starnix_uapi/
device_id.rs

1// Copyright 2021 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use std::fmt;
6use std::ops::Range;
7
8pub const MEM_MAJOR: u32 = 1;
9pub const TTY_MAJOR: u32 = 4;
10pub const TTY_ALT_MAJOR: u32 = 5;
11pub const LOOP_MAJOR: u32 = 7;
12pub const MISC_MAJOR: u32 = 10;
13pub const INPUT_MAJOR: u32 = 13;
14pub const FB_MAJOR: u32 = 29;
15
16// These minor device numbers in the MISC major device appear to be dynamically allocated.
17// The lower bound is taken from observing /proc/misc an Android device. The upper bound is
18// taken from the value of /dev/beep in devices.txt.
19pub const MISC_DYNANIC_MINOR_RANGE: Range<u32> = 52..128;
20
21// TODO: The range for dynamic character devices actually goes all the way to 254, but we
22// still have a few hardcoded devices registered at high numbers. We can expand this range
23// to 254 once we dynamically allocate those devices.
24pub const DYN_MAJOR_RANGE: Range<u32> = 234..252;
25
26pub const MMC_BLOCK_DEVICE_MAJOR: u32 = 179;
27pub const USB_DEVICE_MAJOR: u32 = 189;
28
29// Unclear if this device number is assigned dynamically, but this value is what abarth observed
30// once for /dev/block/zram0.
31pub const ZRAM_MAJOR: u32 = 252;
32
33// This value is observed from dmsetup.
34pub const DEVICE_MAPPER_MAJOR: u32 = 254;
35
36pub const BLOCK_EXTENDED_MAJOR: u32 = 259;
37
38#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
39pub struct DeviceId(u64);
40
41impl DeviceId {
42    pub const NONE: DeviceId = DeviceId(0);
43
44    // MEM
45    pub const NULL: DeviceId = DeviceId::new(MEM_MAJOR, 3);
46    pub const ZERO: DeviceId = DeviceId::new(MEM_MAJOR, 5);
47    pub const FULL: DeviceId = DeviceId::new(MEM_MAJOR, 7);
48    pub const RANDOM: DeviceId = DeviceId::new(MEM_MAJOR, 8);
49    pub const URANDOM: DeviceId = DeviceId::new(MEM_MAJOR, 9);
50    pub const KMSG: DeviceId = DeviceId::new(MEM_MAJOR, 11);
51
52    // TTY_ALT
53    pub const TTY: DeviceId = DeviceId::new(TTY_ALT_MAJOR, 0);
54    pub const PTMX: DeviceId = DeviceId::new(TTY_ALT_MAJOR, 2);
55
56    // MISC
57    pub const HW_RANDOM: DeviceId = DeviceId::new(MISC_MAJOR, 183);
58    pub const UINPUT: DeviceId = DeviceId::new(MISC_MAJOR, 223);
59    pub const FUSE: DeviceId = DeviceId::new(MISC_MAJOR, 229);
60    pub const DEVICE_MAPPER: DeviceId = DeviceId::new(MISC_MAJOR, 236);
61    pub const LOOP_CONTROL: DeviceId = DeviceId::new(MISC_MAJOR, 237);
62
63    // Frame buffer
64    pub const FB0: DeviceId = DeviceId::new(FB_MAJOR, 0);
65
66    // TUN
67    pub const TUN: DeviceId = DeviceId::new(MISC_MAJOR, 200);
68
69    // Block Devices
70    pub const MMCBLK0: DeviceId = DeviceId::new(MMC_BLOCK_DEVICE_MAJOR, 0);
71
72    pub const fn new(major: u32, minor: u32) -> DeviceId {
73        // This encoding is part of the Linux UAPI. The encoded value is
74        // returned to userspace in the stat struct.
75        // See <https://man7.org/linux/man-pages/man3/makedev.3.html>.
76        DeviceId(
77            (((major & 0xfffff000) as u64) << 32)
78                | (((major & 0xfff) as u64) << 8)
79                | (((minor & 0xffffff00) as u64) << 12)
80                | ((minor & 0xff) as u64),
81        )
82    }
83
84    pub const fn new_range(major: u32, minor: Range<u32>) -> Range<DeviceId> {
85        Self::new(major, minor.start)..Self::new(major, minor.end)
86    }
87
88    pub const fn from_bits(dev: u64) -> DeviceId {
89        DeviceId(dev)
90    }
91
92    pub const fn bits(&self) -> u64 {
93        self.0
94    }
95
96    pub fn next_minor(&self) -> Option<DeviceId> {
97        self.minor().checked_add(1).map(|minor| DeviceId::new(self.major(), minor))
98    }
99
100    pub const fn major(&self) -> u32 {
101        ((self.0 >> 32 & 0xfffff000) | ((self.0 >> 8) & 0xfff)) as u32
102    }
103
104    pub const fn minor(&self) -> u32 {
105        ((self.0 >> 12 & 0xffffff00) | (self.0 & 0xff)) as u32
106    }
107}
108
109impl fmt::Display for DeviceId {
110    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
111        write!(f, "{}:{}", self.major(), self.minor())
112    }
113}
114
115impl std::cmp::PartialOrd for DeviceId {
116    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
117        Some(self.cmp(other))
118    }
119}
120
121impl std::cmp::Ord for DeviceId {
122    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
123        (self.major(), self.minor()).cmp(&(other.major(), other.minor()))
124    }
125}
126
127#[cfg(test)]
128mod tests {
129    use super::*;
130
131    #[::fuchsia::test]
132    fn test_device_type() {
133        let dev = DeviceId::new(21, 17);
134        assert_eq!(dev.major(), 21);
135        assert_eq!(dev.minor(), 17);
136
137        let dev = DeviceId::new(0x83af83fe, 0xf98ecba1);
138        assert_eq!(dev.major(), 0x83af83fe);
139        assert_eq!(dev.minor(), 0xf98ecba1);
140    }
141}
starnix_uapi/device_id.rs

starnix_uapi/
device_id.rs
