67e2e57b02
Early on in WASI, we weren't sure whether we should allow preopens to be closed, so conservatively, we disallowed them. Among other things, this protected assumptions in wasi-libc that it can hold onto preopen file descriptors and rely on them always being open. However now, I think it makes sense to relax this restriction. wasi-libc itself doesn't expose the preopen file descriptors, so users shouldn't ever be closing them naively, unless they have wild closes. And toolchains other than wasi-libc may want to close preopens as a way to drop priveleges once the main file handles are opened.
51 lines
1.5 KiB
Rust
51 lines
1.5 KiB
Rust
use std::{env, process};
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use wasi_tests::{assert_errno, open_scratch_directory};
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unsafe fn test_overwrite_preopen(dir_fd: wasi::Fd) {
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let pre_fd: wasi::Fd = (libc::STDERR_FILENO + 1) as wasi::Fd;
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assert!(dir_fd > pre_fd, "dir_fd number");
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let old_dir_filestat = wasi::fd_filestat_get(dir_fd).expect("failed fd_filestat_get");
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// Try to renumber over a preopened directory handle.
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wasi::fd_renumber(dir_fd, pre_fd)
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.expect("renumbering over a preopened file descriptor");
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// Ensure that pre_fd is still open.
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let new_dir_filestat = wasi::fd_filestat_get(pre_fd).expect("failed fd_filestat_get");
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// Ensure that we renumbered.
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assert_eq!(old_dir_filestat.dev, new_dir_filestat.dev);
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assert_eq!(old_dir_filestat.ino, new_dir_filestat.ino);
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// Ensure that dir_fd is closed.
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assert_errno!(
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wasi::fd_fdstat_get(dir_fd).expect_err("failed fd_fdstat_get"),
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wasi::ERRNO_BADF
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);
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}
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fn main() {
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let mut args = env::args();
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let prog = args.next().unwrap();
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let arg = if let Some(arg) = args.next() {
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arg
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} else {
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eprintln!("usage: {} <scratch directory>", prog);
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process::exit(1);
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};
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// Open scratch directory
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let dir_fd = match open_scratch_directory(&arg) {
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Ok(dir_fd) => dir_fd,
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Err(err) => {
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eprintln!("{}", err);
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process::exit(1)
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}
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};
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// Run the tests.
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unsafe { test_overwrite_preopen(dir_fd) }
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}
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