Fix Docker os.Rename invalid cross-device link issue (#386)

* Adds new file.Move func to address a bug with Golang/Docker volumes when using os.Rename

Also uses TempDir for tests instead of live directories and increases test coverage for file.Write

* Goimport the imports

* Make usage of file package name consistent so it no longer clashes with vars

* Remove outputFile if io.Copy fails

common/common.go

@@ -279,7 +279,7 @@ func ExtractPort(host string) int {
 func OutputCSV(filePath string, data [][]string) error {
 	_, err := ioutil.ReadFile(filePath)
 	if err != nil {
-		errTwo := WriteFile(filePath, nil)
+		errTwo := ioutil.WriteFile(filePath, nil, 0770)
 		if errTwo != nil {
 			return errTwo
 		}
@@ -295,11 +295,6 @@ func OutputCSV(filePath string, data [][]string) error {
 	return writer.WriteAll(data)
 }
 
-// WriteFile writes selected data to a file and returns an error
-func WriteFile(file string, data []byte) error {
-	return ioutil.WriteFile(file, data, 0644)
-}
-
 // GetURIPath returns the path of a URL given a URI
 func GetURIPath(uri string) string {
 	urip, err := url.Parse(uri)
@@ -353,8 +348,8 @@ func CreateDir(dir string) error {
 	return os.MkdirAll(dir, 0770)
 }
 
-// ChangePerm lists all the directories and files in an array
-func ChangePerm(directory string) error {
+// ChangePermission lists all the directories and files in an array
+func ChangePermission(directory string) error {
 	return filepath.Walk(directory, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err

common/common_test.go

@@ -504,11 +504,11 @@ func TestCreateDir(t *testing.T) {
 	}
 }
 
-func TestChangePerm(t *testing.T) {
-	testDir := filepath.Join(GetDefaultDataDir(runtime.GOOS), "TestFileASDFGHJ")
+func TestChangePermission(t *testing.T) {
+	testDir := filepath.Join(os.TempDir(), "TestFileASDFGHJ")
 	switch runtime.GOOS {
 	case "windows":
-		err := ChangePerm("*")
+		err := ChangePermission("*")
 		if err == nil {
 			t.Fatal("expected an error on non-existent path")
 		}
@@ -516,7 +516,7 @@ func TestChangePerm(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Mkdir failed. Err: %v", err)
 		}
-		err = ChangePerm(GetDefaultDataDir(runtime.GOOS))
+		err = ChangePermission(testDir)
 		if err != nil {
 			t.Fatalf("ChangePerm was unsuccessful. Err: %v", err)
 		}
@@ -529,7 +529,7 @@ func TestChangePerm(t *testing.T) {
 			t.Fatalf("os.Remove failed. Err: %v", err)
 		}
 	default:
-		err := ChangePerm("")
+		err := ChangePermission("")
 		if err == nil {
 			t.Fatal("expected an error on non-existent path")
 		}
@@ -537,7 +537,7 @@ func TestChangePerm(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Mkdir failed. Err: %v", err)
 		}
-		err = ChangePerm(GetDefaultDataDir(runtime.GOOS))
+		err = ChangePermission(testDir)
 		if err != nil {
 			t.Fatalf("ChangePerm was unsuccessful. Err: %v", err)
 		}

common/file/file.go

@@ -0,0 +1,47 @@
+package file
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+// Write writes selected data to a file or returns an error if it fails. This
+// func also ensures that all files are set to this permission (only rw access
+// for the running user and the group the user is a member of)
+func Write(file string, data []byte) error {
+	return ioutil.WriteFile(file, data, 0770)
+}
+
+// Move moves a file from a source path to a destination path
+// This must be used across the codebase for compatibility with Docker volumes
+// and Golang (fixes Invalid cross-device link when using os.Rename)
+func Move(sourcePath, destPath string) error {
+	inputFile, err := os.Open(sourcePath)
+	if err != nil {
+		return err
+	}
+
+	outputFile, err := os.Create(destPath)
+	if err != nil {
+		inputFile.Close()
+		return err
+	}
+
+	_, err = io.Copy(outputFile, inputFile)
+	inputFile.Close()
+	outputFile.Close()
+	if err != nil {
+		if errRem := os.Remove(destPath); errRem != nil {
+			return fmt.Errorf(
+				"unable to os.Remove error: %s after io.Copy error: %s",
+				errRem,
+				err,
+			)
+		}
+		return err
+	}
+
+	return os.Remove(sourcePath)
+}

common/file/file_test.go

@@ -0,0 +1,106 @@
+package file
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func TestWrite(t *testing.T) {
+	tester := func(in string) error {
+		err := Write(in, []byte("GoCryptoTrader"))
+		if err != nil {
+			return err
+		}
+		return os.Remove(in)
+	}
+
+	type testTable struct {
+		InFile      string
+		ErrExpected bool
+		Cleanup     bool
+	}
+
+	var tests []testTable
+	testFile := filepath.Join(os.TempDir(), "gcttest.txt")
+	switch runtime.GOOS {
+	case "windows":
+		tests = []testTable{
+			{InFile: "*", ErrExpected: true},
+			{InFile: testFile, ErrExpected: false},
+		}
+	default:
+		tests = []testTable{
+			{InFile: "", ErrExpected: true},
+			{InFile: testFile, ErrExpected: false},
+		}
+	}
+
+	for x := range tests {
+		err := tester(tests[x].InFile)
+		if err != nil && !tests[x].ErrExpected {
+			t.Errorf("Test %d failed, unexpected err %s\n", x, err)
+		}
+	}
+}
+
+func TestMove(t *testing.T) {
+	tester := func(in, out string, write bool) error {
+		if write {
+			if err := ioutil.WriteFile(in, []byte("GoCryptoTrader"), 0770); err != nil {
+				return err
+			}
+		}
+
+		if err := Move(in, out); err != nil {
+			return err
+		}
+
+		contents, err := ioutil.ReadFile(out)
+		if err != nil {
+			return err
+		}
+
+		if !strings.Contains(string(contents), "GoCryptoTrader") {
+			return fmt.Errorf("unable to find previously written data")
+		}
+
+		return os.Remove(out)
+	}
+
+	type testTable struct {
+		InFile      string
+		OutFile     string
+		Write       bool
+		ErrExpected bool
+	}
+
+	var tests []testTable
+	switch runtime.GOOS {
+	case "windows":
+		tests = []testTable{
+			{InFile: "*", OutFile: "gct.txt", Write: true, ErrExpected: true},
+			{InFile: "*", OutFile: "gct.txt", Write: false, ErrExpected: true},
+			{InFile: "in.txt", OutFile: "*", Write: true, ErrExpected: true},
+			{InFile: "in.txt", OutFile: "gct.txt", Write: true, ErrExpected: false},
+		}
+	default:
+		tests = []testTable{
+			{InFile: "", OutFile: "gct.txt", Write: true, ErrExpected: true},
+			{InFile: "", OutFile: "gct.txt", Write: false, ErrExpected: true},
+			{InFile: "in.txt", OutFile: "", Write: true, ErrExpected: true},
+			{InFile: "in.txt", OutFile: "gct.txt", Write: true, ErrExpected: false},
+		}
+	}
+
+	for x := range tests {
+		err := tester(tests[x].InFile, tests[x].OutFile, tests[x].Write)
+		if err != nil && !tests[x].ErrExpected {
+			t.Errorf("Test %d failed, unexpected err %s\n", x, err)
+		}
+	}
+}