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
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
use crate::fs::asyncify;

use std::collections::VecDeque;
use std::ffi::OsString;
use std::fs::{FileType, Metadata};
use std::future::Future;
use std::io;
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::sync::Arc;
use std::task::Context;
use std::task::Poll;

#[cfg(test)]
use super::mocks::spawn_blocking;
#[cfg(test)]
use super::mocks::JoinHandle;
#[cfg(not(test))]
use crate::blocking::spawn_blocking;
#[cfg(not(test))]
use crate::blocking::JoinHandle;

const CHUNK_SIZE: usize = 32;

/// Returns a stream over the entries within a directory.
///
/// This is an async version of [`std::fs::read_dir`].
///
/// This operation is implemented by running the equivalent blocking
/// operation on a separate thread pool using [`spawn_blocking`].
///
/// [`spawn_blocking`]: crate::task::spawn_blocking
pub async fn read_dir(path: impl AsRef<Path>) -> io::Result<ReadDir> {
    let path = path.as_ref().to_owned();
    asyncify(|| -> io::Result<ReadDir> {
        let mut std = std::fs::read_dir(path)?;
        let mut buf = VecDeque::with_capacity(CHUNK_SIZE);
        let remain = ReadDir::next_chunk(&mut buf, &mut std);

        Ok(ReadDir(State::Idle(Some((buf, std, remain)))))
    })
    .await
}

/// Reads the entries in a directory.
///
/// This struct is returned from the [`read_dir`] function of this module and
/// will yield instances of [`DirEntry`]. Through a [`DirEntry`] information
/// like the entry's path and possibly other metadata can be learned.
///
/// A `ReadDir` can be turned into a `Stream` with [`ReadDirStream`].
///
/// [`ReadDirStream`]: https://docs.rs/tokio-stream/0.1/tokio_stream/wrappers/struct.ReadDirStream.html
///
/// # Errors
///
/// This stream will return an [`Err`] if there's some sort of intermittent
/// IO error during iteration.
///
/// [`read_dir`]: read_dir
/// [`DirEntry`]: DirEntry
/// [`Err`]: std::result::Result::Err
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct ReadDir(State);

#[derive(Debug)]
enum State {
    Idle(Option<(VecDeque<io::Result<DirEntry>>, std::fs::ReadDir, bool)>),
    Pending(JoinHandle<(VecDeque<io::Result<DirEntry>>, std::fs::ReadDir, bool)>),
}

impl ReadDir {
    /// Returns the next entry in the directory stream.
    ///
    /// # Cancel safety
    ///
    /// This method is cancellation safe.
    pub async fn next_entry(&mut self) -> io::Result<Option<DirEntry>> {
        use crate::future::poll_fn;
        poll_fn(|cx| self.poll_next_entry(cx)).await
    }

    /// Polls for the next directory entry in the stream.
    ///
    /// This method returns:
    ///
    ///  * `Poll::Pending` if the next directory entry is not yet available.
    ///  * `Poll::Ready(Ok(Some(entry)))` if the next directory entry is available.
    ///  * `Poll::Ready(Ok(None))` if there are no more directory entries in this
    ///    stream.
    ///  * `Poll::Ready(Err(err))` if an IO error occurred while reading the next
    ///    directory entry.
    ///
    /// When the method returns `Poll::Pending`, the `Waker` in the provided
    /// `Context` is scheduled to receive a wakeup when the next directory entry
    /// becomes available on the underlying IO resource.
    ///
    /// Note that on multiple calls to `poll_next_entry`, only the `Waker` from
    /// the `Context` passed to the most recent call is scheduled to receive a
    /// wakeup.
    pub fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<io::Result<Option<DirEntry>>> {
        loop {
            match self.0 {
                State::Idle(ref mut data) => {
                    let (buf, _, ref remain) = data.as_mut().unwrap();

                    if let Some(ent) = buf.pop_front() {
                        return Poll::Ready(ent.map(Some));
                    } else if !remain {
                        return Poll::Ready(Ok(None));
                    }

                    let (mut buf, mut std, _) = data.take().unwrap();

                    self.0 = State::Pending(spawn_blocking(move || {
                        let remain = ReadDir::next_chunk(&mut buf, &mut std);
                        (buf, std, remain)
                    }));
                }
                State::Pending(ref mut rx) => {
                    self.0 = State::Idle(Some(ready!(Pin::new(rx).poll(cx))?));
                }
            }
        }
    }

    fn next_chunk(buf: &mut VecDeque<io::Result<DirEntry>>, std: &mut std::fs::ReadDir) -> bool {
        for _ in 0..CHUNK_SIZE {
            let ret = match std.next() {
                Some(ret) => ret,
                None => return false,
            };

            let success = ret.is_ok();

            buf.push_back(ret.map(|std| DirEntry {
                #[cfg(not(any(
                    target_os = "solaris",
                    target_os = "illumos",
                    target_os = "haiku",
                    target_os = "vxworks",
                    target_os = "aix",
                    target_os = "nto",
                    target_os = "vita",
                )))]
                file_type: std.file_type().ok(),
                std: Arc::new(std),
            }));

            if !success {
                break;
            }
        }

        true
    }
}

feature! {
    #![unix]

    use std::os::unix::fs::DirEntryExt;

    impl DirEntry {
        /// Returns the underlying `d_ino` field in the contained `dirent`
        /// structure.
        ///
        /// # Examples
        ///
        /// ```
        /// use tokio::fs;
        ///
        /// # #[tokio::main]
        /// # async fn main() -> std::io::Result<()> {
        /// let mut entries = fs::read_dir(".").await?;
        /// while let Some(entry) = entries.next_entry().await? {
        ///     // Here, `entry` is a `DirEntry`.
        ///     println!("{:?}: {}", entry.file_name(), entry.ino());
        /// }
        /// # Ok(())
        /// # }
        /// ```
        pub fn ino(&self) -> u64 {
            self.as_inner().ino()
        }
    }
}

/// Entries returned by the [`ReadDir`] stream.
///
/// [`ReadDir`]: struct@ReadDir
///
/// This is a specialized version of [`std::fs::DirEntry`] for usage from the
/// Tokio runtime.
///
/// An instance of `DirEntry` represents an entry inside of a directory on the
/// filesystem. Each entry can be inspected via methods to learn about the full
/// path or possibly other metadata through per-platform extension traits.
#[derive(Debug)]
pub struct DirEntry {
    #[cfg(not(any(
        target_os = "solaris",
        target_os = "illumos",
        target_os = "haiku",
        target_os = "vxworks",
        target_os = "aix",
        target_os = "nto",
        target_os = "vita",
    )))]
    file_type: Option<FileType>,
    std: Arc<std::fs::DirEntry>,
}

impl DirEntry {
    /// Returns the full path to the file that this entry represents.
    ///
    /// The full path is created by joining the original path to `read_dir`
    /// with the filename of this entry.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use tokio::fs;
    ///
    /// # async fn dox() -> std::io::Result<()> {
    /// let mut entries = fs::read_dir(".").await?;
    ///
    /// while let Some(entry) = entries.next_entry().await? {
    ///     println!("{:?}", entry.path());
    /// }
    /// # Ok(())
    /// # }
    /// ```
    ///
    /// This prints output like:
    ///
    /// ```text
    /// "./whatever.txt"
    /// "./foo.html"
    /// "./hello_world.rs"
    /// ```
    ///
    /// The exact text, of course, depends on what files you have in `.`.
    pub fn path(&self) -> PathBuf {
        self.std.path()
    }

    /// Returns the bare file name of this directory entry without any other
    /// leading path component.
    ///
    /// # Examples
    ///
    /// ```
    /// use tokio::fs;
    ///
    /// # async fn dox() -> std::io::Result<()> {
    /// let mut entries = fs::read_dir(".").await?;
    ///
    /// while let Some(entry) = entries.next_entry().await? {
    ///     println!("{:?}", entry.file_name());
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub fn file_name(&self) -> OsString {
        self.std.file_name()
    }

    /// Returns the metadata for the file that this entry points at.
    ///
    /// This function will not traverse symlinks if this entry points at a
    /// symlink.
    ///
    /// # Platform-specific behavior
    ///
    /// On Windows this function is cheap to call (no extra system calls
    /// needed), but on Unix platforms this function is the equivalent of
    /// calling `symlink_metadata` on the path.
    ///
    /// # Examples
    ///
    /// ```
    /// use tokio::fs;
    ///
    /// # async fn dox() -> std::io::Result<()> {
    /// let mut entries = fs::read_dir(".").await?;
    ///
    /// while let Some(entry) = entries.next_entry().await? {
    ///     if let Ok(metadata) = entry.metadata().await {
    ///         // Now let's show our entry's permissions!
    ///         println!("{:?}: {:?}", entry.path(), metadata.permissions());
    ///     } else {
    ///         println!("Couldn't get file type for {:?}", entry.path());
    ///     }
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn metadata(&self) -> io::Result<Metadata> {
        let std = self.std.clone();
        asyncify(move || std.metadata()).await
    }

    /// Returns the file type for the file that this entry points at.
    ///
    /// This function will not traverse symlinks if this entry points at a
    /// symlink.
    ///
    /// # Platform-specific behavior
    ///
    /// On Windows and most Unix platforms this function is free (no extra
    /// system calls needed), but some Unix platforms may require the equivalent
    /// call to `symlink_metadata` to learn about the target file type.
    ///
    /// # Examples
    ///
    /// ```
    /// use tokio::fs;
    ///
    /// # async fn dox() -> std::io::Result<()> {
    /// let mut entries = fs::read_dir(".").await?;
    ///
    /// while let Some(entry) = entries.next_entry().await? {
    ///     if let Ok(file_type) = entry.file_type().await {
    ///         // Now let's show our entry's file type!
    ///         println!("{:?}: {:?}", entry.path(), file_type);
    ///     } else {
    ///         println!("Couldn't get file type for {:?}", entry.path());
    ///     }
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn file_type(&self) -> io::Result<FileType> {
        #[cfg(not(any(
            target_os = "solaris",
            target_os = "illumos",
            target_os = "haiku",
            target_os = "vxworks",
            target_os = "aix",
            target_os = "nto",
            target_os = "vita",
        )))]
        if let Some(file_type) = self.file_type {
            return Ok(file_type);
        }

        let std = self.std.clone();
        asyncify(move || std.file_type()).await
    }

    /// Returns a reference to the underlying `std::fs::DirEntry`.
    #[cfg(unix)]
    pub(super) fn as_inner(&self) -> &std::fs::DirEntry {
        &self.std
    }
}