bpo-45138: Expand traced SQL statements in sqlite3 trace callback

[erlend-aasland]

https://bugs.python.org/issue45138

[erlend-aasland]

I'll resolve the conflicting files after GH-29327 has been merged. Fixed.

[erlend-aasland]

Note to self: after GH-29356 has landed, add test for too long SQL statements. Done

[erlend-aasland]

Coverage for trace_callback() is now pretty good.

 1056|       |static int
 1057|       |trace_callback(unsigned int type, void *ctx, void *stmt, void *sql)
 1058|       |#else
 1059|       |static void
 1060|       |trace_callback(void *ctx, const char *sql)
 1061|       |#endif
 1062|     20|{
 1063|     20|#ifdef HAVE_TRACE_V2
 1064|     20|    if (type != SQLITE_TRACE_STMT) {
 1065|      0|        return 0;
 1066|      0|    }
 1067|     20|#endif
 1068|       |
 1069|     20|    PyGILState_STATE gilstate = PyGILState_Ensure();
 1070|       |
 1071|     20|    assert(ctx != NULL);
 1072|     20|    PyObject *py_statement = NULL;
 1073|     20|#ifdef HAVE_TRACE_V2
 1074|     20|    assert(stmt != NULL);
 1075|     20|    const char *expanded_sql = sqlite3_expanded_sql((sqlite3_stmt *)stmt);
 1076|     20|    if (expanded_sql == NULL) {
 1077|      2|        sqlite3 *db = sqlite3_db_handle((sqlite3_stmt *)stmt);
 1078|      2|        if (sqlite3_errcode(db) == SQLITE_NOMEM) {
 1079|      0|            (void)PyErr_NoMemory();
 1080|      0|            goto exit;
 1081|      0|        }
 1082|       |
 1083|      2|        pysqlite_state *state = ((callback_context *)ctx)->state;
 1084|      2|        assert(state != NULL);
 1085|      2|        PyErr_SetString(state->DataError,
 1086|      2|                        "Expanded SQL string exceeds the maximum string "
 1087|      2|                        "length");
 1088|       |
 1089|       |        // Fall back to unexpanded sql
 1090|      2|        py_statement = PyUnicode_FromString((const char *)sql);
 1091|      2|    }
 1092|     18|    else {
 1093|     18|        py_statement = PyUnicode_FromString(expanded_sql);
 1094|     18|        sqlite3_free((void *)expanded_sql);
 1095|     18|    }
 1096|       |#else
 1097|       |    py_statement = PyUnicode_FromString(sql);
 1098|       |#endif
 1099|     20|    if (py_statement) {
 1100|     20|        PyObject *exc, *val, *tb;
 1101|     20|        PyErr_Fetch(&exc, &val, &tb);
 1102|       |
 1103|     20|        PyObject *callable = ((callback_context *)ctx)->callable;
 1104|     20|        PyObject *ret = PyObject_CallOneArg(callable, py_statement);
 1105|     20|        Py_DECREF(py_statement);
 1106|     20|        Py_XDECREF(ret);
 1107|       |
 1108|     20|        _PyErr_ChainExceptions(exc, val, tb);
 1109|     20|    }
 1110|       |
 1111|     20|    if (PyErr_Occurred()) {
 1112|      4|        print_or_clear_traceback((callback_context *)ctx);
 1113|      4|    }
 1114|       |
 1115|     20|exit:
 1116|     20|    PyGILState_Release(gilstate);
 1117|     20|#ifdef HAVE_TRACE_V2
 1118|     20|    return 0;
 1119|     20|#endif
 1120|     20|}

[erlend-aasland]

I believe I've addressed everything here, @pablogsal. Let me know if you want further changes.

[JelleZijlstra]

Thanks, a few small comments

[JelleZijlstra]

Looks good! @gvanrossum I'm planning to merge this change, another SQLite enhancement by Erlend.

[erlend-aasland]

Thanks, @JelleZijlstra!

[kumaraditya303]

This change broke several buildbots See https://buildbot.python.org/all/#/builders/58/builds/1850

[erlend-aasland]

I'm aware, and I'm coming up with a fix for that test.