Remove is-root crate (#9615)

# Description
This PR tries to remove `is-root` crate.

# User-Facing Changes
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helps us keep track of breaking changes. -->

# Tests + Formatting
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---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>

Cargo.lock

@@ -1863,16 +1863,6 @@ dependencies = [
  "once_cell",
 ]
 
-[[package]]
-name = "is-root"
-version = "0.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04a4202a60e86f1c9702706bb42270dadd333f2db7810157563c86f17af3c873"
-dependencies = [
- "users",
- "winapi",
-]
-
 [[package]]
 name = "is-terminal"
 version = "0.4.8"
@@ -2739,7 +2729,6 @@ dependencies = [
  "htmlescape",
  "indexmap 2.0.0",
  "indicatif",
- "is-root",
  "is-terminal",
  "itertools",
  "libc",
@@ -5508,16 +5497,6 @@ dependencies = [
  "percent-encoding",
 ]
 
-[[package]]
-name = "users"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aa4227e95324a443c9fcb06e03d4d85e91aabe9a5a02aa818688b6918b6af486"
-dependencies = [
- "libc",
- "log",
-]
-
 [[package]]
 name = "utf-8"
 version = "0.7.6"

crates/nu-command/Cargo.toml

@@ -50,7 +50,6 @@ fs_extra = "1.3"
 htmlescape = "0.3"
 indexmap = "2.0"
 indicatif = "0.17"
-is-root = "0.1"
 is-terminal = "0.4.8"
 itertools = "0.10"
 log = "0.4"
@@ -110,7 +109,13 @@ optional = true
 version = "3.0"
 
 [target.'cfg(windows)'.dependencies.windows]
-features = ["Win32_Foundation", "Win32_Storage_FileSystem", "Win32_System_SystemServices"]
+features = [
+	"Win32_Foundation",
+	"Win32_Storage_FileSystem",
+	"Win32_System_SystemServices",
+	"Win32_Security",
+	"Win32_System_Threading"
+]
 version = "0.48"
 
 [features]

crates/nu-command/src/experimental/is_admin.rs

@@ -1,4 +1,3 @@
-use is_root::is_root;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
@@ -48,3 +47,62 @@ impl Command for IsAdmin {
         ]
     }
 }
+
+/// Returns `true` if user is root; `false` otherwise
+fn is_root() -> bool {
+    is_root_impl()
+}
+
+#[cfg(unix)]
+fn is_root_impl() -> bool {
+    nix::unistd::Uid::current().is_root()
+}
+
+#[cfg(windows)]
+fn is_root_impl() -> bool {
+    use windows::Win32::{
+        Foundation::{CloseHandle, HANDLE},
+        Security::{GetTokenInformation, TokenElevation, TOKEN_ELEVATION, TOKEN_QUERY},
+        System::Threading::{GetCurrentProcess, OpenProcessToken},
+    };
+
+    let mut handle = HANDLE::default();
+    let mut elevated = false;
+
+    // Checks whether the access token associated with the current process has elevated privileges.
+    // SAFETY: `elevated` only touched by safe code.
+    // `handle` lives long enough, initialized, mutated as out param, used, closed with validity check.
+    // `elevation` only read on success and passed with correct `size`.
+    unsafe {
+        // Opens the access token associated with the current process.
+        if OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &mut handle).as_bool() {
+            let mut elevation = TOKEN_ELEVATION::default();
+            let mut size = std::mem::size_of::<TOKEN_ELEVATION>() as u32;
+
+            // Retrieves elevation token information about the access token associated with the current process.
+            // Call available since XP
+            // https://learn.microsoft.com/en-us/windows/win32/api/securitybaseapi/nf-securitybaseapi-gettokeninformation
+            if GetTokenInformation(
+                handle,
+                TokenElevation,
+                Some(&mut elevation as *mut TOKEN_ELEVATION as *mut _),
+                size,
+                &mut size,
+            )
+            .as_bool()
+            {
+                // Whether the token has elevated privileges.
+                // Safe to read as `GetTokenInformation` will not write outside `elevation` and it succeeded
+                // See: https://learn.microsoft.com/en-us/windows/win32/api/securitybaseapi/nf-securitybaseapi-gettokeninformation#parameters
+                elevated = elevation.TokenIsElevated != 0;
+            }
+        }
+
+        if !handle.is_invalid() {
+            // Closes the object handle.
+            CloseHandle(handle);
+        }
+    }
+
+    elevated
+}