install: report why a target cannot be used as a directory

src/uu/install/locales/en-US.ftl

@@ -28,7 +28,9 @@ install-error-chmod-failed = failed to chmod { $path }
 install-error-chmod-failed-detailed = { $path }: chmod failed with error { $error }
 install-error-chown-failed = failed to chown { $path }: { $error }
 install-error-invalid-target = invalid target { $path }: No such file or directory
-install-error-target-not-dir = target { $path } is not a directory
+install-error-target-not-dir = target { $path }: { $error }
+install-error-target-stat = cannot stat { $path }: { $error }
+install-error-create-regular-file = cannot create regular file { $path }: { $error }
 install-error-backup-failed = cannot backup { $from }: { $error }
 install-error-install-failed = cannot install { $from } to { $to }: { $error }
 install-error-strip-failed = strip program failed: { $error }

src/uu/install/locales/fr-FR.ftl

@@ -28,7 +28,7 @@ install-error-chmod-failed = échec du chmod { $path }
 install-error-chmod-failed-detailed = { $path } : échec du chmod avec l'erreur { $error }
 install-error-chown-failed = échec du chown { $path } : { $error }
 install-error-invalid-target = cible invalide { $path } : Aucun fichier ou répertoire de ce type
-install-error-target-not-dir = la cible { $path } n'est pas un répertoire
+install-error-target-not-dir = la cible { $path } : { $error }
 install-error-backup-failed = impossible de sauvegarder { $from } : { $error }
 install-error-install-failed = impossible d'installer { $from } vers { $to }: { $error }
 install-error-strip-failed = échec du programme strip : { $error }

src/uu/install/src/install.rs

@@ -83,8 +83,14 @@ enum InstallError {
     #[error("{}", translate!("install-error-invalid-target", "path" => .0.quote()))]
     InvalidTarget(PathBuf),
 
-    #[error("{}", translate!("install-error-target-not-dir", "path" => .0.quote()))]
-    TargetDirIsntDir(PathBuf),
+    #[error("{}", translate!("install-error-target-not-dir", "path" => .0.quote(), "error" => strip_errno(.1)))]
+    TargetDirIsntDir(PathBuf, #[source] std::io::Error),
+
+    #[error("{}", translate!("install-error-target-stat", "path" => .0.quote(), "error" => strip_errno(.1)))]
+    TargetStatFailed(PathBuf, #[source] std::io::Error),
+
+    #[error("{}", translate!("install-error-create-regular-file", "path" => .0.quote(), "error" => strip_errno(.1)))]
+    CreateRegularFileFailed(PathBuf, #[source] std::io::Error),
 
     #[error("{}", translate!("install-error-backup-failed", "from" => .0.quote(), "error" => strip_errno(.1)))]
     BackupFailed(PathBuf, #[source] std::io::Error),
@@ -660,9 +666,17 @@ fn standard(mut paths: Vec<OsString>, b: &Behavior) -> UResult<()> {
             None
         };
 
-        // If -t is used, check if target exists as a file before trying to create directories
-        if b.target_dir.is_some() && target.exists() && !target.is_dir() {
-            return Err(InstallError::NotADirectory(target).into());
+        // Reject inaccessible -t targets before trying to create directories.
+        if b.target_dir.is_some() {
+            match metadata(&target) {
+                Ok(meta) if !meta.is_dir() => {
+                    return Err(InstallError::NotADirectory(target).into());
+                }
+                Err(e) if e.kind() != std::io::ErrorKind::NotFound => {
+                    return Err(InstallError::TargetDirAccess(target, e).into());
+                }
+                _ => {}
+            }
         }
 
         if let Some(to_create) = to_create {
@@ -840,14 +854,27 @@ fn metadata_for_source(path: &Path) -> UResult<fs::Metadata> {
 ///
 fn copy_files_into_dir(files: &[PathBuf], target_dir: &Path, b: &Behavior) -> UResult<()> {
     if !target_dir.is_dir() {
+        let reason = metadata(target_dir)
+            .err()
+            .unwrap_or_else(|| rustix::io::Errno::NOTDIR.into());
         if b.target_dir.is_some() {
-            // GNU names why the `-t` directory cannot be used.
-            let reason = metadata(target_dir)
-                .err()
-                .unwrap_or_else(|| rustix::io::Errno::NOTDIR.into());
             return Err(InstallError::TargetDirAccess(target_dir.to_path_buf(), reason).into());
         }
-        return Err(InstallError::TargetDirIsntDir(target_dir.to_path_buf()).into());
+        if files.len() > 1 {
+            return Err(InstallError::TargetDirIsntDir(target_dir.to_path_buf(), reason).into());
+        }
+        if reason.kind() != std::io::ErrorKind::NotFound {
+            return Err(InstallError::TargetStatFailed(target_dir.to_path_buf(), reason).into());
+        }
+        // A trailing slash requires a directory even when its parent exists.
+        let create_error = if is_new_file_path(target_dir) {
+            rustix::io::Errno::NOTDIR.into()
+        } else {
+            reason
+        };
+        return Err(
+            InstallError::CreateRegularFileFailed(target_dir.to_path_buf(), create_error).into(),
+        );
     }
     let mut installed_destinations: HashSet<PathBuf> = HashSet::with_capacity(files.len());
     for sourcepath in files {

tests/by-util/test_install.rs

@@ -85,7 +85,7 @@ fn test_install_failing_not_dir() {
         .arg(file2)
         .arg(file3)
         .fails()
-        .stderr_contains("not a directory");
+        .stderr_contains("Not a directory");
 }
 
 #[test]
@@ -685,7 +685,7 @@ fn test_install_failing_omitting_directory() {
         .arg(dir1)
         .arg(no_dir2)
         .fails()
-        .stderr_contains("is not a directory");
+        .stderr_contains("No such file or directory");
 
     // file1 will be copied before install fails on dir1
     scene
@@ -1107,7 +1107,7 @@ fn test_install_creating_leading_dirs_with_single_source_and_target_dir() {
         .arg(source1)
         .arg(at.plus(target_dir))
         .fails()
-        .stderr_contains("missing_target_dir/' is not a directory");
+        .stderr_contains("missing_target_dir/': Not a directory");
 
     assert!(!at.dir_exists(target_dir));
 
@@ -1143,7 +1143,7 @@ fn test_install_creating_leading_dirs_with_multiple_sources_and_target_dir() {
         .arg(source2)
         .arg(at.plus(target_dir))
         .fails()
-        .stderr_contains("missing_target_dir' is not a directory");
+        .stderr_contains("missing_target_dir': No such file or directory");
 
     assert!(!at.dir_exists(target_dir));
 
@@ -2243,6 +2243,53 @@ fn test_install_target_dir_not_a_directory() {
     assert!(!at.file_exists("missing"));
 }
 
+#[test]
+fn test_install_unusable_target_diagnostics() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+    at.write("source", "new");
+    at.write("other", "other source");
+    at.write("regular", "old");
+
+    for (args, message) in [
+        (
+            vec!["source", "other", "regular"],
+            "target 'regular': Not a directory",
+        ),
+        (
+            vec!["source", "other", "missing"],
+            "target 'missing': No such file or directory",
+        ),
+        (
+            vec!["source", "regular/"],
+            "cannot stat 'regular/': Not a directory",
+        ),
+        (
+            vec!["source", "missing/"],
+            "cannot create regular file 'missing/': Not a directory",
+        ),
+        (
+            vec!["source", "missing/sub/"],
+            "cannot create regular file 'missing/sub/': No such file or directory",
+        ),
+        (
+            vec!["-D", "-t", "regular/sub", "source"],
+            "failed to access 'regular/sub': Not a directory",
+        ),
+    ] {
+        scene
+            .ucmd()
+            .args(&args)
+            .fails_with_code(1)
+            .stderr_only(format!("install: {message}\n"));
+    }
+    assert_eq!(at.read("source"), "new");
+    assert_eq!(at.read("other"), "other source");
+    assert_eq!(at.read("regular"), "old");
+    assert!(!at.dir_exists("missing"));
+    assert!(!at.file_exists("missing"));
+}
+
 #[test]
 fn test_install_root_combined() {
     let ts = TestScenario::new(util_name!());
@@ -2435,7 +2482,7 @@ fn test_install_no_target_directory_creating_leading_dirs_with_single_source_and
         .arg(source1)
         .arg(at.plus(target_dir))
         .fails()
-        .stderr_contains("missing_target_dir/' is not a directory");
+        .stderr_contains("missing_target_dir/': Not a directory");
 
     assert!(!at.dir_exists(target_dir));
 }