Sftp writes should truncate 154 (#155)

* added io integration tests based on unix fs behaviors

* Updated sftp backend to overwrite except after read/seek. fixes #154

* address lint issues

* update changelog

* fixed type in changelog

* forgot to add back intergration flags

* remove no-longer-relevant comment from test case

CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ## [Unreleased]
 
+## [6.11.2] - 2024-01-30
+### Fixed
+- Fixed 154 bug. Updated sftp backend to overwrite except after read/seek.
+
 ## [6.11.1] - 2024-01-22
 ### Fixed
 - Fixed #152 bug where s3 backend failed to read empty files

backend/sftp/file.go

@@ -18,6 +18,8 @@ type File struct {
 	path       string
 	sftpfile   ReadWriteSeekCloser
 	opener     fileOpener
+	seekCalled bool
+	readCalled bool
 }
 
 // this type allow for injecting a mock fileOpener function
@@ -243,6 +245,9 @@ func (f *File) Close() error {
 	f.fileSystem.connTimerStop()
 	defer f.fileSystem.connTimerStart()
 
+	f.seekCalled = false
+	f.readCalled = false
+
 	if f.sftpfile != nil {
 		err := f.sftpfile.Close()
 		if err != nil {
@@ -260,11 +265,13 @@ func (f *File) Read(p []byte) (n int, err error) {
 	f.fileSystem.connTimerStop()
 	defer f.fileSystem.connTimerStart()
 
-	sftpfile, err := f.openFile(os.O_RDONLY)
+	sftpfile, err := f.openFile(os.O_RDWR)
 	if err != nil {
 		return 0, err
 	}
 
+	f.readCalled = true
+
 	return sftpfile.Read(p)
 }
 
@@ -279,6 +286,7 @@ func (f *File) Seek(offset int64, whence int) (int64, error) {
 		return 0, err
 	}
 
+	f.seekCalled = true
 	return sftpfile.Seek(offset, whence)
 }
 
@@ -288,7 +296,12 @@ func (f *File) Write(data []byte) (res int, err error) {
 	f.fileSystem.connTimerStop()
 	defer f.fileSystem.connTimerStart()
 
-	sftpfile, err := f.openFile(os.O_WRONLY | os.O_CREATE)
+	flags := os.O_RDWR | os.O_CREATE
+	if !f.readCalled || f.seekCalled {
+		flags |= os.O_TRUNC
+	}
+
+	sftpfile, err := f.openFile(flags)
 	if err != nil {
 		return 0, err
 	}

backend/testsuite/backend_integration_test.go

@@ -18,11 +18,7 @@ import (
 
 	"github.com/c2fo/vfs/v6"
 	"github.com/c2fo/vfs/v6/backend/azure"
-	"github.com/c2fo/vfs/v6/backend/ftp"
 	"github.com/c2fo/vfs/v6/backend/gs"
-	"github.com/c2fo/vfs/v6/backend/mem"
-	_os "github.com/c2fo/vfs/v6/backend/os"
-	"github.com/c2fo/vfs/v6/backend/s3"
 	"github.com/c2fo/vfs/v6/backend/sftp"
 	"github.com/c2fo/vfs/v6/utils"
 	"github.com/c2fo/vfs/v6/vfssimple"
@@ -33,55 +29,6 @@ type vfsTestSuite struct {
 	testLocations map[string]vfs.Location
 }
 
-func copyOsLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*_os.Location)
-	ret := &cp
-
-	// setup os location
-	exists, err := ret.Exists()
-	if err != nil {
-		panic(err)
-	}
-	if !exists {
-		err := os.Mkdir(ret.Path(), 0755)
-		if err != nil {
-			panic(err)
-		}
-	}
-
-	return ret
-}
-
-func copyMemLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*mem.Location)
-	return &cp
-}
-
-func copyS3Location(loc vfs.Location) vfs.Location {
-	cp := *loc.(*s3.Location)
-	return &cp
-}
-
-func copySFTPLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*sftp.Location)
-	return &cp
-}
-
-func copyFTPLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*ftp.Location)
-	return &cp
-}
-
-func copyGSLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*gs.Location)
-	return &cp
-}
-
-func copyAzureLocation(loc vfs.Location) vfs.Location {
-	cp := *loc.(*azure.Location)
-	return &cp
-}
-
 func buildExpectedURI(fs vfs.FileSystem, volume, path string) string {
 	if fs.Name() == "azure" {
 		azFs := fs.(*azure.FileSystem)
@@ -98,19 +45,19 @@ func (s *vfsTestSuite) SetupSuite() {
 		s.NoError(err)
 		switch l.FileSystem().Scheme() {
 		case "file":
-			s.testLocations[l.FileSystem().Scheme()] = copyOsLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyOsLocation(l)
 		case "s3":
-			s.testLocations[l.FileSystem().Scheme()] = copyS3Location(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyS3Location(l)
 		case "sftp":
-			s.testLocations[l.FileSystem().Scheme()] = copySFTPLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopySFTPLocation(l)
 		case "gs":
-			s.testLocations[l.FileSystem().Scheme()] = copyGSLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyGSLocation(l)
 		case "mem":
-			s.testLocations[l.FileSystem().Scheme()] = copyMemLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyMemLocation(l)
 		case "https":
-			s.testLocations[l.FileSystem().Scheme()] = copyAzureLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyAzureLocation(l)
 		case "ftp":
-			s.testLocations[l.FileSystem().Scheme()] = copyFTPLocation(l)
+			s.testLocations[l.FileSystem().Scheme()] = CopyFTPLocation(l)
 		default:
 			panic(fmt.Sprintf("unknown scheme: %s", l.FileSystem().Scheme()))
 		}
@@ -914,7 +861,7 @@ func (s *vfsTestSuite) File(baseLoc vfs.Location) {
 // gs-specific test cases
 func (s *vfsTestSuite) gsList(baseLoc vfs.Location) {
 	/*
-			test scenario:
+			test description:
 				When a persistent "folder" is created through the UI, it simply creates a zero length object
 		        with a trailing "/". The UI or gsutil knows to interpret these objects as folders but they are
 		        still just objects.  List(), in its current state, should ignore these objects.

backend/testsuite/common.go

@@ -0,0 +1,63 @@
+package testsuite
+
+import (
+	"os"
+
+	"github.com/c2fo/vfs/v6"
+	"github.com/c2fo/vfs/v6/backend/azure"
+	"github.com/c2fo/vfs/v6/backend/ftp"
+	"github.com/c2fo/vfs/v6/backend/gs"
+	"github.com/c2fo/vfs/v6/backend/mem"
+	_os "github.com/c2fo/vfs/v6/backend/os"
+	"github.com/c2fo/vfs/v6/backend/s3"
+	"github.com/c2fo/vfs/v6/backend/sftp"
+)
+
+func CopyOsLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*_os.Location)
+	ret := &cp
+
+	// setup os location
+	exists, err := ret.Exists()
+	if err != nil {
+		panic(err)
+	}
+	if !exists {
+		err := os.Mkdir(ret.Path(), 0750)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	return ret
+}
+
+func CopyMemLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*mem.Location)
+	return &cp
+}
+
+func CopyS3Location(loc vfs.Location) vfs.Location {
+	cp := *loc.(*s3.Location)
+	return &cp
+}
+
+func CopySFTPLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*sftp.Location)
+	return &cp
+}
+
+func CopyFTPLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*ftp.Location)
+	return &cp
+}
+
+func CopyGSLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*gs.Location)
+	return &cp
+}
+
+func CopyAzureLocation(loc vfs.Location) vfs.Location {
+	cp := *loc.(*azure.Location)
+	return &cp
+}