From 01be9bee62dd8f02b5551a43e5f90acac8f5bdf5 Mon Sep 17 00:00:00 2001
From: Nikita Kryuchkov <nkryuchkov10@gmail.com>
Date: Wed, 15 Apr 2020 18:05:49 +0300
Subject: [PATCH] Fix moving files between different drives and filesystems

---
 pkg/util/pathutil/util.go   |  4 +-
 pkg/util/rename/rename.go   | 73 +++++++++++++++++++++++++++++++++++++
 pkg/util/updater/updater.go | 11 +++---
 3 files changed, 82 insertions(+), 6 deletions(-)
 create mode 100644 pkg/util/rename/rename.go

diff --git a/pkg/util/pathutil/util.go b/pkg/util/pathutil/util.go
index 56b0487db5..d3dc14613b 100644
--- a/pkg/util/pathutil/util.go
+++ b/pkg/util/pathutil/util.go
@@ -5,6 +5,8 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+
+	"github.com/SkycoinProject/skywire-mainnet/pkg/util/rename"
 )
 
 const (
@@ -43,7 +45,7 @@ func AtomicWriteFile(filename string, data []byte) error {
 		return err
 	}
 
-	if err := os.Rename(tempFilePath, filename); err != nil {
+	if err := rename.Rename(tempFilePath, filename); err != nil {
 		return err
 	}
 
diff --git a/pkg/util/rename/rename.go b/pkg/util/rename/rename.go
new file mode 100644
index 0000000000..75d6b8e600
--- /dev/null
+++ b/pkg/util/rename/rename.go
@@ -0,0 +1,73 @@
+package rename
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+)
+
+const crossDeviceError = "invalid cross-device link"
+
+// Rename renames (moves) oldPath to newPath using os.Rename.
+// If paths are located on different drives or filesystems, os.Rename fails.
+// In that case, Rename uses a workaround by copying oldPath to newPath and removing oldPath thereafter.
+func Rename(oldPath, newPath string) error {
+	if err := os.Rename(oldPath, newPath); err == nil || err.Error() != crossDeviceError {
+		return err
+	}
+
+	stat, err := os.Stat(oldPath)
+	if err != nil {
+		return fmt.Errorf("stat: %w", err)
+	}
+
+	if !stat.Mode().IsRegular() {
+		return fmt.Errorf("is regular: %w", err)
+	}
+
+	// Paths are located on different devices.
+	if err := move(oldPath, newPath); err != nil {
+		return fmt.Errorf("move: %w", err)
+	}
+
+	if err := os.Chmod(newPath, stat.Mode()); err != nil {
+		return fmt.Errorf("chmod: %w", err)
+	}
+
+	if err := os.Remove(oldPath); err != nil {
+		return fmt.Errorf("remove: %w", err)
+	}
+
+	return nil
+}
+
+func move(oldPath string, newPath string) error {
+	inputFile, err := os.Open(oldPath) // nolint:gosec
+	if err != nil {
+		return fmt.Errorf("open: %w", err)
+	}
+
+	defer func() {
+		if err := inputFile.Close(); err != nil {
+			log.Printf("Failed to close file %q: %v", inputFile.Name(), err)
+		}
+	}()
+
+	outputFile, err := os.Create(newPath)
+	if err != nil {
+		return fmt.Errorf("create: %w", err)
+	}
+
+	defer func() {
+		if err := outputFile.Close(); err != nil {
+			log.Printf("Failed to close file %q: %v", outputFile.Name(), err)
+		}
+	}()
+
+	if _, err = io.Copy(outputFile, inputFile); err != nil {
+		return fmt.Errorf("copy: %w", err)
+	}
+
+	return nil
+}
diff --git a/pkg/util/updater/updater.go b/pkg/util/updater/updater.go
index 9e76a742b3..275d54500f 100644
--- a/pkg/util/updater/updater.go
+++ b/pkg/util/updater/updater.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/SkycoinProject/skywire-mainnet/pkg/restart"
 	"github.com/SkycoinProject/skywire-mainnet/pkg/util/buildinfo"
+	"github.com/SkycoinProject/skywire-mainnet/pkg/util/rename"
 )
 
 const (
@@ -180,13 +181,13 @@ func (u *Updater) updateBinary(downloadedBinariesPath, basePath, binary string)
 		}
 	}
 
-	if err := os.Rename(currentBinaryPath, oldBinaryPath); err != nil {
+	if err := rename.Rename(currentBinaryPath, oldBinaryPath); err != nil {
 		return fmt.Errorf("rename %s to %s: %w", currentBinaryPath, oldBinaryPath, err)
 	}
 
-	if err := os.Rename(downloadedBinaryPath, currentBinaryPath); err != nil {
-		// Try to revert previous os.Rename
-		if err := os.Rename(oldBinaryPath, currentBinaryPath); err != nil {
+	if err := rename.Rename(downloadedBinaryPath, currentBinaryPath); err != nil {
+		// Try to revert previous rename.
+		if err := rename.Rename(oldBinaryPath, currentBinaryPath); err != nil {
 			u.log.Errorf("Failed to rename file %q to %q: %v", oldBinaryPath, currentBinaryPath, err)
 		}
 
@@ -201,7 +202,7 @@ func (u *Updater) updateBinary(downloadedBinariesPath, basePath, binary string)
 func (u *Updater) restore(currentBinaryPath string, toBeRemoved string) {
 	u.removeFiles(currentBinaryPath)
 
-	if err := os.Rename(toBeRemoved, currentBinaryPath); err != nil {
+	if err := rename.Rename(toBeRemoved, currentBinaryPath); err != nil {
 		u.log.Errorf("Failed to rename file %q to %q: %v", toBeRemoved, currentBinaryPath, err)
 	}
 }