nu_utils/
filesystem.rs

1#[cfg(unix)]
2use nix::unistd::{AccessFlags, access};
3#[cfg(any(windows, unix))]
4use std::path::Path;
5
6// The result of checking whether we have permission to cd to a directory
7#[derive(Debug)]
8pub enum PermissionResult {
9    PermissionOk,
10    PermissionDenied,
11}
12
13// TODO: Maybe we should use file_attributes() from https://doc.rust-lang.org/std/os/windows/fs/trait.MetadataExt.html
14// More on that here: https://learn.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants
15#[cfg(windows)]
16pub fn have_permission(dir: impl AsRef<Path>) -> PermissionResult {
17    match dir.as_ref().read_dir() {
18        Err(e) => {
19            if matches!(e.kind(), std::io::ErrorKind::PermissionDenied) {
20                PermissionResult::PermissionDenied
21            } else {
22                PermissionResult::PermissionOk
23            }
24        }
25        Ok(_) => PermissionResult::PermissionOk,
26    }
27}
28
29#[cfg(unix)]
30/// Check that the process' user id has permissions to execute or
31/// in the case of a directory traverse the particular directory
32pub fn have_permission(dir: impl AsRef<Path>) -> PermissionResult {
33    // We check permissions for real user id, but that's fine, because in
34    // proper installations of nushell, effective UID (EUID) rarely differs
35    // from real UID (RUID). We strongly advise against setting the setuid bit
36    // on the nushell executable or shebang scripts starts with `#!/usr/bin/env nu` e.g.
37    // Most Unix systems ignore setuid on shebang by default anyway.
38    access(dir.as_ref(), AccessFlags::X_OK).into()
39}
40
41#[cfg(unix)]
42pub mod users {
43    use nix::unistd::{Gid, Group, Uid, User};
44
45    pub fn get_user_by_uid(uid: Uid) -> Option<User> {
46        User::from_uid(uid).ok().flatten()
47    }
48
49    pub fn get_group_by_gid(gid: Gid) -> Option<Group> {
50        Group::from_gid(gid).ok().flatten()
51    }
52
53    pub fn get_current_uid() -> Uid {
54        Uid::current()
55    }
56
57    pub fn get_current_gid() -> Gid {
58        Gid::current()
59    }
60
61    #[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os = "android")))]
62    pub fn get_current_username() -> Option<String> {
63        get_user_by_uid(get_current_uid()).map(|user| user.name)
64    }
65
66    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "android"))]
67    pub fn current_user_groups() -> Option<Vec<Gid>> {
68        if let Ok(mut groups) = nix::unistd::getgroups() {
69            groups.sort_unstable_by_key(|id| id.as_raw());
70            groups.dedup();
71            Some(groups)
72        } else {
73            None
74        }
75    }
76
77    /// Returns groups for a provided user name and primary group id.
78    ///
79    /// # libc functions used
80    ///
81    /// - [`getgrouplist`](https://docs.rs/libc/*/libc/fn.getgrouplist.html)
82    ///
83    /// # Examples
84    ///
85    /// ```ignore
86    /// use users::get_user_groups;
87    ///
88    /// for group in get_user_groups("stevedore", 1001).expect("Error looking up groups") {
89    ///     println!("User is a member of group #{group}");
90    /// }
91    /// ```
92    #[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os = "android")))]
93    pub fn get_user_groups(username: &str, gid: Gid) -> Option<Vec<Gid>> {
94        use nix::libc::{c_int, gid_t};
95        use std::ffi::CString;
96
97        // MacOS uses i32 instead of gid_t in getgrouplist for unknown reasons
98        #[cfg(target_os = "macos")]
99        let mut buff: Vec<i32> = vec![0; 1024];
100        #[cfg(not(target_os = "macos"))]
101        let mut buff: Vec<gid_t> = vec![0; 1024];
102
103        let name = CString::new(username).ok()?;
104
105        let mut count = buff.len() as c_int;
106
107        // MacOS uses i32 instead of gid_t in getgrouplist for unknown reasons
108        // SAFETY:
109        // int getgrouplist(const char *user, gid_t group, gid_t *groups, int *ngroups);
110        //
111        // `name` is valid CStr to be `const char*` for `user`
112        // every valid value will be accepted for `group`
113        // The capacity for `*groups` is passed in as `*ngroups` which is the buffer max length/capacity (as we initialize with 0)
114        // Following reads from `*groups`/`buff` will only happen after `buff.truncate(*ngroups)`
115        #[cfg(target_os = "macos")]
116        let res = unsafe {
117            nix::libc::getgrouplist(
118                name.as_ptr(),
119                gid.as_raw() as i32,
120                buff.as_mut_ptr(),
121                &mut count,
122            )
123        };
124
125        #[cfg(not(target_os = "macos"))]
126        let res = unsafe {
127            nix::libc::getgrouplist(name.as_ptr(), gid.as_raw(), buff.as_mut_ptr(), &mut count)
128        };
129
130        if res < 0 {
131            None
132        } else {
133            buff.truncate(count as usize);
134            buff.sort_unstable();
135            buff.dedup();
136            // allow trivial cast: on macos i is i32, on linux it's already gid_t
137            #[allow(trivial_numeric_casts)]
138            Some(
139                buff.into_iter()
140                    .map(|id| Gid::from_raw(id as gid_t))
141                    .filter_map(get_group_by_gid)
142                    .map(|group| group.gid)
143                    .collect(),
144            )
145        }
146    }
147}
148
149impl<T, E> From<Result<T, E>> for PermissionResult {
150    fn from(value: Result<T, E>) -> Self {
151        match value {
152            Ok(_) => Self::PermissionOk,
153            Err(_) => Self::PermissionDenied,
154        }
155    }
156}
nu_utils/filesystem.rs

nu_utils/
filesystem.rs
