64 lines
1.6 KiB
Zig
64 lines
1.6 KiB
Zig
const std = @import("std");
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const HeaderSize = @bitSizeOf(Header) / 8;
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const Magic = [4]u8{ 0xf0, 0x9f, 0xa4, 0xb7 };
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const Version = 0;
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const Bom = 0x1234;
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const Header = packed struct {
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magic: [4]u8,
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version: u8,
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bom: u16,
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num_shells: u8,
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num_users: u32,
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num_groups: u32,
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offset_cmph_uid2user: u32,
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offset_cmph_groupname2group: u32,
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offset_cmph_username2user: u32,
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offset_idx: u32,
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offset_groups: u32,
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offset_users: u32,
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offset_groupmembers: u32,
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offset_additional_gids: u32,
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// TODO(motiejus) should we be returning *Header instead? That way all
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// stacks could be smaller by 48 bytes, and we would be referring to
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// it's fields in the mmap'ed region.
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pub fn init(blob: [HeaderSize]u8) Header {
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return @bitCast(Header, blob);
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}
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pub fn asArray(self: *const Header) [HeaderSize]u8 {
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return @bitCast([HeaderSize]u8, self.*);
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}
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};
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const testing = std.testing;
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test "header size is byte-aligned" {
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try testing.expectEqual(HeaderSize * 8, @bitSizeOf(Header));
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}
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test "header pack and unpack" {
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const header = Header{
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.magic = Magic,
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.version = Version,
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.bom = Bom,
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.num_shells = 0,
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.num_users = 0,
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.num_groups = 0,
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.offset_cmph_uid2user = 0,
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.offset_cmph_groupname2group = 0,
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.offset_cmph_username2user = 0,
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.offset_idx = 0,
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.offset_groups = 0,
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.offset_users = 0,
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.offset_groupmembers = 0,
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.offset_additional_gids = 0,
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};
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const blob = header.asArray();
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const header2 = Header.init(blob);
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try testing.expectEqual(header, header2);
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}
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