[dice] Move format_condig_descriptor to diced_open_dice
Test: atest diced_utils_test diced_sample_inputs_test \
diced_test diced_vendor_test diced_open_dice_cbor_test \
diced_client_test
Test: m pvmfw_img microdroid_manager
Test: atest microdroid_manager_test vmbase_example.integration_test
Bug: 267575445
Change-Id: Iba7f775c1d1a3070c119da546edad38c2bbf67ac
diff --git a/diced/open_dice/src/retry.rs b/diced/open_dice/src/retry.rs
new file mode 100644
index 0000000..648fd91
--- /dev/null
+++ b/diced/open_dice/src/retry.rs
@@ -0,0 +1,64 @@
+// Copyright 2023, 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 implements a retry version for multiple DICE functions that
+//! require preallocated output buffer. As the retry functions require
+//! memory allocation on heap, currently we only expose these functions in
+//! std environment.
+
+use crate::bcc::bcc_format_config_descriptor;
+use crate::error::{DiceError, Result};
+use std::ffi::CStr;
+
+/// Retries the given function with bigger output buffer size.
+fn retry_with_bigger_buffer<F>(mut f: F) -> Result<Vec<u8>>
+where
+ F: FnMut(&mut Vec<u8>) -> Result<usize>,
+{
+ const INITIAL_BUFFER_SIZE: usize = 256;
+ const MAX_BUFFER_SIZE: usize = 64 * 1024 * 1024;
+
+ let mut buffer = vec![0u8; INITIAL_BUFFER_SIZE];
+ while buffer.len() <= MAX_BUFFER_SIZE {
+ match f(&mut buffer) {
+ Err(DiceError::BufferTooSmall) => {
+ let new_size = buffer.len() * 2;
+ buffer.resize(new_size, 0);
+ }
+ Err(e) => return Err(e),
+ Ok(actual_size) => {
+ if actual_size > buffer.len() {
+ panic!(
+ "actual_size larger than buffer size: open-dice function
+ may have written past the end of the buffer."
+ );
+ }
+ buffer.truncate(actual_size);
+ return Ok(buffer);
+ }
+ }
+ }
+ Err(DiceError::PlatformError)
+}
+
+/// Formats a configuration descriptor following the BCC's specification.
+pub fn retry_bcc_format_config_descriptor(
+ name: Option<&CStr>,
+ version: Option<u64>,
+ resettable: bool,
+) -> Result<Vec<u8>> {
+ retry_with_bigger_buffer(|buffer| {
+ bcc_format_config_descriptor(name, version, resettable, buffer)
+ })
+}