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
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
//! Provide helpers for making ioctl system calls.
//!
//! This library is pretty low-level and messy. `ioctl` is not fun.
//!
//! What is an `ioctl`?
//! ===================
//!
//! The `ioctl` syscall is the grab-bag syscall on POSIX systems. Don't want to add a new
//! syscall? Make it an `ioctl`! `ioctl` refers to both the syscall, and the commands that can be
//! sent with it. `ioctl` stands for "IO control", and the commands are always sent to a file
//! descriptor.
//!
//! It is common to see `ioctl`s used for the following purposes:
//!
//!   * Provide read/write access to out-of-band data related to a device such as configuration
//!     (for instance, setting serial port options)
//!   * Provide a mechanism for performing full-duplex data transfers (for instance, xfer on SPI
//!     devices).
//!   * Provide access to control functions on a device (for example, on Linux you can send
//!     commands like pause, resume, and eject to the CDROM device.
//!   * Do whatever else the device driver creator thought made most sense.
//!
//! `ioctl`s are synchronous system calls and are similar to read and write calls in that regard.
//! They operate on file descriptors and have an identifier that specifies what the ioctl is.
//! Additionally they may read or write data and therefore need to pass along a data pointer.
//! Besides the semantics of the ioctls being confusing, the generation of this identifer can also
//! be difficult.
//!
//! Historically `ioctl` numbers were arbitrary hard-coded values. In Linux (before 2.6) and some
//! unices this has changed to a more-ordered system where the ioctl numbers are partitioned into
//! subcomponents (For linux this is documented in
//! [`Documentation/ioctl/ioctl-number.rst`](http://elixir.free-electrons.com/linux/latest/source/Documentation/ioctl/ioctl-number.rst)):
//!
//!   * Number: The actual ioctl ID
//!   * Type: A grouping of ioctls for a common purpose or driver
//!   * Size: The size in bytes of the data that will be transferred
//!   * Direction: Whether there is any data and if it's read, write, or both
//!
//! Newer drivers should not generate complete integer identifiers for their `ioctl`s instead
//! preferring to use the 4 components above to generate the final ioctl identifier. Because of
//! how old `ioctl`s are, however, there are many hard-coded `ioctl` identifiers. These are
//! commonly referred to as "bad" in `ioctl` documentation.
//!
//! Defining `ioctl`s
//! =================
//!
//! This library provides several `ioctl_*!` macros for binding `ioctl`s. These generate public
//! unsafe functions that can then be used for calling the ioctl. This macro has a few different
//! ways it can be used depending on the specific ioctl you're working with.
//!
//! A simple `ioctl` is `SPI_IOC_RD_MODE`. This ioctl works with the SPI interface on Linux. This
//! specific `ioctl` reads the mode of the SPI device as a `u8`. It's declared in
//! `/include/uapi/linux/spi/spidev.h` as `_IOR(SPI_IOC_MAGIC, 1, __u8)`. Since it uses the `_IOR`
//! macro, we know it's a `read` ioctl and can use the `ioctl_read!` macro as follows:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
//! const SPI_IOC_TYPE_MODE: u8 = 1;
//! ioctl_read!(spi_read_mode, SPI_IOC_MAGIC, SPI_IOC_TYPE_MODE, u8);
//! # fn main() {}
//! ```
//!
//! This generates the function:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! # use std::mem;
//! # use nix::{libc, Result};
//! # use nix::errno::Errno;
//! # use nix::libc::c_int as c_int;
//! # const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
//! # const SPI_IOC_TYPE_MODE: u8 = 1;
//! pub unsafe fn spi_read_mode(fd: c_int, data: *mut u8) -> Result<c_int> {
//!     let res = libc::ioctl(fd, request_code_read!(SPI_IOC_MAGIC, SPI_IOC_TYPE_MODE, mem::size_of::<u8>()), data);
//!     Errno::result(res)
//! }
//! # fn main() {}
//! ```
//!
//! The return value for the wrapper functions generated by the `ioctl_*!` macros are `nix::Error`s.
//! These are generated by assuming the return value of the ioctl is `-1` on error and everything
//! else is a valid return value. If this is not the case, `Result::map` can be used to map some
//! of the range of "good" values (-Inf..-2, 0..Inf) into a smaller range in a helper function.
//!
//! Writing `ioctl`s generally use pointers as their data source and these should use the
//! `ioctl_write_ptr!`. But in some cases an `int` is passed directly. For these `ioctl`s use the
//! `ioctl_write_int!` macro. This variant does not take a type as the last argument:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! const HCI_IOC_MAGIC: u8 = b'k';
//! const HCI_IOC_HCIDEVUP: u8 = 1;
//! ioctl_write_int!(hci_dev_up, HCI_IOC_MAGIC, HCI_IOC_HCIDEVUP);
//! # fn main() {}
//! ```
//!
//! Some `ioctl`s don't transfer any data, and those should use `ioctl_none!`. This macro
//! doesn't take a type and so it is declared similar to the `write_int` variant shown above.
//!
//! The mode for a given `ioctl` should be clear from the documentation if it has good
//! documentation. Otherwise it will be clear based on the macro used to generate the `ioctl`
//! number where `_IO`, `_IOR`, `_IOW`, and `_IOWR` map to "none", "read", "write_*", and "readwrite"
//! respectively. To determine the specific `write_` variant to use you'll need to find
//! what the argument type is supposed to be. If it's an `int`, then `write_int` should be used,
//! otherwise it should be a pointer and `write_ptr` should be used. On Linux the
//! [`ioctl_list` man page](http://man7.org/linux/man-pages/man2/ioctl_list.2.html) describes a
//! large number of `ioctl`s and describes their argument data type.
//!
//! Using "bad" `ioctl`s
//! --------------------
//!
//! As mentioned earlier, there are many old `ioctl`s that do not use the newer method of
//! generating `ioctl` numbers and instead use hardcoded values. These can be used with the
//! `ioctl_*_bad!` macros. This naming comes from the Linux kernel which refers to these
//! `ioctl`s as "bad". These are a different variant as they bypass calling the macro that generates
//! the ioctl number and instead use the defined value directly.
//!
//! For example the `TCGETS` `ioctl` reads a `termios` data structure for a given file descriptor.
//! It's defined as `0x5401` in `ioctls.h` on Linux and can be implemented as:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! # #[cfg(any(target_os = "android", target_os = "linux"))]
//! # use nix::libc::TCGETS as TCGETS;
//! # #[cfg(any(target_os = "android", target_os = "linux"))]
//! # use nix::libc::termios as termios;
//! # #[cfg(any(target_os = "android", target_os = "linux"))]
//! ioctl_read_bad!(tcgets, TCGETS, termios);
//! # fn main() {}
//! ```
//!
//! The generated function has the same form as that generated by `ioctl_read!`:
//!
//! ```text
//! pub unsafe fn tcgets(fd: c_int, data: *mut termios) -> Result<c_int>;
//! ```
//!
//! Working with Arrays
//! -------------------
//!
//! Some `ioctl`s work with entire arrays of elements. These are supported by the `ioctl_*_buf`
//! family of macros: `ioctl_read_buf`, `ioctl_write_buf`, and `ioctl_readwrite_buf`. Note that
//! there are no "bad" versions for working with buffers. The generated functions include a `len`
//! argument to specify the number of elements (where the type of each element is specified in the
//! macro).
//!
//! Again looking to the SPI `ioctl`s on Linux for an example, there is a `SPI_IOC_MESSAGE` `ioctl`
//! that queues up multiple SPI messages by writing an entire array of `spi_ioc_transfer` structs.
//! `linux/spi/spidev.h` defines a macro to calculate the `ioctl` number like:
//!
//! ```C
//! #define SPI_IOC_MAGIC 'k'
//! #define SPI_MSGSIZE(N) ...
//! #define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)])
//! ```
//!
//! The `SPI_MSGSIZE(N)` calculation is already handled by the `ioctl_*!` macros, so all that's
//! needed to define this `ioctl` is:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
//! const SPI_IOC_TYPE_MESSAGE: u8 = 0;
//! # pub struct spi_ioc_transfer(u64);
//! ioctl_write_buf!(spi_transfer, SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE, spi_ioc_transfer);
//! # fn main() {}
//! ```
//!
//! This generates a function like:
//!
//! ```
//! # #[macro_use] extern crate nix;
//! # use std::mem;
//! # use nix::{libc, Result};
//! # use nix::errno::Errno;
//! # use nix::libc::c_int as c_int;
//! # const SPI_IOC_MAGIC: u8 = b'k';
//! # const SPI_IOC_TYPE_MESSAGE: u8 = 0;
//! # pub struct spi_ioc_transfer(u64);
//! pub unsafe fn spi_message(fd: c_int, data: &mut [spi_ioc_transfer]) -> Result<c_int> {
//!     let res = libc::ioctl(fd,
//!                           request_code_write!(SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE, data.len() * mem::size_of::<spi_ioc_transfer>()),
//!                           data);
//!     Errno::result(res)
//! }
//! # fn main() {}
//! ```
//!
//! Finding `ioctl` Documentation
//! -----------------------------
//!
//! For Linux, look at your system's headers. For example, `/usr/include/linux/input.h` has a lot
//! of lines defining macros which use `_IO`, `_IOR`, `_IOW`, `_IOC`, and `_IOWR`. Some `ioctl`s are
//! documented directly in the headers defining their constants, but others have more extensive
//! documentation in man pages (like termios' `ioctl`s which are in `tty_ioctl(4)`).
//!
//! Documenting the Generated Functions
//! ===================================
//!
//! In many cases, users will wish for the functions generated by the `ioctl`
//! macro to be public and documented. For this reason, the generated functions
//! are public by default. If you wish to hide the ioctl, you will need to put
//! them in a private module.
//!
//! For documentation, it is possible to use doc comments inside the `ioctl_*!` macros. Here is an
//! example :
//!
//! ```
//! # #[macro_use] extern crate nix;
//! # use nix::libc::c_int;
//! ioctl_read! {
//!     /// Make the given terminal the controlling terminal of the calling process. The calling
//!     /// process must be a session leader and not have a controlling terminal already. If the
//!     /// terminal is already the controlling terminal of a different session group then the
//!     /// ioctl will fail with **EPERM**, unless the caller is root (more precisely: has the
//!     /// **CAP_SYS_ADMIN** capability) and arg equals 1, in which case the terminal is stolen
//!     /// and all processes that had it as controlling terminal lose it.
//!     tiocsctty, b't', 19, c_int
//! }
//!
//! # fn main() {}
//! ```
use cfg_if::cfg_if;

#[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
#[macro_use]
mod linux;

#[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
pub use self::linux::*;

#[cfg(any(target_os = "dragonfly",
          target_os = "freebsd",
          target_os = "ios",
          target_os = "macos",
          target_os = "netbsd",
          target_os = "openbsd"))]
#[macro_use]
mod bsd;

#[cfg(any(target_os = "dragonfly",
          target_os = "freebsd",
          target_os = "ios",
          target_os = "macos",
          target_os = "netbsd",
          target_os = "openbsd"))]
pub use self::bsd::*;

/// Convert raw ioctl return value to a Nix result
#[macro_export]
#[doc(hidden)]
macro_rules! convert_ioctl_res {
    ($w:expr) => (
        {
            $crate::errno::Errno::result($w)
        }
    );
}

/// Generates a wrapper function for an ioctl that passes no data to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// The `videodev2` driver on Linux defines the `log_status` `ioctl` as:
///
/// ```C
/// #define VIDIOC_LOG_STATUS         _IO('V', 70)
/// ```
///
/// This can be implemented in Rust like:
///
/// ```no_run
/// # #[macro_use] extern crate nix;
/// ioctl_none!(log_status, b'V', 70);
/// fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_none {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_none!($ioty, $nr) as $crate::sys::ioctl::ioctl_num_type))
        }
    )
}

/// Generates a wrapper function for a "bad" ioctl that passes no data to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl request code
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```no_run
/// # #[macro_use] extern crate nix;
/// # use libc::TIOCNXCL;
/// # use std::fs::File;
/// # use std::os::unix::io::AsRawFd;
/// ioctl_none_bad!(tiocnxcl, TIOCNXCL);
/// fn main() {
///     let file = File::open("/dev/ttyUSB0").unwrap();
///     unsafe { tiocnxcl(file.as_raw_fd()) }.unwrap();
/// }
/// ```
// TODO: add an example using request_code_*!()
#[macro_export(local_inner_macros)]
macro_rules! ioctl_none_bad {
    ($(#[$attr:meta])* $name:ident, $nr:expr) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, $nr as $crate::sys::ioctl::ioctl_num_type))
        }
    )
}

/// Generates a wrapper function for an ioctl that reads data from the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *mut DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```
/// # #[macro_use] extern crate nix;
/// const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
/// const SPI_IOC_TYPE_MODE: u8 = 1;
/// ioctl_read!(spi_read_mode, SPI_IOC_MAGIC, SPI_IOC_TYPE_MODE, u8);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_read {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *mut $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_read!($ioty, $nr, ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for a "bad" ioctl that reads data from the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl request code
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *mut DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```
/// # #[macro_use] extern crate nix;
/// # #[cfg(any(target_os = "android", target_os = "linux"))]
/// ioctl_read_bad!(tcgets, libc::TCGETS, libc::termios);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_read_bad {
    ($(#[$attr:meta])* $name:ident, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *mut $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, $nr as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for an ioctl that writes data through a pointer to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *const DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```
/// # #[macro_use] extern crate nix;
/// # pub struct v4l2_audio {}
/// ioctl_write_ptr!(s_audio, b'V', 34, v4l2_audio);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_write_ptr {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *const $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write!($ioty, $nr, ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for a "bad" ioctl that writes data through a pointer to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl request code
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *const DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```
/// # #[macro_use] extern crate nix;
/// # #[cfg(any(target_os = "android", target_os = "linux"))]
/// ioctl_write_ptr_bad!(tcsets, libc::TCSETS, libc::termios);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_write_ptr_bad {
    ($(#[$attr:meta])* $name:ident, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *const $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, $nr as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

cfg_if!{
    if #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))] {
        /// Generates a wrapper function for a ioctl that writes an integer to the kernel.
        ///
        /// The arguments to this macro are:
        ///
        /// * The function name
        /// * The ioctl identifier
        /// * The ioctl sequence number
        ///
        /// The generated function has the following signature:
        ///
        /// ```rust,ignore
        /// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: nix::sys::ioctl::ioctl_param_type) -> Result<libc::c_int>
        /// ```
        ///
        /// `nix::sys::ioctl::ioctl_param_type` depends on the OS:
        /// *   BSD - `libc::c_int`
        /// *   Linux - `libc::c_ulong`
        ///
        /// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate nix;
        /// ioctl_write_int!(vt_activate, b'v', 4);
        /// # fn main() {}
        /// ```
        #[macro_export(local_inner_macros)]
        macro_rules! ioctl_write_int {
            ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr) => (
                $(#[$attr])*
                pub unsafe fn $name(fd: $crate::libc::c_int,
                                    data: $crate::sys::ioctl::ioctl_param_type)
                                    -> $crate::Result<$crate::libc::c_int> {
                    convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write_int!($ioty, $nr) as $crate::sys::ioctl::ioctl_num_type, data))
                }
            )
        }
    } else {
        /// Generates a wrapper function for a ioctl that writes an integer to the kernel.
        ///
        /// The arguments to this macro are:
        ///
        /// * The function name
        /// * The ioctl identifier
        /// * The ioctl sequence number
        ///
        /// The generated function has the following signature:
        ///
        /// ```rust,ignore
        /// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: nix::sys::ioctl::ioctl_param_type) -> Result<libc::c_int>
        /// ```
        ///
        /// `nix::sys::ioctl::ioctl_param_type` depends on the OS:
        /// *   BSD - `libc::c_int`
        /// *   Linux - `libc::c_ulong`
        ///
        /// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate nix;
        /// const HCI_IOC_MAGIC: u8 = b'k';
        /// const HCI_IOC_HCIDEVUP: u8 = 1;
        /// ioctl_write_int!(hci_dev_up, HCI_IOC_MAGIC, HCI_IOC_HCIDEVUP);
        /// # fn main() {}
        /// ```
        #[macro_export(local_inner_macros)]
        macro_rules! ioctl_write_int {
            ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr) => (
                $(#[$attr])*
                pub unsafe fn $name(fd: $crate::libc::c_int,
                                    data: $crate::sys::ioctl::ioctl_param_type)
                                    -> $crate::Result<$crate::libc::c_int> {
                    convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write!($ioty, $nr, ::std::mem::size_of::<$crate::libc::c_int>()) as $crate::sys::ioctl::ioctl_num_type, data))
                }
            )
        }
    }
}

/// Generates a wrapper function for a "bad" ioctl that writes an integer to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl request code
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: libc::c_int) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Examples
///
/// ```
/// # #[macro_use] extern crate nix;
/// # #[cfg(any(target_os = "android", target_os = "linux"))]
/// ioctl_write_int_bad!(tcsbrk, libc::TCSBRK);
/// # fn main() {}
/// ```
///
/// ```rust
/// # #[macro_use] extern crate nix;
/// const KVMIO: u8 = 0xAE;
/// ioctl_write_int_bad!(kvm_create_vm, request_code_none!(KVMIO, 0x03));
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_write_int_bad {
    ($(#[$attr:meta])* $name:ident, $nr:expr) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: $crate::libc::c_int)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, $nr as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for an ioctl that reads and writes data to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *mut DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Example
///
/// ```
/// # #[macro_use] extern crate nix;
/// # pub struct v4l2_audio {}
/// ioctl_readwrite!(enum_audio, b'V', 65, v4l2_audio);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_readwrite {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *mut $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_readwrite!($ioty, $nr, ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for a "bad" ioctl that reads and writes data to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl request code
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: *mut DATA_TYPE) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
// TODO: Find an example for ioctl_readwrite_bad
#[macro_export(local_inner_macros)]
macro_rules! ioctl_readwrite_bad {
    ($(#[$attr:meta])* $name:ident, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: *mut $ty)
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, $nr as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for an ioctl that reads an array of elements from the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: &mut [DATA_TYPE]) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
// TODO: Find an example for ioctl_read_buf
#[macro_export(local_inner_macros)]
macro_rules! ioctl_read_buf {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: &mut [$ty])
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_read!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for an ioctl that writes an array of elements to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: &[DATA_TYPE]) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
///
/// # Examples
///
/// ```
/// # #[macro_use] extern crate nix;
/// const SPI_IOC_MAGIC: u8 = b'k'; // Defined in linux/spi/spidev.h
/// const SPI_IOC_TYPE_MESSAGE: u8 = 0;
/// # pub struct spi_ioc_transfer(u64);
/// ioctl_write_buf!(spi_transfer, SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE, spi_ioc_transfer);
/// # fn main() {}
/// ```
#[macro_export(local_inner_macros)]
macro_rules! ioctl_write_buf {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: &[$ty])
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}

/// Generates a wrapper function for an ioctl that reads and writes an array of elements to the kernel.
///
/// The arguments to this macro are:
///
/// * The function name
/// * The ioctl identifier
/// * The ioctl sequence number
/// * The data type passed by this ioctl
///
/// The generated function has the following signature:
///
/// ```rust,ignore
/// pub unsafe fn FUNCTION_NAME(fd: libc::c_int, data: &mut [DATA_TYPE]) -> Result<libc::c_int>
/// ```
///
/// For a more in-depth explanation of ioctls, see [`::sys::ioctl`](sys/ioctl/index.html).
// TODO: Find an example for readwrite_buf
#[macro_export(local_inner_macros)]
macro_rules! ioctl_readwrite_buf {
    ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr, $ty:ty) => (
        $(#[$attr])*
        pub unsafe fn $name(fd: $crate::libc::c_int,
                            data: &mut [$ty])
                            -> $crate::Result<$crate::libc::c_int> {
            convert_ioctl_res!($crate::libc::ioctl(fd, request_code_readwrite!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data))
        }
    )
}