starnix_uapi/
device_type.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;
27
28// Unclear if this device number is assigned dynamically, but this value is what abarth observed
29// once for /dev/block/zram0.
30pub const ZRAM_MAJOR: u32 = 252;
31
32// This value is observed from dmsetup.
33pub const DEVICE_MAPPER_MAJOR: u32 = 254;
34
35pub const BLOCK_EXTENDED_MAJOR: u32 = 259;
36
37#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
38pub struct DeviceType(u64);
39
40impl DeviceType {
41    pub const NONE: DeviceType = DeviceType(0);
42
43    // MEM
44    pub const NULL: DeviceType = DeviceType::new(MEM_MAJOR, 3);
45    pub const ZERO: DeviceType = DeviceType::new(MEM_MAJOR, 5);
46    pub const FULL: DeviceType = DeviceType::new(MEM_MAJOR, 7);
47    pub const RANDOM: DeviceType = DeviceType::new(MEM_MAJOR, 8);
48    pub const URANDOM: DeviceType = DeviceType::new(MEM_MAJOR, 9);
49    pub const KMSG: DeviceType = DeviceType::new(MEM_MAJOR, 11);
50
51    // TTY_ALT
52    pub const TTY: DeviceType = DeviceType::new(TTY_ALT_MAJOR, 0);
53    pub const PTMX: DeviceType = DeviceType::new(TTY_ALT_MAJOR, 2);
54
55    // MISC
56    pub const HW_RANDOM: DeviceType = DeviceType::new(MISC_MAJOR, 183);
57    pub const UINPUT: DeviceType = DeviceType::new(MISC_MAJOR, 223);
58    pub const FUSE: DeviceType = DeviceType::new(MISC_MAJOR, 229);
59    pub const DEVICE_MAPPER: DeviceType = DeviceType::new(MISC_MAJOR, 236);
60    pub const LOOP_CONTROL: DeviceType = DeviceType::new(MISC_MAJOR, 237);
61
62    // Frame buffer
63    pub const FB0: DeviceType = DeviceType::new(FB_MAJOR, 0);
64
65    // TUN
66    pub const TUN: DeviceType = DeviceType::new(MISC_MAJOR, 200);
67
68    // Block Devices
69    pub const MMCBLK0: DeviceType = DeviceType::new(MMC_BLOCK_DEVICE_MAJOR, 0);
70
71    pub const fn new(major: u32, minor: u32) -> DeviceType {
72        // This encoding is part of the Linux UAPI. The encoded value is
73        // returned to userspace in the stat struct.
74        // See <https://man7.org/linux/man-pages/man3/makedev.3.html>.
75        DeviceType(
76            (((major & 0xfffff000) as u64) << 32)
77                | (((major & 0xfff) as u64) << 8)
78                | (((minor & 0xffffff00) as u64) << 12)
79                | ((minor & 0xff) as u64),
80        )
81    }
82
83    pub const fn new_range(major: u32, minor: Range<u32>) -> Range<DeviceType> {
84        Self::new(major, minor.start)..Self::new(major, minor.end)
85    }
86
87    pub const fn from_bits(dev: u64) -> DeviceType {
88        DeviceType(dev)
89    }
90
91    pub const fn bits(&self) -> u64 {
92        self.0
93    }
94
95    pub fn next_minor(&self) -> Option<DeviceType> {
96        self.minor().checked_add(1).map(|minor| DeviceType::new(self.major(), minor))
97    }
98
99    pub const fn major(&self) -> u32 {
100        ((self.0 >> 32 & 0xfffff000) | ((self.0 >> 8) & 0xfff)) as u32
101    }
102
103    pub const fn minor(&self) -> u32 {
104        ((self.0 >> 12 & 0xffffff00) | (self.0 & 0xff)) as u32
105    }
106}
107
108impl fmt::Display for DeviceType {
109    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
110        write!(f, "{}:{}", self.major(), self.minor())
111    }
112}
113
114impl std::cmp::PartialOrd for DeviceType {
115    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
116        Some(self.cmp(other))
117    }
118}
119
120impl std::cmp::Ord for DeviceType {
121    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
122        (self.major(), self.minor()).cmp(&(other.major(), other.minor()))
123    }
124}
125
126#[cfg(test)]
127mod tests {
128    use super::*;
129
130    #[::fuchsia::test]
131    fn test_device_type() {
132        let dev = DeviceType::new(21, 17);
133        assert_eq!(dev.major(), 21);
134        assert_eq!(dev.minor(), 17);
135
136        let dev = DeviceType::new(0x83af83fe, 0xf98ecba1);
137        assert_eq!(dev.major(), 0x83af83fe);
138        assert_eq!(dev.minor(), 0xf98ecba1);
139    }
140}
starnix_uapi/device_type.rs

starnix_uapi/
device_type.rs
