summaryrefslogtreecommitdiff
path: root/src/fcntl.rs
blob: 40f4cf940582773e6db03599d775e905cedf5cfe (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
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
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
use {Error, Result, NixPath};
use errno::Errno;
use libc::{self, c_int, c_uint, c_char, size_t, ssize_t};
use sys::stat::Mode;
use std::os::raw;
use std::os::unix::io::RawFd;
use std::ffi::OsStr;
use std::os::unix::ffi::OsStrExt;

#[cfg(any(target_os = "android", target_os = "linux"))]
use sys::uio::IoVec;  // For vmsplice

libc_bitflags!{
    pub struct AtFlags: c_int {
        AT_SYMLINK_NOFOLLOW;
        #[cfg(any(target_os = "android", target_os = "linux"))]
        AT_NO_AUTOMOUNT;
        #[cfg(any(target_os = "android", target_os = "linux"))]
        AT_EMPTY_PATH;
    }
}

libc_bitflags!(
    /// Configuration options for opened files.
    pub struct OFlag: c_int {
        /// Mask for the access mode of the file.
        O_ACCMODE;
        /// Use alternate I/O semantics.
        #[cfg(target_os = "netbsd")]
        O_ALT_IO;
        /// Open the file in append-only mode.
        O_APPEND;
        /// Generate a signal when input or output becomes possible.
        O_ASYNC;
        /// Closes the file descriptor once an `execve` call is made.
        ///
        /// Also sets the file offset to the beginning of the file.
        O_CLOEXEC;
        /// Create the file if it does not exist.
        O_CREAT;
        /// Try to minimize cache effects of the I/O for this file.
        #[cfg(any(target_os = "android",
                  target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "linux",
                  target_os = "netbsd"))]
        O_DIRECT;
        /// If the specified path isn't a directory, fail.
        O_DIRECTORY;
        /// Implicitly follow each `write()` with an `fdatasync()`.
        #[cfg(any(target_os = "android",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd"))]
        O_DSYNC;
        /// Error out if a file was not created.
        O_EXCL;
        /// Open for execute only.
        #[cfg(target_os = "freebsd")]
        O_EXEC;
        /// Open with an exclusive file lock.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd"))]
        O_EXLOCK;
        /// Same as `O_SYNC`.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  all(target_os = "linux", not(target_env = "musl")),
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd"))]
        O_FSYNC;
        /// Allow files whose sizes can't be represented in an `off_t` to be opened.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        O_LARGEFILE;
        /// Do not update the file last access time during `read(2)`s.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        O_NOATIME;
        /// Don't attach the device as the process' controlling terminal.
        O_NOCTTY;
        /// Same as `O_NONBLOCK`.
        O_NDELAY;
        /// `open()` will fail if the given path is a symbolic link.
        O_NOFOLLOW;
        /// When possible, open the file in nonblocking mode.
        O_NONBLOCK;
        /// Don't deliver `SIGPIPE`.
        #[cfg(target_os = "netbsd")]
        O_NOSIGPIPE;
        /// Obtain a file descriptor for low-level access.
        ///
        /// The file itself is not opened and other file operations will fail.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        O_PATH;
        /// Only allow reading.
        ///
        /// This should not be combined with `O_WRONLY` or `O_RDWR`.
        O_RDONLY;
        /// Allow both reading and writing.
        ///
        /// This should not be combined with `O_WRONLY` or `O_RDONLY`.
        O_RDWR;
        /// Similar to `O_DSYNC` but applies to `read`s instead.
        #[cfg(any(target_os = "linux", target_os = "netbsd", target_os = "openbsd"))]
        O_RSYNC;
        /// Skip search permission checks.
        #[cfg(target_os = "netbsd")]
        O_SEARCH;
        /// Open with a shared file lock.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd"))]
        O_SHLOCK;
        /// Implicitly follow each `write()` with an `fsync()`.
        O_SYNC;
        /// Create an unnamed temporary file.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        O_TMPFILE;
        /// Truncate an existing regular file to 0 length if it allows writing.
        O_TRUNC;
        /// Restore default TTY attributes.
        #[cfg(target_os = "freebsd")]
        O_TTY_INIT;
        /// Only allow writing.
        ///
        /// This should not be combined with `O_RDONLY` or `O_RDWR`.
        O_WRONLY;
    }
);

pub fn open<P: ?Sized + NixPath>(path: &P, oflag: OFlag, mode: Mode) -> Result<RawFd> {
    let fd = path.with_nix_path(|cstr| {
        unsafe { libc::open(cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint) }
    })?;

    Errno::result(fd)
}

pub fn openat<P: ?Sized + NixPath>(dirfd: RawFd, path: &P, oflag: OFlag, mode: Mode) -> Result<RawFd> {
    let fd = path.with_nix_path(|cstr| {
        unsafe { libc::openat(dirfd, cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint) }
    })?;
    Errno::result(fd)
}

fn wrap_readlink_result(buffer: &mut[u8], res: ssize_t) -> Result<&OsStr> {
    match Errno::result(res) {
        Err(err) => Err(err),
        Ok(len) => {
            if (len as usize) >= buffer.len() {
                Err(Error::Sys(Errno::ENAMETOOLONG))
            } else {
                Ok(OsStr::from_bytes(&buffer[..(len as usize)]))
            }
        }
    }
}

pub fn readlink<'a, P: ?Sized + NixPath>(path: &P, buffer: &'a mut [u8]) -> Result<&'a OsStr> {
    let res = path.with_nix_path(|cstr| {
        unsafe { libc::readlink(cstr.as_ptr(), buffer.as_mut_ptr() as *mut c_char, buffer.len() as size_t) }
    })?;

    wrap_readlink_result(buffer, res)
}


pub fn readlinkat<'a, P: ?Sized + NixPath>(dirfd: RawFd, path: &P, buffer: &'a mut [u8]) -> Result<&'a OsStr> {
    let res = path.with_nix_path(|cstr| {
        unsafe { libc::readlinkat(dirfd, cstr.as_ptr(), buffer.as_mut_ptr() as *mut c_char, buffer.len() as size_t) }
    })?;

    wrap_readlink_result(buffer, res)
}

/// Computes the raw fd consumed by a function of the form `*at`.
pub(crate) fn at_rawfd(fd: Option<RawFd>) -> raw::c_int {
    match fd {
        None => libc::AT_FDCWD,
        Some(fd) => fd,
    }
}

#[cfg(any(target_os = "android", target_os = "linux"))]
libc_bitflags!(
    /// Additional flags for file sealing, which allows for limiting operations on a file.
    pub struct SealFlag: c_int {
        /// Prevents further calls to `fcntl()` with `F_ADD_SEALS`.
        F_SEAL_SEAL;
        /// The file cannot be reduced in size.
        F_SEAL_SHRINK;
        /// The size of the file cannot be increased.
        F_SEAL_GROW;
        /// The file contents cannot be modified.
        F_SEAL_WRITE;
    }
);

libc_bitflags!(
    /// Additional configuration flags for `fcntl`'s `F_SETFD`.
    pub struct FdFlag: c_int {
        /// The file descriptor will automatically be closed during a successful `execve(2)`.
        FD_CLOEXEC;
    }
);

#[allow(missing_debug_implementations)]
pub enum FcntlArg<'a> {
    F_DUPFD(RawFd),
    F_DUPFD_CLOEXEC(RawFd),
    F_GETFD,
    F_SETFD(FdFlag), // FD_FLAGS
    F_GETFL,
    F_SETFL(OFlag), // O_NONBLOCK
    F_SETLK(&'a libc::flock),
    F_SETLKW(&'a libc::flock),
    F_GETLK(&'a mut libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_SETLK(&'a libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_SETLKW(&'a libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_GETLK(&'a mut libc::flock),
    #[cfg(any(target_os = "android", target_os = "linux"))]
    F_ADD_SEALS(SealFlag),
    #[cfg(any(target_os = "android", target_os = "linux"))]
    F_GET_SEALS,
    #[cfg(any(target_os = "macos", target_os = "ios"))]
    F_FULLFSYNC,
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_GETPIPE_SZ,
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_SETPIPE_SZ(c_int),

    // TODO: Rest of flags
}
pub use self::FcntlArg::*;

// TODO: Figure out how to handle value fcntl returns
pub fn fcntl(fd: RawFd, arg: FcntlArg) -> Result<c_int> {
    let res = unsafe {
        match arg {
            F_DUPFD(rawfd) => libc::fcntl(fd, libc::F_DUPFD, rawfd),
            F_DUPFD_CLOEXEC(rawfd) => libc::fcntl(fd, libc::F_DUPFD_CLOEXEC, rawfd),
            F_GETFD => libc::fcntl(fd, libc::F_GETFD),
            F_SETFD(flag) => libc::fcntl(fd, libc::F_SETFD, flag.bits()),
            F_GETFL => libc::fcntl(fd, libc::F_GETFL),
            F_SETFL(flag) => libc::fcntl(fd, libc::F_SETFL, flag.bits()),
            F_SETLK(flock) => libc::fcntl(fd, libc::F_SETLK, flock),
            F_SETLKW(flock) => libc::fcntl(fd, libc::F_SETLKW, flock),
            F_GETLK(flock) => libc::fcntl(fd, libc::F_GETLK, flock),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            F_ADD_SEALS(flag) => libc::fcntl(fd, libc::F_ADD_SEALS, flag.bits()),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            F_GET_SEALS => libc::fcntl(fd, libc::F_GET_SEALS),
            #[cfg(any(target_os = "macos", target_os = "ios"))]
            F_FULLFSYNC => libc::fcntl(fd, libc::F_FULLFSYNC),
            #[cfg(any(target_os = "linux", target_os = "android"))]
            F_GETPIPE_SZ => libc::fcntl(fd, libc::F_GETPIPE_SZ),
            #[cfg(any(target_os = "linux", target_os = "android"))]
            F_SETPIPE_SZ(size) => libc::fcntl(fd, libc::F_SETPIPE_SZ, size),
            #[cfg(any(target_os = "linux", target_os = "android"))]
            _ => unimplemented!()
        }
    };

    Errno::result(res)
}

#[derive(Clone, Copy)]
#[allow(missing_debug_implementations)]
pub enum FlockArg {
    LockShared,
    LockExclusive,
    Unlock,
    LockSharedNonblock,
    LockExclusiveNonblock,
    UnlockNonblock,
}

pub fn flock(fd: RawFd, arg: FlockArg) -> Result<()> {
    use self::FlockArg::*;

    let res = unsafe {
        match arg {
            LockShared => libc::flock(fd, libc::LOCK_SH),
            LockExclusive => libc::flock(fd, libc::LOCK_EX),
            Unlock => libc::flock(fd, libc::LOCK_UN),
            LockSharedNonblock => libc::flock(fd, libc::LOCK_SH | libc::LOCK_NB),
            LockExclusiveNonblock => libc::flock(fd, libc::LOCK_EX | libc::LOCK_NB),
            UnlockNonblock => libc::flock(fd, libc::LOCK_UN | libc::LOCK_NB),
        }
    };

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

#[cfg(any(target_os = "android", target_os = "linux"))]
libc_bitflags! {
    /// Additional flags to `splice` and friends.
    pub struct SpliceFFlags: c_uint {
        /// Request that pages be moved instead of copied.
        ///
        /// Not applicable to `vmsplice`.
        SPLICE_F_MOVE;
        /// Do not block on I/O.
        SPLICE_F_NONBLOCK;
        /// Hint that more data will be coming in a subsequent splice.
        ///
        /// Not applicable to `vmsplice`.
        SPLICE_F_MORE;
        /// Gift the user pages to the kernel.
        ///
        /// Not applicable to `splice`.
        SPLICE_F_GIFT;
    }
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn splice(fd_in: RawFd, off_in: Option<&mut libc::loff_t>,
          fd_out: RawFd, off_out: Option<&mut libc::loff_t>,
          len: usize, flags: SpliceFFlags) -> Result<usize> {
    use std::ptr;
    let off_in = off_in.map(|offset| offset as *mut _).unwrap_or(ptr::null_mut());
    let off_out = off_out.map(|offset| offset as *mut _).unwrap_or(ptr::null_mut());

    let ret = unsafe { libc::splice(fd_in, off_in, fd_out, off_out, len, flags.bits()) };
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn tee(fd_in: RawFd, fd_out: RawFd, len: usize, flags: SpliceFFlags) -> Result<usize> {
    let ret = unsafe { libc::tee(fd_in, fd_out, len, flags.bits()) };
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn vmsplice(fd: RawFd, iov: &[IoVec<&[u8]>], flags: SpliceFFlags) -> Result<usize> {
    let ret = unsafe {
        libc::vmsplice(fd, iov.as_ptr() as *const libc::iovec, iov.len(), flags.bits())
    };
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux"))]
libc_bitflags!(
    /// Mode argument flags for fallocate determining operation performed on a given range.
    pub struct FallocateFlags: c_int {
        /// File size is not changed.
        ///
        /// offset + len can be greater than file size.
        FALLOC_FL_KEEP_SIZE;
        /// Deallocates space by creating a hole.
        ///
        /// Must be ORed with FALLOC_FL_KEEP_SIZE. Byte range starts at offset and continues for len bytes.
        FALLOC_FL_PUNCH_HOLE;
        /// Removes byte range from a file without leaving a hole.
        ///
        /// Byte range to collapse starts at offset and continues for len bytes.
        FALLOC_FL_COLLAPSE_RANGE;
        /// Zeroes space in specified byte range.
        ///
        /// Byte range starts at offset and continues for len bytes.
        FALLOC_FL_ZERO_RANGE;
        /// Increases file space by inserting a hole within the file size.
        ///
        /// Does not overwrite existing data. Hole starts at offset and continues for len bytes.
        FALLOC_FL_INSERT_RANGE;
        /// Shared file data extants are made private to the file.
        ///
        /// Gaurantees that a subsequent write will not fail due to lack of space.
        FALLOC_FL_UNSHARE_RANGE;
    }
);

/// Manipulates file space.
///
/// Allows the caller to directly manipulate the allocated disk space for the
/// file referred to by fd.
#[cfg(any(target_os = "linux"))]
pub fn fallocate(fd: RawFd, mode: FallocateFlags, offset: libc::off_t, len: libc::off_t) -> Result<c_int> {
    let res = unsafe { libc::fallocate(fd, mode.bits(), offset, len) };
    Errno::result(res)
}