Migrate from libc to rustix.

This migrates terminal_size from using libc directly to using rustix,
which eliminates a few unsafe blocks and manual error handling.

It does also add one new unsafe block, though this is because
`terminal_size_using_fd` is a public safe function that has a `RawFd`
argument. With [I/O safety], which is expected to be [stabilized in Rust 1.63],
there will be new guidance saying be that [such functions should be unsafe].
It's not urgent to make any changes for this right now though.

[I/O safety]: https://github.com/rust-lang/rfcs/blob/master/text/3128-io-safety.md
[expected to be stabilized in Rust 1.63]: rust-lang/rust#87074
[such functions should be unsafe]: https://doc.rust-lang.org/nightly/std/os/unix/io/index.html

Author: sunfishcode

Cargo.toml

@@ -10,8 +10,8 @@ license = "MIT OR Apache-2.0"
 edition = "2018"
 
 
-[target.'cfg(not(windows))'.dependencies.libc]
-version = "0.2"
+[target.'cfg(not(windows))'.dependencies]
+rustix = { version = "0.35.6", features = ["termios"] }
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3"

README.md

@@ -22,7 +22,7 @@ if let Some((Width(w), Height(h))) = size {
 
 ## Minimum Rust Version
 
-This crate requires a minimum rust version of 1.31.0 (2018-12-06)
+This crate requires a minimum rust version of 1.48.0 (2020-11-19)
 
 ## License
 

examples/get_size.rs

@@ -25,17 +25,19 @@ fn run() {
 
 #[cfg(not(windows))]
 fn run() {
+    use std::os::unix::io::AsRawFd;
+
     println!(
         "Size from terminal_size_using_fd(stdout):     {:?}",
-        terminal_size::terminal_size_using_fd(libc::STDOUT_FILENO)
+        terminal_size::terminal_size_using_fd(std::io::stdout().as_raw_fd())
     );
     println!(
         "Size from terminal_size_using_fd(stderr):     {:?}",
-        terminal_size::terminal_size_using_fd(libc::STDERR_FILENO)
+        terminal_size::terminal_size_using_fd(std::io::stderr().as_raw_fd())
     );
     println!(
         "Size from terminal_size_using_fd(stdin):      {:?}",
-        terminal_size::terminal_size_using_fd(libc::STDIN_FILENO)
+        terminal_size::terminal_size_using_fd(std::io::stdin().as_raw_fd())
     );
 }
 

src/lib.rs

@@ -2,7 +2,7 @@
 //!
 //! Supports both Linux, MacOS, and Windows.
 //!
-//!  This crate requires a minimum rust version of 1.31.0 (2018-12-06)
+//!  This crate requires a minimum rust version of 1.48.0 (2020-11-19)
 //!
 //! # Example
 //!

src/unix.rs

@@ -1,37 +1,31 @@
 use super::{Height, Width};
 use std::os::unix::io::RawFd;
+use rustix::fd::{BorrowedFd, AsRawFd};
 
 /// Returns the size of the terminal defaulting to STDOUT, if available.
 ///
 /// If STDOUT is not a tty, returns `None`
 pub fn terminal_size() -> Option<(Width, Height)> {
-    terminal_size_using_fd(libc::STDOUT_FILENO)
+    terminal_size_using_fd(std::io::stdout().as_raw_fd())
 }
 
 /// Returns the size of the terminal using the given file descriptor, if available.
 ///
 /// If the given file descriptor is not a tty, returns `None`
 pub fn terminal_size_using_fd(fd: RawFd) -> Option<(Width, Height)> {
-    use libc::ioctl;
-    use libc::isatty;
-    use libc::{winsize as WinSize, TIOCGWINSZ};
-    let is_tty: bool = unsafe { isatty(fd) == 1 };
+    use rustix::termios::{isatty, tcgetwinsize};
 
-    if !is_tty {
-        return None;
-    }
+    // TODO: Once I/O safety is stabilized, the enlosing function here should
+    // be unsafe due to taking a `RawFd`. We should then move the main
+    // logic here into a new function which takes a `BorrowedFd` and is safe.
+    let fd = unsafe { BorrowedFd::borrow_raw(fd) };
 
-    let mut winsize = WinSize {
-        ws_row: 0,
-        ws_col: 0,
-        ws_xpixel: 0,
-        ws_ypixel: 0,
-    };
-
-    if unsafe { ioctl(fd, TIOCGWINSZ.into(), &mut winsize) } == -1 {
+    if !isatty(fd) {
         return None;
     }
 
+    let winsize = tcgetwinsize(fd).ok()?;
+
     let rows = winsize.ws_row;
     let cols = winsize.ws_col;