Add hostname

Cargo.toml

@@ -8,4 +8,5 @@ members = [
     "usr/src/mei/echo",
     "usr/src/mei/printf",
     "usr/src/mei/false",
+    "usr/src/mei/hostname",
 ]

usr/src/mei/hostname/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "hostname"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "hostname"
+path = "src/hostname.rs"
+
+[dependencies]
+nix = { version = "0.27", features = ["hostname"] }

usr/src/mei/hostname/src/hostname.rs

@@ -0,0 +1,78 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2023 Ezra Barrow All rights reserved.
+ * Use is subject to license terms.
+ */
+
+use nix::unistd::{gethostname, sethostname};
+
+fn usage() {
+    println!("usage: hostname [-s] [system_name]");
+}
+
+//TODO: should probably involve a lot more osstrings as bytes rather than strings
+fn main() -> Result<(), ()> {
+    let mut shortflag = false;
+    let mut newhostname = None;
+    for arg in std::env::args().skip(1) {
+        if arg == "-?" {
+            usage();
+            return Ok(());
+        } else if arg == "-s" {
+            shortflag = true;
+        } else if !arg.starts_with("-") {
+            if newhostname.replace(arg).is_some() {
+                usage();
+                return Ok(());
+            }
+        }
+    }
+    if let Some(hostname) = newhostname {
+        match sethostname(hostname) {
+            Ok(_) => Ok(()),
+            Err(e) => {
+                eprintln!("hostname: error in setting name: {}", e.desc());
+                Err(())
+            }
+        }
+    } else {
+        match gethostname() {
+            Ok(s) => {
+                if shortflag {
+                    println!(
+                        "{}",
+                        s.to_string_lossy().split('.').nth(0).unwrap_or_default()
+                    );
+                } else {
+                    println!("{}", s.to_string_lossy());
+                };
+                Ok(())
+            }
+            Err(_) => {
+                eprintln!("hostname: unable to obtain hostname");
+                Err(())
+            }
+        }
+    }
+}