[avb] Refactor the error thrown by payload verification API

This cl refactors the error by:

- Renaming the error to AvbSlotVerifyError to reveal that it is
the error part of `avb_bindgen::AvbSlotVerifyResult`.
- Moving the error to a separate module as the module `verify`
is becoming too long.

There is no behavior change for this cl.

Bug: 256148034
Test: atest libpvmfw_avb.test && m pvmfw_img
Change-Id: I404600707bb2308836de14cde2097c370d8854dd
diff --git a/pvmfw/avb/src/error.rs b/pvmfw/avb/src/error.rs
new file mode 100644
index 0000000..8b06150
--- /dev/null
+++ b/pvmfw/avb/src/error.rs
@@ -0,0 +1,87 @@
+// Copyright 2022, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! This module contains the error thrown by the payload verification API.
+
+use avb_bindgen::AvbSlotVerifyResult;
+
+use core::fmt;
+
+/// This error is the error part of `AvbSlotVerifyResult`.
+/// It is the error thrown by the payload verification API `verify_payload()`.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum AvbSlotVerifyError {
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT
+    InvalidArgument,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA
+    InvalidMetadata,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_IO
+    Io,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_OOM
+    Oom,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED
+    PublicKeyRejected,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX
+    RollbackIndex,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION
+    UnsupportedVersion,
+    /// AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION
+    Verification,
+}
+
+impl fmt::Display for AvbSlotVerifyError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::InvalidArgument => write!(f, "Invalid parameters."),
+            Self::InvalidMetadata => write!(f, "Invalid metadata."),
+            Self::Io => write!(f, "I/O error while trying to load data or get a rollback index."),
+            Self::Oom => write!(f, "Unable to allocate memory."),
+            Self::PublicKeyRejected => write!(f, "Public key rejected or data not signed."),
+            Self::RollbackIndex => write!(f, "Rollback index is less than its stored value."),
+            Self::UnsupportedVersion => write!(
+                f,
+                "Some of the metadata requires a newer version of libavb than what is in use."
+            ),
+            Self::Verification => write!(f, "Data does not verify."),
+        }
+    }
+}
+
+pub(crate) fn slot_verify_result_to_verify_payload_result(
+    result: AvbSlotVerifyResult,
+) -> Result<(), AvbSlotVerifyError> {
+    match result {
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_OK => Ok(()),
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT => {
+            Err(AvbSlotVerifyError::InvalidArgument)
+        }
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA => {
+            Err(AvbSlotVerifyError::InvalidMetadata)
+        }
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_IO => Err(AvbSlotVerifyError::Io),
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_OOM => Err(AvbSlotVerifyError::Oom),
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED => {
+            Err(AvbSlotVerifyError::PublicKeyRejected)
+        }
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX => {
+            Err(AvbSlotVerifyError::RollbackIndex)
+        }
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION => {
+            Err(AvbSlotVerifyError::UnsupportedVersion)
+        }
+        AvbSlotVerifyResult::AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION => {
+            Err(AvbSlotVerifyError::Verification)
+        }
+    }
+}