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copied!<p>A few comments on your code to help improve it, IMHO. There are functions provided by the python C API that do exactly what you need to do, and make sure everything conforms to the Python way of doing things. It will handle embedded NULL's without a problem.</p> <p>Rather than calling <code>malloc</code> directly, change this:</p> <pre><code>cdef char *ciphertext = <char *>malloc(src_len) </code></pre> <p>to</p> <pre><code>cdef str retval = PyString_FromStringAndSize(PyString_AsString(source), <Py_ssize_t>src_len) cdef char *ciphertext = PyString_AsString(retval) </code></pre> <p>The above lines will create a brand new Python str object initialized to the contents of <code>source</code>. The second line points <code>ciphertext</code> to <code>retval</code>'s internal <code>char *</code> buffer without copying. Whatever modifies <code>ciphertext</code> will modify <code>retval</code>. Since <code>retval</code> is a brand new Python str, it can be modified by C code before being returned from <code>_real_encrypt</code>.</p> <p>See the Python C/API docs on the above functions for more details, <a href="http://docs.python.org/c-api/string.html#PyString_FromStringAndSize" rel="nofollow">here</a> and <a href="http://docs.python.org/c-api/string.html#PyString_AsString" rel="nofollow">here</a>.</p> <p>The net effect saves you a copy. The whole code would be something like:</p> <pre><code>cdef extern from "Python.h": object PyString_FromStringAndSize(char *, Py_ssize_t) char *PyString_AsString(object) def _real_encrypt(self, source): src_len = len(source) cdef str retval = PyString_FromStringAndSize(PyString_AsString(source), <Py_ssize_t>src_len) cdef char *ciphertext = PyString_AsString(retval) cmc.mcrypt_generic_init(self._mcStream, <void *>self._key, len(self._key), NULL) cmc.mcrypt_generic(self._mcStream, <void *>ciphertext, src_len) # since the above initialized ciphertext, the retval str is also correctly initialized, too. cmc.mcrypt_generic_deinit(self._mcStream) return retval </code></pre>

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