process: Add name() method

Don't leak implementation details of Linux proc interfaces to users of
the module.

Author: dezgeg

src/uu/pgrep/src/pgrep.rs

@@ -45,15 +45,15 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
                     // pgrep from procps-ng outputs the process name inside square brackets
                     // if /proc/<PID>/cmdline is empty
                     if it.cmdline.is_empty() {
-                        format!("{} [{}]", it.pid, it.clone().status().get("Name").unwrap())
+                        format!("{} [{}]", it.pid, it.clone().name().unwrap())
                     } else {
                         format!("{} {}", it.pid, it.cmdline)
                     }
                 })
                 .collect()
         } else if matches.get_flag("list-name") {
             pids.into_iter()
-                .map(|it| format!("{} {}", it.pid, it.clone().status().get("Name").unwrap()))
+                .map(|it| format!("{} {}", it.pid, it.clone().name().unwrap()))
                 .collect()
         } else {
             pids.into_iter().map(|it| format!("{}", it.pid)).collect()

src/uu/pgrep/src/process.rs

@@ -274,6 +274,13 @@ impl ProcessInformation {
         Rc::clone(&result)
     }
 
+    pub fn name(&mut self) -> Result<String, io::Error> {
+        self.status()
+            .get("Name")
+            .cloned()
+            .ok_or(io::ErrorKind::InvalidData.into())
+    }
+
     fn get_numeric_stat_field(&mut self, index: usize) -> Result<u64, io::Error> {
         self.stat()
             .get(index)

src/uu/pgrep/src/process_matcher.rs

@@ -208,12 +208,11 @@ fn collect_matched_pids(settings: &Settings) -> Vec<ProcessInformation> {
                 _ => true,
             };
 
-            let binding = pid.status();
-            let name = binding.get("Name").unwrap();
+            let name = pid.name().unwrap();
             let name = if settings.ignore_case {
                 name.to_lowercase()
             } else {
-                name.into()
+                name
             };
             let pattern_matched = {
                 let want = if settings.full {