diff options
Diffstat (limited to 'src/sys')
| -rw-r--r-- | src/sys/ioctl/mod.rs | 68 |
1 files changed, 53 insertions, 15 deletions
diff --git a/src/sys/ioctl/mod.rs b/src/sys/ioctl/mod.rs index f54384e6..4db3fe76 100644 --- a/src/sys/ioctl/mod.rs +++ b/src/sys/ioctl/mod.rs @@ -140,14 +140,55 @@ //! There is also a `bad none`, `bad write_int`/`bad write_ptr`, and `bad readwrite` variant that work //! similar to the standard `none`, `write_int`/`write_ptr`, and `readwrite` variants. //! +//! Working with arrays +//! -------------------- +//! +//! Some `ioctl`s work with entire arrays of elements. These are supported by the `*_buf` variants in +//! the `ioctl!` macro which can be used by specifying `read_buf`, `write_buf`, and +//! `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!` macro, so all that's +//! needed to define this `ioctl` is: +//! //! ``` //! # #[macro_use] extern crate nix; -//! # use nix::libc::TIOCEXCL as TIOCEXCL; -//! ioctl!(bad none tiocexcl with TIOCEXCL); +//! 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 with SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE; spi_ioc_transfer); //! # fn main() {} //! ``` //! -//! More examples on using `ioctl!` can be found in the [rust-spidev crate](https://github.com/rust-embedded/rust-spidev). +//! This generates a function like: +//! +//! ``` +//! # #[macro_use] extern crate nix; +//! # use std::mem; +//! # use nix::{Errno, libc, Result}; +//! # 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, +//! iow!(SPI_IOC_MAGIC, SPI_IOC_TYPE_MESSAGE, data.len() * mem::size_of::<spi_ioc_transfer>()), +//! data); +//! Errno::result(res) +//! } +//! # fn main() {} +//! ``` //! //! Finding ioctl documentation //! --------------------------- @@ -255,28 +296,25 @@ macro_rules! ioctl { convert_ioctl_res!($crate::libc::ioctl(fd, iorw!($ioty, $nr, ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data)) } ); - (read buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( + (read_buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( pub unsafe fn $name(fd: $crate::libc::c_int, - data: *mut $ty, - len: usize) + data: &mut [$ty]) -> $crate::Result<$crate::libc::c_int> { - convert_ioctl_res!($crate::libc::ioctl(fd, ior!($ioty, $nr, len) as $crate::sys::ioctl::ioctl_num_type, data)) + convert_ioctl_res!($crate::libc::ioctl(fd, ior!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data)) } ); - (write buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( + (write_buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( pub unsafe fn $name(fd: $crate::libc::c_int, - data: *const $ty, - len: usize) + data: &[$ty]) -> $crate::Result<$crate::libc::c_int> { - convert_ioctl_res!($crate::libc::ioctl(fd, iow!($ioty, $nr, len) as $crate::sys::ioctl::ioctl_num_type, data)) + convert_ioctl_res!($crate::libc::ioctl(fd, iow!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data)) } ); - (readwrite buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( + (readwrite_buf $name:ident with $ioty:expr, $nr:expr; $ty:ty) => ( pub unsafe fn $name(fd: $crate::libc::c_int, - data: *mut $ty, - len: usize) + data: &mut [$ty]) -> $crate::Result<$crate::libc::c_int> { - convert_ioctl_res!($crate::libc::ioctl(fd, iorw!($ioty, $nr, len) as $crate::sys::ioctl::ioctl_num_type, data)) + convert_ioctl_res!($crate::libc::ioctl(fd, iorw!($ioty, $nr, data.len() * ::std::mem::size_of::<$ty>()) as $crate::sys::ioctl::ioctl_num_type, data)) } ); } |