SERVER-119317 Improve object lifecycle of MD5 hash state (#50001)

GitOrigin-RevId: 0fdd1677b1724f69239befcac04f12b9a605489d

etc/backports_required_for_multiversion_tests.yml

@@ -25,6 +25,8 @@ last-continuous:
     ticket: SERVER-108945
   - test_file: jstests/core/json_schema/json_schema.js
     ticket: SERVER-98676
+  - test_file: jstests/core/filemd5.js
+    ticket: SERVER-119317
   - test_file: jstests/sharding/analyze_shard_key/analyze_shard_key_cmd_validation.js
     ticket: SERVER-95869
   - test_file: jstests/change_streams/change_streams_dynamic_match_expressions.js
@@ -664,6 +666,8 @@ last-lts:
     ticket: SERVER-108945
   - test_file: jstests/core/json_schema/json_schema.js
     ticket: SERVER-98676
+  - test_file: jstests/core/filemd5.js
+    ticket: SERVER-119317
   - test_file: jstests/sharding/analyze_shard_key/analyze_shard_key_cmd_validation.js
     ticket: SERVER-95869
   - test_file: jstests/change_streams/change_streams_dynamic_match_expressions.js

jstests/core/filemd5.js

@@ -24,4 +24,25 @@ assert.commandWorked(db.fs.chunks.insert({files_id: 2, n: 0}));
 assert.commandFailedWithCode(db.runCommand({filemd5: 2, root: "fs"}), 50848);
 assert.commandWorked(db.fs.chunks.update({files_id: 2, n: 0}, {$set: {data: 5}}));
 assert.commandFailedWithCode(db.runCommand({filemd5: 2, root: "fs"}), 50849);
-}());
+
+{
+    const result = assert.commandWorked(
+        db.runCommand({
+            filemd5: ObjectId("000000000000000000000000"),
+            root: "fs",
+            partialOk: true,
+        }),
+    );
+
+    assert(result.md5state !== undefined,
+           "Expected md5state in filemd5 response with partialOk: true");
+    const hex = result.md5state.hex();
+    const totalBytes = hex.length / 2;
+    assert.gt(totalBytes, 72, "md5state expected to be larger than 72 bytes");
+
+    const checkFromByte = 72;
+    const paddingHex = hex.substring(checkFromByte * 2);
+    const allZeros = "0".repeat(paddingHex.length);
+    assert.eq(paddingHex, allZeros, "md5state expected to be zero padded");
+}
+})();

src/mongo/util/md5.cpp

@@ -309,6 +309,8 @@ static void md5_process(md5_state_t* pms, const md5_byte_t* data /*[64]*/) {
 }
 
 void md5_init(md5_state_t* pms) {
+    memset(pms, 0, sizeof(md5_state_t));
+
     pms->count[0] = pms->count[1] = 0;
     pms->abcd[0] = 0x67452301;
     pms->abcd[1] = /*0xefcdab89*/ T_MASK ^ 0x10325476;