cmd: guard empty editor before indexing fields (#17067)

Signed-off-by: Anas Khan <83116240+anxkhn@users.noreply.github.com>

cmd/interactive.go

@@ -653,9 +653,12 @@ func editInExternalEditor(content string) (string, error) {
 	}
 
 	// Check that the editor binary exists
-	name := strings.Fields(editor)[0]
-	if _, err := exec.LookPath(name); err != nil {
-		return "", fmt.Errorf("editor %q not found, set OLLAMA_EDITOR to the path of your preferred editor", name)
+	args := strings.Fields(editor)
+	if len(args) == 0 {
+		return "", fmt.Errorf("no editor configured, set OLLAMA_EDITOR to the path of your preferred editor")
+	}
+	if _, err := exec.LookPath(args[0]); err != nil {
+		return "", fmt.Errorf("editor %q not found, set OLLAMA_EDITOR to the path of your preferred editor", args[0])
 	}
 
 	tmpFile, err := os.CreateTemp("", "ollama-prompt-*.txt")
@@ -672,7 +675,6 @@ func editInExternalEditor(content string) (string, error) {
 	}
 	tmpFile.Close()
 
-	args := strings.Fields(editor)
 	args = append(args, tmpFile.Name())
 	cmd := exec.Command(args[0], args[1:]...)
 	cmd.Stdin = os.Stdin

cmd/interactive_test.go

@@ -85,6 +85,39 @@ func TestExtractFileDataRemovesQuotedFilepath(t *testing.T) {
 	assert.Equal(t, cleaned, "before  after")
 }
 
+func TestEditInExternalEditorWhitespaceOnly(t *testing.T) {
+	// A whitespace-only VISUAL or EDITOR is non-empty, so it bypasses the
+	// editor == "" fallbacks, but strings.Fields collapses it to an empty
+	// slice. Indexing that slice must not panic; it must return an error.
+	cases := []struct {
+		name   string
+		visual string
+		editor string
+	}{
+		{name: "VISUAL whitespace", visual: "\t "},
+		{name: "EDITOR whitespace", editor: "\t "},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("OLLAMA_EDITOR", "")
+			t.Setenv("VISUAL", tt.visual)
+			t.Setenv("EDITOR", tt.editor)
+			_, err := editInExternalEditor("content")
+			assert.Error(t, err)
+		})
+	}
+}
+
+func TestEditInExternalEditorParsesEditorWithArgs(t *testing.T) {
+	// A well-formed editor command with arguments must still be parsed so
+	// its binary is looked up (guards the normal path from regressing).
+	t.Setenv("OLLAMA_EDITOR", "definitely-not-a-real-editor arg1")
+	t.Setenv("VISUAL", "")
+	t.Setenv("EDITOR", "")
+	_, err := editInExternalEditor("content")
+	assert.ErrorContains(t, err, "definitely-not-a-real-editor")
+}
+
 func TestExtractFileDataWAV(t *testing.T) {
 	dir := t.TempDir()
 	fp := filepath.Join(dir, "sample.wav")