feat(python): truncate file path on error msg (#6917)

py-polars/src/file.rs

@@ -1,5 +1,3 @@
-// Credits to https://github.com/omerbenamram/pyo3-file
-use std::borrow::Borrow;
 use std::fs::File;
 use std::io;
 use std::io::{BufReader, Cursor, Read, Seek, SeekFrom, Write};
@@ -191,23 +189,34 @@ pub enum EitherRustPythonFile {
     Rust(BufReader<File>),
 }
 
+fn no_such_file_err(file_path: &str) -> PyResult<()> {
+    let msg = if file_path.len() > 88 {
+        let file_path: String = file_path.chars().rev().take(88).collect();
+        format!("No such file or directory: ...{file_path}",)
+    } else {
+        format!("No such file or directory: {file_path}",)
+    };
+
+    Err(PyErr::new::<PyFileNotFoundError, _>(msg))
+}
+
 ///
 /// # Arguments
 /// * `truncate` - open or create a new file.
 pub fn get_either_file(py_f: PyObject, truncate: bool) -> PyResult<EitherRustPythonFile> {
     Python::with_gil(|py| {
         if let Ok(pstring) = py_f.downcast::<PyString>(py) {
-            let rstring = pstring.to_string();
-            let str_slice: &str = rstring.borrow();
+            let s = pstring.to_str()?;
+            let file_path = std::path::Path::new(&s);
+            let file_path = resolve_homedir(file_path);
             let f = if truncate {
-                BufReader::new(File::create(str_slice)?)
+                BufReader::new(File::create(file_path)?)
             } else {
-                match File::open(str_slice) {
+                match File::open(&file_path) {
                     Ok(file) => BufReader::new(file),
                     Err(_e) => {
-                        return Err(PyErr::new::<PyFileNotFoundError, _>(format!(
-                            "No such file or directory: {str_slice}",
-                        )))
+                        no_such_file_err(s)?;
+                        unreachable!();
                     }
                 }
             };
@@ -234,15 +243,14 @@ pub fn get_mmap_bytes_reader<'a>(py_f: &'a PyAny) -> PyResult<Box<dyn MmapBytesR
     }
     // string so read file
     else if let Ok(pstring) = py_f.downcast::<PyString>() {
-        let s = pstring.to_string();
+        let s = pstring.to_str()?;
         let p = std::path::Path::new(&s);
         let p = resolve_homedir(p);
         let f = match File::open(p) {
             Ok(file) => file,
             Err(_e) => {
-                return Err(PyErr::new::<PyFileNotFoundError, _>(format!(
-                    "No such file or directory: {s}",
-                )))
+                no_such_file_err(s)?;
+                unreachable!();
             }
         };
         Ok(Box::new(f))

py-polars/tests/unit/test_errors.py

@@ -447,3 +447,12 @@ def test_string_numeric_arithmetic_err() -> None:
         pl.ComputeError, match=r"Arithmetic on string and numeric not allowed"
     ):
         df.select(pl.col("s") + 1)
+
+
+def test_file_path_truncate_err() -> None:
+    content = "lskdfj".join(str(i) for i in range(25))
+    with pytest.raises(
+        FileNotFoundError,
+        match=r"\.\.\.42jfdksl32jfdksl22jfdksl12jfdksl02jfdksl91jfdksl81jfdksl71jfdksl61jfdksl51jfdksl41jfdksl",
+    ):
+        pl.read_csv(content)