[RFC 02/14] efi_loader: library function efi_dp_merge

[Heinrich Schuchardt]

On 26.04.24 16:30, Ilias Apalodimas wrote:
> Hi Heinrich,
> 
> On Fri, 26 Apr 2024 at 17:13, Heinrich Schuchardt
> <heinrich.schuchardt at canonical.com> wrote:
>>
>> Provide a function to append a device_path to a list of device paths
>> that is separated by final end nodes.
>>
>> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
>> ---
>>   include/efi_loader.h             |  3 +++
>>   lib/efi_loader/efi_device_path.c | 31 +++++++++++++++++++++++++++++++
>>   2 files changed, 34 insertions(+)
>>
>> diff --git a/include/efi_loader.h b/include/efi_loader.h
>> index 9600941aa32..a7d7b8324f1 100644
>> --- a/include/efi_loader.h
>> +++ b/include/efi_loader.h
>> @@ -944,6 +944,9 @@ struct efi_load_option {
>>
>>   struct efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
>>                                         const efi_guid_t *guid);
>> +struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
>> +                                    efi_uintn_t *size,
>> +                                    const struct efi_device_path *dp2);
>>   struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
>>                                        const struct efi_device_path *dp2,
>>                                        bool split_end_node);
>> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
>> index 46aa59b9e40..16cbe41d32f 100644
>> --- a/lib/efi_loader/efi_device_path.c
>> +++ b/lib/efi_loader/efi_device_path.c
>> @@ -270,6 +270,37 @@ struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
>>          return ndp;
>>   }
>>
>> +/**
>> + * efi_dp_merge() - Concatenate two device paths separated by final end node
>> + *
>> + * @dp1:       first device path
>> + * @size:      pointer to length of @dp1, total size on return
>> + * @dp2:       second device path
>> + *
>> + * Return:     concatenated device path or NULL
>> + */
>> +struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
>> +                                    efi_uintn_t *size,
>> +                                    const struct efi_device_path *dp2)
>> +{
>> +       efi_uintn_t len, len1, len2;
>> +       struct efi_device_path *dp;
>> +       u8 *p;
>> +
>> +       len1 = *size;
>> +       len2 = efi_dp_size(dp2) + sizeof(END);
>> +       len = len1 + len2;
>> +       dp = efi_alloc(len);
>> +       if (!dp)
>> +               return NULL;
>> +       memcpy(dp, dp1, len1);
>> +       p = (u8 *)dp + len1;
>> +       memcpy(p, dp2, len2);
>> +       *size = len;
> 
> Can't we just use efi_dp_concat()?

efi_dp_concat cannot be used to put a device-path end-node in between 
two device-paths that are concatenated. We need that separator in the 
load options.

Best regards

Heinrich

> 
> Thanks
> /Ilias
>> +
>> +       return dp;
>> +}
>> +
>>   /**
>>    * efi_dp_concat() - Concatenate two device paths and add and terminate them
>>    *                   with an end node.
>> --
>> 2.43.0
>>