Add DataShare utility class for Mbed-OS applications
This commit adds a utility class that is available when building an application booted by mcuboot with MCUBOOT_DATA_SHARING enabled.
This utility class, `DataShare`, allows the application to iterate through the shared memory region and get each entry stored there.
Signed-off-by: George Beckstein <george.beckstein@gmail.com>
diff --git a/boot/mbed/include/utils/DataShare.h b/boot/mbed/include/utils/DataShare.h
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+++ b/boot/mbed/include/utils/DataShare.h
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+/**
+ *
+ * Built with ARM Mbed-OS
+ *
+ * Copyright (c) 2019-2021 Embedded Planet, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ */
+
+
+#ifndef DATASHARE_H_
+#define DATASHARE_H_
+
+/**
+ * This is an utility intended to be used by the booted application rather
+ * than by the bootloader
+ */
+#if MCUBOOT_DATA_SHARING && !MCUBOOT_BOOTLOADER_BUILD
+
+#include <stdint.h>
+#include "platform/Span.h"
+
+/* Error codes */
+#define DATA_SHARE_OK 0
+#define DATA_SHARE_ERROR_EOF 1 /* No more TLV entries available */
+#define DATA_SHARE_ERROR_OUT_OF_MEM 2 /* The output buffer was not large enough to hold the contents of the TLV entry */
+#define DATA_SHARE_ERROR_CORRUPT 3 /* Data corruption has been detected */
+
+/**
+ * Class enabling iterator-style access to the TLV-encoded data shared
+ * by an mcuboot-based bootloader.
+ */
+class DataShare
+{
+public:
+
+ /**
+ * Initializes a DataShare iterator at the given base address
+ * @note the configured MCUBOOT_SHARED_DATA_BASE address is used by default
+ */
+ DataShare(uint8_t * shared_base = ((uint8_t *) MCUBOOT_SHARED_DATA_BASE));
+
+ /**
+ * Validates the magic number of the shared data section
+ * @return true if magic number is found, false otherwise
+ */
+ bool is_valid();
+
+ /**
+ * Gets the total size of the shared data region
+ * @return 0 if shared data region is not valid, otherwise the size of the shared data region
+ */
+ uint16_t get_total_size();
+
+ /**
+ * Attempts to get the next TLV entry in the shared data memory
+ * @param[put] type Type code of the data entry
+ * @param[out] out Output buffer span
+ * @param[out] actual_size Size of entry copied to output buffer in bytes
+ * @return err Zero if output buffer contents is valid (successful), non-zero on failure
+ */
+ int get_next(uint16_t *type, mbed::Span<uint8_t> buf, uint16_t *actual_size);
+
+ /**
+ * Resets the iterator-like pointer to the first TLV element in the shared
+ * data region
+ */
+ void rewind();
+
+protected:
+
+ uint8_t *_shared_base;
+ bool _is_valid = false;
+ uint16_t _total_size = 0;
+ uint16_t _current_offset = 0;
+
+};
+
+#endif /* MCUBOOT_DATA_SHARING && !MCUBOOT_BOOTLOADER_BUILD */
+
+#endif /* DATASHARE_H_ */