Check directory existence again when failing to create it to avoid erroring out on race condition

integration_tests/test_functions.sh

@@ -93,7 +93,6 @@ function add_file()
   FILE_NAME=$1
   pushd ${TEST_REPO}
   dd if=/dev/urandom of=${FILE_NAME} bs=1000 count=20000
-    echo ${FILE_NAME} > "${FILE_NAME}"
   popd
 }
 

integration_tests/threaded_test.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+
+. ./test_functions.sh
+
+fixture
+
+pushd ${TEST_REPO}
+${DUPLICACY} init integration-tests $TEST_STORAGE -c 1k
+
+add_file file3
+add_file file4
+
+
+${DUPLICACY} backup -threads 16 
+${DUPLICACY} check --files -stats
+popd

src/duplicacy_filestorage.go

@@ -158,7 +158,11 @@ func (storage *FileStorage) FindChunk(threadIndex int, chunkID string, isFossil
 
             err = os.Mkdir(subDir, 0744)
             if err != nil {
-                return "", false, 0, err
+                // The directory may have been created by other threads so check it again.
+                stat, _ := os.Stat(subDir)
+                if stat == nil || !stat.IsDir() {
+                    return "", false, 0, err
+                }
             }
 
             dir = subDir

src/duplicacy_sftpstorage.go

@@ -215,7 +215,11 @@ func (storage *SFTPStorage) FindChunk(threadIndex int, chunkID string, isFossil
 
             err = storage.client.Mkdir(subDir)
             if err != nil {
-                return "", false, 0, fmt.Errorf("Failed to create the directory %s: %v", subDir, err)
+                // The directory may have been created by other threads so check it again.
+                stat, _ := storage.client.Stat(subDir)
+                if stat == nil || !stat.IsDir() {
+                    return "", false, 0, fmt.Errorf("Failed to create the directory %s: %v", subDir, err)
+                }
             }
 
             dir = subDir