diff --git a/Doc/library/os.rst b/Doc/library/os.rst index 54a5d3b98e8662..1e54cfec609bd2 100644 --- a/Doc/library/os.rst +++ b/Doc/library/os.rst @@ -2338,6 +2338,7 @@ features: This function can support specifying *src_dir_fd* and/or *dst_dir_fd* to supply :ref:`paths relative to directory descriptors `, and :ref:`not following symlinks `. + The default value of *follow_symlinks* is ``False`` on Windows. .. audit-event:: os.link src,dst,src_dir_fd,dst_dir_fd os.link diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py index 4950af42cfe5a4..c9b37fcd8f6327 100644 --- a/Lib/test/test_inspect/test_inspect.py +++ b/Lib/test/test_inspect/test_inspect.py @@ -5844,7 +5844,7 @@ def test_operator_module_has_signatures(self): self._test_module_has_signatures(operator) def test_os_module_has_signatures(self): - unsupported_signature = {'chmod', 'utime'} + unsupported_signature = {'chmod', 'link', 'utime'} unsupported_signature |= {name for name in ['get_terminal_size', 'posix_spawn', 'posix_spawnp', 'register_at_fork', 'startfile'] diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py index c9cbe1541e733e..bb18e49c9e3f82 100644 --- a/Lib/test/test_posix.py +++ b/Lib/test/test_posix.py @@ -1521,6 +1521,50 @@ def test_pidfd_open(self): self.assertEqual(cm.exception.errno, errno.EINVAL) os.close(os.pidfd_open(os.getpid(), 0)) + @unittest.skipUnless(hasattr(os, "link"), "test needs os.link()") + def test_link_follow_symlinks(self): + default_follow = sys.platform.startswith( + ('darwin', 'freebsd', 'netbsd', 'openbsd', 'dragonfly', 'sunos5')) + default_no_follow = sys.platform.startswith(('win32', 'linux')) + orig = os_helper.TESTFN + symlink = orig + 'symlink' + posix.symlink(orig, symlink) + self.addCleanup(os_helper.unlink, symlink) + + with self.subTest('no follow_symlinks'): + # no follow_symlinks -> platform depending + link = orig + 'link' + posix.link(symlink, link) + self.addCleanup(os_helper.unlink, link) + if os.link in os.supports_follow_symlinks or default_follow: + self.assertEqual(posix.lstat(link), posix.lstat(orig)) + elif default_no_follow: + self.assertEqual(posix.lstat(link), posix.lstat(symlink)) + + with self.subTest('follow_symlinks=False'): + # follow_symlinks=False -> duplicate the symlink itself + link = orig + 'link_nofollow' + try: + posix.link(symlink, link, follow_symlinks=False) + except NotImplementedError: + if os.link in os.supports_follow_symlinks or default_no_follow: + raise + else: + self.addCleanup(os_helper.unlink, link) + self.assertEqual(posix.lstat(link), posix.lstat(symlink)) + + with self.subTest('follow_symlinks=True'): + # follow_symlinks=True -> duplicate the target file + link = orig + 'link_following' + try: + posix.link(symlink, link, follow_symlinks=True) + except NotImplementedError: + if os.link in os.supports_follow_symlinks or default_follow: + raise + else: + self.addCleanup(os_helper.unlink, link) + self.assertEqual(posix.lstat(link), posix.lstat(orig)) + # tests for the posix *at functions follow class TestPosixDirFd(unittest.TestCase): diff --git a/Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst b/Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst new file mode 100644 index 00000000000000..842e973b821744 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst @@ -0,0 +1,7 @@ +Fix :func:`os.link` on platforms (like Linux) where the +system :c:func:`!link` function does not follow symlinks. On Linux, +it now follows symlinks by default or if +``follow_symlinks=True`` is specified. On Windows, it now raises an error if +``follow_symlinks=True`` is passed. On macOS, it now raises an error if +``follow_symlinks=False`` is passed and the system :c:func:`!linkat` +function is not available at runtime. diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h index 0125e247ee44d3..6b8cc3d07ab01c 100644 --- a/Modules/clinic/posixmodule.c.h +++ b/Modules/clinic/posixmodule.c.h @@ -1471,7 +1471,7 @@ os_getcwdb(PyObject *module, PyObject *Py_UNUSED(ignored)) PyDoc_STRVAR(os_link__doc__, "link($module, /, src, dst, *, src_dir_fd=None, dst_dir_fd=None,\n" -" follow_symlinks=True)\n" +" follow_symlinks=(os.name != \'nt\'))\n" "--\n" "\n" "Create a hard link to a file.\n" @@ -1530,7 +1530,7 @@ os_link(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwn path_t dst = PATH_T_INITIALIZE_P("link", "dst", 0, 0, 0, 0); int src_dir_fd = DEFAULT_DIR_FD; int dst_dir_fd = DEFAULT_DIR_FD; - int follow_symlinks = 1; + int follow_symlinks = -1; args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, /*minpos*/ 2, /*maxpos*/ 2, /*minkw*/ 0, /*varpos*/ 0, argsbuf); @@ -13398,4 +13398,4 @@ os__emscripten_debugger(PyObject *module, PyObject *Py_UNUSED(ignored)) #ifndef OS__EMSCRIPTEN_DEBUGGER_METHODDEF #define OS__EMSCRIPTEN_DEBUGGER_METHODDEF #endif /* !defined(OS__EMSCRIPTEN_DEBUGGER_METHODDEF) */ -/*[clinic end generated code: output=a5ca2541f2af5462 input=a9049054013a1b77]*/ +/*[clinic end generated code: output=f7b5635e0b948be4 input=a9049054013a1b77]*/ diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c index 04c3b9e987aef8..964e988843110e 100644 --- a/Modules/posixmodule.c +++ b/Modules/posixmodule.c @@ -573,7 +573,11 @@ extern char *ctermid_r(char *); # define HAVE_FACCESSAT_RUNTIME 1 # define HAVE_FCHMODAT_RUNTIME 1 # define HAVE_FCHOWNAT_RUNTIME 1 +#ifdef __wasi__ +# define HAVE_LINKAT_RUNTIME 0 +# else # define HAVE_LINKAT_RUNTIME 1 +# endif # define HAVE_FDOPENDIR_RUNTIME 1 # define HAVE_MKDIRAT_RUNTIME 1 # define HAVE_RENAMEAT_RUNTIME 1 @@ -4346,7 +4350,7 @@ os.link * src_dir_fd : dir_fd = None dst_dir_fd : dir_fd = None - follow_symlinks: bool = True + follow_symlinks: bool(c_default="-1", py_default="(os.name != 'nt')") = PLACEHOLDER Create a hard link to a file. @@ -4364,31 +4368,46 @@ src_dir_fd, dst_dir_fd, and follow_symlinks may not be implemented on your static PyObject * os_link_impl(PyObject *module, path_t *src, path_t *dst, int src_dir_fd, int dst_dir_fd, int follow_symlinks) -/*[clinic end generated code: output=7f00f6007fd5269a input=b0095ebbcbaa7e04]*/ +/*[clinic end generated code: output=7f00f6007fd5269a input=1d5e602d115fed7b]*/ { #ifdef MS_WINDOWS BOOL result = FALSE; #else int result; #endif -#if defined(HAVE_LINKAT) - int linkat_unavailable = 0; -#endif -#ifndef HAVE_LINKAT - if ((src_dir_fd != DEFAULT_DIR_FD) || (dst_dir_fd != DEFAULT_DIR_FD)) { - argument_unavailable_error("link", "src_dir_fd and dst_dir_fd"); - return NULL; +#ifdef HAVE_LINKAT + if (HAVE_LINKAT_RUNTIME) { + if (follow_symlinks < 0) { + follow_symlinks = 1; + } } + else #endif - -#ifndef MS_WINDOWS - if ((src->narrow && dst->wide) || (src->wide && dst->narrow)) { - PyErr_SetString(PyExc_NotImplementedError, - "link: src and dst must be the same type"); - return NULL; - } + { + if ((src_dir_fd != DEFAULT_DIR_FD) || (dst_dir_fd != DEFAULT_DIR_FD)) { + argument_unavailable_error("link", "src_dir_fd and dst_dir_fd"); + return NULL; + } +/* See issue 85527: link() on Linux works like linkat without AT_SYMLINK_FOLLOW, + but on Mac it works like linkat *with* AT_SYMLINK_FOLLOW. */ +#if defined(MS_WINDOWS) || defined(__linux__) + if (follow_symlinks == 1) { + argument_unavailable_error("link", "follow_symlinks=True"); + return NULL; + } +#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) || (defined(__sun) && defined(__SVR4)) + if (follow_symlinks == 0) { + argument_unavailable_error("link", "follow_symlinks=False"); + return NULL; + } +#else + if (follow_symlinks >= 0) { + argument_unavailable_error("link", "follow_symlinks"); + return NULL; + } #endif + } if (PySys_Audit("os.link", "OOii", src->object, dst->object, src_dir_fd == DEFAULT_DIR_FD ? -1 : src_dir_fd, @@ -4406,44 +4425,18 @@ os_link_impl(PyObject *module, path_t *src, path_t *dst, int src_dir_fd, #else Py_BEGIN_ALLOW_THREADS #ifdef HAVE_LINKAT - if ((src_dir_fd != DEFAULT_DIR_FD) || - (dst_dir_fd != DEFAULT_DIR_FD) || - (!follow_symlinks)) { - - if (HAVE_LINKAT_RUNTIME) { - - result = linkat(src_dir_fd, src->narrow, - dst_dir_fd, dst->narrow, - follow_symlinks ? AT_SYMLINK_FOLLOW : 0); - - } -#ifdef __APPLE__ - else { - if (src_dir_fd == DEFAULT_DIR_FD && dst_dir_fd == DEFAULT_DIR_FD) { - /* See issue 41355: This matches the behaviour of !HAVE_LINKAT */ - result = link(src->narrow, dst->narrow); - } else { - linkat_unavailable = 1; - } - } -#endif + if (HAVE_LINKAT_RUNTIME) { + result = linkat(src_dir_fd, src->narrow, + dst_dir_fd, dst->narrow, + follow_symlinks ? AT_SYMLINK_FOLLOW : 0); } else -#endif /* HAVE_LINKAT */ +#endif + { + /* linkat not available */ result = link(src->narrow, dst->narrow); - Py_END_ALLOW_THREADS - -#ifdef HAVE_LINKAT - if (linkat_unavailable) { - /* Either or both dir_fd arguments were specified */ - if (src_dir_fd != DEFAULT_DIR_FD) { - argument_unavailable_error("link", "src_dir_fd"); - } else { - argument_unavailable_error("link", "dst_dir_fd"); - } - return NULL; } -#endif + Py_END_ALLOW_THREADS if (result) return path_error2(src, dst); @@ -5935,12 +5928,6 @@ internal_rename(path_t *src, path_t *dst, int src_dir_fd, int dst_dir_fd, int is return path_error2(src, dst); #else - if ((src->narrow && dst->wide) || (src->wide && dst->narrow)) { - PyErr_Format(PyExc_ValueError, - "%s: src and dst must be the same type", function_name); - return NULL; - } - Py_BEGIN_ALLOW_THREADS #ifdef HAVE_RENAMEAT if (dir_fd_specified) { @@ -10613,12 +10600,6 @@ os_symlink_impl(PyObject *module, path_t *src, path_t *dst, #else - if ((src->narrow && dst->wide) || (src->wide && dst->narrow)) { - PyErr_SetString(PyExc_ValueError, - "symlink: src and dst must be the same type"); - return NULL; - } - Py_BEGIN_ALLOW_THREADS #ifdef HAVE_SYMLINKAT if (dir_fd != DEFAULT_DIR_FD) {