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

// Copyright (c) 2015-2019 Doug Tangren
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.

#[cfg(windows)]
use windows_sys::Win32::System::Console::STD_HANDLE;

#[cfg(windows)]
type WCHAR = u16;

/// possible stream sources
#[derive(Clone, Copy, Debug)]
pub enum Stream {
    Stdout,
    Stderr,
    Stdin,
}

/// returns true if this is a tty
#[cfg(target_family = "unix")]
pub fn is(stream: Stream) -> bool {
    let fd = match stream {
        Stream::Stdout => libc::STDOUT_FILENO,
        Stream::Stderr => libc::STDERR_FILENO,
        Stream::Stdin => libc::STDIN_FILENO,
    };
    unsafe { libc::isatty(fd) != 0 }
}

/// returns true if this is a tty
#[cfg(target_os = "hermit")]
pub fn is(stream: Stream) -> bool {
    let fd = match stream {
        Stream::Stdout => hermit_abi::STDOUT_FILENO,
        Stream::Stderr => hermit_abi::STDERR_FILENO,
        Stream::Stdin => hermit_abi::STDIN_FILENO,
    };
    hermit_abi::isatty(fd)
}

/// returns true if this is a tty
#[cfg(windows)]
pub fn is(stream: Stream) -> bool {
    use windows_sys::Win32::System::Console::{
        STD_ERROR_HANDLE as STD_ERROR, STD_INPUT_HANDLE as STD_INPUT,
        STD_OUTPUT_HANDLE as STD_OUTPUT,
    };

    let (fd, others) = match stream {
        Stream::Stdin => (STD_INPUT, [STD_ERROR, STD_OUTPUT]),
        Stream::Stderr => (STD_ERROR, [STD_INPUT, STD_OUTPUT]),
        Stream::Stdout => (STD_OUTPUT, [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) }
}

/// returns true if this is _not_ a tty
pub fn isnt(stream: Stream) -> bool {
    !is(stream)
}

/// Returns true if any of the given fds are on a console.
#[cfg(windows)]
unsafe fn console_on_any(fds: &[STD_HANDLE]) -> bool {
    use windows_sys::Win32::System::Console::{GetConsoleMode, GetStdHandle};

    for &fd in fds {
        let mut out = 0;
        let handle = GetStdHandle(fd);
        if GetConsoleMode(handle, &mut out) != 0 {
            return true;
        }
    }
    false
}

/// Returns true if there is an MSYS tty on the given handle.
#[cfg(windows)]
unsafe fn msys_tty_on(fd: STD_HANDLE) -> bool {
    use std::os::raw::c_void;
    use std::{mem, slice};

    use windows_sys::Win32::Foundation::MAX_PATH;
    use windows_sys::Win32::Storage::FileSystem::GetFileInformationByHandleEx;
    use windows_sys::Win32::Storage::FileSystem::{FileNameInfo, FILE_NAME_INFO};
    use windows_sys::Win32::System::Console::GetStdHandle;

    let size = mem::size_of::<FILE_NAME_INFO>();
    let mut name_info_bytes = vec![0u8; size + MAX_PATH as usize * 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
}

/// returns true if this is a tty
#[cfg(target_family = "wasm")]
pub fn is(_stream: Stream) -> bool {
    false
}