102 lines
2.5 KiB
Zig
102 lines
2.5 KiB
Zig
const std = @import("std");
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const mem = std.mem;
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const math = std.math;
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const native_endian = @import("builtin").target.cpu.arch.endian();
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const max_shells = @import("shell.zig").max_shells;
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const magic = [4]u8{ 0xf0, 0x9f, 0xa4, 0xb7 };
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const version = 0;
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const Endian = enum(u8) {
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big,
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little,
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fn native() Endian {
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return switch (native_endian) {
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.Little => Endian.little,
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.Big => Endian.big,
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};
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}
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};
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pub const section_length_bits = 6;
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pub const section_length = 1 << section_length_bits;
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pub const Invalid = error{
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InvalidMagic,
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InvalidVersion,
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InvalidEndianess,
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};
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pub const Header = packed struct {
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magic: [4]u8 = magic,
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version: u8 = version,
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endian: Endian = Endian.native(),
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nblocks_shell_blob: u8,
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num_shells: u8,
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num_groups: u32,
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num_users: u32,
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nblocks_bdz_gid: u32,
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nblocks_bdz_groupname: u32,
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nblocks_bdz_uid: u32,
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nblocks_bdz_username: u32,
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nblocks_groups: u64,
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nblocks_users: u64,
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nblocks_groupmembers: u64,
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nblocks_additional_gids: u64,
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pub fn fromBytes(blob: []const u8) Invalid!Header {
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const self = mem.bytesAsValue(Header, blob);
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if (!mem.eql(magic, blob[0..4]))
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return error.InvalidMagic;
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if (self.version != 0)
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return error.InvalidVersion;
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if (self.endian != Endian.native())
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return error.InvalidEndianess;
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return self;
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}
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};
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const testing = std.testing;
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test "Section length is a power of two" {
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try testing.expect(std.math.isPowerOfTwo(section_length));
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}
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test "Header fits into a section" {
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try testing.expect(@sizeOf(Header) <= section_length);
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}
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test "bit header size is equal to @sizeOf(Header)" {
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try testing.expectEqual(@sizeOf(Header) * 8, @bitSizeOf(Header));
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}
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test "header pack, unpack and validation" {
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//const goodHeader = Header{};
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//const gotHeader = try Header.init(goodHeader.asArray());
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//try testing.expectEqual(goodHeader, gotHeader);
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//{
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// var header = goodHeader;
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// header.magic[0] = 0;
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// try testing.expectError(error.InvalidMagic, Header.init(header.asArray()));
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//}
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//{
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// var header = goodHeader;
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// header.bom = 0x3412;
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// try testing.expectError(error.InvalidBom, Header.init(header.asArray()));
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//}
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//{
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// var header = goodHeader;
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// header.offset_bdz_uid2user = 65;
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// try testing.expectError(error.InvalidOffset, Header.init(header.asArray()));
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//}
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}
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