Implement fd_filestat_get for all platforms (#42)

* Implement fd_filestat_get for all platforms

* Remove an old comment

* Remove panics from the syscall wrappers

* Return WASI error type

* Reuse Metadata if possible to save syscalls.

* Refactor the change for two separate fd_filestat_get_impl

* Refactor error handling

src/helpers.rs

@@ -0,0 +1,10 @@
+use crate::{host, Result};
+use std::convert::TryInto;
+use std::time::{SystemTime, UNIX_EPOCH};
+pub(crate) fn systemtime_to_timestamp(st: SystemTime) -> Result<u64> {
+    st.duration_since(UNIX_EPOCH)
+        .map_err(|_| host::__WASI_EINVAL)? // date earlier than UNIX_EPOCH
+        .as_nanos()
+        .try_into()
+        .map_err(|_| host::__WASI_EOVERFLOW) // u128 doesn't fit into u64
+}

src/hostcalls_impl/fs.rs

@@ -730,7 +730,7 @@ pub(crate) fn fd_filestat_get(
         .get_fd_entry(fd, 0, 0)
         .and_then(|fe| fe.fd_object.descriptor.as_file())?;
 
-    let host_filestat = hostcalls_impl::fd_filestat_get(fd)?;
+    let host_filestat = hostcalls_impl::fd_filestat_get_impl(fd)?;
 
     trace!("     | *filestat_ptr={:?}", host_filestat);
 

src/lib.rs

@@ -22,6 +22,7 @@
 
 mod ctx;
 mod fdentry;
+mod helpers;
 mod hostcalls_impl;
 mod sys;
 #[macro_use]

src/sys/mod.rs

@@ -6,17 +6,27 @@ cfg_if! {
         mod unix;
         pub use self::unix::*;
 
-        pub fn errno_from_host(err: i32) -> host::__wasi_errno_t {
+        pub(crate) fn errno_from_host(err: i32) -> host::__wasi_errno_t {
             host_impl::errno_from_nix(nix::errno::from_i32(err))
         }
     } else if #[cfg(windows)] {
         mod windows;
         pub use self::windows::*;
 
-        pub fn errno_from_host(err: i32) -> host::__wasi_errno_t {
+        pub(crate) fn errno_from_host(err: i32) -> host::__wasi_errno_t {
             host_impl::errno_from_win(winx::winerror::WinError::from_u32(err as u32))
         }
     } else {
         compile_error!("wasi-common doesn't compile for this platform yet");
     }
 }
+
+pub(crate) fn errno_from_ioerror(e: std::io::Error) -> host::__wasi_errno_t {
+    match e.raw_os_error() {
+        Some(code) => errno_from_host(code),
+        None => {
+            log::debug!("Inconvertible OS error: {}", e);
+            host::__WASI_EIO
+        }
+    }
+}

src/sys/unix/hostcalls_impl/fs.rs

@@ -3,13 +3,15 @@
 use super::fs_helpers::*;
 use crate::ctx::WasiCtx;
 use crate::fdentry::FdEntry;
-use crate::sys::errno_from_host;
+use crate::helpers::systemtime_to_timestamp;
 use crate::sys::fdentry_impl::determine_type_rights;
 use crate::sys::host_impl;
+use crate::sys::{errno_from_host, errno_from_ioerror};
 use crate::{host, wasm32, Result};
 use nix::libc::{self, c_long, c_void, off_t};
+use std::convert::TryInto;
 use std::ffi::CString;
-use std::fs::File;
+use std::fs::{File, Metadata};
 use std::os::unix::fs::FileExt;
 use std::os::unix::prelude::{AsRawFd, FromRawFd};
 
@@ -356,11 +358,54 @@ pub(crate) fn path_rename(
     }
 }
 
-pub(crate) fn fd_filestat_get(fd: &File) -> Result<host::__wasi_filestat_t> {
-    use nix::sys::stat::fstat;
-    let filestat =
-        fstat(fd.as_raw_fd()).map_err(|err| host_impl::errno_from_nix(err.as_errno().unwrap()))?;
-    host_impl::filestat_from_nix(filestat)
+pub(crate) fn fd_filestat_get_impl(file: &std::fs::File) -> Result<host::__wasi_filestat_t> {
+    use std::os::unix::fs::MetadataExt;
+
+    let metadata = file.metadata().map_err(errno_from_ioerror)?;
+    Ok(host::__wasi_filestat_t {
+        st_dev: metadata.dev(),
+        st_ino: metadata.ino(),
+        st_nlink: metadata
+            .nlink()
+            .try_into()
+            .map_err(|_| host::__WASI_EOVERFLOW)?, // u64 doesn't fit into u32
+        st_size: metadata.len(),
+        st_atim: metadata
+            .accessed()
+            .map_err(errno_from_ioerror)
+            .and_then(systemtime_to_timestamp)?,
+        st_ctim: metadata
+            .ctime()
+            .try_into()
+            .map_err(|_| host::__WASI_EOVERFLOW)?, // i64 doesn't fit into u64
+        st_mtim: metadata
+            .modified()
+            .map_err(errno_from_ioerror)
+            .and_then(systemtime_to_timestamp)?,
+        st_filetype: filetype(&metadata),
+    })
+}
+
+fn filetype(metadata: &Metadata) -> host::__wasi_filetype_t {
+    use std::os::unix::fs::FileTypeExt;
+    let ftype = metadata.file_type();
+    if ftype.is_file() {
+        host::__WASI_FILETYPE_REGULAR_FILE
+    } else if ftype.is_dir() {
+        host::__WASI_FILETYPE_DIRECTORY
+    } else if ftype.is_symlink() {
+        host::__WASI_FILETYPE_SYMBOLIC_LINK
+    } else if ftype.is_char_device() {
+        host::__WASI_FILETYPE_CHARACTER_DEVICE
+    } else if ftype.is_block_device() {
+        host::__WASI_FILETYPE_BLOCK_DEVICE
+    } else if ftype.is_socket() || ftype.is_fifo() {
+        // TODO we should use getsockopt to find out if it's
+        // SOCKET_STREAM or SOCKET_DGRAM
+        host::__WASI_FILETYPE_SOCKET_STREAM
+    } else {
+        host::__WASI_FILETYPE_UNKNOWN
+    }
 }
 
 pub(crate) fn fd_filestat_set_times(

src/sys/windows/hostcalls_impl/fs.rs

@@ -3,11 +3,13 @@
 use super::fs_helpers::*;
 use crate::ctx::WasiCtx;
 use crate::fdentry::FdEntry;
-use crate::sys::errno_from_host;
+use crate::helpers::systemtime_to_timestamp;
+use crate::sys::{errno_from_ioerror, errno_from_host};
 use crate::sys::fdentry_impl::determine_type_rights;
 use crate::sys::host_impl;
 use crate::{host, Result};
-use std::fs::File;
+use std::convert::TryInto;
+use std::fs::{File, Metadata};
 use std::io::{self, Seek, SeekFrom};
 use std::os::windows::fs::FileExt;
 use std::os::windows::prelude::{AsRawHandle, FromRawHandle};
@@ -173,8 +175,65 @@ pub(crate) fn path_rename(
     unimplemented!("path_rename")
 }
 
-pub(crate) fn fd_filestat_get(fd: &File) -> Result<host::__wasi_filestat_t> {
-    unimplemented!("fd_filestat_get")
+pub(crate) fn num_hardlinks(file: &File, _metadata: &Metadata) -> io::Result<u64> {
+    Ok(winx::file::get_fileinfo(file)?.nNumberOfLinks.into())
+}
+
+pub(crate) fn device_id(file: &File, _metadata: &Metadata) -> io::Result<u64> {
+    Ok(winx::file::get_fileinfo(file)?.dwVolumeSerialNumber.into())
+}
+
+pub(crate) fn file_serial_no(file: &File, _metadata: &Metadata) -> io::Result<u64> {
+    let info = winx::file::get_fileinfo(file)?;
+    let high = info.nFileIndexHigh;
+    let low = info.nFileIndexLow;
+    let no = ((high as u64) << 32) | (low as u64);
+    Ok(no)
+}
+
+pub(crate) fn change_time(file: &File, _metadata: &Metadata) -> io::Result<i64> {
+    winx::file::change_time(file)
+}
+
+pub(crate) fn fd_filestat_get_impl(file: &std::fs::File) -> Result<host::__wasi_filestat_t> {
+    let metadata = file.metadata().map_err(errno_from_ioerror)?;
+    Ok(host::__wasi_filestat_t {
+        st_dev: device_id(file, &metadata).map_err(errno_from_ioerror)?,
+        st_ino: file_serial_no(file, &metadata).map_err(errno_from_ioerror)?,
+        st_nlink: num_hardlinks(file, &metadata)
+            .map_err(errno_from_ioerror)?
+            .try_into()
+            .map_err(|_| host::__WASI_EOVERFLOW)?, // u64 doesn't fit into u32
+        st_size: metadata.len(),
+        st_atim: metadata
+            .accessed()
+            .map_err(errno_from_ioerror)
+            .and_then(systemtime_to_timestamp)?,
+        st_ctim: change_time(file, &metadata)
+            .map_err(errno_from_ioerror)?
+            .try_into()
+            .map_err(|_| host::__WASI_EOVERFLOW)?, // i64 doesn't fit into u64
+        st_mtim: metadata
+            .modified()
+            .map_err(errno_from_ioerror)
+            .and_then(systemtime_to_timestamp)?,
+        st_filetype: filetype(&metadata).map_err(errno_from_ioerror)?,
+    })
+}
+
+fn filetype(metadata: &Metadata) -> io::Result<host::__wasi_filetype_t> {
+    let ftype = metadata.file_type();
+    let ret = if ftype.is_file() {
+        host::__WASI_FILETYPE_REGULAR_FILE
+    } else if ftype.is_dir() {
+        host::__WASI_FILETYPE_DIRECTORY
+    } else if ftype.is_symlink() {
+        host::__WASI_FILETYPE_SYMBOLIC_LINK
+    } else {
+        host::__WASI_FILETYPE_UNKNOWN
+    };
+
+    Ok(ret)
 }
 
 pub(crate) fn fd_filestat_set_times(

winx/src/file.rs

@@ -1,9 +1,11 @@
 #![allow(non_camel_case_types)]
 use crate::{winerror, Result};
-use std::ffi::{OsStr, OsString};
-use std::os::windows::prelude::{OsStrExt, OsStringExt, RawHandle};
+use std::ffi::{c_void, OsStr, OsString};
+use std::fs::File;
+use std::io;
+use std::os::windows::prelude::{AsRawHandle, OsStrExt, OsStringExt, RawHandle};
 use winapi::shared::minwindef::{self, DWORD};
-use winapi::um::{fileapi, fileapi::GetFileType, winbase, winnt};
+use winapi::um::{fileapi, fileapi::GetFileType, minwinbase, winbase, winnt};
 
 /// Maximum total path length for Unicode in Windows.
 /// [Maximum path length limitation]: https://docs.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file#maximum-path-length-limitation
@@ -457,3 +459,48 @@ pub fn openat<S: AsRef<OsStr>>(
         Ok(handle)
     }
 }
+
+// Taken from Rust libstd, file libstd/sys/windows/fs.rs
+fn cvt(i: winapi::shared::minwindef::BOOL) -> io::Result<()> {
+    if i == 0 {
+        Err(io::Error::last_os_error())
+    } else {
+        Ok(())
+    }
+}
+
+pub fn get_fileinfo(file: &File) -> io::Result<fileapi::BY_HANDLE_FILE_INFORMATION> {
+    use fileapi::{GetFileInformationByHandle, BY_HANDLE_FILE_INFORMATION};
+    use std::mem;
+
+    let handle = file.as_raw_handle();
+    let info = unsafe {
+        let mut info: BY_HANDLE_FILE_INFORMATION = mem::zeroed();
+        cvt(GetFileInformationByHandle(handle, &mut info))?;
+        info
+    };
+
+    Ok(info)
+}
+
+pub fn change_time(file: &File) -> io::Result<i64> {
+    use fileapi::FILE_BASIC_INFO;
+    use minwinbase::FileBasicInfo;
+    use std::mem;
+    use winbase::GetFileInformationByHandleEx;
+
+    let handle = file.as_raw_handle();
+    let tm = unsafe {
+        let mut info: FILE_BASIC_INFO = mem::zeroed();
+        let infosize = mem::size_of_val(&info);
+        cvt(GetFileInformationByHandleEx(
+            handle,
+            FileBasicInfo,
+            &mut info as *mut FILE_BASIC_INFO as *mut c_void,
+            infosize as u32,
+        ))?;
+        *info.ChangeTime.QuadPart()
+    };
+
+    Ok(tm)
+}