[FAB-7954] Errors not handled for JSON marshaling

Upon code review in statecouchdb.go and couchdb.go, it appears
there are occurrences of the following error producing functions
without errors captured and handled:

json.Marshal()
json.Unmarhsal()
decoder.Decode()
   e.g. json.NewDecoder(resp.Body).Decode(&dbResponse)
   e.g. decoder.Decode(&genericMap)

Change-Id: Id632d636d7e2de817abb60961f908f7ad5222bec
Signed-off-by: Chris Elder <chris.elder@us.ibm.com>

core/ledger/util/couchdb/couchdb.go

@@ -312,7 +312,6 @@ func (dbclient *CouchDatabase) CreateDatabaseIfNotExist() error {
 
  return err
  }
-
  defer closeResponseBody(resp)
 
  logger.Infof("Created state database %s", dbclient.DBName)
@@ -343,7 +342,10 @@ func (dbclient *CouchDatabase) GetDatabaseInfo() (*DBInfo, *DBReturn, error) {
  defer closeResponseBody(resp)
 
  dbResponse := &DBInfo{}
- json.NewDecoder(resp.Body).Decode(&dbResponse)
+ decodeErr := json.NewDecoder(resp.Body).Decode(&dbResponse)
+ if decodeErr != nil {
+ return nil, nil, decodeErr
+ }
 
  // trace the database info response
  if logger.IsEnabledFor(logging.DEBUG) {
@@ -382,9 +384,9 @@ func (couchInstance *CouchInstance) VerifyCouchConfig() (*ConnectionInfo, *DBRet
  defer closeResponseBody(resp)
 
  dbResponse := &ConnectionInfo{}
- errJSON := json.NewDecoder(resp.Body).Decode(&dbResponse)
- if errJSON != nil {
- return nil, nil, fmt.Errorf("Unable to connect to CouchDB, check the hostname and port: %s", errJSON.Error())
+ decodeErr := json.NewDecoder(resp.Body).Decode(&dbResponse)
+ if decodeErr != nil {
+ return nil, nil, decodeErr
  }
 
  // trace the database info response
@@ -429,7 +431,10 @@ func (dbclient *CouchDatabase) DropDatabase() (*DBOperationResponse, error) {
  defer closeResponseBody(resp)
 
  dbResponse := &DBOperationResponse{}
- json.NewDecoder(resp.Body).Decode(&dbResponse)
+ decodeErr := json.NewDecoder(resp.Body).Decode(&dbResponse)
+ if decodeErr != nil {
+ return nil, decodeErr
+ }
 
  if dbResponse.Ok == true {
  logger.Debugf("Dropped database %s ", dbclient.DBName)
@@ -470,7 +475,10 @@ func (dbclient *CouchDatabase) EnsureFullCommit() (*DBOperationResponse, error)
  defer closeResponseBody(resp)
 
  dbResponse := &DBOperationResponse{}
- json.NewDecoder(resp.Body).Decode(&dbResponse)
+ decodeErr := json.NewDecoder(resp.Body).Decode(&dbResponse)
+ if decodeErr != nil {
+ return nil, decodeErr
+ }
 
  if dbResponse.Ok == true {
  logger.Debugf("_ensure_full_commit database %s ", dbclient.DBName)
@@ -626,7 +634,10 @@ func createAttachmentPart(couchDoc *CouchDoc, defaultBoundary string) (bytes.Buf
  //unmarshal the data into the generic map
  decoder := json.NewDecoder(bytes.NewBuffer(couchDoc.JSONValue))
  decoder.UseNumber()
- decoder.Decode(&genericMap)
+ decodeErr := decoder.Decode(&genericMap)
+ if decodeErr != nil {
+ return *writeBuffer, "", decodeErr
+ }
 
  //add all key/values to the attachmentJSONMap
  for jsonKey, jsonValue := range genericMap {
@@ -635,7 +646,11 @@ func createAttachmentPart(couchDoc *CouchDoc, defaultBoundary string) (bytes.Buf
 
  }
 
- filesForUpload, _ := json.Marshal(attachmentJSONMap)
+ filesForUpload, err := json.Marshal(attachmentJSONMap)
+ if err != nil {
+ return *writeBuffer, "", err
+ }
+
  logger.Debugf(string(filesForUpload))
 
  //create the header for the JSON
@@ -1336,7 +1351,10 @@ func (dbclient *CouchDatabase) BatchUpdateDocuments(documents []*CouchDoc) ([]*B
  var document = make(map[string]interface{})
 
  //unmarshal the JSON component of the CouchDoc into the document
- json.Unmarshal(jsonDocument.JSONValue, &document)
+ err = json.Unmarshal(jsonDocument.JSONValue, &document)
+ if err != nil {
+ return nil, err
+ }
 
  //iterate through any attachments
  if len(jsonDocument.Attachments) > 0 {
@@ -1365,7 +1383,6 @@ func (dbclient *CouchDatabase) BatchUpdateDocuments(documents []*CouchDoc) ([]*B
  documentMap["docs"] = jsonDocumentMap
 
  bulkDocsJSON, err := json.Marshal(documentMap)
-
  if err != nil {
  return nil, err
  }
@@ -1557,7 +1574,10 @@ func (couchInstance *CouchInstance) handleRequest(method, connectURL string, dat
  errorBytes := []byte(jsonError)
 
  //Unmarshal the response
- json.Unmarshal(errorBytes, &couchDBReturn)
+ err = json.Unmarshal(errorBytes, &couchDBReturn)
+ if err != nil {
+ return nil, nil, err
+ }
 
  //Log the 500 error with the retry count and continue
  logger.Warningf("Retrying couchdb request in %s. Attempt:%v Couch DB Error:%s, Status Code:%v Reason:%v",
@@ -1604,7 +1624,10 @@ func (couchInstance *CouchInstance) handleRequest(method, connectURL string, dat
  errorBytes := []byte(jsonError)
 
  //marshal the response
- json.Unmarshal(errorBytes, &couchDBReturn)
+ err = json.Unmarshal(errorBytes, &couchDBReturn)
+ if err != nil {
+ return nil, nil, err
+ }
 
  logger.Debugf("Couch DB Error:%s, Status Code:%v, Reason:%s",
  couchDBReturn.Error, resp.StatusCode, couchDBReturn.Reason)