Modules/posixmodule.c (part 8)

Source:

cpython 3.14 @ ab2d84fe1023/Modules/posixmodule.c ↗

This annotation covers file metadata. See modules_posix7_detail for os.open, os.read, os.write, and os.close.

Map

Lines	Symbol	Role
1-80	os.stat	Get file status by path (follows symlinks)
81-160	os.lstat	Get file status without following symlinks
161-240	os.fstat	Get file status by file descriptor
241-360	stat_result	Named tuple holding st_mode, st_size, etc.
361-500	os.access	Test file existence and permissions

Reading

os.stat

// CPython: Modules/posixmodule.c:3840 os_stat_impl
static PyObject *
os_stat_impl(PyObject *module, path_t *path, int dir_fd, int follow_symlinks)
{
    STRUCT_STAT st;
    int result;
    Py_BEGIN_ALLOW_THREADS
    result = STAT(path->narrow, &st);
    Py_END_ALLOW_THREADS
    if (result != 0)
        return path_error(path);
    return _pystat_fromstructstat(module, &st);
}

STAT expands to stat or statat depending on dir_fd and follow_symlinks. Py_BEGIN_ALLOW_THREADS releases the GIL during the syscall, allowing other threads to run while waiting on a slow filesystem.

stat_result

// CPython: Modules/posixmodule.c:3620 _pystat_fromstructstat
static PyObject *
_pystat_fromstructstat(PyObject *module, STRUCT_STAT *st)
{
    posix_state *state = get_posix_state(module);
    PyObject *v = PyStructSequence_New(state->StatResultType);
    PyStructSequence_SET_ITEM(v, 0, PyLong_FromLong((long)st->st_mode));
    PyStructSequence_SET_ITEM(v, 1, _PyLong_FromIno_t(st->st_ino));
    PyStructSequence_SET_ITEM(v, 2, _PyLong_FromDev_t(st->st_dev));
    PyStructSequence_SET_ITEM(v, 3, PyLong_FromLong((long)st->st_nlink));
    PyStructSequence_SET_ITEM(v, 4, PyLong_FromLong((long)st->st_uid));
    PyStructSequence_SET_ITEM(v, 5, PyLong_FromLong((long)st->st_gid));
    PyStructSequence_SET_ITEM(v, 6, PyLong_FromLong((long)st->st_size));
    /* timestamps */
    ...
    return v;
}

stat_result is a PyStructSequence: it behaves like a named tuple. Fields are accessible by index (e.g., st[0] for st_mode) or by name (st.st_mode).

os.access

// CPython: Modules/posixmodule.c:4020 os_access_impl
static PyObject *
os_access_impl(PyObject *module, path_t *path, int mode,
               int dir_fd, int effective_ids, int follow_symlinks)
{
    int result;
    Py_BEGIN_ALLOW_THREADS
#ifdef MS_WINDOWS
    result = win32_access(path, mode);
#else
    result = access(path->narrow, mode);
#endif
    Py_END_ALLOW_THREADS
    return PyBool_FromLong(!result);
}

os.access(path, os.R_OK) tests whether the current process can read path. effective_ids=True uses effective UID/GID instead of real UID/GID, relevant when setuid is involved.

gopy notes

os.stat is module/os.Stat in module/os/module.go using os.Stat(path). stat_result is objects.StatResult built from os.FileInfo. os.lstat uses os.Lstat. os.fstat calls os.File.Stat(). os.access uses syscall.Access on Unix.