io/os: Implement IsTerminal trait on Stdio

library/std/src/io/mod.rs

@@ -273,6 +273,8 @@ pub use self::error::{Error, ErrorKind, Result};
 #[unstable(feature = "internal_output_capture", issue = "none")]
 #[doc(no_inline, hidden)]
 pub use self::stdio::set_output_capture;
+#[unstable(feature = "is_terminal", issue = "80937")]
+pub use self::stdio::IsTerminal;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::stdio::{stderr, stdin, stdout, Stderr, Stdin, Stdout};
 #[stable(feature = "rust1", since = "1.0.0")]

library/std/src/io/stdio.rs

@@ -965,3 +965,57 @@ pub fn _eprint(args: fmt::Arguments<'_>) {
 
 #[cfg(test)]
 pub use realstd::io::{_eprint, _print};
+
+/// Trait to determine if stdio stream (Stdin, Stdout, Stderr) is a terminal/tty.
+#[unstable(feature = "is_terminal", issue = "80937")]
+pub trait IsTerminal {
+    /// returns true if stdio stream (Stdin, Stdout, Stderr) is a terminal/tty.
+    fn is_terminal() -> bool;
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+cfg_if::cfg_if! {
+    if #[cfg(any(unix, windows, hermit))] {
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stdin {
+            fn is_terminal() -> bool {
+               stdio::Stdin::is_terminal()
+            }
+        }
+
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stdout {
+            fn is_terminal() -> bool {
+                stdio::Stdout::is_terminal()
+            }
+        }
+
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stderr {
+            fn is_terminal() -> bool {
+                stdio::Stderr::is_terminal()
+            }
+        }
+    } else {
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stdin {
+            fn is_terminal() -> bool {
+                false
+            }
+        }
+
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stdout {
+            fn is_terminal() -> bool {
+                false
+            }
+        }
+
+        #[unstable(feature = "is_terminal", issue = "80937")]
+        impl IsTerminal for Stderr {
+            fn is_terminal() -> bool {
+                false
+            }
+        }
+    }
+}

library/std/src/lib.rs

@@ -335,6 +335,7 @@
 #![feature(unwind_attributes)]
 #![feature(vec_into_raw_parts)]
 #![feature(vec_spare_capacity)]
+#![feature(is_terminal)]
 // NB: the above list is sorted to minimize merge conflicts.
 #![default_lib_allocator]
 

library/std/src/sys/hermit/ext/io.rs

@@ -0,0 +1,23 @@
+use crate::io;
+use crate::sys;
+use crate::sys::hermit::abi;
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdin {
+    fn is_terminal() -> bool {
+        abi::isatty(abi::STDIN_FILENO)
+    }
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdout {
+    fn is_terminal() -> bool {
+        abi::isatty(abi::STDOUT_FILENO)
+    }
+}
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stderr {
+    fn is_terminal() -> bool {
+        abi::isatty(abi::STDERR_FILENO)
+    }
+}

library/std/src/sys/hermit/ext/mod.rs

@@ -2,6 +2,7 @@
 #![allow(missing_docs)]
 
 pub mod ffi;
+pub mod io;
 
 /// A prelude for conveniently writing platform-specific code.
 ///

library/std/src/sys/unix/ext/io.rs

@@ -181,3 +181,23 @@ impl<'a> AsRawFd for io::StderrLock<'a> {
         libc::STDERR_FILENO
     }
 }
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdin {
+    fn is_terminal() -> bool {
+        unsafe { libc::isatty(libc::STDIN_FILENO) != 0 }
+    }
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdout {
+    fn is_terminal() -> bool {
+        unsafe { libc::isatty(libc::STDOUT_FILENO) != 0 }
+    }
+}
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stderr {
+    fn is_terminal() -> bool {
+        unsafe { libc::isatty(libc::STDERR_FILENO) != 0 }
+    }
+}

library/std/src/sys/windows/c.rs

@@ -388,6 +388,12 @@ pub struct FILE_BASIC_INFO {
     pub FileAttributes: DWORD,
 }
 
+#[repr(C)]
+pub struct FILE_NAME_INFO {
+    FileNameLength: DWORD,
+    FileName: [WCHAR; 1],
+}
+
 #[repr(C)]
 pub struct FILE_END_OF_FILE_INFO {
     pub EndOfFile: LARGE_INTEGER,

library/std/src/sys/windows/ext/io.rs

@@ -220,3 +220,141 @@ impl IntoRawSocket for net::UdpSocket {
         self.into_inner().into_socket().into_inner()
     }
 }
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdin {
+    fn is_terminal() -> bool {
+        use c::{
+            STD_ERROR_HANDLE as STD_ERROR, STD_INPUT_HANDLE as STD_INPUT,
+            STD_OUTPUT_HANDLE as STD_OUTPUT,
+        };
+
+        let fd = STD_INPUT;
+        let others = [STD_ERROR, STD_OUTPUT];
+
+        if unsafe { console_on_any(&[fd]) } {
+            // False positives aren't possible. If we got a console then
+            // we definitely have a tty on stdin.
+            return true;
+        }
+
+        // At this point, we *could* have a false negative. We can determine that
+        // this is true negative if we can detect the presence of a console on
+        // any of the other streams. If another stream has a console, then we know
+        // we're in a Windows console and can therefore trust the negative.
+        if unsafe { console_on_any(&others) } {
+            return false;
+        }
+
+        // Otherwise, we fall back to a very strange msys hack to see if we can
+        // sneakily detect the presence of a tty.
+        unsafe { msys_tty_on(fd) }
+    }
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stdout {
+    fn is_terminal() -> bool {
+        use c::{
+            STD_ERROR_HANDLE as STD_ERROR, STD_INPUT_HANDLE as STD_INPUT,
+            STD_OUTPUT_HANDLE as STD_OUTPUT,
+        };
+
+        let fd = STD_OUTPUT;
+        let others = [STD_INPUT, STD_ERROR];
+
+        if unsafe { console_on_any(&[fd]) } {
+            // False positives aren't possible. If we got a console then
+            // we definitely have a tty on stdin.
+            return true;
+        }
+
+        // At this point, we *could* have a false negative. We can determine that
+        // this is true negative if we can detect the presence of a console on
+        // any of the other streams. If another stream has a console, then we know
+        // we're in a Windows console and can therefore trust the negative.
+        if unsafe { console_on_any(&others) } {
+            return false;
+        }
+
+        // Otherwise, we fall back to a very strange msys hack to see if we can
+        // sneakily detect the presence of a tty.
+        unsafe { msys_tty_on(fd) }
+    }
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+impl io::IsTerminal for sys::stdio::Stderr {
+    fn is_terminal() -> bool {
+        use c::{
+            STD_ERROR_HANDLE as STD_ERROR, STD_INPUT_HANDLE as STD_INPUT,
+            STD_OUTPUT_HANDLE as STD_OUTPUT,
+        };
+
+        let fd = STD_ERROR;
+        let others = [STD_INPUT, STD_OUTPUT];
+
+        if unsafe { console_on_any(&[fd]) } {
+            // False positives aren't possible. If we got a console then
+            // we definitely have a tty on stdin.
+            return true;
+        }
+
+        // At this point, we *could* have a false negative. We can determine that
+        // this is true negative if we can detect the presence of a console on
+        // any of the other streams. If another stream has a console, then we know
+        // we're in a Windows console and can therefore trust the negative.
+        if unsafe { console_on_any(&others) } {
+            return false;
+        }
+
+        // Otherwise, we fall back to a very strange msys hack to see if we can
+        // sneakily detect the presence of a tty.
+        unsafe { msys_tty_on(fd) }
+    }
+}
+
+#[unstable(feature = "is_terminal", issue = "80937")]
+unsafe fn console_on_any(fds: &[c::DWORD]) -> bool {
+    use c::{GetConsoleMode, GetStdHandle};
+
+    for &fd in fds {
+        let mut out = 0;
+        let handle = GetStdHandle(fd);
+        if GetConsoleMode(handle, &mut out) != 0 {
+            return true;
+        }
+    }
+    false
+}
+#[unstable(feature = "is_terminal", issue = "80937")]
+unsafe fn msys_tty_on(fd: c::DWORD) -> bool {
+    use std::{mem, slice};
+
+    use c::{
+        c_void, FileNameInfo, GetFileInformationByHandleEx, GetStdHandle, FILE_NAME_INFO, MAX_PATH,
+    };
+
+    let size = mem::size_of::<FILE_NAME_INFO>();
+    let mut name_info_bytes = vec![0u8; size + MAX_PATH * mem::size_of::<WCHAR>()];
+    let res = GetFileInformationByHandleEx(
+        GetStdHandle(fd),
+        FileNameInfo,
+        &mut *name_info_bytes as *mut _ as *mut c_void,
+        name_info_bytes.len() as u32,
+    );
+    if res == 0 {
+        return false;
+    }
+    let name_info: &FILE_NAME_INFO = &*(name_info_bytes.as_ptr() as *const FILE_NAME_INFO);
+    let s =
+        slice::from_raw_parts(name_info.FileName.as_ptr(), name_info.FileNameLength as usize / 2);
+    let name = String::from_utf16_lossy(s);
+    // This checks whether 'pty' exists in the file name, which indicates that
+    // a pseudo-terminal is attached. To mitigate against false positives
+    // (e.g., an actual file name that contains 'pty'), we also require that
+    // either the strings 'msys-' or 'cygwin-' are in the file name as well.)
+    let is_msys = name.contains("msys-") || name.contains("cygwin-");
+    let is_pty = name.contains("-pty");
+    is_msys && is_pty
+}

library/test/src/cli.rs

@@ -1,9 +1,9 @@
 //! Module converting command-line arguments into test configuration.
 
 use std::env;
+use std::io::{IsTerminal, Stdout};
 use std::path::PathBuf;
 
-use super::helpers::isatty;
 use super::options::{ColorConfig, Options, OutputFormat, RunIgnored};
 use super::time::TestTimeOptions;
 
@@ -30,7 +30,7 @@ pub struct TestOpts {
 impl TestOpts {
     pub fn use_color(&self) -> bool {
         match self.color {
-            ColorConfig::AutoColor => !self.nocapture && isatty::stdout_isatty(),
+            ColorConfig::AutoColor => !self.nocapture && Stdout::is_terminal(),
             ColorConfig::AlwaysColor => true,
             ColorConfig::NeverColor => false,
         }

library/test/src/helpers/mod.rs

@@ -3,5 +3,4 @@
 
 pub mod concurrency;
 pub mod exit_code;
-pub mod isatty;
 pub mod metrics;

library/test/src/lib.rs

@@ -30,6 +30,7 @@
 #![feature(termination_trait_lib)]
 #![feature(test)]
 #![feature(total_cmp)]
+#![feature(is_terminal)]
 
 // Public reexports
 pub use self::bench::{black_box, Bencher};