sha1dc: declare all variables at begininng of block

This is required to appease ancient C language standards, which
msvc 2008 still requires for Python 2.7 on Windows.

Differential Revision: https://phab.mercurial-scm.org/D7877

mercurial/thirdparty/sha1dc/cext.c

@@ -1,197 +1,198 b''
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
 
 #include "lib/sha1.h"
 
 #if PY_MAJOR_VERSION >= 3
 #define IS_PY3K
 #endif
 
 /* helper to switch things like string literal depending on Python version */
 #ifdef IS_PY3K
 #define PY23(py2, py3) py3
 #else
 #define PY23(py2, py3) py2
 #endif
 
 static char sha1dc_doc[] = "Efficient detection of SHA1 collision constructs.";
 
 /* clang-format off */
 typedef struct {
 	PyObject_HEAD
 	SHA1_CTX ctx;
 } pysha1ctx;
 /* clang-format on */
 
 static int pysha1ctx_init(pysha1ctx *self, PyObject *args)
 {
 	const char *data = NULL;
 	Py_ssize_t len;
 
 	SHA1DCInit(&(self->ctx));
 	/* We don't want "safe" sha1s, wherein sha1dc can give you a
 	   different hash for something that's trying to give you a
 	   collision. We just want to detect collisions.
 	 */
 	SHA1DCSetSafeHash(&(self->ctx), 0);
 	if (!PyArg_ParseTuple(args, PY23("|s#", "|y#"), &data, &len)) {
 		return -1;
 	}
 	if (data) {
 		SHA1DCUpdate(&(self->ctx), data, len);
 	}
 	return 0;
 }
 
 static void pysha1ctx_dealloc(pysha1ctx *self)
 {
 	PyObject_Del(self);
 }
 
 static PyObject *pysha1ctx_update(pysha1ctx *self, PyObject *args)
 {
 	const char *data;
 	Py_ssize_t len;
 	if (!PyArg_ParseTuple(args, PY23("s#", "y#"), &data, &len)) {
 		return NULL;
 	}
 	SHA1DCUpdate(&(self->ctx), data, len);
 	Py_RETURN_NONE;
 }
 
 /* it is intentional that this take a ctx by value, as that clones the
    context so we can keep using .update() without poisoning the state
    with padding.
 */
 static int finalize(SHA1_CTX ctx, unsigned char *hash_out)
 {
 	if (SHA1DCFinal(hash_out, &ctx)) {
 		PyErr_SetString(PyExc_OverflowError,
 		                "sha1 collision attack detected");
 		return 0;
 	}
 	return 1;
 }
 
 static PyObject *pysha1ctx_digest(pysha1ctx *self)
 {
 	unsigned char hash[20];
 	if (!finalize(self->ctx, hash)) {
 		return NULL;
 	}
 	return PyBytes_FromStringAndSize((char *)hash, 20);
 }
 
 static PyObject *pysha1ctx_hexdigest(pysha1ctx *self)
 {
+	static const char hexdigit[] = "0123456789abcdef";
 	unsigned char hash[20];
+	char hexhash[40];
+	int i;
 	if (!finalize(self->ctx, hash)) {
 		return NULL;
 	}
-	char hexhash[40];
-	static const char hexdigit[] = "0123456789abcdef";
-	for (int i = 0; i < 20; ++i) {
+	for (i = 0; i < 20; ++i) {
 		hexhash[i * 2] = hexdigit[hash[i] >> 4];
 		hexhash[i * 2 + 1] = hexdigit[hash[i] & 15];
 	}
 	return PyString_FromStringAndSize(hexhash, 40);
 }
 
 static PyTypeObject sha1ctxType;
 
 static PyObject *pysha1ctx_copy(pysha1ctx *self)
 {
 	pysha1ctx *clone = (pysha1ctx *)PyObject_New(pysha1ctx, &sha1ctxType);
 	if (!clone) {
 		return NULL;
 	}
 	clone->ctx = self->ctx;
 	return (PyObject *)clone;
 }
 
 static PyMethodDef pysha1ctx_methods[] = {
     {"update", (PyCFunction)pysha1ctx_update, METH_VARARGS,
      "Update this hash object's state with the provided bytes."},
     {"digest", (PyCFunction)pysha1ctx_digest, METH_NOARGS,
      "Return the digest value as a string of binary data."},
     {"hexdigest", (PyCFunction)pysha1ctx_hexdigest, METH_NOARGS,
      "Return the digest value as a string of hexadecimal digits."},
     {"copy", (PyCFunction)pysha1ctx_copy, METH_NOARGS,
      "Return a copy of the hash object."},
     {NULL},
 };
 
 /* clang-format off */
 static PyTypeObject sha1ctxType = {
 	PyVarObject_HEAD_INIT(NULL, 0)                    /* header */
 	"sha1dc.sha1",                                    /* tp_name */
 	sizeof(pysha1ctx),                                /* tp_basicsize */
 	0,                                                /* tp_itemsize */
 	(destructor)pysha1ctx_dealloc,                    /* tp_dealloc */
 	0,                                                /* tp_print */
 	0,                                                /* tp_getattr */
 	0,                                                /* tp_setattr */
 	0,                                                /* tp_compare */
 	0,                                                /* tp_repr */
 	0,                                                /* tp_as_number */
 	0,                                                /* tp_as_sequence */
 	0,                                                /* tp_as_mapping */
 	0,                                                /* tp_hash */
 	0,                                                /* tp_call */
 	0,                                                /* tp_str */
 	0,                                                /* tp_getattro */
 	0,                                                /* tp_setattro */
 	0,                                                /* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT,                               /* tp_flags */
 	"sha1 implementation that looks for collisions",  /* tp_doc */
 	0,                                                /* tp_traverse */
 	0,                                                /* tp_clear */
 	0,                                                /* tp_richcompare */
 	0,                                                /* tp_weaklistoffset */
 	0,                                                /* tp_iter */
 	0,                                                /* tp_iternext */
 	pysha1ctx_methods,                                /* tp_methods */
 	0,                                                /* tp_members */
 	0,                                                /* tp_getset */
 	0,                                                /* tp_base */
 	0,                                                /* tp_dict */
 	0,                                                /* tp_descr_get */
 	0,                                                /* tp_descr_set */
 	0,                                                /* tp_dictoffset */
 	(initproc)pysha1ctx_init,                         /* tp_init */
 	0,                                                /* tp_alloc */
 };
 /* clang-format on */
 
 static PyMethodDef methods[] = {
     {NULL, NULL},
 };
 
 static void module_init(PyObject *mod)
 {
 	sha1ctxType.tp_new = PyType_GenericNew;
 	if (PyType_Ready(&sha1ctxType) < 0) {
 		return;
 	}
 	Py_INCREF(&sha1ctxType);
 
 	PyModule_AddObject(mod, "sha1", (PyObject *)&sha1ctxType);
 }
 
 #ifdef IS_PY3K
 static struct PyModuleDef sha1dc_module = {PyModuleDef_HEAD_INIT, "sha1dc",
                                            sha1dc_doc, -1, methods};
 
 PyMODINIT_FUNC PyInit_sha1dc(void)
 {
 	PyObject *mod = PyModule_Create(&sha1dc_module);
 	module_init(mod);
 	return mod;
 }
 #else
 PyMODINIT_FUNC initsha1dc(void)
 {
 	PyObject *mod = Py_InitModule3("sha1dc", methods, sha1dc_doc);
 	module_init(mod);
 }
 #endif