Add Linux ioctl creation utilities (#9748)

* Add Linux ioctl creation utilities

* Apply suggestions from code review

Co-authored-by: Veikka Tuominen <git@vexu.eu>

* Update lib/std/os/linux.zig

Co-authored-by: zigazeljko <ziga.zeljko@gmail.com>

Co-authored-by: Veikka Tuominen <git@vexu.eu>
Co-authored-by: zigazeljko <ziga.zeljko@gmail.com>

lib/std/os/linux.zig

@@ -89,6 +89,7 @@ pub const user_desc = arch_bits.user_desc;
 pub const tls = @import("linux/tls.zig");
 pub const pie = @import("linux/start_pie.zig");
 pub const BPF = @import("linux/bpf.zig");
+pub const IOCTL = @import("linux/ioctl.zig");
 
 pub const MAP = struct {
     pub usingnamespace arch_bits.MAP;
@@ -2585,18 +2586,18 @@ pub const T = struct {
     pub const IOCGSID = 0x5429;
     pub const IOCGRS485 = 0x542E;
     pub const IOCSRS485 = 0x542F;
-    pub const IOCGPTN = 0x80045430;
-    pub const IOCSPTLCK = 0x40045431;
-    pub const IOCGDEV = 0x80045432;
+    pub const IOCGPTN = IOCTL.IOR('T', 0x30, c_uint);
+    pub const IOCSPTLCK = IOCTL.IOW('T', 0x31, c_int);
+    pub const IOCGDEV = IOCTL.IOR('T', 0x32, c_uint);
     pub const CGETX = 0x5432;
     pub const CSETX = 0x5433;
     pub const CSETXF = 0x5434;
     pub const CSETXW = 0x5435;
-    pub const IOCSIG = 0x40045436;
+    pub const IOCSIG = IOCTL.IOW('T', 0x36, c_int);
     pub const IOCVHANGUP = 0x5437;
-    pub const IOCGPKT = 0x80045438;
-    pub const IOCGPTLCK = 0x80045439;
-    pub const IOCGEXCL = 0x80045440;
+    pub const IOCGPKT = IOCTL.IOR('T', 0x38, c_int);
+    pub const IOCGPTLCK = IOCTL.IOR('T', 0x39, c_int);
+    pub const IOCGEXCL = IOCTL.IOR('T', 0x40, c_int);
 };
 
 pub const EPOLL = struct {

lib/std/os/linux/ioctl.zig

@@ -0,0 +1,56 @@
+const std = @import("../../std.zig");
+
+const bits = switch (@import("builtin").cpu.arch) {
+    .mips,
+    .mipsel,
+    .mips64,
+    .mips64el,
+    .powerpc,
+    .powerpcle,
+    .powerpc64,
+    .powerpc64le,
+    .sparc,
+    .sparcv9,
+    .sparcel,
+    => .{ .size = 13, .dir = 3, .none = 1, .read = 2, .write = 4 },
+    else => .{ .size = 14, .dir = 2, .none = 0, .read = 2, .write = 1 },
+};
+
+const Direction = std.meta.Int(.unsigned, bits.dir);
+
+pub const Request = packed struct {
+    nr: u8,
+    io_type: u8,
+    size: std.meta.Int(.unsigned, bits.size),
+    dir: Direction,
+};
+
+fn io_impl(dir: Direction, io_type: u8, nr: u8, comptime T: type) u32 {
+    const request = Request{
+        .dir = dir,
+        .size = @sizeOf(T),
+        .io_type = io_type,
+        .nr = nr,
+    };
+    return @bitCast(u32, request);
+}
+
+pub fn IO(io_type: u8, nr: u8) u32 {
+    return io_impl(bits.none, io_type, nr, void);
+}
+
+pub fn IOR(io_type: u8, nr: u8, comptime T: type) u32 {
+    return io_impl(bits.read, io_type, nr, T);
+}
+
+pub fn IOW(io_type: u8, nr: u8, comptime T: type) u32 {
+    return io_impl(bits.write, io_type, nr, T);
+}
+
+pub fn IOWR(io_type: u8, nr: u8, comptime T: type) u32 {
+    return io_impl(bits.read | bits.write, io_type, nr, T);
+}
+
+comptime {
+    std.debug.assert(@bitSizeOf(Request) == 32);
+}