dsp: file: Add encode req & decode resp for DfOpen command

Added encode/decode APIs for DfOpen command(0x01)
which is defined in DSP0242 Version 1.0.0 Section: 9.2.

Change-Id: I5a975a7ae2bbd4115898486984ad96016590b04b
Signed-off-by: Chau Ly <chaul@amperecomputing.com>
diff --git a/tests/dsp/file.cpp b/tests/dsp/file.cpp
new file mode 100644
index 0000000..f738377
--- /dev/null
+++ b/tests/dsp/file.cpp
@@ -0,0 +1,166 @@
+#include <libpldm/file.h>
+#include <libpldm/pldm_types.h>
+
+#include <array>
+#include <cstdint>
+#include <cstring>
+#include <vector>
+
+#include "msgbuf.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#ifdef LIBPLDM_API_TESTING
+TEST(EncodeDfOpenReq, GoodTest)
+{
+    uint8_t instance_id = 0;
+    uint16_t file_identifier = 0x0100;
+    bitfield16_t file_attribute;
+    file_attribute.value = 0x0400;
+    std::array<uint8_t, PLDM_DF_OPEN_REQ_BYTES> requestMsg = {0x00, 0x01, 0x00,
+                                                              0x04};
+
+    const struct pldm_file_df_open_req req_data = {file_identifier,
+                                                   file_attribute};
+
+    PLDM_MSG_DEFINE_P(requestPtr, PLDM_DF_OPEN_REQ_BYTES);
+    auto rc = encode_pldm_file_df_open_req(instance_id, &req_data, requestPtr,
+                                           PLDM_DF_OPEN_REQ_BYTES);
+
+    ASSERT_EQ(rc, 0);
+    EXPECT_EQ(
+        0, memcmp(requestPtr->payload, requestMsg.data(), sizeof(requestMsg)));
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(EncodeDfOpenReq, BadTestUnAllocatedPtrParams)
+{
+    uint8_t instance_id = 0;
+    uint16_t file_identifier = 0x0100;
+    bitfield16_t file_attribute;
+    file_attribute.value = 0x0400;
+    int rc;
+
+    const struct pldm_file_df_open_req req_data = {file_identifier,
+                                                   file_attribute};
+
+    PLDM_MSG_DEFINE_P(requestPtr, PLDM_DF_OPEN_REQ_BYTES);
+    rc = encode_pldm_file_df_open_req(instance_id, &req_data, nullptr,
+                                      PLDM_DF_OPEN_REQ_BYTES);
+    EXPECT_EQ(rc, -EINVAL);
+
+    rc = encode_pldm_file_df_open_req(instance_id, nullptr, requestPtr,
+                                      PLDM_DF_OPEN_REQ_BYTES);
+    EXPECT_EQ(rc, -EINVAL);
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(EncodeDfOpenReq, BadTestInvalidExpectedOutputMsgLength)
+{
+    uint8_t instance_id = 0;
+    uint16_t file_identifier = 0x0100;
+    bitfield16_t file_attribute;
+    file_attribute.value = 0x0400;
+    int rc;
+
+    const struct pldm_file_df_open_req req_data = {file_identifier,
+                                                   file_attribute};
+
+    PLDM_MSG_DEFINE_P(requestPtr, PLDM_DF_OPEN_REQ_BYTES);
+    rc = encode_pldm_file_df_open_req(instance_id, &req_data, requestPtr, 1);
+    EXPECT_EQ(rc, -EOVERFLOW);
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(DecodeDfOpenResp, GoodTest)
+{
+    uint8_t completion_code = PLDM_SUCCESS;
+    uint16_t file_descriptor = 20;
+
+    struct pldm_file_df_open_resp resp_data = {};
+
+    PLDM_MSGBUF_DEFINE_P(buf);
+    int rc;
+
+    static constexpr const size_t payload_length = PLDM_DF_OPEN_RESP_BYTES;
+
+    PLDM_MSG_DEFINE_P(responseMsg, payload_length);
+
+    rc = pldm_msgbuf_init_errno(buf, 0, responseMsg->payload, payload_length);
+    ASSERT_EQ(rc, 0);
+
+    pldm_msgbuf_insert_uint8(buf, completion_code);
+    pldm_msgbuf_insert_uint16(buf, file_descriptor);
+
+    ASSERT_EQ(pldm_msgbuf_complete_consumed(buf), 0);
+
+    rc = decode_pldm_file_df_open_resp(responseMsg, payload_length, &resp_data);
+
+    ASSERT_EQ(rc, 0);
+    EXPECT_EQ(resp_data.completion_code, completion_code);
+    EXPECT_EQ(resp_data.file_descriptor, file_descriptor);
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(DecodeDfOpenResp, BadTestUnAllocatedPtrParams)
+{
+    uint8_t completion_code = PLDM_SUCCESS;
+    uint16_t file_descriptor = 20;
+
+    struct pldm_file_df_open_resp resp_data = {};
+
+    PLDM_MSGBUF_DEFINE_P(buf);
+    int rc;
+
+    static constexpr const size_t payload_length = PLDM_DF_OPEN_RESP_BYTES;
+
+    PLDM_MSG_DEFINE_P(responseMsg, payload_length);
+
+    rc = pldm_msgbuf_init_errno(buf, 0, responseMsg->payload, payload_length);
+    ASSERT_EQ(rc, 0);
+
+    pldm_msgbuf_insert_uint8(buf, completion_code);
+    pldm_msgbuf_insert_uint16(buf, file_descriptor);
+
+    ASSERT_EQ(pldm_msgbuf_complete_consumed(buf), 0);
+
+    rc = decode_pldm_file_df_open_resp(nullptr, payload_length, &resp_data);
+    EXPECT_EQ(rc, -EINVAL);
+
+    rc = decode_pldm_file_df_open_resp(responseMsg, payload_length, nullptr);
+    EXPECT_EQ(rc, -EINVAL);
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(DecodeDfOpenResp, BadTestInvalidExpectedInputMsgLength)
+{
+    uint8_t completion_code = PLDM_SUCCESS;
+    uint16_t file_descriptor = 20;
+
+    struct pldm_file_df_open_resp resp_data = {};
+
+    PLDM_MSGBUF_DEFINE_P(buf);
+    int rc;
+
+    static constexpr const size_t payload_length = PLDM_DF_OPEN_RESP_BYTES;
+
+    PLDM_MSG_DEFINE_P(responseMsg, payload_length);
+
+    rc = pldm_msgbuf_init_errno(buf, 0, responseMsg->payload, payload_length);
+    ASSERT_EQ(rc, 0);
+
+    pldm_msgbuf_insert_uint8(buf, completion_code);
+    pldm_msgbuf_insert_uint16(buf, file_descriptor);
+
+    ASSERT_EQ(pldm_msgbuf_complete_consumed(buf), 0);
+
+    rc = decode_pldm_file_df_open_resp(responseMsg, 0, &resp_data);
+    EXPECT_EQ(rc, -EOVERFLOW);
+}
+#endif