wasmer_wasix/syscalls/wasi/
path_rename.rs

1use std::path::PathBuf;
2
3use anyhow::Context;
4
5use super::*;
6use crate::syscalls::*;
7
8/// ### `path_rename()`
9/// Rename a file or directory
10/// Inputs:
11/// - `Fd old_fd`
12///     The base directory for `old_path`
13/// - `const char* old_path`
14///     Pointer to UTF8 bytes, the file to be renamed
15/// - `u32 old_path_len`
16///     The number of bytes to read from `old_path`
17/// - `Fd new_fd`
18///     The base directory for `new_path`
19/// - `const char* new_path`
20///     Pointer to UTF8 bytes, the new file name
21/// - `u32 new_path_len`
22///     The number of bytes to read from `new_path`
23#[instrument(level = "trace", skip_all, fields(%old_fd, %new_fd, old_path = field::Empty, new_path = field::Empty), ret)]
24pub fn path_rename<M: MemorySize>(
25    mut ctx: FunctionEnvMut<'_, WasiEnv>,
26    old_fd: WasiFd,
27    old_path: WasmPtr<u8, M>,
28    old_path_len: M::Offset,
29    new_fd: WasiFd,
30    new_path: WasmPtr<u8, M>,
31    new_path_len: M::Offset,
32) -> Result<Errno, WasiError> {
33    WasiEnv::do_pending_operations(&mut ctx)?;
34
35    let env = ctx.data();
36    let (memory, mut state, inodes) = unsafe { env.get_memory_and_wasi_state_and_inodes(&ctx, 0) };
37    let source_str = unsafe { get_input_str_ok!(&memory, old_path, old_path_len) };
38    Span::current().record("old_path", source_str.as_str());
39    let target_str = unsafe { get_input_str_ok!(&memory, new_path, new_path_len) };
40    Span::current().record("new_path", target_str.as_str());
41
42    let ret = path_rename_internal(&mut ctx, old_fd, &source_str, new_fd, &target_str)?;
43    let env = ctx.data();
44
45    if ret == Errno::Success {
46        #[cfg(feature = "journal")]
47        if env.enable_journal {
48            JournalEffector::save_path_rename(&mut ctx, old_fd, source_str, new_fd, target_str)
49                .map_err(|err| {
50                    tracing::error!("failed to save path rename event - {}", err);
51                    WasiError::Exit(ExitCode::from(Errno::Fault))
52                })?;
53        }
54    }
55    Ok(ret)
56}
57
58pub fn path_rename_internal(
59    ctx: &mut FunctionEnvMut<'_, WasiEnv>,
60    source_fd: WasiFd,
61    source_path: &str,
62    target_fd: WasiFd,
63    target_path: &str,
64) -> Result<Errno, WasiError> {
65    let env = ctx.data();
66    let (memory, mut state, inodes) = unsafe { env.get_memory_and_wasi_state_and_inodes(&ctx, 0) };
67
68    {
69        let source_fd = wasi_try_ok!(state.fs.get_fd(source_fd));
70        if !source_fd.inner.rights.contains(Rights::PATH_RENAME_SOURCE) {
71            return Ok(Errno::Access);
72        }
73        let target_fd = wasi_try_ok!(state.fs.get_fd(target_fd));
74        if !target_fd.inner.rights.contains(Rights::PATH_RENAME_TARGET) {
75            return Ok(Errno::Access);
76        }
77    }
78
79    // this is to be sure the source file is fetched from the filesystem if needed
80    wasi_try_ok!(
81        state
82            .fs
83            .get_inode_at_path(inodes, source_fd, source_path, true)
84    );
85    // Create the destination inode if the file exists.
86    let _ = state
87        .fs
88        .get_inode_at_path(inodes, target_fd, target_path, true);
89    let (source_parent_inode, source_entry_name) = wasi_try_ok!(state.fs.get_parent_inode_at_path(
90        inodes,
91        source_fd,
92        Path::new(source_path),
93        true
94    ));
95    let (target_parent_inode, target_entry_name) = wasi_try_ok!(state.fs.get_parent_inode_at_path(
96        inodes,
97        target_fd,
98        Path::new(target_path),
99        true
100    ));
101    let host_adjusted_source_path = {
102        let guard = source_parent_inode.read();
103        match guard.deref() {
104            Kind::Dir { path, .. } => path.join(&source_entry_name),
105            Kind::Root { .. } => return Ok(Errno::Notcapable),
106            Kind::Socket { .. }
107            | Kind::PipeTx { .. }
108            | Kind::PipeRx { .. }
109            | Kind::DuplexPipe { .. }
110            | Kind::EventNotifications { .. }
111            | Kind::Epoll { .. } => return Ok(Errno::Inval),
112            Kind::Symlink { .. } | Kind::File { .. } | Kind::Buffer { .. } => {
113                debug!("fatal internal logic error: parent of inode is not a directory");
114                return Ok(Errno::Inval);
115            }
116        }
117    };
118    let mut need_create = true;
119    let host_adjusted_target_path = {
120        let guard = target_parent_inode.read();
121        match guard.deref() {
122            Kind::Dir { entries, path, .. } => {
123                if entries.contains_key(&target_entry_name) {
124                    need_create = false;
125                }
126                path.join(&target_entry_name)
127            }
128            Kind::Root { .. } => return Ok(Errno::Notcapable),
129            Kind::Socket { .. }
130            | Kind::PipeTx { .. }
131            | Kind::PipeRx { .. }
132            | Kind::DuplexPipe { .. }
133            | Kind::EventNotifications { .. }
134            | Kind::Epoll { .. } => return Ok(Errno::Inval),
135            Kind::Symlink { .. } | Kind::File { .. } | Kind::Buffer { .. } => {
136                debug!("fatal internal logic error: parent of inode is not a directory");
137                return Ok(Errno::Inval);
138            }
139        }
140    };
141
142    let source_entry = {
143        let mut guard = source_parent_inode.write();
144        match guard.deref_mut() {
145            Kind::Dir { entries, .. } => {
146                wasi_try_ok!(entries.remove(&source_entry_name).ok_or(Errno::Noent))
147            }
148            Kind::Root { .. } => return Ok(Errno::Notcapable),
149            Kind::Socket { .. }
150            | Kind::PipeRx { .. }
151            | Kind::PipeTx { .. }
152            | Kind::DuplexPipe { .. }
153            | Kind::EventNotifications { .. }
154            | Kind::Epoll { .. } => {
155                return Ok(Errno::Inval);
156            }
157            Kind::Symlink { .. } | Kind::File { .. } | Kind::Buffer { .. } => {
158                debug!("fatal internal logic error: parent of inode is not a directory");
159                return Ok(Errno::Inval);
160            }
161        }
162    };
163
164    {
165        let mut guard = source_entry.write();
166        match guard.deref_mut() {
167            Kind::File { path, .. } => {
168                let result = {
169                    let path_clone = path.clone();
170                    drop(guard);
171                    let state = state;
172                    let host_adjusted_target_path = host_adjusted_target_path.clone();
173                    __asyncify_light(env, None, async move {
174                        state
175                            .fs_rename(path_clone, &host_adjusted_target_path)
176                            .await
177                    })?
178                };
179                // if the above operation failed we have to revert the previous change and then fail
180                if let Err(e) = result {
181                    let mut guard = source_parent_inode.write();
182                    if let Kind::Dir { entries, .. } = guard.deref_mut() {
183                        entries.insert(source_entry_name, source_entry);
184                        return Ok(e);
185                    }
186                } else {
187                    let mut guard = source_entry.write();
188                    if let Kind::File { path, .. } = guard.deref_mut() {
189                        *path = host_adjusted_target_path.clone();
190                    } else {
191                        unreachable!()
192                    }
193                }
194            }
195            Kind::Dir { path, .. } => {
196                let cloned_path = path.clone();
197                let res = {
198                    let state = state;
199                    let host_adjusted_target_path = host_adjusted_target_path.clone();
200                    __asyncify_light(env, None, async move {
201                        state
202                            .fs_rename(cloned_path, &host_adjusted_target_path)
203                            .await
204                    })?
205                };
206                if let Err(e) = res {
207                    return Ok(e);
208                }
209                {
210                    let source_dir_path = path.clone();
211                    drop(guard);
212                    rename_inode_tree(&source_entry, &source_dir_path, &host_adjusted_target_path);
213                }
214            }
215            Kind::Symlink {
216                base_po_dir,
217                path_to_symlink,
218                relative_path,
219            } => {
220                let is_ephemeral = state
221                    .fs
222                    .ephemeral_symlink_at(host_adjusted_source_path.as_path())
223                    .is_some();
224                let res = {
225                    let state = state;
226                    let from = host_adjusted_source_path.clone();
227                    let to = host_adjusted_target_path.clone();
228                    __asyncify_light(env, None, async move { state.fs_rename(from, to).await })?
229                };
230                match (res, is_ephemeral) {
231                    (Ok(()), _) | (Err(Errno::Noent), true) => {}
232                    (Err(e), _) => {
233                        let mut guard = source_parent_inode.write();
234                        if let Kind::Dir { entries, .. } = guard.deref_mut() {
235                            entries.insert(source_entry_name, source_entry.clone());
236                            return Ok(e);
237                        }
238                    }
239                }
240
241                let (new_base_po_dir, new_path_to_symlink) =
242                    wasi_try_ok!(state.fs.path_into_pre_open_and_relative_path_owned(
243                        host_adjusted_target_path.as_path()
244                    ));
245                *base_po_dir = new_base_po_dir;
246                *path_to_symlink = new_path_to_symlink.clone();
247                if is_ephemeral {
248                    state.fs.move_ephemeral_symlink(
249                        host_adjusted_source_path.as_path(),
250                        host_adjusted_target_path.as_path(),
251                        new_base_po_dir,
252                        new_path_to_symlink,
253                        relative_path.clone(),
254                    );
255                }
256            }
257            Kind::Buffer { .. }
258            | Kind::Socket { .. }
259            | Kind::PipeTx { .. }
260            | Kind::PipeRx { .. }
261            | Kind::DuplexPipe { .. }
262            | Kind::Epoll { .. }
263            | Kind::EventNotifications { .. } => {}
264            Kind::Root { .. } => unreachable!("The root can not be moved"),
265        }
266    }
267
268    let source_size = source_entry.stat.read().unwrap().st_size;
269
270    if need_create {
271        let mut guard = target_parent_inode.write();
272        if let Kind::Dir { entries, .. } = guard.deref_mut() {
273            let result = entries.insert(target_entry_name.clone(), source_entry);
274            assert!(
275                result.is_none(),
276                "fatal error: race condition on filesystem detected or internal logic error"
277            );
278        }
279    }
280
281    // The target entry is created, one way or the other
282    let target_inode = state
283        .fs
284        .get_inode_at_path(inodes, target_fd, target_path, true)
285        .expect("Expected target inode to exist, and it's too late to safely fail");
286    *target_inode.name.write().unwrap() = target_entry_name.into();
287    target_inode.stat.write().unwrap().st_size = source_size;
288
289    // If the rename replaced an existing destination entry, clear any stale
290    // ephemeral symlink mapping for that path.
291    state
292        .fs
293        .unregister_ephemeral_symlink(host_adjusted_target_path.as_path());
294
295    Ok(Errno::Success)
296}
297
298fn rename_inode_tree(inode: &InodeGuard, source_dir_path: &Path, target_dir_path: &Path) {
299    let children;
300
301    let mut guard = inode.write();
302    match guard.deref_mut() {
303        Kind::File { path, .. } => {
304            *path = adjust_path(path, source_dir_path, target_dir_path);
305            return;
306        }
307        Kind::Dir { path, entries, .. } => {
308            *path = adjust_path(path, source_dir_path, target_dir_path);
309            children = entries.values().cloned().collect::<Vec<_>>();
310        }
311        _ => return,
312    }
313    drop(guard);
314
315    for child in children {
316        rename_inode_tree(&child, source_dir_path, target_dir_path);
317    }
318}
319
320fn adjust_path(path: &Path, source_dir_path: &Path, target_dir_path: &Path) -> PathBuf {
321    let relative_path = path
322        .strip_prefix(source_dir_path)
323        .with_context(|| format!("Expected path {path:?} to be a subpath of {source_dir_path:?}"))
324        .expect("Fatal filesystem error");
325    target_dir_path.join(relative_path)
326}
wasmer_wasix/syscalls/wasi/path_rename.rs

wasmer_wasix/syscalls/wasi/
path_rename.rs
