1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
use crate::types::PyString;
#[cfg(windows)]
use crate::PyErr;
use crate::{
    ffi, AsPyPointer, FromPyObject, IntoPy, PyAny, PyObject, PyResult, PyTryFrom, Python,
    ToPyObject,
};
use std::borrow::Cow;
use std::ffi::{OsStr, OsString};
#[cfg(not(windows))]
use std::os::raw::c_char;

impl ToPyObject for OsStr {
    fn to_object(&self, py: Python<'_>) -> PyObject {
        // If the string is UTF-8, take the quick and easy shortcut
        if let Some(valid_utf8_path) = self.to_str() {
            return valid_utf8_path.to_object(py);
        }

        // All targets besides windows support the std::os::unix::ffi::OsStrExt API:
        // https://doc.rust-lang.org/src/std/sys_common/mod.rs.html#59
        #[cfg(not(windows))]
        {
            #[cfg(target_os = "wasi")]
            let bytes = std::os::wasi::ffi::OsStrExt::as_bytes(self);
            #[cfg(not(target_os = "wasi"))]
            let bytes = std::os::unix::ffi::OsStrExt::as_bytes(self);

            let ptr = bytes.as_ptr() as *const c_char;
            let len = bytes.len() as ffi::Py_ssize_t;
            unsafe {
                // DecodeFSDefault automatically chooses an appropriate decoding mechanism to
                // parse os strings losslessly (i.e. surrogateescape most of the time)
                let pystring = ffi::PyUnicode_DecodeFSDefaultAndSize(ptr, len);
                PyObject::from_owned_ptr(py, pystring)
            }
        }

        #[cfg(windows)]
        {
            let wstr: Vec<u16> = std::os::windows::ffi::OsStrExt::encode_wide(self).collect();

            unsafe {
                // This will not panic because the data from encode_wide is well-formed Windows
                // string data
                PyObject::from_owned_ptr(
                    py,
                    ffi::PyUnicode_FromWideChar(wstr.as_ptr(), wstr.len() as ffi::Py_ssize_t),
                )
            }
        }
    }
}

// There's no FromPyObject implementation for &OsStr because albeit possible on Unix, this would
// be impossible to implement on Windows. Hence it's omitted entirely

impl FromPyObject<'_> for OsString {
    fn extract(ob: &PyAny) -> PyResult<Self> {
        let pystring = <PyString as PyTryFrom>::try_from(ob)?; // Cast PyAny to PyString

        #[cfg(not(windows))]
        {
            // Decode from Python's lossless bytes string representation back into raw bytes
            let fs_encoded_bytes = unsafe {
                crate::Py::<crate::types::PyBytes>::from_owned_ptr(
                    ob.py(),
                    ffi::PyUnicode_EncodeFSDefault(pystring.as_ptr()),
                )
            };

            // Create an OsStr view into the raw bytes from Python
            #[cfg(target_os = "wasi")]
            let os_str: &OsStr = std::os::wasi::ffi::OsStrExt::from_bytes(
                fs_encoded_bytes.as_ref(ob.py()).as_bytes(),
            );
            #[cfg(not(target_os = "wasi"))]
            let os_str: &OsStr = std::os::unix::ffi::OsStrExt::from_bytes(
                fs_encoded_bytes.as_ref(ob.py()).as_bytes(),
            );

            Ok(os_str.to_os_string())
        }

        #[cfg(windows)]
        {
            // Take the quick and easy shortcut if UTF-8
            if let Ok(utf8_string) = pystring.to_str() {
                return Ok(utf8_string.to_owned().into());
            }

            // Get an owned allocated wide char buffer from PyString, which we have to deallocate
            // ourselves
            let size =
                unsafe { ffi::PyUnicode_AsWideChar(pystring.as_ptr(), std::ptr::null_mut(), 0) };
            if size == -1 {
                return Err(PyErr::fetch(ob.py()));
            }

            let mut buffer = vec![0; size as usize];
            let bytes_read =
                unsafe { ffi::PyUnicode_AsWideChar(pystring.as_ptr(), buffer.as_mut_ptr(), size) };
            assert_eq!(bytes_read, size);

            // Copy wide char buffer into OsString
            let os_string = std::os::windows::ffi::OsStringExt::from_wide(&buffer);

            Ok(os_string)
        }
    }
}

impl IntoPy<PyObject> for &'_ OsStr {
    #[inline]
    fn into_py(self, py: Python<'_>) -> PyObject {
        self.to_object(py)
    }
}

impl ToPyObject for Cow<'_, OsStr> {
    #[inline]
    fn to_object(&self, py: Python<'_>) -> PyObject {
        (self as &OsStr).to_object(py)
    }
}

impl IntoPy<PyObject> for Cow<'_, OsStr> {
    #[inline]
    fn into_py(self, py: Python<'_>) -> PyObject {
        self.to_object(py)
    }
}

impl ToPyObject for OsString {
    #[inline]
    fn to_object(&self, py: Python<'_>) -> PyObject {
        (self as &OsStr).to_object(py)
    }
}

impl IntoPy<PyObject> for OsString {
    fn into_py(self, py: Python<'_>) -> PyObject {
        self.to_object(py)
    }
}

impl<'a> IntoPy<PyObject> for &'a OsString {
    fn into_py(self, py: Python<'_>) -> PyObject {
        self.to_object(py)
    }
}

#[cfg(test)]
mod tests {
    use crate::{types::PyString, IntoPy, PyObject, Python, ToPyObject};
    use std::fmt::Debug;
    use std::{
        borrow::Cow,
        ffi::{OsStr, OsString},
    };

    #[test]
    #[cfg(not(windows))]
    fn test_non_utf8_conversion() {
        Python::with_gil(|py| {
            #[cfg(not(target_os = "wasi"))]
            use std::os::unix::ffi::OsStrExt;
            #[cfg(target_os = "wasi")]
            use std::os::wasi::ffi::OsStrExt;

            // this is not valid UTF-8
            let payload = &[250, 251, 252, 253, 254, 255, 0, 255];
            let os_str = OsStr::from_bytes(payload);

            // do a roundtrip into Pythonland and back and compare
            let py_str: PyObject = os_str.into_py(py);
            let os_str_2: OsString = py_str.extract(py).unwrap();
            assert_eq!(os_str, os_str_2);
        });
    }

    #[test]
    fn test_topyobject_roundtrip() {
        Python::with_gil(|py| {
            fn test_roundtrip<T: ToPyObject + AsRef<OsStr> + Debug>(py: Python<'_>, obj: T) {
                let pyobject = obj.to_object(py);
                let pystring: &PyString = pyobject.extract(py).unwrap();
                assert_eq!(pystring.to_string_lossy(), obj.as_ref().to_string_lossy());
                let roundtripped_obj: OsString = pystring.extract().unwrap();
                assert_eq!(obj.as_ref(), roundtripped_obj.as_os_str());
            }
            let os_str = OsStr::new("Hello\0\n🐍");
            test_roundtrip::<&OsStr>(py, os_str);
            test_roundtrip::<Cow<'_, OsStr>>(py, Cow::Borrowed(os_str));
            test_roundtrip::<Cow<'_, OsStr>>(py, Cow::Owned(os_str.to_os_string()));
            test_roundtrip::<OsString>(py, os_str.to_os_string());
        });
    }

    #[test]
    fn test_intopy_roundtrip() {
        Python::with_gil(|py| {
            fn test_roundtrip<T: IntoPy<PyObject> + AsRef<OsStr> + Debug + Clone>(
                py: Python<'_>,
                obj: T,
            ) {
                let pyobject = obj.clone().into_py(py);
                let pystring: &PyString = pyobject.extract(py).unwrap();
                assert_eq!(pystring.to_string_lossy(), obj.as_ref().to_string_lossy());
                let roundtripped_obj: OsString = pystring.extract().unwrap();
                assert!(obj.as_ref() == roundtripped_obj.as_os_str());
            }
            let os_str = OsStr::new("Hello\0\n🐍");
            test_roundtrip::<&OsStr>(py, os_str);
            test_roundtrip::<OsString>(py, os_str.to_os_string());
            test_roundtrip::<&OsString>(py, &os_str.to_os_string());
        })
    }
}