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 mut need_create = true;
102    let host_adjusted_target_path = {
103        let guard = target_parent_inode.read();
104        match guard.deref() {
105            Kind::Dir { entries, path, .. } => {
106                if entries.contains_key(&target_entry_name) {
107                    need_create = false;
108                }
109                path.join(&target_entry_name)
110            }
111            Kind::Root { .. } => return Ok(Errno::Notcapable),
112            Kind::Socket { .. }
113            | Kind::PipeTx { .. }
114            | Kind::PipeRx { .. }
115            | Kind::DuplexPipe { .. }
116            | Kind::EventNotifications { .. }
117            | Kind::Epoll { .. } => return Ok(Errno::Inval),
118            Kind::Symlink { .. } | Kind::File { .. } | Kind::Buffer { .. } => {
119                debug!("fatal internal logic error: parent of inode is not a directory");
120                return Ok(Errno::Inval);
121            }
122        }
123    };
124
125    let source_entry = {
126        let mut guard = source_parent_inode.write();
127        match guard.deref_mut() {
128            Kind::Dir { entries, .. } => {
129                wasi_try_ok!(entries.remove(&source_entry_name).ok_or(Errno::Noent))
130            }
131            Kind::Root { .. } => return Ok(Errno::Notcapable),
132            Kind::Socket { .. }
133            | Kind::PipeRx { .. }
134            | Kind::PipeTx { .. }
135            | Kind::DuplexPipe { .. }
136            | Kind::EventNotifications { .. }
137            | Kind::Epoll { .. } => {
138                return Ok(Errno::Inval);
139            }
140            Kind::Symlink { .. } | Kind::File { .. } | Kind::Buffer { .. } => {
141                debug!("fatal internal logic error: parent of inode is not a directory");
142                return Ok(Errno::Inval);
143            }
144        }
145    };
146
147    {
148        let mut guard = source_entry.write();
149        match guard.deref_mut() {
150            Kind::File { path, .. } => {
151                let result = {
152                    let path_clone = path.clone();
153                    drop(guard);
154                    let state = state;
155                    let host_adjusted_target_path = host_adjusted_target_path.clone();
156                    __asyncify_light(env, None, async move {
157                        state
158                            .fs_rename(path_clone, &host_adjusted_target_path)
159                            .await
160                    })?
161                };
162                // if the above operation failed we have to revert the previous change and then fail
163                if let Err(e) = result {
164                    let mut guard = source_parent_inode.write();
165                    if let Kind::Dir { entries, .. } = guard.deref_mut() {
166                        entries.insert(source_entry_name, source_entry);
167                        return Ok(e);
168                    }
169                } else {
170                    let mut guard = source_entry.write();
171                    if let Kind::File { path, .. } = guard.deref_mut() {
172                        *path = host_adjusted_target_path;
173                    } else {
174                        unreachable!()
175                    }
176                }
177            }
178            Kind::Dir { path, .. } => {
179                let cloned_path = path.clone();
180                let res = {
181                    let state = state;
182                    let host_adjusted_target_path = host_adjusted_target_path.clone();
183                    __asyncify_light(env, None, async move {
184                        state
185                            .fs_rename(cloned_path, &host_adjusted_target_path)
186                            .await
187                    })?
188                };
189                if let Err(e) = res {
190                    return Ok(e);
191                }
192                {
193                    let source_dir_path = path.clone();
194                    drop(guard);
195                    rename_inode_tree(&source_entry, &source_dir_path, &host_adjusted_target_path);
196                }
197            }
198            Kind::Buffer { .. }
199            | Kind::Symlink { .. }
200            | Kind::Socket { .. }
201            | Kind::PipeTx { .. }
202            | Kind::PipeRx { .. }
203            | Kind::DuplexPipe { .. }
204            | Kind::Epoll { .. }
205            | Kind::EventNotifications { .. } => {}
206            Kind::Root { .. } => unreachable!("The root can not be moved"),
207        }
208    }
209
210    let source_size = source_entry.stat.read().unwrap().st_size;
211
212    if need_create {
213        let mut guard = target_parent_inode.write();
214        if let Kind::Dir { entries, .. } = guard.deref_mut() {
215            let result = entries.insert(target_entry_name.clone(), source_entry);
216            assert!(
217                result.is_none(),
218                "fatal error: race condition on filesystem detected or internal logic error"
219            );
220        }
221    }
222
223    // The target entry is created, one way or the other
224    let target_inode = state
225        .fs
226        .get_inode_at_path(inodes, target_fd, target_path, true)
227        .expect("Expected target inode to exist, and it's too late to safely fail");
228    *target_inode.name.write().unwrap() = target_entry_name.into();
229    target_inode.stat.write().unwrap().st_size = source_size;
230
231    Ok(Errno::Success)
232}
233
234fn rename_inode_tree(inode: &InodeGuard, source_dir_path: &Path, target_dir_path: &Path) {
235    let children;
236
237    let mut guard = inode.write();
238    match guard.deref_mut() {
239        Kind::File { path, .. } => {
240            *path = adjust_path(path, source_dir_path, target_dir_path);
241            return;
242        }
243        Kind::Dir { path, entries, .. } => {
244            *path = adjust_path(path, source_dir_path, target_dir_path);
245            children = entries.values().cloned().collect::<Vec<_>>();
246        }
247        _ => return,
248    }
249    drop(guard);
250
251    for child in children {
252        rename_inode_tree(&child, source_dir_path, target_dir_path);
253    }
254}
255
256fn adjust_path(path: &Path, source_dir_path: &Path, target_dir_path: &Path) -> PathBuf {
257    let relative_path = path
258        .strip_prefix(source_dir_path)
259        .with_context(|| format!("Expected path {path:?} to be a subpath of {source_dir_path:?}"))
260        .expect("Fatal filesystem error");
261    target_dir_path.join(relative_path)
262}
wasmer_wasix/syscalls/wasi/path_rename.rs

wasmer_wasix/syscalls/wasi/
path_rename.rs
