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- /*
- * Copyright (c) 2023, Andrew Kaster <akaster@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
- #include <AK/ByteBuffer.h>
- #include <AK/Error.h>
- #include <AK/IterationDecision.h>
- #include <AK/MemoryStream.h>
- #include <AK/StringView.h>
- #include <LibDeviceTree/FlattenedDeviceTree.h>
- namespace DeviceTree {
- static ErrorOr<StringView> read_string_view(ReadonlyBytes bytes, StringView error_string)
- {
- auto len = strnlen(reinterpret_cast<char const*>(bytes.data()), bytes.size());
- if (len == bytes.size()) {
- return Error::from_string_view_or_print_error_and_return_errno(error_string, EINVAL);
- }
- return StringView { bytes.slice(0, len) };
- }
- ErrorOr<void> walk_device_tree(FlattenedDeviceTreeHeader const& header, ReadonlyBytes raw_device_tree, DeviceTreeCallbacks callbacks)
- {
- ReadonlyBytes struct_bytes { raw_device_tree.data() + header.off_dt_struct, header.size_dt_struct };
- FixedMemoryStream stream(struct_bytes);
- char const* begin_strings_block = reinterpret_cast<char const*>(raw_device_tree.data() + header.off_dt_strings);
- FlattenedDeviceTreeTokenType prev_token = EndNode;
- StringView current_node_name;
- while (!stream.is_eof()) {
- auto current_token = TRY(stream.read_value<BigEndian<u32>>());
- switch (current_token) {
- case BeginNode: {
- current_node_name = TRY(read_string_view(struct_bytes.slice(stream.offset()), "Non-null terminated name for FDT_BEGIN_NODE token!"sv));
- size_t const consume_len = round_up_to_power_of_two(current_node_name.length() + 1, 4);
- TRY(stream.discard(consume_len));
- if (callbacks.on_node_begin) {
- if (IterationDecision::Break == TRY(callbacks.on_node_begin(current_node_name)))
- return {};
- }
- break;
- }
- case EndNode:
- if (callbacks.on_node_end) {
- if (IterationDecision::Break == TRY(callbacks.on_node_end(current_node_name)))
- return {};
- }
- break;
- case Property: {
- if (prev_token == EndNode) {
- return Error::from_string_view_or_print_error_and_return_errno("Invalid node sequence, FDT_PROP after FDT_END_NODE"sv, EINVAL);
- }
- auto len = TRY(stream.read_value<BigEndian<u32>>());
- auto nameoff = TRY(stream.read_value<BigEndian<u32>>());
- if (nameoff >= header.size_dt_strings) {
- return Error::from_string_view_or_print_error_and_return_errno("Invalid name offset in FDT_PROP"sv, EINVAL);
- }
- size_t const prop_name_max_len = header.size_dt_strings - nameoff;
- size_t const prop_name_len = strnlen(begin_strings_block + nameoff, prop_name_max_len);
- if (prop_name_len == prop_name_max_len) {
- return Error::from_string_view_or_print_error_and_return_errno("Non-null terminated name for FDT_PROP token!"sv, EINVAL);
- }
- StringView prop_name(begin_strings_block + nameoff, prop_name_len);
- if (len >= stream.remaining()) {
- return Error::from_string_view_or_print_error_and_return_errno("Property value length too large"sv, EINVAL);
- }
- ReadonlyBytes prop_value;
- if (len != 0) {
- prop_value = { struct_bytes.slice(stream.offset()).data(), len };
- size_t const consume_len = round_up_to_power_of_two(static_cast<u32>(len), 4);
- TRY(stream.discard(consume_len));
- }
- if (callbacks.on_property) {
- if (IterationDecision::Break == TRY(callbacks.on_property(prop_name, prop_value)))
- return {};
- }
- break;
- }
- case NoOp:
- if (callbacks.on_noop) {
- if (IterationDecision::Break == TRY(callbacks.on_noop()))
- return {};
- }
- break;
- case End: {
- if (prev_token == BeginNode || prev_token == Property) {
- return Error::from_string_view_or_print_error_and_return_errno("Invalid node sequence, FDT_END after BEGIN_NODE or PROP"sv, EINVAL);
- }
- if (!stream.is_eof()) {
- return Error::from_string_view_or_print_error_and_return_errno("Expected EOF at FTD_END but more data remains"sv, EINVAL);
- }
- if (callbacks.on_end) {
- return callbacks.on_end();
- }
- return {};
- }
- default:
- return Error::from_string_view_or_print_error_and_return_errno("Invalid token"sv, EINVAL);
- }
- prev_token = static_cast<FlattenedDeviceTreeTokenType>(static_cast<u32>(current_token));
- }
- return Error::from_string_view_or_print_error_and_return_errno("Unexpected end of stream"sv, EINVAL);
- }
- } // namespace DeviceTree
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