Add libpq version discovery

doc/src/extensions.rst

@@ -197,6 +197,16 @@ functionalities defined by the |DBAPI|_.
 
     .. versionadded:: 2.2.0
 
+.. function:: libpq_version()
+
+    Query actual ``libpq`` version loaded.
+
+    This function throws `NotSupportedError` if it was compiled with
+    ``libpq < 9.1``.
+
+    .. seealso:: libpq docs for `PQlibVersion()`__
+
+        .. __: http://www.postgresql.org/docs/current/static/libpq-misc.html#LIBPQ-PQLIBVERSION
 
 .. _sql-adaptation-objects:
 

doc/src/module.rst

@@ -109,6 +109,12 @@ The module interface respects the standard defined in the |DBAPI|_.
     by the interface.  For `psycopg2` is ``pyformat``.  See also
     :ref:`query-parameters`.
 
+.. data:: __libpq_version__
+
+   Integer contant containing the version of ``libpq`` this `psycopg2`
+   module was compiled with.  If this value is ``>= 90100`` then you
+   may query for the actually loaded version of libpq using
+   `~psycopg2.extensions.libpq_version()`.
 
 
 .. index::

lib/__init__.py

@@ -57,7 +57,7 @@ from psycopg2._psycopg import IntegrityError, InterfaceError, InternalError
 from psycopg2._psycopg import NotSupportedError, OperationalError
 
 from psycopg2._psycopg import _connect, apilevel, threadsafety, paramstyle
-from psycopg2._psycopg import __version__
+from psycopg2._psycopg import __version__, __libpq_version__
 
 from psycopg2 import tz
 

lib/extensions.py

@@ -56,7 +56,7 @@ try:
 except ImportError:
     pass
 
-from psycopg2._psycopg import adapt, adapters, encodings, connection, cursor, lobject, Xid
+from psycopg2._psycopg import adapt, adapters, encodings, connection, cursor, lobject, Xid, libpq_version
 from psycopg2._psycopg import string_types, binary_types, new_type, new_array_type, register_type
 from psycopg2._psycopg import ISQLQuote, Notify, Diagnostics, Column
 

psycopg/psycopgmodule.c

@@ -300,6 +300,19 @@ exit:
     return rv;
 }
 
+#define psyco_libpq_version_doc "Query actual libpq version loaded."
+
+static PyObject*
+psyco_libpq_version(PyObject *self)
+{
+#if PG_VERSION_HEX >= 0x090100
+    return PyInt_FromLong(PQlibVersion());
+#else
+    PyErr_SetString(NotSupportedError, "version discovery is not supported in libpq < 9.1");
+    return NULL;
+#endif
+}
+
 /* psyco_encodings_fill
 
    Fill the module's postgresql<->python encoding table */
@@ -704,6 +717,8 @@ static PyMethodDef psycopgMethods[] = {
      METH_VARARGS|METH_KEYWORDS, typecast_from_python_doc},
     {"new_array_type", (PyCFunction)typecast_array_from_python,
      METH_VARARGS|METH_KEYWORDS, typecast_array_from_python_doc},
+    {"libpq_version", (PyCFunction)psyco_libpq_version,
+     METH_NOARGS, psyco_libpq_version_doc},
 
     {"Date",  (PyCFunction)psyco_Date,
      METH_VARARGS, psyco_Date_doc},
@@ -899,6 +914,7 @@ INIT_MODULE(_psycopg)(void)
     /* set some module's parameters */
     PyModule_AddStringConstant(module, "__version__", PSYCOPG_VERSION);
     PyModule_AddStringConstant(module, "__doc__", "psycopg PostgreSQL driver");
+    PyModule_AddIntConstant(module, "__libpq_version__", PG_VERSION_NUM);
     PyModule_AddObject(module, "apilevel", Text_FromUTF8(APILEVEL));
     PyModule_AddObject(module, "threadsafety", PyInt_FromLong(THREADSAFETY));
     PyModule_AddObject(module, "paramstyle", Text_FromUTF8(PARAMSTYLE));

setup.py

@@ -416,6 +416,9 @@ class psycopg_build_ext(build_ext):
                                                                 % pgversion)
                 sys.exit(1)
 
+            define_macros.append(("PG_VERSION_NUM", "%d%02d%02d" %
+                                  (pgmajor, pgminor, pgpatch)))
+
             define_macros.append(("PG_VERSION_HEX", "0x%02X%02X%02X" %
                                   (pgmajor, pgminor, pgpatch)))
 

tests/testutils.py

@@ -236,6 +236,43 @@ def skip_after_postgres(*ver):
         return skip_after_postgres__
     return skip_after_postgres_
 
+def libpq_version():
+    import psycopg2
+    v = psycopg2.__libpq_version__
+    if v >= 90100:
+        v = psycopg2.extensions.libpq_version()
+    return v
+
+def skip_before_libpq(*ver):
+    """Skip a test if libpq we're linked to is older than a certain version."""
+    ver = ver + (0,) * (3 - len(ver))
+    def skip_before_libpq_(f):
+        @wraps(f)
+        def skip_before_libpq__(self):
+            v = libpq_version()
+            if v < int("%d%02d%02d" % ver):
+                return self.skipTest("skipped because libpq %d" % v)
+            else:
+                return f(self)
+
+        return skip_before_libpq__
+    return skip_before_libpq_
+
+def skip_after_libpq(*ver):
+    """Skip a test if libpq we're linked to is newer than a certain version."""
+    ver = ver + (0,) * (3 - len(ver))
+    def skip_after_libpq_(f):
+        @wraps(f)
+        def skip_after_libpq__(self):
+            v = libpq_version()
+            if v >= int("%d%02d%02d" % ver):
+                return self.skipTest("skipped because libpq %s" % v)
+            else:
+                return f(self)
+
+        return skip_after_libpq__
+    return skip_after_libpq_
+
 def skip_before_python(*ver):
     """Skip a test on Python before a certain version."""
     def skip_before_python_(f):