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https://github.com/SerenityOS/serenity
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aa2d76cd78
This utility lists all devices' major number allocations, for character and block devices. It can help the user to figure out the DeviceMapper service manages spawning of device nodes in /dev and other associated files under the /tmp/system/devicemap directory.
58 lines
2.2 KiB
C++
58 lines
2.2 KiB
C++
/*
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* Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/JsonArray.h>
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#include <AK/JsonObject.h>
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#include <AK/NumberFormat.h>
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#include <AK/StringView.h>
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#include <LibCore/ArgsParser.h>
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#include <LibCore/File.h>
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#include <LibCore/System.h>
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#include <LibMain/Main.h>
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ErrorOr<int> serenity_main(Main::Arguments arguments)
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{
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TRY(Core::System::pledge("stdio rpath"));
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TRY(Core::System::unveil("/sys/kernel/chardev_major_allocs", "r"));
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TRY(Core::System::unveil("/sys/kernel/blockdev_major_allocs", "r"));
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TRY(Core::System::unveil(nullptr, nullptr));
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Core::ArgsParser args_parser;
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args_parser.set_general_help("List major device number allocations.");
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args_parser.parse(arguments);
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outln("Character devices:");
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{
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auto file = TRY(Core::File::open("/sys/kernel/chardev_major_allocs"sv, Core::File::OpenMode::Read));
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auto file_contents = TRY(file->read_until_eof());
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auto json_result = TRY(JsonValue::from_string(file_contents));
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auto const& json = json_result.as_array();
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json.for_each([&](auto& value) {
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auto& major_number_allocation_object = value.as_object();
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auto family_name = major_number_allocation_object.get_byte_string("family_name"sv).value_or({});
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auto allocated_number = major_number_allocation_object.get_u64("allocated_number"sv).value_or(0);
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outln("{:3d} {}", allocated_number, family_name);
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});
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}
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outln();
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outln("Block devices:");
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{
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auto file = TRY(Core::File::open("/sys/kernel/blockdev_major_allocs"sv, Core::File::OpenMode::Read));
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auto file_contents = TRY(file->read_until_eof());
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auto json_result = TRY(JsonValue::from_string(file_contents));
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auto const& json = json_result.as_array();
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json.for_each([&](auto& value) {
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auto& major_number_allocation_object = value.as_object();
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auto family_name = major_number_allocation_object.get_byte_string("family_name"sv).value_or({});
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auto allocated_number = major_number_allocation_object.get_u64("allocated_number"sv).value_or(0);
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outln("{:3d} {}", allocated_number, family_name);
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});
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}
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return 0;
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}
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