SERVER-34975 Treat an OID-embedded timestamp as unsigned.

5 files changed, 22 insertions, 12 deletions

diff --git a/src/mongo/bson/oid.cpp b/src/mongo/bson/oid.cpp
index 26d90d97bad..ca9c6e558a9 100644
--- a/src/mongo/bson/oid.cpp
+++ b/src/mongo/bson/oid.cpp
@@ -162,10 +162,6 @@ void OID::init(Date_t date, bool max) {
     std::memcpy(_view().view(kInstanceUniqueOffset), &rest, kInstanceUniqueSize + kIncrementSize);
 }
 
-time_t OID::asTimeT() const {
-    return getTimestamp();
-}
-
 std::string OID::toString() const {
     return toHexLower(_data, kOIDSize);
 }
diff --git a/src/mongo/bson/oid.h b/src/mongo/bson/oid.h
index 4474a12dbe2..7f4f31a4369 100644
--- a/src/mongo/bson/oid.h
+++ b/src/mongo/bson/oid.h
@@ -176,9 +176,8 @@ public:
      */
     void initFromTermNumber(int64_t term);
 
-    time_t asTimeT() const;
     Date_t asDateT() const {
-        return Date_t::fromMillisSinceEpoch(asTimeT() * 1000LL);
+        return Date_t::fromMillisSinceEpoch(getTimestamp() * 1000LL);
     }
 
     // True iff the OID is not empty
@@ -198,8 +197,8 @@ public:
     static unsigned getMachineId();  // used by the 'features' command
     static void regenMachineId();
 
-    // Timestamp is 4 bytes so we just use int32_t
-    typedef int32_t Timestamp;
+    // Timestamp is a 4-byte positive integer so we use uint32_t
+    typedef uint32_t Timestamp;
 
     // Wrappers so we can return stuff by value.
     struct InstanceUnique {
diff --git a/src/mongo/bson/oid_test.cpp b/src/mongo/bson/oid_test.cpp
index 8be156ae41d..6d34d6a5808 100644
--- a/src/mongo/bson/oid_test.cpp
+++ b/src/mongo/bson/oid_test.cpp
@@ -109,7 +109,7 @@ TEST(Basic, Deserialize) {
         0xDEu,
         0xADu,
         0xBEu,
-        0xEFu,  // timestamp is -559038737 (signed)
+        0xEFu,  // timestamp is 3735928559 (unsigned)
         0x00u,
         0x00u,
         0x00u,
@@ -122,7 +122,7 @@ TEST(Basic, Deserialize) {
 
     OID o1 = OID::from(OIDbytes);
 
-    ASSERT_EQUALS(o1.getTimestamp(), -559038737);
+    ASSERT_EQUALS(o1.getTimestamp(), 3735928559);
     OID::InstanceUnique u = o1.getInstanceUnique();
     for (std::size_t i = 0; i < OID::kInstanceUniqueSize; ++i) {
         ASSERT_EQUALS(u.bytes[i], 0x00u);
@@ -158,7 +158,7 @@ TEST(Basic, FromTerm) {
     auto oidHead = oidStr.substr(0, 8);
     auto oidTail = oidStr.substr(oidStr.length() - 1);
 
-    ASSERT_EQUALS("7fffffff", oidHead);
+    ASSERT_EQUALS("ffffffff", oidHead);
     ASSERT_EQUALS(term, std::stoi(oidTail));
 }
 }
diff --git a/src/mongo/db/pipeline/expression_convert_test.cpp b/src/mongo/db/pipeline/expression_convert_test.cpp
index 3cc94e92e8e..9db02ed058e 100644
--- a/src/mongo/db/pipeline/expression_convert_test.cpp
+++ b/src/mongo/db/pipeline/expression_convert_test.cpp
@@ -1947,6 +1947,21 @@ TEST_F(ExpressionConvertTest, ConvertObjectIdToDate) {
               "2017-10-19T13:30:00.000Z");
 }
 
+TEST_F(ExpressionConvertTest, ConvertObjectIdToDateFuture) {
+    auto expCtx = getExpCtx();
+
+    auto spec = BSON("$convert" << BSON("input"
+                                        << "$path1"
+                                        << "to"
+                                        << "date"));
+    auto convertExp = Expression::parseExpression(expCtx, spec, expCtx->variablesParseState);
+
+    Document oidInput{{"path1", OID("8071be82122d3312074f0300")}};
+
+    ASSERT_EQ(dateToISOStringUTC(convertExp->evaluate(oidInput).getDate()),
+              "2038-04-15T09:53:06.000Z");
+}
+
 TEST_F(ExpressionConvertTest, ConvertStringToInt) {
     auto expCtx = getExpCtx();
 
diff --git a/src/mongo/dbtests/jsobjtests.cpp b/src/mongo/dbtests/jsobjtests.cpp
index b670cab1dae..68ce6c52d63 100644
--- a/src/mongo/dbtests/jsobjtests.cpp
+++ b/src/mongo/dbtests/jsobjtests.cpp
@@ -1390,7 +1390,7 @@ public:
         oid.init(base);
 
         ASSERT_EQUALS(base.toMillisSinceEpoch() / 1000, oid.asDateT().toMillisSinceEpoch() / 1000);
-        ASSERT_EQUALS(base.toTimeT(), oid.asTimeT());
+        ASSERT_EQUALS(base.toTimeT(), static_cast<time_t>(oid.getTimestamp()));
     }
 };