bpo-33729: Fix issues with arguments parsing in hashlib. (GH-8346)

* help(hashlib) didn't work because of incorrect module name in blake2b and
  blake2s classes.
* Constructors blake2*(), sha3_*(), shake_*() and keccak_*() incorrectly
  accepted keyword argument "string" for binary data, but documented as
  accepting the "data" keyword argument. Now this parameter is positional-only.
* Keyword-only parameters in blake2b() and blake2s() were not documented as
  keyword-only.
* Default value for some parameters of blake2b() and blake2s() was None,
  which is not acceptable value.
* The length argument for shake_*.digest() was wrapped out to 32 bits.
* The argument for shake_128.digest() and shake_128.hexdigest() was not
  positional-only as intended.
* TypeError messages for incorrect arguments in all constructors sha3_*(),
  shake_*() and keccak_*() incorrectly referred to sha3_224.

Also made the following enhancements:

* More accurately specified input and result types for strings, bytes and
  bytes-like objects.
* Unified positional parameter names for update() and constructors.
* Improved formatting.

2 files changed, 51 insertions, 80 deletions

diff --git a/Modules/_sha3/clinic/sha3module.c.h b/Modules/_sha3/clinic/sha3module.c.h
index a1e80b0..b2a896e 100644
--- a/Modules/_sha3/clinic/sha3module.c.h
+++ b/Modules/_sha3/clinic/sha3module.c.h
@@ -2,33 +2,6 @@
 preserve
 [clinic start generated code]*/
 
-PyDoc_STRVAR(py_sha3_new__doc__,
-"sha3_224(string=None)\n"
-"--\n"
-"\n"
-"Return a new SHA3 hash object with a hashbit length of 28 bytes.");
-
-static PyObject *
-py_sha3_new_impl(PyTypeObject *type, PyObject *data);
-
-static PyObject *
-py_sha3_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
-{
-    PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"string", NULL};
-    static _PyArg_Parser _parser = {"|O:sha3_224", _keywords, 0};
-    PyObject *data = NULL;
-
-    if (!_PyArg_ParseTupleAndKeywordsFast(args, kwargs, &_parser,
-        &data)) {
-        goto exit;
-    }
-    return_value = py_sha3_new_impl(type, data);
-
-exit:
-    return return_value;
-}
-
 PyDoc_STRVAR(_sha3_sha3_224_copy__doc__,
 "copy($self, /)\n"
 "--\n"
@@ -51,7 +24,7 @@ PyDoc_STRVAR(_sha3_sha3_224_digest__doc__,
 "digest($self, /)\n"
 "--\n"
 "\n"
-"Return the digest value as a string of binary data.");
+"Return the digest value as a bytes object.");
 
 #define _SHA3_SHA3_224_DIGEST_METHODDEF    \
     {"digest", (PyCFunction)_sha3_sha3_224_digest, METH_NOARGS, _sha3_sha3_224_digest__doc__},
@@ -84,36 +57,33 @@ _sha3_sha3_224_hexdigest(SHA3object *self, PyObject *Py_UNUSED(ignored))
 }
 
 PyDoc_STRVAR(_sha3_sha3_224_update__doc__,
-"update($self, obj, /)\n"
+"update($self, data, /)\n"
 "--\n"
 "\n"
-"Update this hash object\'s state with the provided string.");
+"Update this hash object\'s state with the provided bytes-like object.");
 
 #define _SHA3_SHA3_224_UPDATE_METHODDEF    \
     {"update", (PyCFunction)_sha3_sha3_224_update, METH_O, _sha3_sha3_224_update__doc__},
 
 PyDoc_STRVAR(_sha3_shake_128_digest__doc__,
-"digest($self, /, length)\n"
+"digest($self, length, /)\n"
 "--\n"
 "\n"
-"Return the digest value as a string of binary data.");
+"Return the digest value as a bytes object.");
 
 #define _SHA3_SHAKE_128_DIGEST_METHODDEF    \
-    {"digest", (PyCFunction)_sha3_shake_128_digest, METH_FASTCALL|METH_KEYWORDS, _sha3_shake_128_digest__doc__},
+    {"digest", (PyCFunction)_sha3_shake_128_digest, METH_O, _sha3_shake_128_digest__doc__},
 
 static PyObject *
 _sha3_shake_128_digest_impl(SHA3object *self, unsigned long length);
 
 static PyObject *
-_sha3_shake_128_digest(SHA3object *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+_sha3_shake_128_digest(SHA3object *self, PyObject *arg)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"length", NULL};
-    static _PyArg_Parser _parser = {"k:digest", _keywords, 0};
     unsigned long length;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &length)) {
+    if (!PyArg_Parse(arg, "O&:digest", _PyLong_UnsignedLong_Converter, &length)) {
         goto exit;
     }
     return_value = _sha3_shake_128_digest_impl(self, length);
@@ -123,27 +93,24 @@ exit:
 }
 
 PyDoc_STRVAR(_sha3_shake_128_hexdigest__doc__,
-"hexdigest($self, /, length)\n"
+"hexdigest($self, length, /)\n"
 "--\n"
 "\n"
 "Return the digest value as a string of hexadecimal digits.");
 
 #define _SHA3_SHAKE_128_HEXDIGEST_METHODDEF    \
-    {"hexdigest", (PyCFunction)_sha3_shake_128_hexdigest, METH_FASTCALL|METH_KEYWORDS, _sha3_shake_128_hexdigest__doc__},
+    {"hexdigest", (PyCFunction)_sha3_shake_128_hexdigest, METH_O, _sha3_shake_128_hexdigest__doc__},
 
 static PyObject *
 _sha3_shake_128_hexdigest_impl(SHA3object *self, unsigned long length);
 
 static PyObject *
-_sha3_shake_128_hexdigest(SHA3object *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+_sha3_shake_128_hexdigest(SHA3object *self, PyObject *arg)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"length", NULL};
-    static _PyArg_Parser _parser = {"k:hexdigest", _keywords, 0};
     unsigned long length;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &length)) {
+    if (!PyArg_Parse(arg, "O&:hexdigest", _PyLong_UnsignedLong_Converter, &length)) {
         goto exit;
     }
     return_value = _sha3_shake_128_hexdigest_impl(self, length);
@@ -151,4 +118,4 @@ _sha3_shake_128_hexdigest(SHA3object *self, PyObject *const *args, Py_ssize_t na
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=a3aeb6c3b2fbd905 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=bf823532a7bffe68 input=a9049054013a1b77]*/
diff --git a/Modules/_sha3/sha3module.c b/Modules/_sha3/sha3module.c
index 970ce16..f5032fc 100644
--- a/Modules/_sha3/sha3module.c
+++ b/Modules/_sha3/sha3module.c
@@ -170,21 +170,20 @@ newSHA3object(PyTypeObject *type)
 }
 
 
-/*[clinic input]
-@classmethod
-_sha3.sha3_224.__new__ as py_sha3_new
-    string as data: object = NULL
-
-Return a new SHA3 hash object with a hashbit length of 28 bytes.
-[clinic start generated code]*/
-
 static PyObject *
-py_sha3_new_impl(PyTypeObject *type, PyObject *data)
-/*[clinic end generated code: output=8d5c34279e69bf09 input=d7c582b950a858b6]*/
+py_sha3_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 {
     SHA3object *self = NULL;
     Py_buffer buf = {NULL, NULL};
     HashReturn res;
+    PyObject *data = NULL;
+
+    if (!_PyArg_NoKeywords(_PyType_Name(type), kwargs)) {
+        return NULL;
+    }
+    if (!PyArg_UnpackTuple(args, _PyType_Name(type), 0, 1, &data)) {
+        return NULL;
+    }
 
     self = newSHA3object(type);
     if (self == NULL) {
@@ -292,12 +291,12 @@ _sha3_sha3_224_copy_impl(SHA3object *self)
 /*[clinic input]
 _sha3.sha3_224.digest
 
-Return the digest value as a string of binary data.
+Return the digest value as a bytes object.
 [clinic start generated code]*/
 
 static PyObject *
 _sha3_sha3_224_digest_impl(SHA3object *self)
-/*[clinic end generated code: output=fd531842e20b2d5b input=a5807917d219b30e]*/
+/*[clinic end generated code: output=fd531842e20b2d5b input=5b2a659536bbd248]*/
 {
     unsigned char digest[SHA3_MAX_DIGESTSIZE + SHA3_LANESIZE];
     SHA3_state temp;
@@ -347,20 +346,20 @@ _sha3_sha3_224_hexdigest_impl(SHA3object *self)
 /*[clinic input]
 _sha3.sha3_224.update
 
-    obj: object
+    data: object
     /
 
-Update this hash object's state with the provided string.
+Update this hash object's state with the provided bytes-like object.
 [clinic start generated code]*/
 
 static PyObject *
-_sha3_sha3_224_update(SHA3object *self, PyObject *obj)
-/*[clinic end generated code: output=06721d55b483e0af input=be44bf0d1c279791]*/
+_sha3_sha3_224_update(SHA3object *self, PyObject *data)
+/*[clinic end generated code: output=d3223352286ed357 input=a887f54dcc4ae227]*/
 {
     Py_buffer buf;
     HashReturn res;
 
-    GET_BUFFER_VIEW_OR_ERROUT(obj, &buf);
+    GET_BUFFER_VIEW_OR_ERROUT(data, &buf);
 
     /* add new data, the function takes the length in bits not bytes */
     if (self->lock == NULL && buf.len >= HASHLIB_GIL_MINSIZE) {
@@ -529,44 +528,49 @@ static PyGetSetDef SHA3_getseters[] = {
         py_sha3_new,        /* tp_new */ \
     }
 
+PyDoc_STRVAR(sha3_224__doc__,
+"sha3_224([data]) -> SHA3 object\n\
+\n\
+Return a new SHA3 hash object with a hashbit length of 28 bytes.");
+
 PyDoc_STRVAR(sha3_256__doc__,
-"sha3_256([string]) -> SHA3 object\n\
+"sha3_256([data]) -> SHA3 object\n\
 \n\
 Return a new SHA3 hash object with a hashbit length of 32 bytes.");
 
 PyDoc_STRVAR(sha3_384__doc__,
-"sha3_384([string]) -> SHA3 object\n\
+"sha3_384([data]) -> SHA3 object\n\
 \n\
 Return a new SHA3 hash object with a hashbit length of 48 bytes.");
 
 PyDoc_STRVAR(sha3_512__doc__,
-"sha3_512([string]) -> SHA3 object\n\
+"sha3_512([data]) -> SHA3 object\n\
 \n\
 Return a new SHA3 hash object with a hashbit length of 64 bytes.");
 
-SHA3_TYPE(SHA3_224type, "_sha3.sha3_224", py_sha3_new__doc__, SHA3_methods);
+SHA3_TYPE(SHA3_224type, "_sha3.sha3_224", sha3_224__doc__, SHA3_methods);
 SHA3_TYPE(SHA3_256type, "_sha3.sha3_256", sha3_256__doc__, SHA3_methods);
 SHA3_TYPE(SHA3_384type, "_sha3.sha3_384", sha3_384__doc__, SHA3_methods);
 SHA3_TYPE(SHA3_512type, "_sha3.sha3_512", sha3_512__doc__, SHA3_methods);
 
 #ifdef PY_WITH_KECCAK
 PyDoc_STRVAR(keccak_224__doc__,
-"keccak_224([string]) -> Keccak object\n\
+"keccak_224([data]) -> Keccak object\n\
 \n\
 Return a new Keccak hash object with a hashbit length of 28 bytes.");
 
 PyDoc_STRVAR(keccak_256__doc__,
-"keccak_256([string]) -> Keccak object\n\
+"keccak_256([data]) -> Keccak object\n\
 \n\
 Return a new Keccak hash object with a hashbit length of 32 bytes.");
 
 PyDoc_STRVAR(keccak_384__doc__,
-"keccak_384([string]) -> Keccak object\n\
+"keccak_384([data]) -> Keccak object\n\
 \n\
 Return a new Keccak hash object with a hashbit length of 48 bytes.");
 
 PyDoc_STRVAR(keccak_512__doc__,
-"keccak_512([string]) -> Keccak object\n\
+"keccak_512([data]) -> Keccak object\n\
 \n\
 Return a new Keccak hash object with a hashbit length of 64 bytes.");
 
@@ -624,15 +628,15 @@ _SHAKE_digest(SHA3object *self, unsigned long digestlen, int hex)
 /*[clinic input]
 _sha3.shake_128.digest
 
-    length: unsigned_long(bitwise=True)
-    \
+    length: unsigned_long
+    /
 
-Return the digest value as a string of binary data.
+Return the digest value as a bytes object.
 [clinic start generated code]*/
 
 static PyObject *
 _sha3_shake_128_digest_impl(SHA3object *self, unsigned long length)
-/*[clinic end generated code: output=2313605e2f87bb8f input=608c8ca80ae9d115]*/
+/*[clinic end generated code: output=2313605e2f87bb8f input=418ef6a36d2e6082]*/
 {
     return _SHAKE_digest(self, length, 0);
 }
@@ -641,15 +645,15 @@ _sha3_shake_128_digest_impl(SHA3object *self, unsigned long length)
 /*[clinic input]
 _sha3.shake_128.hexdigest
 
-    length: unsigned_long(bitwise=True)
-    \
+    length: unsigned_long
+    /
 
 Return the digest value as a string of hexadecimal digits.
 [clinic start generated code]*/
 
 static PyObject *
 _sha3_shake_128_hexdigest_impl(SHA3object *self, unsigned long length)
-/*[clinic end generated code: output=bf8e2f1e490944a8 input=64e56b4760db4573]*/
+/*[clinic end generated code: output=bf8e2f1e490944a8 input=69fb29b0926ae321]*/
 {
     return _SHAKE_digest(self, length, 1);
 }
@@ -664,12 +668,12 @@ static PyMethodDef SHAKE_methods[] = {
 };
 
 PyDoc_STRVAR(shake_128__doc__,
-"shake_128([string]) -> SHAKE object\n\
+"shake_128([data]) -> SHAKE object\n\
 \n\
 Return a new SHAKE hash object.");
 
 PyDoc_STRVAR(shake_256__doc__,
-"shake_256([string]) -> SHAKE object\n\
+"shake_256([data]) -> SHAKE object\n\
 \n\
 Return a new SHAKE hash object.");