T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Revert fstatat on *nix and test symlinks in path_filestat calls (#1725)

Browse Source 
* Revert fstatat on *nix and test symlinks in path_filestat calls

This commit effectively reverts too eager refactoring on my part which
resulted in incorrect `path_filestat_{get, set_times}` behaviour on
*nix hosts. In the presence of symlinks, neither of the calls would
work properly.

In order to shield ourselves from similar errors in the future, I've
augmented the `path_filestat` test cases with symlink checks as well.

* Pass appropriate flags to fstatat and utimensat

* Fix formatting

* Fix Windows build

* Expand final symlinks if follow is set on Windows

* Fix formatting

* Do not follow symlinks unless specified on Windows

* Update comments and restart CI

* Skip testing volatile atim field
This commit is contained in:
Jakub Konka
2020-05-20 21:02:24 +02:00
committed by GitHub
parent 1f620e1b46
commit 348be6f3ed
7 changed files with 202 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
crates/test-programs/wasi-tests/src/bin/path_filestat.rs
View File

@@ -55,31 +55,20 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
assert_eq!(stat.size, 0, "file size should be 0");
// Check path_filestat_set_times
let old_atim = stat.atim;
let new_mtim = stat.mtim - 100;
wasi::path_filestat_set_times(
dir_fd,
0,
"file",
// on purpose: the syscall should not touch atim, because
// neither of the ATIM flags is set
new_mtim,
new_mtim,
wasi::FSTFLAGS_MTIM,
)
wasi::path_filestat_set_times(dir_fd, 0, "file", 0, new_mtim, wasi::FSTFLAGS_MTIM)
.expect("path_filestat_set_times should succeed");
stat = wasi::path_filestat_get(dir_fd, 0, "file")
.expect("reading file stats after path_filestat_set_times");
assert_eq!(stat.mtim, new_mtim, "mtim should change");
assert_eq!(stat.atim, old_atim, "atim should not change");
assert_eq!(
wasi::path_filestat_set_times(
dir_fd,
0,
"file",
new_mtim,
0,
new_mtim,
wasi::FSTFLAGS_MTIM | wasi::FSTFLAGS_MTIM_NOW,
)
@@ -93,16 +82,14 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
stat = wasi::path_filestat_get(dir_fd, 0, "file")
.expect("reading file stats after ERRNO_INVAL fd_filestat_set_times");
assert_eq!(stat.mtim, new_mtim, "mtim should not change");
assert_eq!(stat.atim, old_atim, "atim should not change");
let new_atim = old_atim - 100;
assert_eq!(
wasi::path_filestat_set_times(
dir_fd,
0,
"file",
new_atim,
new_atim,
0,
0,
wasi::FSTFLAGS_ATIM | wasi::FSTFLAGS_ATIM_NOW,
)
.expect_err("ATIM & ATIM_NOW can't both be set")
@@ -111,14 +98,46 @@ unsafe fn test_path_filestat(dir_fd: wasi::Fd) {
"errno should be ERRNO_INVAL"
);
// check if the times were untouched
// Create a symlink
wasi::path_symlink("file", dir_fd, "symlink").expect("creating symlink to a file");
// Check path_filestat_set_times on the symlink itself
let mut sym_stat = wasi::path_filestat_get(dir_fd, 0, "file").expect("reading file stats");
let sym_new_mtim = sym_stat.mtim - 200;
wasi::path_filestat_set_times(dir_fd, 0, "symlink", 0, sym_new_mtim, wasi::FSTFLAGS_MTIM)
.expect("path_filestat_set_times should succeed on symlink");
sym_stat = wasi::path_filestat_get(dir_fd, 0, "symlink")
.expect("reading file stats after path_filestat_set_times");
assert_eq!(sym_stat.mtim, sym_new_mtim, "mtim should change");
// Now, dereference the symlink
sym_stat = wasi::path_filestat_get(dir_fd, wasi::LOOKUPFLAGS_SYMLINK_FOLLOW, "symlink")
.expect("reading file stats on the dereferenced symlink");
assert_eq!(
sym_stat.mtim, stat.mtim,
"symlink mtim should be equal to pointee's when dereferenced"
);
// Finally, change stat of the original file by dereferencing the symlink
wasi::path_filestat_set_times(
dir_fd,
wasi::LOOKUPFLAGS_SYMLINK_FOLLOW,
"symlink",
0,
sym_stat.mtim,
wasi::FSTFLAGS_MTIM,
)
.expect("path_filestat_set_times should succeed on setting stat on original file");
stat = wasi::path_filestat_get(dir_fd, 0, "file")
.expect("reading file stats after ERRNO_INVAL path_filestat_set_times");
assert_eq!(stat.mtim, new_mtim, "mtim should not change");
assert_eq!(stat.atim, old_atim, "atim should not change");
.expect("reading file stats after path_filestat_set_times");
assert_eq!(stat.mtim, sym_stat.mtim, "mtim should change");
wasi::fd_close(file_fd).expect("closing a file");
wasi::path_unlink_file(dir_fd, "file").expect("removing a file");
wasi::path_unlink_file(dir_fd, "symlink").expect("removing a symlink");
}
fn main() {
let mut args = env::args();

13
crates/wasi-common/src/handle.rs
View File

@@ -135,6 +135,19 @@ pub(crate) trait Handle {
fn create_directory(&self, _path: &str) -> Result<()> {
Err(Errno::Acces)
}
fn filestat_get_at(&self, _path: &str, _follow: bool) -> Result<types::Filestat> {
Err(Errno::Acces)
}
fn filestat_set_times_at(
&self,
_path: &str,
_atim: types::Timestamp,
_mtim: types::Timestamp,
_fst_flags: types::Fstflags,
_follow: bool,
) -> Result<()> {
Err(Errno::Acces)
}
fn openat(
&self,
_path: &str,

25
crates/wasi-common/src/snapshots/wasi_snapshot_preview1.rs
View File

@@ -469,15 +469,8 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
let required_rights = HandleRights::from_base(types::Rights::PATH_FILESTAT_GET);
let entry = self.get_entry(dirfd)?;
let (dirfd, path) = path::get(&entry, &required_rights, flags, path, false)?;
let host_filestat = dirfd
.openat(
&path,
false,
false,
types::Oflags::empty(),
types::Fdflags::empty(),
)?
.filestat_get()?;
let host_filestat =
dirfd.filestat_get_at(&path, flags.contains(&types::Lookupflags::SYMLINK_FOLLOW))?;
Ok(host_filestat)
}
@@ -493,15 +486,13 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
let required_rights = HandleRights::from_base(types::Rights::PATH_FILESTAT_SET_TIMES);
let entry = self.get_entry(dirfd)?;
let (dirfd, path) = path::get(&entry, &required_rights, flags, path, false)?;
dirfd
.openat(
dirfd.filestat_set_times_at(
&path,
false,
false,
types::Oflags::empty(),
types::Fdflags::empty(),
)?
.filestat_set_times(atim, mtim, fst_flags)?;
atim,
mtim,
fst_flags,
flags.contains(&types::Lookupflags::SYMLINK_FOLLOW),
)?;
Ok(())
}

13
crates/wasi-common/src/sys/osdir.rs
View File

@@ -69,6 +69,19 @@ impl Handle for OsDir {
fn create_directory(&self, path: &str) -> Result<()> {
path::create_directory(self, path)
}
fn filestat_get_at(&self, path: &str, follow: bool) -> Result<types::Filestat> {
path::filestat_get_at(self, path, follow)
}
fn filestat_set_times_at(
&self,
path: &str,
atim: types::Timestamp,
mtim: types::Timestamp,
fst_flags: types::Fstflags,
follow: bool,
) -> Result<()> {
path::filestat_set_times_at(self, path, atim, mtim, fst_flags, follow)
}
fn openat(
&self,
path: &str,

57
crates/wasi-common/src/sys/unix/path.rs
View File

@@ -1,7 +1,8 @@
use crate::handle::{Handle, HandleRights};
use crate::sys::osdir::OsDir;
use crate::sys::AsFile;
use crate::wasi::{types, Errno, Result};
use std::convert::TryFrom;
use std::convert::{TryFrom, TryInto};
use std::ffi::OsStr;
use std::fs::File;
use std::os::unix::prelude::{AsRawFd, FromRawFd, OsStrExt};
@@ -204,3 +205,57 @@ pub(crate) fn remove_directory(dirfd: &OsDir, path: &str) -> Result<()> {
unsafe { unlinkat(dirfd.as_raw_fd(), path, AtFlag::REMOVEDIR)? };
Ok(())
}
pub(crate) fn filestat_get_at(dirfd: &OsDir, path: &str, follow: bool) -> Result<types::Filestat> {
use yanix::file::{fstatat, AtFlag};
let flags = if follow {
AtFlag::empty()
} else {
AtFlag::SYMLINK_NOFOLLOW
};
let stat = unsafe { fstatat(dirfd.as_raw_fd(), path, flags)? };
let stat = stat.try_into()?;
Ok(stat)
}
pub(crate) fn filestat_set_times_at(
dirfd: &OsDir,
path: &str,
atim: types::Timestamp,
mtim: types::Timestamp,
fst_flags: types::Fstflags,
follow: bool,
) -> Result<()> {
use std::time::{Duration, UNIX_EPOCH};
use yanix::filetime::*;
let set_atim = fst_flags.contains(&types::Fstflags::ATIM);
let set_atim_now = fst_flags.contains(&types::Fstflags::ATIM_NOW);
let set_mtim = fst_flags.contains(&types::Fstflags::MTIM);
let set_mtim_now = fst_flags.contains(&types::Fstflags::MTIM_NOW);
if (set_atim && set_atim_now) || (set_mtim && set_mtim_now) {
return Err(Errno::Inval);
}
let atim = if set_atim {
let time = UNIX_EPOCH + Duration::from_nanos(atim);
FileTime::FileTime(filetime::FileTime::from_system_time(time))
} else if set_atim_now {
FileTime::Now
} else {
FileTime::Omit
};
let mtim = if set_mtim {
let time = UNIX_EPOCH + Duration::from_nanos(mtim);
FileTime::FileTime(filetime::FileTime::from_system_time(time))
} else if set_mtim_now {
FileTime::Now
} else {
FileTime::Omit
};
utimensat(&*dirfd.as_file()?, path, atim, mtim, !follow)?;
Ok(())
}

41
crates/wasi-common/src/sys/windows/path.rs
View File

@@ -1,6 +1,6 @@
use crate::handle::{Handle, HandleRights};
use crate::sys::osdir::OsDir;
use crate::sys::AsFile;
use crate::sys::{fd, AsFile};
use crate::wasi::{types, Errno, Result};
use std::convert::TryFrom;
use std::ffi::{OsStr, OsString};
@@ -494,3 +494,42 @@ pub(crate) fn remove_directory(dirfd: &OsDir, path: &str) -> Result<()> {
let path = concatenate(dirfd, path)?;
std::fs::remove_dir(&path).map_err(Into::into)
}
pub(crate) fn filestat_get_at(dirfd: &OsDir, path: &str, follow: bool) -> Result<types::Filestat> {
use winx::file::Flags;
let path = concatenate(dirfd, path)?;
let mut opts = OpenOptions::new();
if !follow {
// By specifying FILE_FLAG_OPEN_REPARSE_POINT, we force Windows to *not* dereference symlinks.
opts.custom_flags(Flags::FILE_FLAG_OPEN_REPARSE_POINT.bits());
}
let file = opts.read(true).open(path)?;
let stat = fd::filestat_get(&file)?;
Ok(stat)
}
pub(crate) fn filestat_set_times_at(
dirfd: &OsDir,
path: &str,
atim: types::Timestamp,
mtim: types::Timestamp,
fst_flags: types::Fstflags,
follow: bool,
) -> Result<()> {
use winx::file::{AccessMode, Flags};
let path = concatenate(dirfd, path)?;
let mut opts = OpenOptions::new();
if !follow {
// By specifying FILE_FLAG_OPEN_REPARSE_POINT, we force Windows to *not* dereference symlinks.
opts.custom_flags(Flags::FILE_FLAG_OPEN_REPARSE_POINT.bits());
}
let file = opts
.access_mode(AccessMode::FILE_WRITE_ATTRIBUTES.bits())
.open(path)?;
fd::filestat_set_times(&file, atim, mtim, fst_flags)?;
Ok(())
}

30
crates/wasi-common/src/virtfs.rs
View File

@@ -600,6 +600,36 @@ impl Handle for VirtualDir {
}
}
}
fn filestat_get_at(&self, path: &str, _follow: bool) -> Result<types::Filestat> {
let stat = self
.openat(
path,
false,
false,
types::Oflags::empty(),
types::Fdflags::empty(),
)?
.filestat_get()?;
Ok(stat)
}
fn filestat_set_times_at(
&self,
path: &str,
atim: types::Timestamp,
mtim: types::Timestamp,
fst_flags: types::Fstflags,
_follow: bool,
) -> Result<()> {
self.openat(
path,
false,
false,
types::Oflags::empty(),
types::Fdflags::empty(),
)?
.filestat_set_times(atim, mtim, fst_flags)?;
Ok(())
}
fn openat(
&self,
path: &str,