rustix/ioctl/
linux.rs

1//! `ioctl` opcode behavior for Linux platforms.
2
3use super::{Direction, Opcode};
4use consts::*;
5
6/// Compose an opcode from its component parts.
7pub(super) const fn compose_opcode(
8    dir: Direction,
9    group: Opcode,
10    num: Opcode,
11    size: Opcode,
12) -> Opcode {
13    macro_rules! mask_and_shift {
14        ($val:expr, $shift:expr, $mask:expr) => {{
15            ($val & $mask) << $shift
16        }};
17    }
18
19    let dir = match dir {
20        Direction::None => NONE,
21        Direction::Read => READ,
22        Direction::Write => WRITE,
23        Direction::ReadWrite => READ | WRITE,
24    };
25
26    mask_and_shift!(group, GROUP_SHIFT, GROUP_MASK)
27        | mask_and_shift!(num, NUM_SHIFT, NUM_MASK)
28        | mask_and_shift!(size, SIZE_SHIFT, SIZE_MASK)
29        | mask_and_shift!(dir, DIR_SHIFT, DIR_MASK)
30}
31
32const NUM_BITS: Opcode = 8;
33const GROUP_BITS: Opcode = 8;
34
35const NUM_SHIFT: Opcode = 0;
36const GROUP_SHIFT: Opcode = NUM_SHIFT + NUM_BITS;
37const SIZE_SHIFT: Opcode = GROUP_SHIFT + GROUP_BITS;
38const DIR_SHIFT: Opcode = SIZE_SHIFT + SIZE_BITS;
39
40const NUM_MASK: Opcode = (1 << NUM_BITS) - 1;
41const GROUP_MASK: Opcode = (1 << GROUP_BITS) - 1;
42const SIZE_MASK: Opcode = (1 << SIZE_BITS) - 1;
43const DIR_MASK: Opcode = (1 << DIR_BITS) - 1;
44
45#[cfg(any(
46    target_arch = "x86",
47    target_arch = "arm",
48    target_arch = "s390x",
49    target_arch = "x86_64",
50    target_arch = "aarch64",
51    target_arch = "riscv32",
52    target_arch = "riscv64",
53    target_arch = "loongarch64",
54    target_arch = "csky"
55))]
56mod consts {
57    use super::Opcode;
58
59    pub(super) const NONE: Opcode = 0;
60    pub(super) const READ: Opcode = 2;
61    pub(super) const WRITE: Opcode = 1;
62    pub(super) const SIZE_BITS: Opcode = 14;
63    pub(super) const DIR_BITS: Opcode = 2;
64}
65
66#[cfg(any(
67    target_arch = "mips",
68    target_arch = "mips32r6",
69    target_arch = "mips64",
70    target_arch = "mips64r6",
71    target_arch = "powerpc",
72    target_arch = "powerpc64",
73    target_arch = "sparc",
74    target_arch = "sparc64"
75))]
76mod consts {
77    use super::Opcode;
78
79    pub(super) const NONE: Opcode = 1;
80    pub(super) const READ: Opcode = 2;
81    pub(super) const WRITE: Opcode = 4;
82    pub(super) const SIZE_BITS: Opcode = 13;
83    pub(super) const DIR_BITS: Opcode = 3;
84}
85
86#[cfg(test)]
87mod tests {
88    #[allow(unused_imports)]
89    use super::*;
90
91    #[cfg(not(any(
92    // These have no ioctl opcodes defined in linux_raw_sys so we can't use
93    // that as a known-good value for this test.
94    target_arch = "sparc",
95    target_arch = "sparc64"
96)))]
97    #[test]
98    fn check_known_opcodes() {
99        use crate::backend::c::{c_long, c_uint};
100        use core::mem::size_of;
101
102        // _IOR('U', 15, unsigned int)
103        assert_eq!(
104            compose_opcode(
105                Direction::Read,
106                b'U' as Opcode,
107                15,
108                size_of::<c_uint>() as Opcode
109            ),
110            linux_raw_sys::ioctl::USBDEVFS_CLAIMINTERFACE as Opcode
111        );
112
113        // _IOW('v', 2, long)
114        assert_eq!(
115            compose_opcode(
116                Direction::Write,
117                b'v' as Opcode,
118                2,
119                size_of::<c_long>() as Opcode
120            ),
121            linux_raw_sys::ioctl::FS_IOC_SETVERSION as Opcode
122        );
123    }
124}
rustix/ioctl/linux.rs

rustix/ioctl/
linux.rs
