4b7677e4da
* Add more comments. * Use `contains` from bitflags. * Format wasi-test source. * Remove permission check from Windows `path_open` impl.
64 lines
2.2 KiB
Rust
64 lines
2.2 KiB
Rust
use more_asserts::assert_gt;
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// The `wasi` crate version 0.9.0 and beyond, doesn't
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// seem to define these constants, so we do it ourselves.
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pub const STDIN_FD: wasi::Fd = 0x0;
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pub const STDOUT_FD: wasi::Fd = 0x1;
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pub const STDERR_FD: wasi::Fd = 0x2;
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/// Opens a fresh file descriptor for `path` where `path` should be a preopened
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/// directory.
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pub fn open_scratch_directory(path: &str) -> Result<wasi::Fd, String> {
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unsafe {
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for i in 3.. {
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let stat = match wasi::fd_prestat_get(i) {
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Ok(s) => s,
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Err(_) => break,
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};
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if stat.pr_type != wasi::PREOPENTYPE_DIR {
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continue;
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}
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let mut dst = Vec::with_capacity(stat.u.dir.pr_name_len);
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if wasi::fd_prestat_dir_name(i, dst.as_mut_ptr(), dst.capacity()).is_err() {
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continue;
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}
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dst.set_len(stat.u.dir.pr_name_len);
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if dst == path.as_bytes() {
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let (base, inherit) = fd_get_rights(i);
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return Ok(
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wasi::path_open(i, 0, ".", wasi::OFLAGS_DIRECTORY, base, inherit, 0)
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.expect("failed to open dir"),
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);
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}
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}
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Err(format!("failed to find scratch dir"))
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}
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}
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pub unsafe fn create_file(dir_fd: wasi::Fd, filename: &str) {
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let file_fd =
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wasi::path_open(dir_fd, 0, filename, wasi::OFLAGS_CREAT, 0, 0, 0).expect("creating a file");
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assert_gt!(
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file_fd,
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libc::STDERR_FILENO as wasi::Fd,
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"file descriptor range check",
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);
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wasi::fd_close(file_fd).expect("closing a file");
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}
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// Returns: (rights_base, rights_inheriting)
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pub unsafe fn fd_get_rights(fd: wasi::Fd) -> (wasi::Rights, wasi::Rights) {
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let fdstat = wasi::fd_fdstat_get(fd).expect("fd_fdstat_get failed");
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(fdstat.fs_rights_base, fdstat.fs_rights_inheriting)
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}
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pub unsafe fn drop_rights(fd: wasi::Fd, drop_base: wasi::Rights, drop_inheriting: wasi::Rights) {
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let (current_base, current_inheriting) = fd_get_rights(fd);
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let new_base = current_base & !drop_base;
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let new_inheriting = current_inheriting & !drop_inheriting;
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wasi::fd_fdstat_set_rights(fd, new_base, new_inheriting).expect("dropping fd rights");
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}
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