Merge pull request #2774 from enkore/f/cleanup-c

Some C/Cython cleanup

src/borg/_hashindex.c

@@ -280,7 +280,7 @@ hashindex_read(PyObject *file_py, int permit_compact)
 {
     Py_ssize_t length, buckets_length, bytes_read;
     Py_buffer header_buffer;
-    PyObject *header_bytes, *length_object, *bucket_bytes;
+    PyObject *header_bytes, *length_object, *bucket_bytes, *tmp;
     HashHeader *header;
     HashIndex *index = NULL;
 
@@ -307,7 +307,8 @@ hashindex_read(PyObject *file_py, int permit_compact)
      * Hash the header
      * If the header is corrupted this bails before doing something stupid (like allocating 3.8 TB of memory)
      */
-    Py_XDECREF(PyObject_CallMethod(file_py, "hash_part", "s", "HashHeader"));
+    tmp = PyObject_CallMethod(file_py, "hash_part", "s", "HashHeader");
+    Py_XDECREF(tmp);
     if(PyErr_Occurred()) {
         if(PyErr_ExceptionMatches(PyExc_AttributeError)) {
             /* Be able to work with regular file objects which do not have a hash_part method. */
@@ -329,7 +330,8 @@ hashindex_read(PyObject *file_py, int permit_compact)
         goto fail_decref_header;
     }
 
-    Py_XDECREF(PyObject_CallMethod(file_py, "seek", "ni", (Py_ssize_t)sizeof(HashHeader), SEEK_SET));
+    tmp = PyObject_CallMethod(file_py, "seek", "ni", (Py_ssize_t)sizeof(HashHeader), SEEK_SET);
+    Py_XDECREF(tmp);
     if(PyErr_Occurred()) {
         goto fail_decref_header;
     }
@@ -479,7 +481,7 @@ hashindex_free(HashIndex *index)
 static void
 hashindex_write(HashIndex *index, PyObject *file_py)
 {
-    PyObject *length_object, *buckets_view;
+    PyObject *length_object, *buckets_view, *tmp;
     Py_ssize_t length;
     Py_ssize_t buckets_length = (Py_ssize_t)index->num_buckets * index->bucket_size;
     HashHeader header = {
@@ -507,7 +509,8 @@ hashindex_write(HashIndex *index, PyObject *file_py)
     /*
      * Hash the header
      */
-    Py_XDECREF(PyObject_CallMethod(file_py, "hash_part", "s", "HashHeader"));
+    tmp = PyObject_CallMethod(file_py, "hash_part", "s", "HashHeader");
+    Py_XDECREF(tmp);
     if(PyErr_Occurred()) {
         if(PyErr_ExceptionMatches(PyExc_AttributeError)) {
             /* Be able to work with regular file objects which do not have a hash_part method. */

src/borg/crypto/low_level.pyx

@@ -6,6 +6,7 @@ from math import ceil
 
 from libc.stdlib cimport malloc, free
 from cpython.buffer cimport PyBUF_SIMPLE, PyObject_GetBuffer, PyBuffer_Release
+from cpython.bytes cimport PyBytes_FromStringAndSize
 
 API_VERSION = '1.1_01'
 
@@ -201,19 +202,18 @@ cdef class AES:
 
 
 def hmac_sha256(key, data):
-    md = bytes(32)
     cdef Py_buffer data_buf = ro_buffer(data)
     cdef const unsigned char *key_ptr = key
     cdef int key_len = len(key)
-    cdef unsigned char *md_ptr = md
+    cdef unsigned char md[32]
     try:
         with nogil:
-            rc = HMAC(EVP_sha256(), key_ptr, key_len, <const unsigned char*> data_buf.buf, data_buf.len, md_ptr, NULL)
-        if rc != md_ptr:
+            rc = HMAC(EVP_sha256(), key_ptr, key_len, <const unsigned char*> data_buf.buf, data_buf.len, md, NULL)
+        if rc != md:
             raise Exception('HMAC(EVP_sha256) failed')
     finally:
         PyBuffer_Release(&data_buf)
-    return md
+    return PyBytes_FromStringAndSize(<char*> &md[0], 32)
 
 
 cdef blake2b_update_from_buffer(blake2b_state *state, obj):
@@ -232,8 +232,7 @@ def blake2b_256(key, data):
     if blake2b_init(&state, 32) == -1:
         raise Exception('blake2b_init() failed')
 
-    md = bytes(32)
-    cdef unsigned char *md_ptr = md
+    cdef unsigned char md[32]
     cdef unsigned char *key_ptr = key
 
     # This is secure, because BLAKE2 is not vulnerable to length-extension attacks (unlike SHA-1/2, MD-5 and others).
@@ -246,11 +245,11 @@ def blake2b_256(key, data):
         raise Exception('blake2b_update() failed')
     blake2b_update_from_buffer(&state, data)
 
-    rc = blake2b_final(&state, md_ptr, 32)
+    rc = blake2b_final(&state, &md[0], 32)
     if rc == -1:
         raise Exception('blake2b_final() failed')
 
-    return md
+    return PyBytes_FromStringAndSize(<char*> &md[0], 32)
 
 
 def hkdf_hmac_sha512(ikm, salt, info, output_length):