SERVER-7172 Support testing whether a field is updatable.

4 files changed, 247 insertions, 2 deletions

diff --git a/src/mongo/db/ops/SConscript b/src/mongo/db/ops/SConscript
index 23cde6d7c12..7eb9e5f64e8 100644
--- a/src/mongo/db/ops/SConscript
+++ b/src/mongo/db/ops/SConscript
@@ -2,7 +2,8 @@
 
 Import("env")
 
-env.StaticLibrary('update', ['path_support.cpp'],
+env.StaticLibrary('update', ['field_checker.cpp',
+                             'path_support.cpp'],
                   LIBDEPS=['$BUILD_DIR/mongo/bson',
                            '$BUILD_DIR/mongo/foundation',
                            '$BUILD_DIR/mongo/db/common'])
@@ -11,4 +12,3 @@ env.CppUnitTest('field_checker_test', ['field_checker_test.cpp'], LIBDEPS=['upda
 
 env.CppUnitTest('path_support_test', ['path_support_test.cpp'],
                 LIBDEPS=['update', '$BUILD_DIR/mongo/mutable_bson_test_utils'])
-
diff --git a/src/mongo/db/ops/field_checker.cpp b/src/mongo/db/ops/field_checker.cpp
new file mode 100644
index 00000000000..7c097a8ac95
--- /dev/null
+++ b/src/mongo/db/ops/field_checker.cpp
@@ -0,0 +1,72 @@
+/**
+ *    Copyright (C) 2013 10gen Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mongo/db/ops/field_checker.h"
+
+#include "mongo/base/error_codes.h"
+#include "mongo/db/field_ref.h"
+
+namespace mongo {
+namespace fieldchecker {
+
+    Status basicIsUpdatable(const FieldRef& field) {
+        StringData firstPart = field.getPart(0);
+        if (firstPart.compare("_id") == 0) {
+            return Status(ErrorCodes::BadValue, "updated cannot affect the _id");
+        }
+        return Status::OK();
+    }
+
+    Status isUpdatable(const FieldRef& field) {
+        Status status = basicIsUpdatable(field);
+        if (! status.isOK()) {
+            return status;
+        }
+
+        StringData firstPart = field.getPart(0);
+        if (firstPart[0] == '$') {
+            return Status(ErrorCodes::BadValue, "field name cannot start with $");
+        }
+
+        return Status::OK();
+    }
+
+    Status isUpdatableLegacy(const FieldRef& field) {
+        return basicIsUpdatable(field);
+    }
+
+    bool isPositional(const FieldRef& fieldRef, size_t* pos, size_t* count) {
+
+        // 'count' is optional.
+        size_t dummy;
+        if (count == NULL) {
+            count = &dummy;
+        }
+
+        *count = 0;
+        size_t size = fieldRef.numParts();
+        for (size_t i=0; i<size; i++) {
+            StringData fieldPart = fieldRef.getPart(i);
+            if ((fieldPart.size() == 1) && (fieldPart[0] == '$')) {
+                if (*count == 0) *pos = i;
+                (*count)++;
+            }
+        }
+        return *count > 0;
+    }
+
+} // namespace fieldchecker
+} // namespace mongo
diff --git a/src/mongo/db/ops/field_checker.h b/src/mongo/db/ops/field_checker.h
new file mode 100644
index 00000000000..1a375e16942
--- /dev/null
+++ b/src/mongo/db/ops/field_checker.h
@@ -0,0 +1,55 @@
+/**
+ *    Copyright (C) 2013 10gen Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "mongo/base/status.h"
+
+namespace mongo {
+
+    class FieldRef;
+
+    namespace fieldchecker {
+
+        /**
+         * Returns OK if all the below conditions on 'field' are valid:
+         *   + Non-empty
+         *   + Not the _id field (or a subfield of the _id field, such as _id.x.y)
+         *   + Does not start or end with a '.'
+         *   + Does not start with a $
+         * Otherwise returns a code indicating cause of failure.
+         */
+        Status isUpdatable(const FieldRef& field);
+
+        /**
+         * Same behavior of isUpdatable but allowing update fields to start with '$'. This
+         * supports $unset on legacy fields.
+         */
+        Status isUpdatableLegacy(const FieldRef& field);
+
+        /**
+         * Returns true, the position 'pos' of the first $-sign if present in 'fieldRef', and
+         * how many other $-signs were found in 'count'. Otherwise return false.
+         *
+         * Note:
+         *   isPositional assumes that the field is updatable. Call isUpdatable() above to
+         *   verify.
+         */
+        bool isPositional(const FieldRef& fieldRef, size_t* pos, size_t* count = NULL);
+
+    } // namespace fieldchecker
+
+} // namespace mongo
diff --git a/src/mongo/db/ops/field_checker_test.cpp b/src/mongo/db/ops/field_checker_test.cpp
new file mode 100644
index 00000000000..715cc5c45ea
--- /dev/null
+++ b/src/mongo/db/ops/field_checker_test.cpp
@@ -0,0 +1,118 @@
+/**
+ *    Copyright 2013 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#include "mongo/db/ops/field_checker.h"
+
+#include "mongo/base/error_codes.h"
+#include "mongo/base/status.h"
+#include "mongo/db/field_ref.h"
+#include "mongo/unittest/unittest.h"
+
+namespace {
+
+    using mongo::ErrorCodes;
+    using mongo::FieldRef;
+    using mongo::fieldchecker::isUpdatable;
+    using mongo::fieldchecker::isUpdatableLegacy;
+    using mongo::fieldchecker::isPositional;
+    using mongo::Status;
+
+    TEST(IsUpdatable, Basics) {
+        FieldRef fieldRef;
+        fieldRef.parse("x");
+        ASSERT_OK(isUpdatable(fieldRef));
+    }
+
+    TEST(IsUpdatable, DottedFields) {
+        FieldRef fieldRef;
+        fieldRef.parse("x.y.z");
+        ASSERT_OK(isUpdatable(fieldRef));
+    }
+
+    TEST(IsUpdatable, SpecialIDField) {
+        FieldRef fieldRefID;
+        fieldRefID.parse("_id");
+        ASSERT_NOT_OK(isUpdatable(fieldRefID));
+
+        FieldRef fieldRefIDX;
+        fieldRefIDX.parse("_id.x");
+        ASSERT_NOT_OK(isUpdatable(fieldRefIDX));
+
+        FieldRef fieldRefXID;
+        fieldRefXID.parse("x._id");
+        ASSERT_OK(isUpdatable(fieldRefXID));
+
+        FieldRef fieldRefXIDZ;
+        fieldRefXIDZ.parse("x._id.z");
+        ASSERT_OK(isUpdatable(fieldRefXIDZ));
+    }
+
+    TEST(IsUpdatable, PositionalFields) {
+        FieldRef fieldRefXDollar;
+        fieldRefXDollar.parse("x.$");
+        ASSERT_OK(isUpdatable(fieldRefXDollar));
+
+        FieldRef fieldRefXDollarZ;
+        fieldRefXDollarZ.parse("x.$.z");
+        ASSERT_OK(isUpdatable(fieldRefXDollarZ));
+
+        // A document never starts with an array.
+        FieldRef fieldRefDollarB;
+        fieldRefDollarB.parse("$.b");
+        ASSERT_NOT_OK(isUpdatable(fieldRefDollarB));
+
+        FieldRef fieldRefDollar;
+        fieldRefDollar.parse("$foo");
+        ASSERT_NOT_OK(isUpdatable(fieldRefDollar));
+    }
+
+    TEST(IsUpdatableLegacy, Basics) {
+        FieldRef fieldRefDollar;
+        fieldRefDollar.parse("$foo");
+        ASSERT_OK(isUpdatableLegacy(fieldRefDollar));
+    }
+
+    TEST(isPositional, EntireArrayItem) {
+        FieldRef fieldRefPositional;
+        fieldRefPositional.parse("a.$");
+        size_t pos;
+        size_t count;
+        ASSERT_TRUE(isPositional(fieldRefPositional, &pos, &count));
+        ASSERT_EQUALS(pos, 1u);
+        ASSERT_EQUALS(count, 1u);
+    }
+
+    TEST(isPositional, ArraySubObject) {
+        FieldRef fieldRefPositional;
+        fieldRefPositional.parse("a.$.b");
+        size_t pos;
+        size_t count;
+        ASSERT_TRUE(isPositional(fieldRefPositional, &pos, &count));
+        ASSERT_EQUALS(pos, 1u);
+        ASSERT_EQUALS(count, 1u);
+    }
+
+    TEST(isPositional, MultiplePositional) {
+        FieldRef fieldRefPositional;
+        fieldRefPositional.parse("a.$.b.$.c");
+        size_t pos;
+        size_t count;
+        ASSERT_TRUE(isPositional(fieldRefPositional, &pos, &count));
+        ASSERT_EQUALS(pos, 1u);
+        ASSERT_EQUALS(count, 2u);
+    }
+
+} // unnamed namespace