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update WASI fs abstraction to open files on each rw #448

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update WASI fs abstraction to open files on each rw #448

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72 changes: 62 additions & 10 deletions lib/wasi/src/state.rs
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Expand Up @@ -18,65 +18,117 @@ pub const MAX_SYMLINKS: usize = 100;

#[derive(Debug)]
pub enum WasiFile {
HostFile(fs::File),
HostFile { path: PathBuf, offset: u64 },
}

impl WasiFile {
pub fn new_host_file(path: PathBuf) -> WasiFile {
WasiFile::HostFile { path, offset: 0 }
}
}

impl Write for WasiFile {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
match self {
WasiFile::HostFile(hf) => hf.write(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().write(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.write(buf)
}
}
}

fn flush(&mut self) -> io::Result<()> {
match self {
WasiFile::HostFile(hf) => hf.flush(),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().write(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.flush()
}
}
}

fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
match self {
WasiFile::HostFile(hf) => hf.write_all(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().write(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.write_all(buf)
}
}
}

fn write_fmt(&mut self, fmt: ::std::fmt::Arguments) -> io::Result<()> {
match self {
WasiFile::HostFile(hf) => hf.write_fmt(fmt),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().write(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.write_fmt(fmt)
}
}
}
}

impl Read for WasiFile {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
match self {
WasiFile::HostFile(hf) => hf.read(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().read(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.read(buf)
}
}
}

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
match self {
WasiFile::HostFile(hf) => hf.read_to_end(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().read(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.read_to_end(buf)
}
}
}

fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
match self {
WasiFile::HostFile(hf) => hf.read_to_string(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().read(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.read_to_string(buf)
}
}
}

fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
match self {
WasiFile::HostFile(hf) => hf.read_exact(buf),
WasiFile::HostFile { path, offset } => {
let mut file = fs::OpenOptions::new().read(true).open(path)?;
file.seek(io::SeekFrom::Start(*offset))?;
file.read_exact(buf)
}
}
}
}

impl Seek for WasiFile {
fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
match self {
WasiFile::HostFile(hf) => hf.seek(pos),
WasiFile::HostFile { path, offset } => {
match pos {
io::SeekFrom::Start(v) => {
*offset = v;
}
io::SeekFrom::Current(v) => {
*offset = ((*offset as i64) + v) as u64;
}
io::SeekFrom::End(v) => {
// TODO: investigate this for an off by 1 error
*offset = (path.metadata()?.len() as i64 - v) as u64;
}
};
Ok(*offset)
}
}
}
}
Expand Down
25 changes: 8 additions & 17 deletions lib/wasi/src/syscalls/mod.rs
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Expand Up @@ -1248,18 +1248,12 @@ pub fn path_filestat_get(
})
} else {
debug!("Opening host file {:#?}", &cumulative_path);
let real_open_file = wasi_try!(std::fs::OpenOptions::new()
.read(true)
.write(true)
.open(&cumulative_path)
.map_err(|_| __WASI_ENOENT));

state.fs.inodes.insert(InodeVal {
stat: __wasi_filestat_t::default(),
is_preopened: false, // is this correct?
name: last_segment.clone(),
kind: Kind::File {
handle: WasiFile::HostFile(real_open_file),
handle: WasiFile::new_host_file(cumulative_path),
},
})
};
Expand Down Expand Up @@ -1538,32 +1532,29 @@ pub fn path_open(
}
} else {
// file is not a dir
let real_opened_file = {
{
let mut open_options = std::fs::OpenOptions::new();
let open_options = open_options.read(true).write(true);
let open_options = open_options.read(true);
let open_options = if o_flags & __WASI_O_CREAT != 0 {
debug!(
"File {:?} may be created when opened if it does not exist",
&file_path
);
open_options.create(true)
open_options.write(true).create(true)
} else {
open_options
};
let open_options = if o_flags & __WASI_O_TRUNC != 0 {
debug!("File {:?} will be truncated when opened", &file_path);
open_options.truncate(true)
open_options.write(true).truncate(true)
} else {
open_options
};
debug!("Opening host file {:?}", &file_path);
let real_open_file =
wasi_try!(open_options.open(&file_path).map_err(|_| __WASI_EIO));

real_open_file
};
wasi_try!(open_options.open(&file_path).map_err(|_| __WASI_EIO));
}
Kind::File {
handle: WasiFile::HostFile(real_opened_file),
handle: WasiFile::new_host_file(file_path),
}
};

Expand Down