Work in progress on writable encodingqstring-writable-encoding

Would help using adapt(unicode) to quote strings without a connection,
see ticket #331.

Currently in heisenbug state: if test_connection_wins_anyway and
test_encoding_default run (in this order), the latter fail because the
returned value is "'\xe8 '", with an extra space. Skipping the first
test, the second succeed.

The bad value is returned by the libpq:

    ql = PQescapeString(to+eq+1, from, len);

just returns len = 2 and an extra space in the string... meh.

1 files changed, 53 insertions, 18 deletions

diff --git a/psycopg/adapter_qstring.c b/psycopg/adapter_qstring.c
index 2e3ab0a..1e256cf 100644
--- a/psycopg/adapter_qstring.c
+++ b/psycopg/adapter_qstring.c
@@ -36,28 +36,43 @@ static const char *default_encoding = "latin1";
 
 /* qstring_quote - do the quote process on plain and unicode strings */
 
+const char *
+_qstring_get_encoding(qstringObject *self)
+{
+    /* if the wrapped object is an unicode object we can encode it to match
+       conn->encoding but if the encoding is not specified we don't know what
+       to do and we raise an exception */
+    if (self->conn) {
+        return self->conn->codec;
+    }
+    else {
+        return self->encoding ? self->encoding : default_encoding;
+    }
+}
+
 static PyObject *
 qstring_quote(qstringObject *self)
 {
     PyObject *str = NULL;
     char *s, *buffer = NULL;
     Py_ssize_t len, qlen;
-    const char *encoding = default_encoding;
+    const char *encoding;
     PyObject *rv = NULL;
 
-    /* if the wrapped object is an unicode object we can encode it to match
-       conn->encoding but if the encoding is not specified we don't know what
-       to do and we raise an exception */
-    if (self->conn) {
-        encoding = self->conn->codec;
-    }
-
+    encoding = _qstring_get_encoding(self);
     Dprintf("qstring_quote: encoding to %s", encoding);
 
-    if (PyUnicode_Check(self->wrapped) && encoding) {
-        str = PyUnicode_AsEncodedString(self->wrapped, encoding, NULL);
-        Dprintf("qstring_quote: got encoded object at %p", str);
-        if (str == NULL) goto exit;
+    if (PyUnicode_Check(self->wrapped)) {
+        if (encoding) {
+            str = PyUnicode_AsEncodedString(self->wrapped, encoding, NULL);
+            Dprintf("qstring_quote: got encoded object at %p", str);
+            if (str == NULL) goto exit;
+        }
+        else {
+            PyErr_SetString(PyExc_TypeError,
+                "missing encoding to encode unicode object");
+            goto exit;
+        }
     }
 
 #if PY_MAJOR_VERSION < 3
@@ -150,13 +165,32 @@ qstring_conform(qstringObject *self, PyObject *args)
 static PyObject *
 qstring_get_encoding(qstringObject *self)
 {
-    const char *encoding = default_encoding;
+    const char *encoding;
+    encoding = _qstring_get_encoding(self);
+    return Text_FromUTF8(encoding);
+}
 
-    if (self->conn) {
-        encoding = self->conn->codec;
-    }
+static int
+qstring_set_encoding(qstringObject *self, PyObject *pyenc)
+{
+    int rv = -1;
+    const char *tmp;
+    char *cenc;
 
-    return Text_FromUTF8(encoding);
+    /* get a C copy of the encoding (which may come from unicode) */
+    Py_INCREF(pyenc);
+    if (!(pyenc = psycopg_ensure_bytes(pyenc))) { goto exit; }
+    if (!(tmp = Bytes_AsString(pyenc))) { goto exit; }
+    if (0 > psycopg_strdup(&cenc, tmp, 0)) { goto exit; }
+
+    Dprintf("qstring_set_encoding: encoding set to %s", cenc);
+    PyMem_Free((void *)self->encoding);
+    self->encoding = cenc;
+    rv = 0;
+
+exit:
+    Py_XDECREF(pyenc);
+    return rv;
 }
 
 /** the QuotedString object **/
@@ -183,7 +217,7 @@ static PyMethodDef qstringObject_methods[] = {
 static PyGetSetDef qstringObject_getsets[] = {
     { "encoding",
         (getter)qstring_get_encoding,
-        (setter)NULL,
+        (setter)qstring_set_encoding,
         "current encoding of the adapter" },
     {NULL}
 };
@@ -216,6 +250,7 @@ qstring_dealloc(PyObject* obj)
     Py_CLEAR(self->wrapped);
     Py_CLEAR(self->buffer);
     Py_CLEAR(self->conn);
+    PyMem_Free((void *)self->encoding);
 
     Dprintf("qstring_dealloc: deleted qstring object at %p, refcnt = "
         FORMAT_CODE_PY_SSIZE_T,