shred: Implemented --force option (#2012)

src/uu/shred/src/shred.rs

@@ -259,6 +259,7 @@ static AFTER_HELP: &str =
      ";
 
 pub mod options {
+    pub const FORCE: &str = "force";
     pub const FILE: &str = "file";
     pub const ITERATIONS: &str = "iterations";
     pub const SIZE: &str = "size";
@@ -278,6 +279,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .about(ABOUT)
         .after_help(AFTER_HELP)
         .usage(&usage[..])
+        .arg(
+            Arg::with_name(options::FORCE)
+                .long(options::FORCE)
+                .short("f")
+                .help("change permissions to allow writing if necessary"),
+        )
         .arg(
             Arg::with_name(options::ITERATIONS)
                 .long(options::ITERATIONS)
@@ -354,8 +361,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     // TODO: implement --random-source
 
-    // TODO: implement --force
-
+    let force = matches.is_present(options::FORCE);
     let remove = matches.is_present(options::REMOVE);
     let size_arg = match matches.value_of(options::SIZE) {
         Some(s) => Some(s.to_string()),
@@ -375,7 +381,9 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     }
 
     for path_str in matches.values_of(options::FILE).unwrap() {
-        wipe_file(&path_str, iterations, remove, size, exact, zero, verbose);
+        wipe_file(
+            &path_str, iterations, remove, size, exact, zero, verbose, force,
+        );
     }
 
     0
@@ -439,18 +447,40 @@ fn wipe_file(
     exact: bool,
     zero: bool,
     verbose: bool,
+    force: bool,
 ) {
     // Get these potential errors out of the way first
     let path: &Path = Path::new(path_str);
     if !path.exists() {
-        println!("{}: {}: No such file or directory", NAME, path.display());
+        show_error!("{}: No such file or directory", path.display());
         return;
     }
     if !path.is_file() {
-        println!("{}: {}: Not a file", NAME, path.display());
+        show_error!("{}: Not a file", path.display());
         return;
     }
 
+    // If force is true, set file permissions to not-readonly.
+    if force {
+        let metadata = match fs::metadata(path) {
+            Ok(m) => m,
+            Err(e) => {
+                show_error!("{}", e);
+                return;
+            }
+        };
+
+        let mut perms = metadata.permissions();
+        perms.set_readonly(false);
+        match fs::set_permissions(path, perms) {
+            Err(e) => {
+                show_error!("{}", e);
+                return;
+            }
+            _ => {}
+        }
+    }
+
     // Fill up our pass sequence
     let mut pass_sequence: Vec<PassType> = Vec::new();
 
@@ -489,11 +519,13 @@ fn wipe_file(
 
     {
         let total_passes: usize = pass_sequence.len();
-        let mut file: File = OpenOptions::new()
-            .write(true)
-            .truncate(false)
-            .open(path)
-            .expect("Failed to open file for writing");
+        let mut file: File = match OpenOptions::new().write(true).truncate(false).open(path) {
+            Ok(f) => f,
+            Err(e) => {
+                show_error!("{}: failed to open for writing: {}", path.display(), e);
+                return;
+            }
+        };
 
         // NOTE: it does not really matter what we set for total_bytes and gen_type here, so just
         //       use bogus values
@@ -523,14 +555,23 @@ fn wipe_file(
                 }
             }
             // size is an optional argument for exactly how many bytes we want to shred
-            do_pass(&mut file, path, &mut generator, *pass_type, size)
-                .expect("File write pass failed");
+            match do_pass(&mut file, path, &mut generator, *pass_type, size) {
+                Ok(_) => {}
+                Err(e) => {
+                    show_error!("{}: File write pass failed: {}", path.display(), e);
+                }
+            }
             // Ignore failed writes; just keep trying
         }
     }
 
     if remove {
-        do_remove(path, path_str, verbose).expect("Failed to remove file");
+        match do_remove(path, path_str, verbose) {
+            Ok(_) => {}
+            Err(e) => {
+                show_error!("{}: failed to remove file: {}", path.display(), e);
+            }
+        }
     }
 }
 

tests/by-util/test_shred.rs

@@ -1 +1,51 @@
-// ToDO: add tests
+use crate::common::util::*;
+
+#[test]
+fn test_shred_remove() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    let file_a = "test_shred_remove_a";
+    let file_b = "test_shred_remove_b";
+
+    // Create file_a and file_b.
+    at.touch(file_a);
+    at.touch(file_b);
+
+    // Shred file_a.
+    scene.ucmd().arg("-u").arg(file_a).run();
+
+    // file_a was deleted, file_b exists.
+    assert!(!at.file_exists(file_a));
+    assert!(at.file_exists(file_b));
+}
+
+#[cfg(not(target_os = "freebsd"))]
+#[test]
+fn test_shred_force() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    let file = "test_shred_force";
+
+    // Create file_a.
+    at.touch(file);
+    assert!(at.file_exists(file));
+
+    // Make file_a readonly.
+    at.set_readonly(file);
+
+    // Try shred -u.
+    let result = scene.ucmd().arg("-u").arg(file).run();
+    println!("stderr = {:?}", result.stderr);
+    println!("stdout = {:?}", result.stdout);
+
+    // file_a was not deleted because it is readonly.
+    assert!(at.file_exists(file));
+
+    // Try shred -u -f.
+    scene.ucmd().arg("-u").arg("-f").arg(file).run();
+
+    // file_a was deleted.
+    assert!(!at.file_exists(file));
+}

tests/common/util.rs

@@ -351,6 +351,13 @@ impl AtPath {
         String::from(self.minus(name).to_str().unwrap())
     }
 
+    pub fn set_readonly(&self, name: &str) {
+        let metadata = fs::metadata(self.plus(name)).unwrap();
+        let mut permissions = metadata.permissions();
+        permissions.set_readonly(true);
+        fs::set_permissions(self.plus(name), permissions).unwrap();
+    }
+
     pub fn open(&self, name: &str) -> File {
         log_info("open", self.plus_as_string(name));
         File::open(self.plus(name)).unwrap()