std\sys\io\is_terminal/
windows.rs

1use crate::ffi::c_void;
2use crate::mem::size_of;
3use crate::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle};
4use crate::sys::c;
5
6pub fn is_terminal(h: &impl AsHandle) -> bool {
7    handle_is_console(h.as_handle())
8}
9
10fn handle_is_console(handle: BorrowedHandle<'_>) -> bool {
11    // A null handle means the process has no console.
12    if handle.as_raw_handle().is_null() {
13        return false;
14    }
15
16    let mut out = 0;
17    if unsafe { c::GetConsoleMode(handle.as_raw_handle(), &mut out) != 0 } {
18        // False positives aren't possible. If we got a console then we definitely have a console.
19        return true;
20    }
21
22    // Otherwise, we fall back to an msys hack to see if we can detect the presence of a pty.
23    msys_tty_on(handle)
24}
25
26fn msys_tty_on(handle: BorrowedHandle<'_>) -> bool {
27    // Early return if the handle is not a pipe.
28    if unsafe { c::GetFileType(handle.as_raw_handle()) != c::FILE_TYPE_PIPE } {
29        return false;
30    }
31
32    /// Mirrors [`FILE_NAME_INFO`], giving it a fixed length that we can stack
33    /// allocate
34    ///
35    /// [`FILE_NAME_INFO`]: https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-file_name_info
36    #[repr(C)]
37    #[allow(non_snake_case)]
38    struct FILE_NAME_INFO {
39        FileNameLength: u32,
40        FileName: [u16; c::MAX_PATH as usize],
41    }
42    let mut name_info = FILE_NAME_INFO { FileNameLength: 0, FileName: [0; c::MAX_PATH as usize] };
43    // Safety: buffer length is fixed.
44    let res = unsafe {
45        c::GetFileInformationByHandleEx(
46            handle.as_raw_handle(),
47            c::FileNameInfo,
48            (&raw mut name_info) as *mut c_void,
49            size_of::<FILE_NAME_INFO>() as u32,
50        )
51    };
52    if res == 0 {
53        return false;
54    }
55
56    // Use `get` because `FileNameLength` can be out of range.
57    let s = match name_info.FileName.get(..name_info.FileNameLength as usize / 2) {
58        None => return false,
59        Some(s) => s,
60    };
61    let name = String::from_utf16_lossy(s);
62    // Get the file name only.
63    let name = name.rsplit('\\').next().unwrap_or(&name);
64    // This checks whether 'pty' exists in the file name, which indicates that
65    // a pseudo-terminal is attached. To mitigate against false positives
66    // (e.g., an actual file name that contains 'pty'), we also require that
67    // the file name begins with either the strings 'msys-' or 'cygwin-'.)
68    let is_msys = name.starts_with("msys-") || name.starts_with("cygwin-");
69    let is_pty = name.contains("-pty");
70    is_msys && is_pty
71}
std\sys\io\is_terminal/windows.rs

std\sys\io\is_terminal/
windows.rs
