users: tool unsupported on OpenBSD

- utmpx not supported on OpenBSD

  - add src/uu/users/src/platform directory and platform/mod.rs for conditional compilation
    according to target_os
  - platform/openbsd.rs: implementation on OpenBSD (unsupported tool)
  - platform/unix.rs: implementation on other OS
  - src/uu/users/src/users.rs: use platform module for uucore::main function

src/uu/users/src/platform/mod.rs

@@ -0,0 +1,14 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+#[cfg(not(target_os = "openbsd"))]
+mod unix;
+#[cfg(not(target_os = "openbsd"))]
+pub use self::unix::*;
+
+#[cfg(target_os = "openbsd")]
+mod openbsd;
+#[cfg(target_os = "openbsd")]
+pub use self::openbsd::*;

src/uu/users/src/platform/openbsd.rs

@@ -0,0 +1,17 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// Specific implementation for OpenBSD: tool unsupported (utmpx not supported)
+
+use crate::uu_app;
+
+use uucore::error::UResult;
+
+pub fn uumain(args: impl uucore::Args) -> UResult<()> {
+    let _matches = uu_app().try_get_matches_from(args)?;
+
+    println!("unsupported command on OpenBSD");
+    Ok(())
+}

src/uu/users/src/platform/unix.rs

@@ -0,0 +1,53 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// spell-checker:ignore (paths) wtmp
+
+use crate::uu_app;
+
+use std::ffi::OsString;
+use std::path::Path;
+
+use uucore::error::UResult;
+use uucore::utmpx::{self, Utmpx};
+
+static ARG_FILES: &str = "files";
+
+fn get_long_usage() -> String {
+    format!(
+        "Output who is currently logged in according to FILE.
+If FILE is not specified, use {}.  /var/log/wtmp as FILE is common.",
+        utmpx::DEFAULT_FILE
+    )
+}
+
+pub fn uumain(args: impl uucore::Args) -> UResult<()> {
+    let matches = uu_app()
+        .after_help(get_long_usage())
+        .try_get_matches_from(args)?;
+
+    let files: Vec<&Path> = matches
+        .get_many::<OsString>(ARG_FILES)
+        .map(|v| v.map(AsRef::as_ref).collect())
+        .unwrap_or_default();
+
+    let filename = if files.is_empty() {
+        utmpx::DEFAULT_FILE.as_ref()
+    } else {
+        files[0]
+    };
+
+    let mut users = Utmpx::iter_all_records_from(filename)
+        .filter(Utmpx::is_user_process)
+        .map(|ut| ut.user())
+        .collect::<Vec<_>>();
+
+    if !users.is_empty() {
+        users.sort();
+        println!("{}", users.join(" "));
+    }
+
+    Ok(())
+}

src/uu/users/src/users.rs

@@ -5,57 +5,19 @@
 
 // spell-checker:ignore (paths) wtmp
 
-use std::ffi::OsString;
-use std::path::Path;
-
 use clap::builder::ValueParser;
 use clap::{crate_version, Arg, Command};
-use uucore::error::UResult;
-use uucore::utmpx::{self, Utmpx};
 use uucore::{format_usage, help_about, help_usage};
 
+mod platform;
+
 const ABOUT: &str = help_about!("users.md");
 const USAGE: &str = help_usage!("users.md");
 
 static ARG_FILES: &str = "files";
 
-fn get_long_usage() -> String {
-    format!(
-        "Output who is currently logged in according to FILE.
-If FILE is not specified, use {}.  /var/log/wtmp as FILE is common.",
-        utmpx::DEFAULT_FILE
-    )
-}
-
 #[uucore::main]
-pub fn uumain(args: impl uucore::Args) -> UResult<()> {
-    let matches = uu_app()
-        .after_help(get_long_usage())
-        .try_get_matches_from(args)?;
-
-    let files: Vec<&Path> = matches
-        .get_many::<OsString>(ARG_FILES)
-        .map(|v| v.map(AsRef::as_ref).collect())
-        .unwrap_or_default();
-
-    let filename = if files.is_empty() {
-        utmpx::DEFAULT_FILE.as_ref()
-    } else {
-        files[0]
-    };
-
-    let mut users = Utmpx::iter_all_records_from(filename)
-        .filter(Utmpx::is_user_process)
-        .map(|ut| ut.user())
-        .collect::<Vec<_>>();
-
-    if !users.is_empty() {
-        users.sort();
-        println!("{}", users.join(" "));
-    }
-
-    Ok(())
-}
+use platform::uumain;
 
 pub fn uu_app() -> Command {
     Command::new(uucore::util_name())