Update Misc/NEWS for issues #14127 and #14705. (And, technically, #10148.)

Modules/posixmodule.c

@@ -398,6 +398,268 @@ static int win32_can_symlink = 0;
 #endif
 #endif
 
+/*
+ * De-vararg'd PyArg_ParseTupleAndKeywords()
+ */
+typedef struct argument_path_s {
+    struct argument_path_s *next;
+    PyObject *object;
+    char *format;
+    wchar_t **wide;
+    char **narrow;
+    Py_ssize_t *length;
+} argument_path_t;
+
+typedef struct {
+    PyObject *args;
+    PyObject *kwargs;
+    char format[32];
+    char *format_trace;
+    char *keywords[8];
+    int keyword_count;
+    PyObject **varargs[16];
+    int vararg_count;
+    const char *function_name;
+    argument_path_t *path_head;
+} argument_parser_table_t;
+
+#define APT_DECLARE(apt, fname) \
+    argument_parser_table_t apt; \
+    memset(&apt, 0, sizeof(apt)); \
+    apt.function_name = fname; \
+    apt.args = args; \
+    apt.kwargs = kwargs; \
+    apt.format_trace = apt.format
+
+#define _APT_ARGUMENT_OBJECT(apt, name, variable, format) \
+    *apt.format_trace++ = (format); \
+    apt.keywords[apt.keyword_count++] = (name); \
+    apt.varargs[apt.vararg_count++] = (PyObject **)(variable); \
+
+#define APT_ARGUMENT_OBJECT(apt, name, variable) \
+    _APT_ARGUMENT_OBJECT(apt, name, variable, 'O')
+
+#define APT_ARGUMENT_OBJECT_WITH_CONVERTER(apt, name, variable, converter) \
+    apt.varargs[apt.vararg_count++] = (PyObject **)converter; \
+    APT_ARGUMENT_OBJECT(apt, name, variable); \
+    *apt.format_trace++ = '&'; \
+
+#define APT_ARGUMENT_UNICODE(apt, name, variable) \
+    _APT_ARGUMENT_OBJECT(apt, name, variable, 'U')
+
+#define APT_ARGUMENT_BYTES(apt, name, variable) \
+    _APT_ARGUMENT_OBJECT(apt, name, variable, 'y')
+
+#define APT_ARGUMENT_INT(apt, name, variable) \
+    _APT_ARGUMENT_OBJECT(apt, name, variable, 'i')
+
+static int
+bool_converter(PyObject *object, void *address) {
+    int *output = (int *)address;
+    int value = PyObject_IsTrue(object);
+    if (value == -1)
+        return 0;
+    *output = value;
+    return 1;
+}
+
+#define APT_ARGUMENT_BOOL(apt, name, variable) \
+    _APT_ARGUMENT_OBJECT(apt, name, variable, 'p')
+
+#if !MS_WINDOWS
+    #define _APT_DEFAULT_PATH_TYPE 'U'
+    #define _APT_PATH_BEFORE ;
+    #define _APT_PATH_AFTER ;
+#else
+    #define _APT_DEFAULT_PATH_TYPE 'O'
+    #define _APT_PATH_BEFORE apt.varargs[apt.vararg_count++] = (PyObject **)PyUnicode_FSConverter;
+    #define _APT_PATH_AFTER *apt.format_trace++ = '&';
+#endif
+
+#define APT_ARGUMENT_PATH(apt, name, w, n, l) \
+    { \
+    argument_path_t *_path_ = (argument_path_t *)alloca(sizeof(argument_path_t)); \
+    _APT_PATH_BEFORE; \
+    memset(_path_, 0, sizeof(*_path_)); \
+    _path_->wide = w; \
+    _path_->narrow = n; \
+    _path_->length = l; \
+    _path_->next = apt.path_head; \
+    apt.path_head = _path_; \
+    _APT_ARGUMENT_OBJECT(apt, name, &_path_->object, _APT_DEFAULT_PATH_TYPE); \
+    _APT_PATH_AFTER; \
+    } \
+
+#define APT_OPTIONAL(apt) \
+    *apt.format_trace++ = '|' \
+
+#define APT_KEYWORD_ONLY(apt) \
+    *apt.format_trace++ = '$' \
+
+
+static int apt_parse(argument_parser_table_t *apt) {
+    argument_path_t *trace;
+
+    *apt->format_trace++ = ':';
+    strcpy(apt->format_trace, apt->function_name);
+    apt->keywords[apt->keyword_count] = NULL;
+
+    for (;;) {
+        int result;
+
+        switch (apt->vararg_count) {
+        case 0:
+            PyErr_SetString(PyExc_RuntimeError, "suspiciously too few arguments for apt_parse");
+            return 0;
+
+        #define APT_PREAMBLE \
+            result = PyArg_ParseTupleAndKeywords(apt->args, apt->kwargs, apt->format, apt->keywords, \
+
+        #define APT_POSTSCRIPT \
+                ); \
+            break; \
+
+        case 1:
+            APT_PREAMBLE
+                apt->varargs[0]
+            APT_POSTSCRIPT
+        case 2:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1]
+            APT_POSTSCRIPT
+        case 3:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2]
+            APT_POSTSCRIPT
+        case 4:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2],
+                apt->varargs[3]
+            APT_POSTSCRIPT
+        case 5:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2],
+                apt->varargs[3],
+                apt->varargs[4]
+            APT_POSTSCRIPT
+        case 6:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2],
+                apt->varargs[3],
+                apt->varargs[4],
+                apt->varargs[5]
+            APT_POSTSCRIPT
+        case 7:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2],
+                apt->varargs[3],
+                apt->varargs[4],
+                apt->varargs[5],
+                apt->varargs[6]
+            APT_POSTSCRIPT
+        case 8:
+            APT_PREAMBLE
+                apt->varargs[0],
+                apt->varargs[1],
+                apt->varargs[2],
+                apt->varargs[3],
+                apt->varargs[4],
+                apt->varargs[5],
+                apt->varargs[6],
+                apt->varargs[7]
+            APT_POSTSCRIPT
+        default:
+            PyErr_SetString(PyExc_RuntimeError, "too many arguments for apt_parse");
+            return 0;
+        }
+
+    if (result) {
+        for (trace = apt->path_head; trace != NULL; trace = trace->next) {
+#if MS_WINDOWS
+            switch (*trace->format) {
+            case 'U':
+                *trace->wide = PyUnicode_AsUnicode(trace->object);
+                if (trace->length)
+                    *trace->length = PyUnicode_GET_SIZE(trace->object);
+                break;
+            case 'y'
+                if (win32_warn_bytes_api())
+                    return 0;
+                *trace->narrow = trace->object;
+                if (trace->length)
+                    *trace->length = strlen((char *)trace->object);
+                break;
+            default:
+                PyErr_SetString(PyExc_RuntimeError, "unexpected format character in apt_parse");
+                return 0;
+            }
+#else
+            assert(*trace->format == 'O');
+            *trace->narrow = PyBytes_AsString(trace->object);
+            if (trace->length)
+                *trace->length = PyBytes_GET_SIZE(trace->object);
+#endif
+        }
+        return result;
+    }
+
+#if !MS_WINDOWS
+    break;
+#else
+    for (trace = apt->path_head; trace != NULL; trace = trace->next) {
+        /*
+         * try flipping paths between wide and narrow.
+         *
+         * each element always started with wide.
+         * so:
+         *   * if we see a wide, flip it to narrow and stop.
+         *   * if we see a narrow, flip it to wide and move on to the next field.
+         *   * if we run out of fields, we have exhausted all possibilities.  fail.
+         *
+         * (conceptually it helps to think of the fields as a binary number
+         *  with as many digits as there are entries in the path list.
+         *  wide is 0, narrow is 1.  we keep incrementing the number
+         *  until we wrap around to 0 again.)
+         */
+            if (*trace->format == 'U') {
+                *trace->format = 'y';
+                break;
+            }
+            if (*trace->format == 'y') {
+                *trace->format = 'U';
+                continue;
+            }
+            PyErr_SetString(PyExc_RuntimeError, "unexpected format character in apt_parse");
+            return 0;
+        }
+    if (!trace)
+        break;
+#endif
+    }
+
+    return 0;
+}
+
+static void apt_cleanup(argument_parser_table_t *apt) {
+#if !MS_WINDOWS
+    argument_path_t *trace;
+    for (trace = apt->path_head; trace != NULL; trace = trace->next) {
+        Py_XDECREF(trace->object);
+    }
+#endif
+}
+
 /* A helper used by a number of POSIX-only functions */
 #ifndef MS_WINDOWS
 static int
@@ -1942,6 +2204,12 @@ posix_do_stat(PyObject *self, PyObject *args,
 
 /* POSIX methods */
 
+#ifdef AT_FDCWD
+#define DEFAULT_DIR_FD AT_FDCWD
+#else
+#define DEFAULT_DIR_FD (-100)
+#endif
+
 PyDoc_STRVAR(posix_access__doc__,
 "access(path, mode) -> True if granted, False otherwise\n\n\
 Use the real uid/gid to test for access to a path.  Note that most\n\
@@ -1951,34 +2219,54 @@ specified access to the path.  The mode argument can be F_OK to test\n\
 existence, or the inclusive-OR of R_OK, W_OK, and X_OK.");
 
 static PyObject *
-posix_access(PyObject *self, PyObject *args)
+posix_access(PyObject *self, PyObject *args, PyObject *kwargs)
 {
-    const char *path;
     int mode;
+    int dir_fd = DEFAULT_DIR_FD;
+    wchar_t *wide_path;
+    char *path;
+    int follow_symlinks = 1;
+    int effective_ids = 0;
 
 #ifdef MS_WINDOWS
     DWORD attr;
-    PyObject *po;
-    if (PyArg_ParseTuple(args, "Ui:access", &po, &mode)) {
-        wchar_t* wpath = PyUnicode_AsUnicode(po);
-        if (wpath == NULL)
-            return NULL;
-        Py_BEGIN_ALLOW_THREADS
-        attr = GetFileAttributesW(wpath);
-        Py_END_ALLOW_THREADS
-        goto finish;
-    }
-    /* Drop the argument parsing error as narrow strings
-       are also valid. */
-    PyErr_Clear();
-    if (!PyArg_ParseTuple(args, "yi:access", &path, &mode))
-        return NULL;
-    if (win32_warn_bytes_api())
+#else
+    int res;
+#endif
+
+    APT_DECLARE(apt, "access");
+    APT_ARGUMENT_PATH(apt, "path", &wide_path, &path, NULL);
+    APT_ARGUMENT_INT(apt, "mode", &mode);
+    APT_OPTIONAL(apt);
+    APT_KEYWORD_ONLY(apt);
+    APT_ARGUMENT_INT(apt, "dir_fd", &dir_fd);
+    APT_ARGUMENT_BOOL(apt, "follow_symlinks", &follow_symlinks);
+    APT_ARGUMENT_BOOL(apt, "effective_ids", &effective_ids);
+
+#define ACCESS_FAIL_IF_KEYWORD_USED \
+    if (dir_fd != DEFAULT_DIR_FD) \
+        PyErr_SetString(PyExc_NotImplementedError, "access: dir_fd unavailable on this platform"); \
+    if (!follow_symlinks) \
+        PyErr_SetString(PyExc_NotImplementedError, "access: follow_symlinks unavailable on this platform"); \
+    if (effective_ids) \
+        PyErr_SetString(PyExc_NotImplementedError, "access: effective_ids unavailable on this platform")
+
+    if (!apt_parse(&apt))
         return NULL;
+    Py_RETURN_NONE;
+
+#ifdef MS_WINDOWS
+    ACCESS_FAIL_IF_KEYWORD_USED;
+
     Py_BEGIN_ALLOW_THREADS
+    if (wide != NULL)
+        attr = GetFileAttributesW(wide_path);
+    else
         attr = GetFileAttributesA(path);
     Py_END_ALLOW_THREADS
-finish:
+
+    apt_cleanup(&apt);
+
     if (attr == 0xFFFFFFFF)
         /* File does not exist, or cannot read attributes */
         return PyBool_FromLong(0);
@@ -1989,16 +2277,28 @@ finish:
                            || !(attr & FILE_ATTRIBUTE_READONLY)
                            || (attr & FILE_ATTRIBUTE_DIRECTORY));
 #else
-    PyObject *opath;
-    int res;
-    if (!PyArg_ParseTuple(args, "O&i:access",
-                          PyUnicode_FSConverter, &opath, &mode))
-        return NULL;
-    path = PyBytes_AsString(opath);
+
+    if ((dir_fd != DEFAULT_DIR_FD)
+        || effective_ids || !follow_symlinks) {
+#ifdef HAVE_FACCESSAT
+        int flags = 0;
+        if (!follow_symlinks)
+            flags |= AT_SYMLINK_NOFOLLOW;
+        if (effective_ids)
+            flags |= AT_EACCESS;
+        Py_BEGIN_ALLOW_THREADS
+        res = faccessat(dir_fd, path, mode, flags);
+        Py_END_ALLOW_THREADS
+#else
+        ACCESS_FAIL_IF_KEYWORD_USED;
+#endif
+    } else {
         Py_BEGIN_ALLOW_THREADS
         res = access(path, mode);
         Py_END_ALLOW_THREADS
-    Py_DECREF(opath);
+    }
+
+    apt_cleanup(&apt);
     return PyBool_FromLong(res == 0);
 #endif
 }
@@ -10596,7 +10896,9 @@ get_terminal_size(PyObject *self, PyObject *args)
 
 
 static PyMethodDef posix_methods[] = {
-    {"access",          posix_access, METH_VARARGS, posix_access__doc__},
+    {"access",          (PyCFunction)posix_access,
+                        METH_VARARGS | METH_KEYWORDS,
+                        posix_access__doc__},
 #ifdef HAVE_TTYNAME
     {"ttyname",         posix_ttyname, METH_VARARGS, posix_ttyname__doc__},
 #endif