Add GetFileHandle method to dump entry

This commit introduces the GetFileHandle method in the dump entry
interface. This method provides direct access to the Unix file
handle of the dump entry, facilitating more direct read operations
on the dump file.

The returned file descriptor will be read-only, ensuring the integrity
of the dump file.

This change is primarily introduced to support the PLDM for offloading
the dump to the host and bmcweb for offloading the dump to Redfish
clients. Previously, a direct file path was provided for these
operations. However, if the applications are running in a non-root
context, they may lack the necessary access to the file. By providing
a file handle, this access issue is resolved.

Change-Id: I1c9dd5ae6dad503288f39227876e13308043fefd
Signed-off-by: Dhruvaraj Subhashchandran <dhruvaraj@in.ibm.com>
diff --git a/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml b/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
index 34c0868..fcb275e 100644
--- a/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
+++ b/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
@@ -30,6 +30,22 @@
           - xyz.openbmc_project.Common.Error.NotAllowed
           - xyz.openbmc_project.Common.Error.Unavailable
 
+    - name: GetFileHandle
+      description: >
+          This method provides the Unix file handle for the dump entry. The file
+          handle returned can be used by clients to directly read the contents
+          of file in their own context, without relying on additional API calls.
+          The mode of the file descriptor is read-only.
+      returns:
+          - name: fd
+            type: unixfd
+            description: >
+                The file descriptor to the dump file.
+      errors:
+          - xyz.openbmc_project.Common.File.Error.Open
+          - xyz.openbmc_project.Common.Error.NotAllowed
+          - xyz.openbmc_project.Common.Error.Unavailable
+
 properties:
     - name: Size
       type: uint64