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Implement __wasi_fd_fdstat_get for Windows.

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This commit fully implements `__wasi_fd_fdstat_get` on Windows so that
the descriptor flags can be determined.

It does this by calling into `NtQueryInformationFile` (safe to call from
user mode) to get the open mode and access of the underlying OS handle.

`NtQueryInformationFile` isn't included in the `winapi` crate, so it is
manually being linked against.

This commit also fixes several bugs on Windows:

* Ignore `__WASI_FDFLAG_NONBLOCK` by not setting `FILE_FLAG_OVERLAPPED`
  on file handles (the POSIX behavior for `O_NONBLOCK` on files).
* Use `FILE_FLAG_WRITE_THROUGH` for the `__WASI_FDFLAG_?SYNC` flags.
* `__WASI_FDFLAG_APPEND` should disallow `FILE_WRITE_DATA` access to
  force append-only on write operations.
* Use `GENERIC_READ` and `GENERIC_WRITE` access flags.  The
  latter is required when opening a file for truncation.
This commit is contained in:
Peter Huene
2019-11-12 16:41:54 -08:00
committed by Jakub Konka
parent 3e7bc745a2
commit 0cf54ffeba
11 changed files with 245 additions and 172 deletions
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64
crates/wasi-common/src/sys/windows/host_impl.rs
View File

@@ -1,13 +1,7 @@
//! WASI host types specific to Windows host.
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(unused)]
use crate::{wasi, Error, Result};
use std::ffi::OsStr;
use std::fs::OpenOptions;
use std::os::windows::ffi::OsStrExt;
use std::os::windows::fs::OpenOptionsExt;
use winx::file::{AccessMode, Attributes, CreationDisposition, Flags};
pub(crate) fn errno_from_win(error: winx::winerror::WinError) -> wasi::__wasi_errno_t {
// TODO: implement error mapping between Windows and WASI
@@ -40,64 +34,6 @@ pub(crate) fn errno_from_win(error: winx::winerror::WinError) -> wasi::__wasi_er
}
}
pub(crate) fn fdflags_from_win(mode: AccessMode) -> wasi::__wasi_fdflags_t {
let mut fdflags = 0;
// TODO verify this!
if mode.contains(AccessMode::FILE_APPEND_DATA) {
fdflags |= wasi::__WASI_FDFLAGS_APPEND;
}
if mode.contains(AccessMode::SYNCHRONIZE) {
fdflags |= wasi::__WASI_FDFLAGS_DSYNC;
fdflags |= wasi::__WASI_FDFLAGS_RSYNC;
fdflags |= wasi::__WASI_FDFLAGS_SYNC;
}
// The NONBLOCK equivalent is FILE_FLAG_OVERLAPPED
// but it seems winapi doesn't provide a mechanism
// for checking whether the handle supports async IO.
// On the contrary, I've found some dicsussion online
// which suggests that on Windows all handles should
// generally be assumed to be opened with async support
// and then the program should fallback should that **not**
// be the case at the time of the operation.
// TODO: this requires further investigation
fdflags
}
pub(crate) fn win_from_fdflags(fdflags: wasi::__wasi_fdflags_t) -> (AccessMode, Flags) {
let mut access_mode = AccessMode::empty();
let mut flags = Flags::empty();
// TODO verify this!
if fdflags & wasi::__WASI_FDFLAGS_NONBLOCK != 0 {
flags.insert(Flags::FILE_FLAG_OVERLAPPED);
}
if fdflags & wasi::__WASI_FDFLAGS_APPEND != 0 {
access_mode.insert(AccessMode::FILE_APPEND_DATA);
}
if fdflags & wasi::__WASI_FDFLAGS_DSYNC != 0
|| fdflags & wasi::__WASI_FDFLAGS_RSYNC != 0
|| fdflags & wasi::__WASI_FDFLAGS_SYNC != 0
{
access_mode.insert(AccessMode::SYNCHRONIZE);
}
(access_mode, flags)
}
pub(crate) fn win_from_oflags(oflags: wasi::__wasi_oflags_t) -> CreationDisposition {
if oflags & wasi::__WASI_OFLAGS_CREAT != 0 {
if oflags & wasi::__WASI_OFLAGS_EXCL != 0 {
CreationDisposition::CREATE_NEW
} else {
CreationDisposition::CREATE_ALWAYS
}
} else if oflags & wasi::__WASI_OFLAGS_TRUNC != 0 {
CreationDisposition::TRUNCATE_EXISTING
} else {
CreationDisposition::OPEN_EXISTING
}
}
/// Creates owned WASI path from OS string.
///
/// NB WASI spec requires OS string to be valid UTF-8. Otherwise,