64 lines
1.8 KiB
Zig
64 lines
1.8 KiB
Zig
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const std = @import("std");
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/// TODO: move this to std
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/// This definition enables the use of Zig types with a cmsghdr structure.
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/// The oddity of this layout is that the data must be aligned to @sizeOf(usize)
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/// rather than its natural alignment.
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pub fn Cmsghdr(comptime T: type) type {
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const Header = extern struct {
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len: usize,
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level: c_int,
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@"type": c_int,
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};
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const data_align = @sizeOf(usize);
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const data_offset = std.mem.alignForward(@sizeOf(Header), data_align);
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return extern struct {
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const Self = @This();
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bytes: [data_offset + @sizeOf(T)]u8 align(@alignOf(Header)),
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pub fn init(args: struct {
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level: c_int,
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@"type": c_int,
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data: T,
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}) Self {
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var self: Self = undefined;
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self.headerPtr().* = .{
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.len = data_offset + @sizeOf(T),
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.level = args.level,
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.@"type" = args.@"type",
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};
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self.dataPtr().* = args.data;
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return self;
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}
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// TODO: include this version if we submit a PR to add this to std
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pub fn initNoData(args: struct {
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level: c_int,
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@"type": c_int,
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}) Self {
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var self: Self = undefined;
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self.headerPtr().* = .{
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.len = data_offset + @sizeOf(T),
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.level = args.level,
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.@"type" = args.@"type",
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};
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return self;
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}
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pub fn headerPtr(self: *Self) *Header {
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return @ptrCast(*Header, self);
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}
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pub fn dataPtr(self: *Self) *align(data_align) T {
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return @ptrCast(*T, self.bytes[data_offset..]);
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}
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};
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}
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test {
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std.testing.refAllDecls(Cmsghdr([3]std.os.fd_t));
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}
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