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Unify fd_readdir impl between *nixes (#613)

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* Unify fd_readdir impl between *nixes

This commit unifies the implementation of `fd_readdir` between Linux
and BSD hosts. In particular, it re-uses the `Dirent`, `Entry`, and
`Dir` (among others) building blocks introduced recently when
`fd_readdir` was being implemented on Windows.

Notable changes:
* on BSD, wraps `readdir` syscall in an `Iterator` of the mutex-locked
  `Dir` struct
* on BSD, removes `DirStream` struct from `OsFile`; `OsFile` now holds a
  mutex to `Dir`
* makes `Dir` iterators implementation specific (Linux has its own,
  and so does BSD)

* Lock mutex once only; explain dir in OsFile

* Add more comments
This commit is contained in:
Jakub Konka
2019-11-24 10:29:55 +01:00
committed by GitHub
parent bbe2a797ba
commit c45f70999a
7 changed files with 192 additions and 263 deletions
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83
crates/wasi-common/src/hostcalls_impl/fs.rs
View File

@@ -578,41 +578,6 @@ pub(crate) unsafe fn path_open(
enc_fd_byref(memory, fd_out_ptr, guest_fd)
}
pub(crate) unsafe fn fd_readdir(
wasi_ctx: &mut WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
buf: wasi32::uintptr_t,
buf_len: wasi32::size_t,
cookie: wasi::__wasi_dircookie_t,
buf_used: wasi32::uintptr_t,
) -> Result<()> {
trace!(
"fd_readdir(fd={:?}, buf={:#x?}, buf_len={}, cookie={:#x?}, buf_used={:#x?})",
fd,
buf,
buf_len,
cookie,
buf_used,
);
enc_usize_byref(memory, buf_used, 0)?;
let file = wasi_ctx
.get_fd_entry_mut(fd)?
.as_descriptor_mut(wasi::__WASI_RIGHTS_FD_READDIR, 0)?
.as_file_mut()?;
let host_buf = dec_slice_of_mut_u8(memory, buf, buf_len)?;
trace!(" | (buf,buf_len)={:?}", host_buf);
let host_bufused = hostcalls_impl::fd_readdir(file, host_buf, cookie)?;
trace!(" | *buf_used={:?}", host_bufused);
enc_usize_byref(memory, buf_used, host_bufused)
}
pub(crate) unsafe fn path_readlink(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
@@ -1032,6 +997,53 @@ pub(crate) unsafe fn fd_prestat_dir_name(
enc_slice_of_u8(memory, path.as_bytes(), path_ptr)
}
pub(crate) unsafe fn fd_readdir(
wasi_ctx: &mut WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
buf: wasi32::uintptr_t,
buf_len: wasi32::size_t,
cookie: wasi::__wasi_dircookie_t,
buf_used: wasi32::uintptr_t,
) -> Result<()> {
trace!(
"fd_readdir(fd={:?}, buf={:#x?}, buf_len={}, cookie={:#x?}, buf_used={:#x?})",
fd,
buf,
buf_len,
cookie,
buf_used,
);
enc_usize_byref(memory, buf_used, 0)?;
let file = wasi_ctx
.get_fd_entry_mut(fd)?
.as_descriptor_mut(wasi::__WASI_RIGHTS_FD_READDIR, 0)?
.as_file_mut()?;
let mut host_buf = dec_slice_of_mut_u8(memory, buf, buf_len)?;
trace!(" | (buf,buf_len)={:?}", host_buf);
let iter = hostcalls_impl::fd_readdir(file, cookie)?;
let mut host_bufused = 0;
for dirent in iter {
let dirent_raw = dirent?.to_wasi_raw()?;
let offset = dirent_raw.len();
if host_buf.len() < offset {
break;
} else {
host_buf[0..offset].copy_from_slice(&dirent_raw);
host_bufused += offset;
host_buf = &mut host_buf[offset..];
}
}
trace!(" | *buf_used={:?}", host_bufused);
enc_usize_byref(memory, buf_used, host_bufused)
}
#[allow(dead_code)] // trouble with sockets
#[derive(Clone, Copy, Debug)]
#[repr(u8)]
@@ -1061,7 +1073,6 @@ pub(crate) struct Dirent {
}
impl Dirent {
#![allow(unused)] // temporarily, until BSD catches up with this change
/// Serialize the directory entry to the format define by `__wasi_fd_readdir`,
/// so that the serialized entries can be concatenated by the implementation.
pub fn to_wasi_raw(&self) -> Result<Vec<u8>> {