wasmer_wasix/syscalls/wasi/
path_symlink.rs

1use super::*;
2use crate::syscalls::*;
3
4/// ### `path_symlink()`
5/// Create a symlink
6/// Inputs:
7/// - `const char *old_path`
8///     Array of UTF-8 bytes representing the source path
9/// - `u32 old_path_len`
10///     The number of bytes to read from `old_path`
11/// - `Fd fd`
12///     The base directory from which the paths are understood
13/// - `const char *new_path`
14///     Array of UTF-8 bytes representing the target path
15/// - `u32 new_path_len`
16///     The number of bytes to read from `new_path`
17#[instrument(level = "trace", skip_all, fields(%fd, old_path = field::Empty, new_path = field::Empty), ret)]
18pub fn path_symlink<M: MemorySize>(
19    mut ctx: FunctionEnvMut<'_, WasiEnv>,
20    old_path: WasmPtr<u8, M>,
21    old_path_len: M::Offset,
22    fd: WasiFd,
23    new_path: WasmPtr<u8, M>,
24    new_path_len: M::Offset,
25) -> Result<Errno, WasiError> {
26    WasiEnv::do_pending_operations(&mut ctx)?;
27
28    let env = ctx.data();
29    let (memory, mut state, inodes) = unsafe { env.get_memory_and_wasi_state_and_inodes(&ctx, 0) };
30    let old_path_str = unsafe { get_input_str_ok!(&memory, old_path, old_path_len) };
31    Span::current().record("old_path", old_path_str.as_str());
32    let new_path_str = unsafe { get_input_str_ok!(&memory, new_path, new_path_len) };
33    Span::current().record("new_path", new_path_str.as_str());
34
35    wasi_try_ok!(path_symlink_internal(
36        &mut ctx,
37        &old_path_str,
38        fd,
39        &new_path_str
40    ));
41    let env = ctx.data();
42
43    #[cfg(feature = "journal")]
44    if env.enable_journal {
45        JournalEffector::save_path_symlink(&mut ctx, old_path_str, fd, new_path_str).map_err(
46            |err| {
47                tracing::error!("failed to save path symbolic link event - {}", err);
48                WasiError::Exit(ExitCode::from(Errno::Fault))
49            },
50        )?;
51    }
52
53    Ok(Errno::Success)
54}
55
56pub fn path_symlink_internal(
57    ctx: &mut FunctionEnvMut<'_, WasiEnv>,
58    old_path: &str,
59    fd: WasiFd,
60    new_path: &str,
61) -> Result<(), Errno> {
62    let env = ctx.data();
63    let (memory, mut state, inodes) = unsafe { env.get_memory_and_wasi_state_and_inodes(&ctx, 0) };
64
65    let base_fd = state.fs.get_fd(fd)?;
66    if !base_fd.inner.rights.contains(Rights::PATH_SYMLINK) {
67        return Err(Errno::Access);
68    }
69
70    // get the depth of the parent + 1 (UNDER INVESTIGATION HMMMMMMMM THINK FISH ^ THINK FISH)
71    let old_path_path = std::path::Path::new(old_path);
72    let (source_inode, _) = state
73        .fs
74        .get_parent_inode_at_path(inodes, fd, old_path_path, true)?;
75    let depth = state.fs.path_depth_from_fd(fd, source_inode);
76
77    // depth == -1 means folder is not relative. See issue #3233.
78    let depth = match depth {
79        Ok(depth) => depth as i32 - 1,
80        Err(_) => -1,
81    };
82
83    let new_path_path = std::path::Path::new(new_path);
84    let (target_parent_inode, entry_name) =
85        state
86            .fs
87            .get_parent_inode_at_path(inodes, fd, new_path_path, true)?;
88
89    // short circuit if anything is wrong, before we create an inode
90    {
91        let guard = target_parent_inode.read();
92        match guard.deref() {
93            Kind::Dir { entries, .. } => {
94                if entries.contains_key(&entry_name) {
95                    return Err(Errno::Exist);
96                }
97            }
98            Kind::Root { .. } => return Err(Errno::Notcapable),
99            Kind::Socket { .. }
100            | Kind::PipeRx { .. }
101            | Kind::PipeTx { .. }
102            | Kind::DuplexPipe { .. }
103            | Kind::EventNotifications { .. }
104            | Kind::Epoll { .. } => return Err(Errno::Inval),
105            Kind::File { .. } | Kind::Symlink { .. } | Kind::Buffer { .. } => {
106                unreachable!("get_parent_inode_at_path returned something other than a Dir or Root")
107            }
108        }
109    }
110
111    let mut source_path = std::path::Path::new(old_path);
112    let mut relative_path = std::path::PathBuf::new();
113    for _ in 0..depth {
114        relative_path.push("..");
115    }
116    relative_path.push(source_path);
117
118    let kind = Kind::Symlink {
119        base_po_dir: fd,
120        path_to_symlink: std::path::PathBuf::from(new_path),
121        relative_path,
122    };
123    let new_inode =
124        state
125            .fs
126            .create_inode_with_default_stat(inodes, kind, false, entry_name.clone().into());
127
128    {
129        let mut guard = target_parent_inode.write();
130        if let Kind::Dir { entries, .. } = guard.deref_mut() {
131            entries.insert(entry_name, new_inode);
132        }
133    }
134
135    Ok(())
136}
wasmer_wasix/syscalls/wasi/path_symlink.rs

wasmer_wasix/syscalls/wasi/
path_symlink.rs
