Program crash on Reader.read_exact

[vwim]

Here's a little snippet to show the problem. Since I updated to the latest rustc I don't get a full crash report, so this is all I got.

use std::io;

fn main() {
    let mut b = io::BufReader::new(b"Hello world!");

    //let r = b.read_exact(2000000000000);  //<-- Works as expected, prints error "end of file"
    let r = b.read_exact(200000000000000);  //<-- When input way too large it causes a crash

    match r {
        Ok(_) => (),
        Err(e) => println!("{}", e)
    }
}

rustc 0.13.0-nightly (8bca470 2014-12-08 00:12:30 +0000)
binary: rustc
commit-hash: 8bca470
commit-date: 2014-12-08 00:12:30 +0000
host: x86_64-apple-darwin
release: 0.13.0-nightly

OS: Mac OS X 10.9.4

[sfackler]

read_exact allocates a Vec to store the data it returns. Your OS is not willing to allocate 200 terabytes of memory, which causes the program to abort.

[vwim]

Your right, didn't think about that :)
Now i'm wondering, should it just crash or give some sort of error?

[sfackler]

It's certainly desired to try to print something before aborting when running out of memory: #14674.

[thestinger]

This is working as intended. Printing an error instead of just aborting is covered by #14674. There's currently no better way to deal with this short of bubbling up out-of-memory errors everywhere.