summaryrefslogtreecommitdiff
path: root/src/sys/inotify.rs
blob: 4880a4a514e778d8baba10154f924d8f2cc3c8b7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
//! Monitoring API for filesystem events.
//!
//! Inotify is a Linux-only API to monitor filesystems events.
//!
//! For more documentation, please read [inotify(7)](http://man7.org/linux/man-pages/man7/inotify.7.html).
//! 
//! # Examples
//!
//! Monitor all events happening in directory "test":
//! ```no_run
//! # use nix::sys::inotify::{AddWatchFlags,InitFlags,Inotify};
//! #
//! // We create a new inotify instance.
//! let instance = Inotify::init(InitFlags::empty()).unwrap();
//!
//! // We add a new watch on directory "test" for all events.
//! let wd = instance.add_watch("test", AddWatchFlags::IN_ALL_EVENTS).unwrap();
//!
//! loop {
//!     // We read from our inotify instance for events.
//!     let events = instance.read_events().unwrap();
//!     println!("Events: {:?}", events);
//! }
//! ```

use libc::{
    c_char,
    c_int,
};
use std::ffi::{OsString,OsStr,CStr};
use std::os::unix::ffi::OsStrExt;
use std::mem::{MaybeUninit, size_of};
use std::os::unix::io::{RawFd,AsRawFd,FromRawFd};
use std::ptr;
use crate::unistd::read;
use crate::Result;
use crate::NixPath;
use crate::errno::Errno;

libc_bitflags! {
    /// Configuration options for [`inotify_add_watch`](fn.inotify_add_watch.html).
    pub struct AddWatchFlags: u32 {
        IN_ACCESS;
        IN_MODIFY;
        IN_ATTRIB;
        IN_CLOSE_WRITE;
        IN_CLOSE_NOWRITE;
        IN_OPEN;
        IN_MOVED_FROM;
        IN_MOVED_TO;
        IN_CREATE;
        IN_DELETE;
        IN_DELETE_SELF;
        IN_MOVE_SELF;

        IN_UNMOUNT;
        IN_Q_OVERFLOW;
        IN_IGNORED;

        IN_CLOSE;
        IN_MOVE;

        IN_ONLYDIR;
        IN_DONT_FOLLOW;

        IN_ISDIR;
        IN_ONESHOT;
        IN_ALL_EVENTS;
    }
}

libc_bitflags! {
    /// Configuration options for [`inotify_init1`](fn.inotify_init1.html).
    pub struct InitFlags: c_int {
        IN_CLOEXEC;
        IN_NONBLOCK;
    }
}

/// An inotify instance. This is also a file descriptor, you can feed it to
/// other interfaces consuming file descriptors, epoll for example.
#[derive(Debug, Clone, Copy)]
pub struct Inotify {
    fd: RawFd
}

/// This object is returned when you create a new watch on an inotify instance.
/// It is then returned as part of an event once triggered. It allows you to
/// know which watch triggered which event. 
#[derive(Debug, Clone, Copy, Hash, Eq, PartialEq, Ord, PartialOrd)]
pub struct WatchDescriptor {
    wd: i32
}

/// A single inotify event.
///
/// For more documentation see, [inotify(7)](http://man7.org/linux/man-pages/man7/inotify.7.html).
#[derive(Debug)]
pub struct InotifyEvent {
    /// Watch descriptor. This field corresponds to the watch descriptor you
    /// were issued when calling add_watch. It allows you to know which watch
    /// this event comes from. 
    pub wd: WatchDescriptor,
    /// Event mask. This field is a bitfield describing the exact event that
    /// occured.
    pub mask: AddWatchFlags,
    /// This cookie is a number that allows you to connect related events. For
    /// now only IN_MOVED_FROM and IN_MOVED_TO can be connected. 
    pub cookie: u32,
    /// Filename. This field exists only if the event was triggered for a file
    /// inside the watched directory.
    pub name: Option<OsString>
}

impl Inotify {
    /// Initialize a new inotify instance.
    ///
    /// Returns a Result containing an inotify instance.
    ///
    /// For more information see, [inotify_init(2)](http://man7.org/linux/man-pages/man2/inotify_init.2.html).
    pub fn init(flags: InitFlags) -> Result<Inotify> {
        let res = Errno::result(unsafe {
            libc::inotify_init1(flags.bits())
        });

        res.map(|fd| Inotify { fd })
    }

    /// Adds a new watch on the target file or directory. 
    ///
    /// Returns a watch descriptor. This is not a File Descriptor! 
    ///
    /// For more information see, [inotify_add_watch(2)](http://man7.org/linux/man-pages/man2/inotify_add_watch.2.html).
    pub fn add_watch<P: ?Sized + NixPath>(self,
                                          path: &P,
                                          mask: AddWatchFlags) 
                                            -> Result<WatchDescriptor>
    {
        let res = path.with_nix_path(|cstr| {
            unsafe {
                libc::inotify_add_watch(self.fd, cstr.as_ptr(), mask.bits())
            }
        })?;

        Errno::result(res).map(|wd| WatchDescriptor { wd })
    }

    /// Removes an existing watch using the watch descriptor returned by
    /// inotify_add_watch.
    ///
    /// Returns an EINVAL error if the watch descriptor is invalid.
    ///
    /// For more information see, [inotify_rm_watch(2)](http://man7.org/linux/man-pages/man2/inotify_rm_watch.2.html).
    #[cfg(target_os = "linux")]
    pub fn rm_watch(self, wd: WatchDescriptor) -> Result<()> {
        let res = unsafe { libc::inotify_rm_watch(self.fd, wd.wd) };

        Errno::result(res).map(drop)
    }

    #[cfg(target_os = "android")]
    pub fn rm_watch(self, wd: WatchDescriptor) -> Result<()> {
        let res = unsafe { libc::inotify_rm_watch(self.fd, wd.wd as u32) };

        Errno::result(res).map(drop)
    }

    /// Reads a collection of events from the inotify file descriptor. This call
    /// can either be blocking or non blocking depending on whether IN_NONBLOCK
    /// was set at initialization. 
    /// 
    /// Returns as many events as available. If the call was non blocking and no
    /// events could be read then the EAGAIN error is returned.
    pub fn read_events(self) -> Result<Vec<InotifyEvent>> {
        let header_size = size_of::<libc::inotify_event>();
        const BUFSIZ: usize = 4096;
        let mut buffer = [0u8; BUFSIZ];
        let mut events = Vec::new();
        let mut offset = 0;

        let nread = read(self.fd, &mut buffer)?;

        while (nread - offset) >= header_size {
            let event = unsafe {
                let mut event = MaybeUninit::<libc::inotify_event>::uninit();
                ptr::copy_nonoverlapping(
                    buffer.as_ptr().add(offset),
                    event.as_mut_ptr() as *mut u8,
                    (BUFSIZ - offset).min(header_size)
                );
                event.assume_init()
            };

            let name = match event.len {
                0 => None,
                _ => {
                    let ptr = unsafe { 
                        buffer
                            .as_ptr()
                            .add(offset + header_size)
                            as *const c_char
                    };
                    let cstr = unsafe { CStr::from_ptr(ptr) };
                
                    Some(OsStr::from_bytes(cstr.to_bytes()).to_owned())
                }
            };

            events.push(InotifyEvent {
                wd: WatchDescriptor { wd: event.wd },
                mask: AddWatchFlags::from_bits_truncate(event.mask),
                cookie: event.cookie,
                name
            });

            offset += header_size + event.len as usize;
        }

        Ok(events)
    }
}

impl AsRawFd for Inotify {
    fn as_raw_fd(&self) -> RawFd {
        self.fd
    }
}

impl FromRawFd for Inotify {
    unsafe fn from_raw_fd(fd: RawFd) -> Self {
        Inotify { fd }
    }
}