fix(cd): on android/termux fails to cd into /sdcard (nushell#10329)

fix on android/termux fails to cd into /sdcard or any directory that
user has access via group

fixes nushell#8095

I am not aware how this works on other platform so feel free to modify
this pr or even close it if it is not correct

# Description
on android or on linux to check if the user belongs to given directory
group, use `libc::getgroups` function

# User-Facing Changes
NA

crates/nu-command/src/filesystem/cd.rs

@@ -229,7 +229,16 @@ fn have_permission(dir: impl AsRef<Path>) -> PermissionResult<'static> {
  }
 }
 
-#[cfg(unix)]
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn any_group(_current_user_gid: gid_t, owner_group: u32) -> bool {
+ use crate::filesystem::util::users;
+ let Some(user_groups) = users::current_user_groups() else {
+ return false;
+ };
+ user_groups.iter().any(|gid| gid.as_raw() == owner_group)
+}
+
+#[cfg(all(unix, not(any(target_os = "linux", target_os = "android"))))]
 fn any_group(current_user_gid: gid_t, owner_group: u32) -> bool {
  use crate::filesystem::util::users;
 

crates/nu-command/src/filesystem/util.rs

@@ -165,9 +165,8 @@ pub fn is_older(src: &Path, dst: &Path) -> Option<bool> {
 
 #[cfg(unix)]
 pub mod users {
- use libc::{c_int, gid_t, uid_t};
+ use libc::{gid_t, uid_t};
  use nix::unistd::{Gid, Group, Uid, User};
- use std::ffi::CString;
 
  pub fn get_user_by_uid(uid: uid_t) -> Option<User> {
  User::from_uid(Uid::from_raw(uid)).ok().flatten()
@@ -185,13 +184,38 @@ pub mod users {
  Gid::current().as_raw()
  }
 
+ #[cfg(not(any(target_os = "linux", target_os = "android")))]
  pub fn get_current_username() -> Option<String> {
  User::from_uid(Uid::current())
  .ok()
  .flatten()
  .map(|user| user.name)
  }
 
+ #[cfg(any(target_os = "linux", target_os = "android"))]
+ pub fn current_user_groups() -> Option<Vec<Gid>> {
+ // SAFETY:
+ // if first arg is 0 then it ignores second argument and returns number of groups present for given user.
+ let ngroups = unsafe { libc::getgroups(0, core::ptr::null::<gid_t> as *mut _) };
+ let mut buff: Vec<gid_t> = vec![0; ngroups as usize];
+
+ // SAFETY:
+ // buff is the size of ngroups and getgroups reads max ngroups elements into buff
+ let found = unsafe { libc::getgroups(ngroups, buff.as_mut_ptr()) };
+
+ if found < 0 {
+ None
+ } else {
+ buff.truncate(found as usize);
+ buff.sort_unstable();
+ buff.dedup();
+ buff.into_iter()
+ .filter_map(|i| get_group_by_gid(i as gid_t))
+ .map(|group| group.gid)
+ .collect::<Vec<_>>()
+ .into()
+ }
+ }
  /// Returns groups for a provided user name and primary group id.
  ///
  /// # libc functions used
@@ -207,7 +231,9 @@ pub mod users {
  /// println!("User is a member of group #{group}");
  /// }
  /// ```
+ #[cfg(not(any(target_os = "linux", target_os = "android")))]
  pub fn get_user_groups(username: &str, gid: gid_t) -> Option<Vec<Gid>> {
+ use std::ffi::CString;
  // MacOS uses i32 instead of gid_t in getgrouplist for unknown reasons
  #[cfg(target_os = "macos")]
  let mut buff: Vec<i32> = vec![0; 1024];
@@ -218,7 +244,7 @@ pub mod users {
  return None;
  };
 
- let mut count = buff.len() as c_int;
+ let mut count = buff.len() as libc::c_int;
 
  // MacOS uses i32 instead of gid_t in getgrouplist for unknown reasons
  // SAFETY: