jqrutils 0.0.1

Small Unix utilities: quiet, errfail
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
144
145
146
147
148
149
150
151
152
153

use std::env;
use std::io::{self, Read, Write};
use std::process::{Command, ExitCode, Stdio};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

#[derive(Copy, Clone)]
enum Output {
    Stdout,
    Stderr,
}

struct State {
    streaming: bool,
    buffer: Vec<(Output, Vec<u8>)>,
}

impl State {
    fn flush(&mut self) {
        for (output, data) in self.buffer.drain(..) {
            let _ = match output {
                Output::Stdout => io::stdout().write_all(&data),
                Output::Stderr => io::stderr().write_all(&data),
            };
        }
        self.streaming = true;
    }
}

fn read_pipe(mut pipe: impl Read, output: Output, state: &Mutex<State>) {
    let mut buf = [0u8; 8192];
    loop {
        match pipe.read(&mut buf) {
            Ok(0) | Err(_) => break,
            Ok(n) => {
                let data = buf[..n].to_vec();
                let mut s = state.lock().unwrap();
                if s.streaming {
                    drop(s);
                    let _ = match output {
                        Output::Stdout => io::stdout().write_all(&data),
                        Output::Stderr => io::stderr().write_all(&data),
                    };
                } else {
                    s.buffer.push((output, data));
                }
            }
        }
    }
}

fn main() -> ExitCode {
    let args: Vec<String> = env::args().skip(1).collect();

    let (timeout, cmd_start) = match args.first().map(|s| s.as_str()) {
        Some("-t") => {
            let secs: f64 = match args.get(1) {
                None => {
                    eprintln!("quiet: -t requires a numeric argument");
                    return ExitCode::from(1);
                }
                Some(s) => match s.parse() {
                    Ok(v) => v,
                    Err(_) => {
                        eprintln!("quiet: invalid timeout '{}', -t requires a numeric argument", s);
                        return ExitCode::from(1);
                    }
                },
            };
            (Some(secs), 2)
        }
        _ => (None, 0),
    };

    let cmd_args = &args[cmd_start..];
    let cmd_args = if cmd_args.first().map(|s| s.as_str()) == Some("--") {
        &cmd_args[1..]
    } else {
        cmd_args
    };

    if cmd_args.is_empty() {
        eprintln!("Usage: quiet [-t <seconds>] [--] <command> [args...]");
        return ExitCode::from(1);
    }

    let mut child = match Command::new(&cmd_args[0])
        .args(&cmd_args[1..])
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn()
    {
        Ok(c) => c,
        Err(e) => {
            eprintln!("quiet: {}: {}", cmd_args[0], e);
            return ExitCode::from(127);
        }
    };

    let state = Arc::new(Mutex::new(State {
        streaming: false,
        buffer: Vec::new(),
    }));

    let stdout = child.stdout.take().unwrap();
    let stderr = child.stderr.take().unwrap();

    let s1 = Arc::clone(&state);
    let t1 = thread::spawn(move || read_pipe(stdout, Output::Stdout, &s1));

    let s2 = Arc::clone(&state);
    let t2 = thread::spawn(move || read_pipe(stderr, Output::Stderr, &s2));

    let timeout_cancel = if let Some(secs) = timeout {
        let s3 = Arc::clone(&state);
        let (tx, rx) = std::sync::mpsc::channel::<()>();
        thread::spawn(move || {
            use std::sync::mpsc::RecvTimeoutError;
            if rx.recv_timeout(Duration::from_secs_f64(secs)) == Err(RecvTimeoutError::Timeout) {
                let mut s = s3.lock().unwrap();
                if !s.streaming {
                    s.flush();
                }
            }
        });
        Some(tx)
    } else {
        None
    };

    let status = child.wait().expect("failed to wait on child");
    t1.join().unwrap();
    t2.join().unwrap();
    drop(timeout_cancel);

    let mut s = state.lock().unwrap();
    if !s.streaming && !status.success() {
        s.flush();
    }

    #[cfg(unix)]
    let code = {
        use std::os::unix::process::ExitStatusExt;
        status
            .code()
            .unwrap_or_else(|| status.signal().map(|s| 128 + s).unwrap_or(1))
    };
    #[cfg(not(unix))]
    let code = status.code().unwrap_or(1);

    ExitCode::from(code as u8)
}