 
> This fix the DMI test failure in some platforms when the real size of
> SMBIOS segment are smaller than the value in "Structure table maximum
> size" field
> 
> Signed-off-by: Ge Song <ge.song at hxt-semitech.com>
> ---
> Change since V1:
>    * Correct the increase of buffer pointer p in for loop.
>    * Since the open() has no O_NONBLOCK flag, remove the unnecessary
>      judgement.
>   src/dmi/dmicheck/dmicheck.c | 32 +++++++++++++++++++-
>   1 file changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/src/dmi/dmicheck/dmicheck.c b/src/dmi/dmicheck/dmicheck.c
> index 8497c2ab..a95b47c0 100644
> --- a/src/dmi/dmicheck/dmicheck.c
> +++ b/src/dmi/dmicheck/dmicheck.c
> @@ -276,6 +276,36 @@ static int dmi_load_file(const char* filename, void *buf, size_t size)
>   	return FWTS_OK;
>   }
>   
> +static int dmi_load_file_variable_size(const char* filename, void *buf, size_t *size)
> +{
> +	int fd;
> +	char *p;
> +	ssize_t count;
> +	size_t sz, total;
> +
> +	sz = *size;
> +	(void)memset(buf, 0, sz);
> +
> +	if ((fd = open(filename, O_RDONLY)) < 0)
> +		return FWTS_ERROR;
> +
> +	for (p = buf, total = count = 0; ; p += count) {
> +		count = read(fd, p, sz - total);
> +		if (count == -1) {
> +			close(fd);
> +			return FWTS_ERROR;
> +		}
> +		if (count == 0)
> +			break;
> +
> +		total += (size_t)count;
> +	}
> +
> +	(void)close(fd);
> +	*size = total;
> +	return FWTS_OK;
> +}
> +
>   static void* dmi_table_smbios(fwts_framework *fw, fwts_smbios_entry *entry)
>   {
>   	off_t addr = (off_t)entry->struct_table_address;
> @@ -358,7 +388,7 @@ static void* dmi_table_smbios30(fwts_framework *fw, fwts_smbios30_entry *entry)
>   		table = malloc(length);
>   		if (!table)
>   			return NULL;
> -		if (dmi_load_file("/sys/firmware/dmi/tables/DMI", table, length) == FWTS_OK) {
> +		if (dmi_load_file_variable_size("/sys/firmware/dmi/tables/DMI", table, &length) == FWTS_OK) {
>   			fwts_log_info(fw, "SMBIOS30 table loaded from /sys/firmware/dmi/tables/DMI\n");
>   			return table;
>   		}
> 


Acked-by: Alex Hung <alex.hung at canonical.com>