CDRIVER-581: Don't assume write concern defaults in URI parsing

False safe/journal values should be explicitly set on the write concern. Additionally, w=1 should not be parsed as MONGOC_WRITE_CONCERN_W_DEFAULT, since the driver would then omit it from the write concern and allow a different server-side default to be applied.

Closes #195

Author: jmikola

src/mongoc/mongoc-uri.c

@@ -717,10 +717,9 @@ _mongoc_uri_build_write_concern (mongoc_uri_t *uri) /* IN */
    write_concern = mongoc_write_concern_new ();
 
    if (bson_iter_init_find_case (&iter, &uri->options, "safe") &&
-       BSON_ITER_HOLDS_BOOL (&iter) &&
-       !bson_iter_bool (&iter)) {
+       BSON_ITER_HOLDS_BOOL (&iter)) {
       mongoc_write_concern_set_w (write_concern,
-                                  MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED);
+                                  bson_iter_bool (&iter) ? 1 : MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED);
    }
 
    if (bson_iter_init_find_case (&iter, &uri->options, "wtimeoutms") &&
@@ -729,9 +728,8 @@ _mongoc_uri_build_write_concern (mongoc_uri_t *uri) /* IN */
    }
 
    if (bson_iter_init_find_case (&iter, &uri->options, "journal") &&
-       BSON_ITER_HOLDS_BOOL (&iter) &&
-       bson_iter_bool (&iter)) {
-      mongoc_write_concern_set_journal (write_concern, true);
+       BSON_ITER_HOLDS_BOOL (&iter)) {
+      mongoc_write_concern_set_journal (write_concern, bson_iter_bool (&iter));
    }
 
    if (bson_iter_init_find_case (&iter, &uri->options, "w")) {
@@ -747,12 +745,8 @@ _mongoc_uri_build_write_concern (mongoc_uri_t *uri) /* IN */
             mongoc_write_concern_set_w (write_concern,
                                         MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED);
             break;
-         case 1:
-            mongoc_write_concern_set_w (write_concern,
-                                        MONGOC_WRITE_CONCERN_W_DEFAULT);
-            break;
          default:
-            if (value > 1) {
+            if (value > 0) {
                mongoc_write_concern_set_w (write_concern, value);
                break;
             }

tests/test-mongoc-uri.c

@@ -132,6 +132,20 @@ test_mongoc_uri_new (void)
    ASSERT(!bson_iter_next(&iter));
    mongoc_uri_destroy(uri);
 
+   uri = mongoc_uri_new("mongodb://localhost/?safe=false&journal=false");
+   options = mongoc_uri_get_options(uri);
+   ASSERT(options);
+   ASSERT_CMPINT(bson_count_keys(options), ==, 2);
+   ASSERT(bson_iter_init(&iter, options));
+   ASSERT(bson_iter_find_case(&iter, "safe"));
+   ASSERT(BSON_ITER_HOLDS_BOOL(&iter));
+   ASSERT(!bson_iter_bool(&iter));
+   ASSERT(bson_iter_find_case(&iter, "journal"));
+   ASSERT(BSON_ITER_HOLDS_BOOL(&iter));
+   ASSERT(!bson_iter_bool(&iter));
+   ASSERT(!bson_iter_next(&iter));
+   mongoc_uri_destroy(uri);
+
    uri = mongoc_uri_new("mongodb:///tmp/mongodb-27017.sock/?ssl=false");
    ASSERT(uri);
    ASSERT_CMPSTR(mongoc_uri_get_hosts(uri)->host, "/tmp/mongodb-27017.sock");
@@ -413,17 +427,17 @@ test_mongoc_uri_write_concern (void)
    int i;
    static const write_concern_test tests [] = {
       { "mongodb://localhost/?safe=false", true, MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED },
-      { "mongodb://localhost/?safe=true", true, MONGOC_WRITE_CONCERN_W_DEFAULT },
+      { "mongodb://localhost/?safe=true", true, 1 },
       { "mongodb://localhost/?w=-1", true, MONGOC_WRITE_CONCERN_W_ERRORS_IGNORED },
       { "mongodb://localhost/?w=0", true, MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED },
-      { "mongodb://localhost/?w=1", true, MONGOC_WRITE_CONCERN_W_DEFAULT },
+      { "mongodb://localhost/?w=1", true, 1 },
       { "mongodb://localhost/?w=2", true, 2 },
       { "mongodb://localhost/?w=majority", true, MONGOC_WRITE_CONCERN_W_MAJORITY },
       { "mongodb://localhost/?w=10", true, 10 },
       { "mongodb://localhost/?w=", true, MONGOC_WRITE_CONCERN_W_DEFAULT },
       { "mongodb://localhost/?w=mytag", true, MONGOC_WRITE_CONCERN_W_TAG, "mytag" },
       { "mongodb://localhost/?w=mytag&safe=false", true, MONGOC_WRITE_CONCERN_W_TAG, "mytag" },
-      { "mongodb://localhost/?w=1&safe=false", true, MONGOC_WRITE_CONCERN_W_DEFAULT },
+      { "mongodb://localhost/?w=1&safe=false", true, 1 },
       { NULL }
    };