hashsum: warn on file not found rather than fail

src/uu/hashsum/src/hashsum.rs

@@ -498,7 +498,8 @@ where
     I: Iterator<Item = &'a OsStr>,
 {
     let mut bad_format = 0;
-    let mut failed = 0;
+    let mut failed_cksum = 0;
+    let mut failed_open_file = 0;
     let binary_marker = if options.binary { "*" } else { " " };
     for filename in files {
         let filename = Path::new(filename);
@@ -574,8 +575,19 @@ where
                         }
                     },
                 };
-                let f = File::open(ck_filename)
-                    .map_err_context(|| "failed to open file".to_string())?;
+                let f = match File::open(ck_filename) {
+                    Err(_) => {
+                        failed_open_file += 1;
+                        println!(
+                            "{}: {}: No such file or directory",
+                            uucore::util_name(),
+                            ck_filename
+                        );
+                        println!("{}: FAILED open or read", ck_filename);
+                        continue;
+                    }
+                    Ok(file) => file,
+                };
                 let mut ckf = BufReader::new(Box::new(f) as Box<dyn Read>);
                 let real_sum = digest_reader(
                     &mut options.digest,
@@ -602,7 +614,7 @@ where
                     if !options.status {
                         println!("{}: FAILED", ck_filename);
                     }
-                    failed += 1;
+                    failed_cksum += 1;
                 }
             }
         } else {
@@ -628,8 +640,15 @@ where
             Ordering::Greater => show_warning!("{} lines are improperly formatted", bad_format),
             _ => {}
         };
-        if failed > 0 {
-            show_warning!("{} computed checksum did NOT match", failed);
+        if failed_cksum > 0 {
+            show_warning!("{} computed checksum did NOT match", failed_cksum);
+        }
+        match failed_open_file.cmp(&1) {
+            Ordering::Equal => show_warning!("{} listed file could not be read", failed_open_file),
+            Ordering::Greater => {
+                show_warning!("{} listed files could not be read", failed_open_file);
+            }
+            _ => {}
         }
     }
 

tests/by-util/test_hashsum.rs

@@ -1,5 +1,5 @@
 use crate::common::util::*;
-// spell-checker:ignore checkfile, nonames, testf
+// spell-checker:ignore checkfile, nonames, testf, ntestf
 macro_rules! get_hash(
     ($str:expr) => (
         $str.split(' ').collect::<Vec<&str>>()[0]
@@ -117,6 +117,26 @@ fn test_check_sha1() {
         .stderr_is("");
 }
 
+#[test]
+fn test_check_file_not_found_warning() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    at.write("testf", "foobar\n");
+    at.write(
+        "testf.sha1",
+        "988881adc9fc3655077dc2d4d757d480b5ea0e11  testf\n",
+    );
+    at.remove("testf");
+    scene
+        .ccmd("sha1sum")
+        .arg("-c")
+        .arg(at.subdir.join("testf.sha1"))
+        .succeeds()
+        .stdout_is("sha1sum: testf: No such file or directory\ntestf: FAILED open or read\n")
+        .stderr_is("sha1sum: warning: 1 listed file could not be read");
+}
+
 #[test]
 fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails().code_is(1);