Rawscreen and AlternateScreen should disable Ctrl+C signal on windows console

[3kyro]

Or maybe just provide a method to enable/disable the SIGINT signal and just treat it as other keyboard events. Currently pressing Ctrl+C in a windows terminal immediately terminates the process, making for example a feature similar to nodejs' press Ctrl+C twice to exit.

Below my failed attempt to come up with a PR for this:

By following the CTRL+C and CTRL+BREAK Signals in widows console documentation, it appears that one should:

1. use the SetConsoleMode function to disable the ENABLE_PROCESSED_INPUT flag or
2. call SetConsoleCtrlHandler with NULL and True as arguments.

For option 1:

RawModeCommand seems to be where we should look

pub struct RawModeCommand {
    mask: DWORD,
}
use self::wincon::{ENABLE_LINE_INPUT, ENABLE_WRAP_AT_EOL_OUTPUT};
impl RawModeCommand {
    pub fn new() -> Self {
        RawModeCommand {
            mask: ENABLE_WRAP_AT_EOL_OUTPUT | ENABLE_LINE_INPUT,
        }
    }
}

impl RawModeCommand {
    /// Enables raw mode.
    pub fn enable(&mut self) -> io::Result<()> {
        let console_mode = ConsoleMode::new()?;

        let dw_mode = console_mode.mode()?;

        let new_mode = dw_mode & !self.mask;

        console_mode.set_mode(new_mode)?;

        Ok(())
    }

    /// Disables raw mode.
    pub fn disable(&self) -> io::Result<()> {
        let console_mode = ConsoleMode::new()?;

        let dw_mode = console_mode.mode()?;

        let new_mode = dw_mode | self.mask;

        console_mode.set_mode(new_mode)?;

        return Ok(());
    }
}

Disabling ENABLE_PROCESS_INPUT 0x0001 will not work because the handle needs to be an input handle and not a output handle as is the case each time a ConsoleMode instance is created.

A note: ENABLE_LINE_INPUT and ENABLE_WRAP_AT_EOL_OUTPUT are both 0x0002 and so mask: ENABLE_WRAP_AT_EOL_OUTPUT | ENABLE_LINE_INPUT, could be just
mask: ENABLE_WRAP_AT_EOL_OUTPUT,

2. SetConsoleCtrlHandler takes as arguments an Option type and an i32 and should be set to NULL and true respectively. Creating a method for ConsoleMode such as:

pub fn set_ctrl_handler(&self) { unsafe { SetConsoleCtrlHandler(None, 1); } }
and calling it on initialization does not work as well.

[TimonPost]

Can be closed in favor for #250