fix: proper read error for device files with -files0-from

src/find/mod.rs

@@ -15,6 +15,7 @@ use std::io::{self, stderr, stdout, BufRead, BufReader, Write};
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::time::SystemTime;
+use uucore::error;
 use walkdir::WalkDir;
 
 pub struct Config {
@@ -160,6 +161,8 @@ struct ParsedInfo {
 /// <https://www.gnu.org/software/findutils/manual/html_node/find_html/Starting-points.html>
 struct Files0Paths {
     reader: Box<dyn BufRead>,
+    /// Kept so that read errors can be reported GNU-style with the offending file name.
+    name: String,
 }
 
 impl Files0Paths {
@@ -168,11 +171,19 @@ impl Files0Paths {
         let reader: Box<dyn BufRead> = if name == "-" {
             Box::new(BufReader::new(io::stdin()))
         } else {
-            let file = std::fs::File::open(name)
-                .map_err(|e| format!("cannot open '{}' for reading: {}", name, e))?;
+            let file = std::fs::File::open(name).map_err(|e| {
+                format!(
+                    "cannot open ‘{}’ for reading: {}",
+                    name,
+                    error::strip_errno(&e)
+                )
+            })?;
             Box::new(BufReader::new(file))
         };
-        Ok(Self { reader })
+        Ok(Self {
+            reader,
+            name: name.to_string(),
+        })
     }
 }
 
@@ -183,7 +194,14 @@ impl Iterator for Files0Paths {
         loop {
             let mut buffer = Vec::new();
             match self.reader.read_until(0, &mut buffer) {
-                Err(e) => return Some(Err(e.into())),
+                Err(e) => {
+                    return Some(Err(format!(
+                        "‘{}’: read error: {}",
+                        self.name,
+                        error::strip_errno(&e)
+                    )
+                    .into()));
+                }
                 Ok(0) => return None,
                 Ok(_) => {}
             }

tests/test_find.rs

@@ -1631,3 +1631,23 @@ fn find_exits_cleanly_on_broken_pipe() {
         "find panicked instead of exiting cleanly on a broken pipe:\n{stderr}"
     );
 }
+
+#[test]
+#[cfg(target_os = "linux")]
+fn files0_from_special_file_read_error() {
+    for path in &["/dev/vhost-net", "/dev/vhost-vsock"] {
+        if !Path::new(path).exists() {
+            continue;
+        }
+
+        let file_list_failure = ucmd().arg("-files0-from").arg(path).fails();
+
+        let error_output = file_list_failure.no_stdout().stderr_str();
+        assert!(
+            error_output.contains("read error")
+                || (error_output.contains("cannot open")
+                    && error_output.contains("Permission denied")),
+            "unexpected stderr for {path}: {error_output}"
+        );
+    }
+}