Includes ensurepip and venv packages in nuget package.

1 files changed, 241 insertions, 171 deletions

diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 0f62b1c019..920b46fc28 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -153,6 +153,9 @@ typedef struct {
     PyObject *codecs_encode;
     /* builtins.getattr, used for saving nested names with protocol < 4 */
     PyObject *getattr;
+    /* functools.partial, used for implementing __newobj_ex__ with protocols
+       2 and 3 */
+    PyObject *partial;
 } PickleState;
 
 /* Forward declaration of the _pickle module definition. */
@@ -190,6 +193,7 @@ _Pickle_ClearState(PickleState *st)
     Py_CLEAR(st->import_mapping_3to2);
     Py_CLEAR(st->codecs_encode);
     Py_CLEAR(st->getattr);
+    Py_CLEAR(st->partial);
 }
 
 /* Initialize the given pickle module state. */
@@ -200,6 +204,7 @@ _Pickle_InitState(PickleState *st)
     PyObject *copyreg = NULL;
     PyObject *compat_pickle = NULL;
     PyObject *codecs = NULL;
+    PyObject *functools = NULL;
 
     builtins = PyEval_GetBuiltins();
     if (builtins == NULL)
@@ -314,12 +319,21 @@ _Pickle_InitState(PickleState *st)
     }
     Py_CLEAR(codecs);
 
+    functools = PyImport_ImportModule("functools");
+    if (!functools)
+        goto error;
+    st->partial = PyObject_GetAttrString(functools, "partial");
+    if (!st->partial)
+        goto error;
+    Py_CLEAR(functools);
+
     return 0;
 
   error:
     Py_CLEAR(copyreg);
     Py_CLEAR(compat_pickle);
     Py_CLEAR(codecs);
+    Py_CLEAR(functools);
     _Pickle_ClearState(st);
     return -1;
 }
@@ -331,43 +345,20 @@ static PyObject *
 _Pickle_FastCall(PyObject *func, PyObject *obj)
 {
     PyObject *result;
-    PyObject *arg_tuple = PyTuple_New(1);
-
-    /* Note: this function used to reuse the argument tuple. This used to give
-       a slight performance boost with older pickle implementations where many
-       unbuffered reads occurred (thus needing many function calls).
-
-       However, this optimization was removed because it was too complicated
-       to get right. It abused the C API for tuples to mutate them which led
-       to subtle reference counting and concurrency bugs. Furthermore, the
-       introduction of protocol 4 and the prefetching optimization via peek()
-       significantly reduced the number of function calls we do. Thus, the
-       benefits became marginal at best. */
 
-    if (arg_tuple == NULL) {
-        Py_DECREF(obj);
-        return NULL;
-    }
-    PyTuple_SET_ITEM(arg_tuple, 0, obj);
-    result = PyObject_Call(func, arg_tuple, NULL);
-    Py_CLEAR(arg_tuple);
+    result = _PyObject_CallArg1(func, obj);
+    Py_DECREF(obj);
     return result;
 }
 
 /*************************************************************************/
 
-static int
-stack_underflow(void)
-{
-    PickleState *st = _Pickle_GetGlobalState();
-    PyErr_SetString(st->UnpicklingError, "unpickling stack underflow");
-    return -1;
-}
-
 /* Internal data type used as the unpickling stack. */
 typedef struct {
     PyObject_VAR_HEAD
     PyObject **data;
+    int mark_set;          /* is MARK set? */
+    Py_ssize_t fence;      /* position of top MARK or 0 */
     Py_ssize_t allocated;  /* number of slots in data allocated */
 } Pdata;
 
@@ -398,6 +389,8 @@ Pdata_New(void)
     if (!(self = PyObject_New(Pdata, &Pdata_Type)))
         return NULL;
     Py_SIZE(self) = 0;
+    self->mark_set = 0;
+    self->fence = 0;
     self->allocated = 8;
     self->data = PyMem_MALLOC(self->allocated * sizeof(PyObject *));
     if (self->data)
@@ -415,8 +408,7 @@ Pdata_clear(Pdata *self, Py_ssize_t clearto)
 {
     Py_ssize_t i = Py_SIZE(self);
 
-    if (clearto < 0)
-        return stack_underflow();
+    assert(clearto >= self->fence);
     if (clearto >= i)
         return 0;
 
@@ -452,6 +444,17 @@ Pdata_grow(Pdata *self)
     return -1;
 }
 
+static int
+Pdata_stack_underflow(Pdata *self)
+{
+    PickleState *st = _Pickle_GetGlobalState();
+    PyErr_SetString(st->UnpicklingError,
+                    self->mark_set ?
+                    "unexpected MARK found" :
+                    "unpickling stack underflow");
+    return -1;
+}
+
 /* D is a Pdata*.  Pop the topmost element and store it into V, which
  * must be an lvalue holding PyObject*.  On stack underflow, UnpicklingError
  * is raised and V is set to NULL.
@@ -459,9 +462,8 @@ Pdata_grow(Pdata *self)
 static PyObject *
 Pdata_pop(Pdata *self)
 {
-    if (Py_SIZE(self) == 0) {
-        PickleState *st = _Pickle_GetGlobalState();
-        PyErr_SetString(st->UnpicklingError, "bad pickle data");
+    if (Py_SIZE(self) <= self->fence) {
+        Pdata_stack_underflow(self);
         return NULL;
     }
     return self->data[--Py_SIZE(self)];
@@ -493,6 +495,10 @@ Pdata_poptuple(Pdata *self, Py_ssize_t start)
     PyObject *tuple;
     Py_ssize_t len, i, j;
 
+    if (start < self->fence) {
+        Pdata_stack_underflow(self);
+        return NULL;
+    }
     len = Py_SIZE(self) - start;
     tuple = PyTuple_New(len);
     if (tuple == NULL)
@@ -860,7 +866,7 @@ _write_size64(char *out, size_t value)
 {
     size_t i;
 
-    assert(sizeof(size_t) <= 8);
+    Py_BUILD_ASSERT(sizeof(size_t) <= 8);
 
     for (i = 0; i < sizeof(size_t); i++) {
         out[i] = (unsigned char)((value >> (8 * i)) & 0xff);
@@ -1086,6 +1092,14 @@ _Unpickler_SetStringInput(UnpicklerObject *self, PyObject *input)
 }
 
 static int
+bad_readline(void)
+{
+    PickleState *st = _Pickle_GetGlobalState();
+    PyErr_SetString(st->UnpicklingError, "pickle data was truncated");
+    return -1;
+}
+
+static int
 _Unpickler_SkipConsumed(UnpicklerObject *self)
 {
     Py_ssize_t consumed;
@@ -1134,9 +1148,7 @@ _Unpickler_ReadFromFile(UnpicklerObject *self, Py_ssize_t n)
         return -1;
 
     if (n == READ_WHOLE_LINE) {
-        PyObject *empty_tuple = PyTuple_New(0);
-        data = PyObject_Call(self->readline, empty_tuple, NULL);
-        Py_DECREF(empty_tuple);
+        data = _PyObject_CallNoArg(self->readline);
     }
     else {
         PyObject *len;
@@ -1174,21 +1186,9 @@ _Unpickler_ReadFromFile(UnpicklerObject *self, Py_ssize_t n)
     return read_size;
 }
 
-/* Read `n` bytes from the unpickler's data source, storing the result in `*s`.
-
-   This should be used for all data reads, rather than accessing the unpickler's
-   input buffer directly. This method deals correctly with reading from input
-   streams, which the input buffer doesn't deal with.
-
-   Note that when reading from a file-like object, self->next_read_idx won't
-   be updated (it should remain at 0 for the entire unpickling process). You
-   should use this function's return value to know how many bytes you can
-   consume.
-
-   Returns -1 (with an exception set) on failure. On success, return the
-   number of chars read. */
+/* Don't call it directly: use _Unpickler_Read() */
 static Py_ssize_t
-_Unpickler_Read(UnpicklerObject *self, char **s, Py_ssize_t n)
+_Unpickler_ReadImpl(UnpicklerObject *self, char **s, Py_ssize_t n)
 {
     Py_ssize_t num_read;
 
@@ -1199,27 +1199,43 @@ _Unpickler_Read(UnpicklerObject *self, char **s, Py_ssize_t n)
                         "read would overflow (invalid bytecode)");
         return -1;
     }
-    if (self->next_read_idx + n <= self->input_len) {
-        *s = self->input_buffer + self->next_read_idx;
-        self->next_read_idx += n;
-        return n;
-    }
-    if (!self->read) {
-        PyErr_Format(PyExc_EOFError, "Ran out of input");
-        return -1;
-    }
+
+    /* This case is handled by the _Unpickler_Read() macro for efficiency */
+    assert(self->next_read_idx + n > self->input_len);
+
+    if (!self->read)
+        return bad_readline();
+
     num_read = _Unpickler_ReadFromFile(self, n);
     if (num_read < 0)
         return -1;
-    if (num_read < n) {
-        PyErr_Format(PyExc_EOFError, "Ran out of input");
-        return -1;
-    }
+    if (num_read < n)
+        return bad_readline();
     *s = self->input_buffer;
     self->next_read_idx = n;
     return n;
 }
 
+/* Read `n` bytes from the unpickler's data source, storing the result in `*s`.
+
+   This should be used for all data reads, rather than accessing the unpickler's
+   input buffer directly. This method deals correctly with reading from input
+   streams, which the input buffer doesn't deal with.
+
+   Note that when reading from a file-like object, self->next_read_idx won't
+   be updated (it should remain at 0 for the entire unpickling process). You
+   should use this function's return value to know how many bytes you can
+   consume.
+
+   Returns -1 (with an exception set) on failure. On success, return the
+   number of chars read. */
+#define _Unpickler_Read(self, s, n) \
+    (((n) <= (self)->input_len - (self)->next_read_idx)      \
+     ? (*(s) = (self)->input_buffer + (self)->next_read_idx, \
+        (self)->next_read_idx += (n),                        \
+        (n))                                                 \
+     : _Unpickler_ReadImpl(self, (s), (n)))
+
 static Py_ssize_t
 _Unpickler_CopyLine(UnpicklerObject *self, char *line, Py_ssize_t len,
                     char **result)
@@ -1238,7 +1254,7 @@ _Unpickler_CopyLine(UnpicklerObject *self, char *line, Py_ssize_t len,
 }
 
 /* Read a line from the input stream/buffer. If we run off the end of the input
-   before hitting \n, return the data we found.
+   before hitting \n, raise an error.
 
    Returns the number of chars read, or -1 on failure. */
 static Py_ssize_t
@@ -1254,20 +1270,16 @@ _Unpickler_Readline(UnpicklerObject *self, char **result)
             return _Unpickler_CopyLine(self, line_start, num_read, result);
         }
     }
-    if (self->read) {
-        num_read = _Unpickler_ReadFromFile(self, READ_WHOLE_LINE);
-        if (num_read < 0)
-            return -1;
-        self->next_read_idx = num_read;
-        return _Unpickler_CopyLine(self, self->input_buffer, num_read, result);
-    }
+    if (!self->read)
+        return bad_readline();
 
-    /* If we get here, we've run off the end of the input string. Return the
-       remaining string and let the caller figure it out. */
-    *result = self->input_buffer + self->next_read_idx;
-    num_read = i - self->next_read_idx;
-    self->next_read_idx = i;
-    return num_read;
+    num_read = _Unpickler_ReadFromFile(self, READ_WHOLE_LINE);
+    if (num_read < 0)
+        return -1;
+    if (num_read == 0 || self->input_buffer[num_read - 1] != '\n')
+        return bad_readline();
+    self->next_read_idx = num_read;
+    return _Unpickler_CopyLine(self, self->input_buffer, num_read, result);
 }
 
 /* Returns -1 (with an exception set) on failure, 0 on success. The memo array
@@ -1934,7 +1946,7 @@ save_long(PicklerObject *self, PyObject *obj)
         if (repr == NULL)
             goto error;
 
-        string = _PyUnicode_AsStringAndSize(repr, &size);
+        string = PyUnicode_AsUTF8AndSize(repr, &size);
         if (string == NULL)
             goto error;
 
@@ -2091,38 +2103,35 @@ save_bytes(PicklerObject *self, PyObject *obj)
 static PyObject *
 raw_unicode_escape(PyObject *obj)
 {
-    PyObject *repr;
     char *p;
     Py_ssize_t i, size;
-    size_t expandsize;
     void *data;
     unsigned int kind;
+    _PyBytesWriter writer;
 
     if (PyUnicode_READY(obj))
         return NULL;
 
+    _PyBytesWriter_Init(&writer);
+
     size = PyUnicode_GET_LENGTH(obj);
     data = PyUnicode_DATA(obj);
     kind = PyUnicode_KIND(obj);
-    if (kind == PyUnicode_4BYTE_KIND)
-        expandsize = 10;
-    else
-        expandsize = 6;
 
-    if ((size_t)size > (size_t)PY_SSIZE_T_MAX / expandsize)
-        return PyErr_NoMemory();
-    repr = PyBytes_FromStringAndSize(NULL, expandsize * size);
-    if (repr == NULL)
-        return NULL;
-    if (size == 0)
-        return repr;
-    assert(Py_REFCNT(repr) == 1);
+    p = _PyBytesWriter_Alloc(&writer, size);
+    if (p == NULL)
+        goto error;
+    writer.overallocate = 1;
 
-    p = PyBytes_AS_STRING(repr);
     for (i=0; i < size; i++) {
         Py_UCS4 ch = PyUnicode_READ(kind, data, i);
         /* Map 32-bit characters to '\Uxxxxxxxx' */
         if (ch >= 0x10000) {
+            /* -1: subtract 1 preallocated byte */
+            p = _PyBytesWriter_Prepare(&writer, p, 10-1);
+            if (p == NULL)
+                goto error;
+
             *p++ = '\\';
             *p++ = 'U';
             *p++ = Py_hexdigits[(ch >> 28) & 0xf];
@@ -2134,8 +2143,13 @@ raw_unicode_escape(PyObject *obj)
             *p++ = Py_hexdigits[(ch >> 4) & 0xf];
             *p++ = Py_hexdigits[ch & 15];
         }
-        /* Map 16-bit characters to '\uxxxx' */
+        /* Map 16-bit characters, '\\' and '\n' to '\uxxxx' */
         else if (ch >= 256 || ch == '\\' || ch == '\n') {
+            /* -1: subtract 1 preallocated byte */
+            p = _PyBytesWriter_Prepare(&writer, p, 6-1);
+            if (p == NULL)
+                goto error;
+
             *p++ = '\\';
             *p++ = 'u';
             *p++ = Py_hexdigits[(ch >> 12) & 0xf];
@@ -2147,14 +2161,16 @@ raw_unicode_escape(PyObject *obj)
         else
             *p++ = (char) ch;
     }
-    size = p - PyBytes_AS_STRING(repr);
-    if (_PyBytes_Resize(&repr, size) < 0)
-        return NULL;
-    return repr;
+
+    return _PyBytesWriter_Finish(&writer, p);
+
+error:
+    _PyBytesWriter_Dealloc(&writer);
+    return NULL;
 }
 
 static int
-write_utf8(PicklerObject *self, char *data, Py_ssize_t size)
+write_utf8(PicklerObject *self, const char *data, Py_ssize_t size)
 {
     char header[9];
     Py_ssize_t len;
@@ -2853,7 +2869,7 @@ save_dict(PicklerObject *self, PyObject *obj)
         } else {
             _Py_IDENTIFIER(items);
 
-            items = _PyObject_CallMethodId(obj, &PyId_items, "()");
+            items = _PyObject_CallMethodId(obj, &PyId_items, NULL);
             if (items == NULL)
                 goto error;
             iter = PyObject_GetIter(items);
@@ -3530,11 +3546,9 @@ save_reduce(PicklerObject *self, PyObject *args, PyObject *obj)
             PyErr_Clear();
         }
         else if (PyUnicode_Check(name)) {
-            if (self->proto >= 4) {
-                _Py_IDENTIFIER(__newobj_ex__);
-                use_newobj_ex = _PyUnicode_EqualToASCIIId(
-                        name, &PyId___newobj_ex__);
-            }
+            _Py_IDENTIFIER(__newobj_ex__);
+            use_newobj_ex = _PyUnicode_EqualToASCIIId(
+                    name, &PyId___newobj_ex__);
             if (!use_newobj_ex) {
                 _Py_IDENTIFIER(__newobj__);
                 use_newobj = _PyUnicode_EqualToASCIIId(name, &PyId___newobj__);
@@ -3577,11 +3591,58 @@ save_reduce(PicklerObject *self, PyObject *args, PyObject *obj)
             return -1;
         }
 
-        if (save(self, cls, 0) < 0 ||
-            save(self, args, 0) < 0 ||
-            save(self, kwargs, 0) < 0 ||
-            _Pickler_Write(self, &newobj_ex_op, 1) < 0) {
-            return -1;
+        if (self->proto >= 4) {
+            if (save(self, cls, 0) < 0 ||
+                save(self, args, 0) < 0 ||
+                save(self, kwargs, 0) < 0 ||
+                _Pickler_Write(self, &newobj_ex_op, 1) < 0) {
+                return -1;
+            }
+        }
+        else {
+            PyObject *newargs;
+            PyObject *cls_new;
+            Py_ssize_t i;
+            _Py_IDENTIFIER(__new__);
+
+            newargs = PyTuple_New(Py_SIZE(args) + 2);
+            if (newargs == NULL)
+                return -1;
+
+            cls_new = _PyObject_GetAttrId(cls, &PyId___new__);
+            if (cls_new == NULL) {
+                Py_DECREF(newargs);
+                return -1;
+            }
+            PyTuple_SET_ITEM(newargs, 0, cls_new);
+            Py_INCREF(cls);
+            PyTuple_SET_ITEM(newargs, 1, cls);
+            for (i = 0; i < Py_SIZE(args); i++) {
+                PyObject *item = PyTuple_GET_ITEM(args, i);
+                Py_INCREF(item);
+                PyTuple_SET_ITEM(newargs, i + 2, item);
+            }
+
+            callable = PyObject_Call(st->partial, newargs, kwargs);
+            Py_DECREF(newargs);
+            if (callable == NULL)
+                return -1;
+
+            newargs = PyTuple_New(0);
+            if (newargs == NULL) {
+                Py_DECREF(callable);
+                return -1;
+            }
+
+            if (save(self, callable, 0) < 0 ||
+                save(self, newargs, 0) < 0 ||
+                _Pickler_Write(self, &reduce_op, 1) < 0) {
+                Py_DECREF(newargs);
+                Py_DECREF(callable);
+                return -1;
+            }
+            Py_DECREF(newargs);
+            Py_DECREF(callable);
         }
     }
     else if (use_newobj) {
@@ -3871,10 +3932,7 @@ save(PicklerObject *self, PyObject *obj, int pers_save)
             /* Check for a __reduce__ method. */
             reduce_func = _PyObject_GetAttrId(obj, &PyId___reduce__);
             if (reduce_func != NULL) {
-                PyObject *empty_tuple = PyTuple_New(0);
-                reduce_value = PyObject_Call(reduce_func, empty_tuple,
-                                             NULL);
-                Py_DECREF(empty_tuple);
+                reduce_value = _PyObject_CallNoArg(reduce_func);
             }
             else {
                 PyErr_Format(st->PicklingError,
@@ -4391,7 +4449,7 @@ Pickler_set_memo(PicklerObject *self, PyObject *obj)
     }
     else {
         PyErr_Format(PyExc_TypeError,
-                     "'memo' attribute must be an PicklerMemoProxy object"
+                     "'memo' attribute must be a PicklerMemoProxy object"
                      "or dict, not %.200s", Py_TYPE(obj)->tp_name);
         return -1;
     }
@@ -4420,8 +4478,6 @@ Pickler_get_persid(PicklerObject *self)
 static int
 Pickler_set_persid(PicklerObject *self, PyObject *value)
 {
-    PyObject *tmp;
-
     if (value == NULL) {
         PyErr_SetString(PyExc_TypeError,
                         "attribute deletion is not supported");
@@ -4433,10 +4489,8 @@ Pickler_set_persid(PicklerObject *self, PyObject *value)
         return -1;
     }
 
-    tmp = self->pers_func;
     Py_INCREF(value);
-    self->pers_func = value;
-    Py_XDECREF(tmp);      /* self->pers_func can be NULL, so be careful. */
+    Py_XSETREF(self->pers_func, value);
 
     return 0;
 }
@@ -4518,13 +4572,19 @@ find_class(UnpicklerObject *self, PyObject *module_name, PyObject *global_name)
 static Py_ssize_t
 marker(UnpicklerObject *self)
 {
-    PickleState *st = _Pickle_GetGlobalState();
+    Py_ssize_t mark;
+
     if (self->num_marks < 1) {
+        PickleState *st = _Pickle_GetGlobalState();
         PyErr_SetString(st->UnpicklingError, "could not find MARK");
         return -1;
     }
 
-    return self->marks[--self->num_marks];
+    mark = self->marks[--self->num_marks];
+    self->stack->mark_set = self->num_marks != 0;
+    self->stack->fence = self->num_marks ?
+            self->marks[self->num_marks - 1] : 0;
+    return mark;
 }
 
 static int
@@ -4535,14 +4595,6 @@ load_none(UnpicklerObject *self)
 }
 
 static int
-bad_readline(void)
-{
-    PickleState *st = _Pickle_GetGlobalState();
-    PyErr_SetString(st->UnpicklingError, "pickle data was truncated");
-    return -1;
-}
-
-static int
 load_int(UnpicklerObject *self)
 {
     PyObject *value;
@@ -4985,7 +5037,7 @@ load_counted_tuple(UnpicklerObject *self, Py_ssize_t len)
     PyObject *tuple;
 
     if (Py_SIZE(self->stack) < len)
-        return stack_underflow();
+        return Pdata_stack_underflow(self->stack);
 
     tuple = Pdata_poptuple(self->stack, Py_SIZE(self->stack) - len);
     if (tuple == NULL)
@@ -5067,6 +5119,13 @@ load_dict(UnpicklerObject *self)
     if ((dict = PyDict_New()) == NULL)
         return -1;
 
+    if ((j - i) % 2 != 0) {
+        PickleState *st = _Pickle_GetGlobalState();
+        PyErr_SetString(st->UnpicklingError, "odd number of items for DICT");
+        Py_DECREF(dict);
+        return -1;
+    }
+
     for (k = i + 1; k < j; k += 2) {
         key = self->stack->data[k - 1];
         value = self->stack->data[k];
@@ -5134,7 +5193,7 @@ load_obj(UnpicklerObject *self)
         return -1;
 
     if (Py_SIZE(self->stack) - i < 1)
-        return stack_underflow();
+        return Pdata_stack_underflow(self->stack);
 
     args = Pdata_poptuple(self->stack, i + 1);
     if (args == NULL)
@@ -5457,12 +5516,15 @@ load_pop(UnpicklerObject *self)
      */
     if (self->num_marks > 0 && self->marks[self->num_marks - 1] == len) {
         self->num_marks--;
-    } else if (len > 0) {
+        self->stack->mark_set = self->num_marks != 0;
+        self->stack->fence = self->num_marks ?
+                self->marks[self->num_marks - 1] : 0;
+    } else if (len <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
+    else {
         len--;
         Py_DECREF(self->stack->data[len]);
         Py_SIZE(self->stack) = len;
-    } else {
-        return stack_underflow();
     }
     return 0;
 }
@@ -5484,10 +5546,10 @@ static int
 load_dup(UnpicklerObject *self)
 {
     PyObject *last;
-    Py_ssize_t len;
+    Py_ssize_t len = Py_SIZE(self->stack);
 
-    if ((len = Py_SIZE(self->stack)) <= 0)
-        return stack_underflow();
+    if (len <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     last = self->stack->data[len - 1];
     PDATA_APPEND(self->stack, last, -1);
     return 0;
@@ -5670,8 +5732,8 @@ load_put(UnpicklerObject *self)
         return -1;
     if (len < 2)
         return bad_readline();
-    if (Py_SIZE(self->stack) <= 0)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     value = self->stack->data[Py_SIZE(self->stack) - 1];
 
     key = PyLong_FromString(s, NULL, 10);
@@ -5699,8 +5761,8 @@ load_binput(UnpicklerObject *self)
     if (_Unpickler_Read(self, &s, 1) < 0)
         return -1;
 
-    if (Py_SIZE(self->stack) <= 0)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     value = self->stack->data[Py_SIZE(self->stack) - 1];
 
     idx = Py_CHARMASK(s[0]);
@@ -5718,8 +5780,8 @@ load_long_binput(UnpicklerObject *self)
     if (_Unpickler_Read(self, &s, 4) < 0)
         return -1;
 
-    if (Py_SIZE(self->stack) <= 0)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     value = self->stack->data[Py_SIZE(self->stack) - 1];
 
     idx = calc_binsize(s, 4);
@@ -5737,8 +5799,8 @@ load_memoize(UnpicklerObject *self)
 {
     PyObject *value;
 
-    if (Py_SIZE(self->stack) <= 0)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     value = self->stack->data[Py_SIZE(self->stack) - 1];
 
     return _Unpickler_MemoPut(self, self->memo_len, value);
@@ -5752,8 +5814,8 @@ do_append(UnpicklerObject *self, Py_ssize_t x)
     Py_ssize_t len, i;
 
     len = Py_SIZE(self->stack);
-    if (x > len || x <= 0)
-        return stack_underflow();
+    if (x > len || x <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     if (len == x)  /* nothing to do */
         return 0;
 
@@ -5802,8 +5864,8 @@ do_append(UnpicklerObject *self, Py_ssize_t x)
 static int
 load_append(UnpicklerObject *self)
 {
-    if (Py_SIZE(self->stack) - 1 <= 0)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) - 1 <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     return do_append(self, Py_SIZE(self->stack) - 1);
 }
 
@@ -5825,8 +5887,8 @@ do_setitems(UnpicklerObject *self, Py_ssize_t x)
     int status = 0;
 
     len = Py_SIZE(self->stack);
-    if (x > len || x <= 0)
-        return stack_underflow();
+    if (x > len || x <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     if (len == x)  /* nothing to do */
         return 0;
     if ((len - x) % 2 != 0) {
@@ -5879,8 +5941,8 @@ load_additems(UnpicklerObject *self)
     if (mark < 0)
         return -1;
     len = Py_SIZE(self->stack);
-    if (mark > len || mark <= 0)
-        return stack_underflow();
+    if (mark > len || mark <= self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
     if (len == mark)  /* nothing to do */
         return 0;
 
@@ -5935,8 +5997,8 @@ load_build(UnpicklerObject *self)
     /* Stack is ... instance, state.  We want to leave instance at
      * the stack top, possibly mutated via instance.__setstate__(state).
      */
-    if (Py_SIZE(self->stack) < 2)
-        return stack_underflow();
+    if (Py_SIZE(self->stack) - 2 < self->stack->fence)
+        return Pdata_stack_underflow(self->stack);
 
     PDATA_POP(self->stack, state);
     if (state == NULL)
@@ -6072,7 +6134,8 @@ load_mark(UnpicklerObject *self)
         self->marks_size = (Py_ssize_t)alloc;
     }
 
-    self->marks[self->num_marks++] = Py_SIZE(self->stack);
+    self->stack->mark_set = 1;
+    self->marks[self->num_marks++] = self->stack->fence = Py_SIZE(self->stack);
 
     return 0;
 }
@@ -6155,6 +6218,8 @@ load(UnpicklerObject *self)
     char *s = NULL;
 
     self->num_marks = 0;
+    self->stack->mark_set = 0;
+    self->stack->fence = 0;
     self->proto = 0;
     if (Py_SIZE(self->stack))
         Pdata_clear(self->stack, 0);
@@ -6167,8 +6232,13 @@ load(UnpicklerObject *self)
     case opcode: if (load_func(self, (arg)) < 0) break; continue;
 
     while (1) {
-        if (_Unpickler_Read(self, &s, 1) < 0)
-            break;
+        if (_Unpickler_Read(self, &s, 1) < 0) {
+            PickleState *st = _Pickle_GetGlobalState();
+            if (PyErr_ExceptionMatches(st->UnpicklingError)) {
+                PyErr_Format(PyExc_EOFError, "Ran out of input");
+            }
+            return NULL;
+        }
 
         switch ((enum opcode)s[0]) {
         OP(NONE, load_none)
@@ -6240,15 +6310,19 @@ load(UnpicklerObject *self)
             break;
 
         default:
-            if (s[0] == '\0') {
-                PyErr_SetNone(PyExc_EOFError);
-            }
-            else {
+            {
                 PickleState *st = _Pickle_GetGlobalState();
-                PyErr_Format(st->UnpicklingError,
-                             "invalid load key, '%c'.", s[0]);
+                unsigned char c = (unsigned char) *s;
+                if (0x20 <= c && c <= 0x7e && c != '\'' && c != '\\') {
+                    PyErr_Format(st->UnpicklingError,
+                                 "invalid load key, '%c'.", c);
+                }
+                else {
+                    PyErr_Format(st->UnpicklingError,
+                                 "invalid load key, '\\x%02x'.", c);
+                }
+                return NULL;
             }
-            return NULL;
         }
 
         break;                  /* and we are done! */
@@ -6859,8 +6933,6 @@ Unpickler_get_persload(UnpicklerObject *self)
 static int
 Unpickler_set_persload(UnpicklerObject *self, PyObject *value)
 {
-    PyObject *tmp;
-
     if (value == NULL) {
         PyErr_SetString(PyExc_TypeError,
                         "attribute deletion is not supported");
@@ -6873,10 +6945,8 @@ Unpickler_set_persload(UnpicklerObject *self, PyObject *value)
         return -1;
     }
 
-    tmp = self->pers_func;
     Py_INCREF(value);
-    self->pers_func = value;
-    Py_XDECREF(tmp);      /* self->pers_func can be NULL, so be careful. */
+    Py_XSETREF(self->pers_func, value);
 
     return 0;
 }