Release memory when overwriting oneof fields.

Update issue 131
Status: FixedInGit

pb_decode.c

@@ -48,6 +48,7 @@ static bool checkreturn pb_skip_string(pb_istream_t *stream);
 
 #ifdef PB_ENABLE_MALLOC
 static bool checkreturn allocate_field(pb_istream_t *stream, void *pData, size_t data_size, size_t array_size);
+static bool checkreturn pb_release_union_field(pb_istream_t *stream, pb_field_iter_t *iter);
 static void pb_release_single_field(const pb_field_iter_t *iter);
 #endif
 
@@ -628,6 +629,16 @@ static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type
 
 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iter_t *iter)
 {
+#ifdef PB_ENABLE_MALLOC
+    /* When decoding an oneof field, check if there is old data that must be
+     * released first. */
+    if (PB_HTYPE(iter->pos->type) == PB_HTYPE_ONEOF)
+    {
+        if (!pb_release_union_field(stream, iter))
+            return false;
+    }
+#endif
+
     switch (PB_ATYPE(iter->pos->type))
     {
         case PB_ATYPE_STATIC:
@@ -936,6 +947,34 @@ bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *
 }
 
 #ifdef PB_ENABLE_MALLOC
+/* Given an oneof field, if there has already been a field inside this oneof,
+ * release it before overwriting with a different one. */
+static bool pb_release_union_field(pb_istream_t *stream, pb_field_iter_t *iter)
+{
+    pb_size_t old_tag = *(pb_size_t*)iter->pSize; /* Previous which_ value */
+    pb_size_t new_tag = iter->pos->tag; /* New which_ value */
+
+    if (old_tag == 0)
+        return true; /* Ok, no old data in union */
+
+    if (old_tag == new_tag)
+        return true; /* Ok, old data is of same type => merge */
+
+    /* Release old data. The find can fail if the message struct contains
+     * invalid data. */
+    if (!pb_field_iter_find(iter, old_tag))
+        PB_RETURN_ERROR(stream, "invalid union tag");
+
+    pb_release_single_field(iter);
+
+    /* Restore iterator to where it should be.
+     * This shouldn't fail unless the pb_field_t structure is corrupted. */
+    if (!pb_field_iter_find(iter, new_tag))
+        PB_RETURN_ERROR(stream, "iterator error");
+    
+    return true;
+}
+
 static void pb_release_single_field(const pb_field_iter_t *iter)
 {
     pb_type_t type;

tests/mem_release/mem_release.c

@@ -14,8 +14,31 @@
 
 static char *test_str_arr[] = {"1", "2", ""};
 static SubMessage test_msg_arr[] = {SubMessage_init_zero, SubMessage_init_zero};
+static pb_extension_t ext1, ext2;
 
-static bool do_test()
+static void fill_TestMessage(TestMessage *msg)
+{
+    msg->static_req_submsg.dynamic_str = "12345";
+    msg->static_req_submsg.dynamic_str_arr_count = 3;
+    msg->static_req_submsg.dynamic_str_arr = test_str_arr;
+    msg->static_req_submsg.dynamic_submsg_count = 2;
+    msg->static_req_submsg.dynamic_submsg = test_msg_arr;
+    msg->static_req_submsg.dynamic_submsg[1].dynamic_str = "abc";
+    msg->static_opt_submsg.dynamic_str = "abc";
+    msg->has_static_opt_submsg = true;
+    msg->dynamic_submsg = &msg->static_req_submsg;
+
+    msg->extensions = &ext1;
+    ext1.type = &dynamic_ext;
+    ext1.dest = &msg->static_req_submsg;
+    ext1.next = &ext2;
+    ext2.type = &static_ext;
+    ext2.dest = &msg->static_req_submsg;
+    ext2.next = NULL;
+}
+
+/* Basic fields, nested submessages, extensions */
+static bool test_TestMessage()
 {
     uint8_t buffer[256];
     size_t msgsize;
@@ -23,25 +46,9 @@ static bool do_test()
     /* Construct a message with various fields filled in */
     {
         TestMessage msg = TestMessage_init_zero;
-        pb_extension_t ext1, ext2;
         pb_ostream_t stream;
-        msg.static_req_submsg.dynamic_str = "12345";
-        msg.static_req_submsg.dynamic_str_arr_count = 3;
-        msg.static_req_submsg.dynamic_str_arr = test_str_arr;
-        msg.static_req_submsg.dynamic_submsg_count = 2;
-        msg.static_req_submsg.dynamic_submsg = test_msg_arr;
-        msg.static_req_submsg.dynamic_submsg[1].dynamic_str = "abc";
-        msg.static_opt_submsg.dynamic_str = "abc";
-        msg.has_static_opt_submsg = true;
-        msg.dynamic_submsg = &msg.static_req_submsg;
-        
-        msg.extensions = &ext1;
-        ext1.type = &dynamic_ext;
-        ext1.dest = &msg.static_req_submsg;
-        ext1.next = &ext2;
-        ext2.type = &static_ext;
-        ext2.dest = &msg.static_req_submsg;
-        ext2.next = NULL;
+
+        fill_TestMessage(&msg);
         
         stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
         if (!pb_encode(&stream, TestMessage_fields, &msg))
@@ -61,8 +68,7 @@ static bool do_test()
         TestMessage msg = TestMessage_init_zero;
         pb_istream_t stream;
         SubMessage ext2_dest;
-        pb_extension_t ext1, ext2;
-        
+
         msg.extensions = &ext1;
         ext1.type = &dynamic_ext;
         ext1.dest = NULL;
@@ -102,9 +108,76 @@ static bool do_test()
     return true;
 }
 
+/* Oneofs */
+static bool test_OneofMessage()
+{
+    uint8_t buffer[256];
+    size_t msgsize;
+
+    {
+        pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
+
+        /* Encode first with TestMessage */
+        {
+            OneofMessage msg = OneofMessage_init_zero;
+            msg.which_msgs = OneofMessage_msg1_tag;
+
+            fill_TestMessage(&msg.msgs.msg1);
+
+            if (!pb_encode(&stream, OneofMessage_fields, &msg))
+            {
+                fprintf(stderr, "Encode failed: %s\n", PB_GET_ERROR(&stream));
+                return false;
+            }
+        }
+
+        /* Encode second with SubMessage, invoking 'merge' behaviour */
+        {
+            OneofMessage msg = OneofMessage_init_zero;
+            msg.which_msgs = OneofMessage_msg2_tag;
+
+            msg.first = 999;
+            msg.msgs.msg2.dynamic_str = "ABCD";
+            msg.last = 888;
+
+            if (!pb_encode(&stream, OneofMessage_fields, &msg))
+            {
+                fprintf(stderr, "Encode failed: %s\n", PB_GET_ERROR(&stream));
+                return false;
+            }
+        }
+        msgsize = stream.bytes_written;
+    }
+
+    {
+        OneofMessage msg = OneofMessage_init_zero;
+        pb_istream_t stream = pb_istream_from_buffer(buffer, msgsize);
+        if (!pb_decode(&stream, OneofMessage_fields, &msg))
+        {
+            fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&stream));
+            return false;
+        }
+
+        TEST(msg.first == 999);
+        TEST(msg.which_msgs == OneofMessage_msg2_tag);
+        TEST(msg.msgs.msg2.dynamic_str);
+        TEST(strcmp(msg.msgs.msg2.dynamic_str, "ABCD") == 0);
+        TEST(msg.msgs.msg2.dynamic_str_arr == NULL);
+        TEST(msg.msgs.msg2.dynamic_submsg == NULL);
+        TEST(msg.last == 888);
+
+        pb_release(OneofMessage_fields, &msg);
+        TEST(get_alloc_count() == 0);
+        pb_release(OneofMessage_fields, &msg);
+        TEST(get_alloc_count() == 0);
+    }
+
+    return true;
+}
+
 int main()
 {
-    if (do_test())
+    if (test_TestMessage() && test_OneofMessage())
         return 0;
     else
         return 1;

tests/mem_release/mem_release.proto

@@ -22,3 +22,13 @@ extend TestMessage
     optional SubMessage static_ext = 101 [(nanopb).type = FT_STATIC];
 }
 
+message OneofMessage
+{
+    required int32 first = 1;
+    oneof msgs
+    {
+        TestMessage msg1 = 2;
+        SubMessage msg2 = 3;
+    }
+    required int32 last = 4;
+}