feat: Add support for O_TRUNC and O_APPEND flags

cmd/stfs/cmd/serve_ftp.go

@@ -203,6 +203,7 @@ var serveFTPCmd = &cobra.Command{
 					viper.GetString(cacheWriteFlag),
 				)
 			},
+			true, // FTP needs read permission for `STOR` command even if O_WRONLY is set
 
 			logger.PrintHeader,
 		)

cmd/stfs/cmd/serve_http.go

@@ -127,6 +127,7 @@ var serveHTTPCmd = &cobra.Command{
 
 			"",    // We never write
 			nil,   // We never write
+			false, // We never write
 
 			logger.PrintHeader,
 		)

internal/fs/file.go

@@ -199,8 +199,6 @@ func (f *File) closeWithoutLocking() error {
 }
 
 func (f *File) enterWriteMode() error {
-	log.Println("File.enterWriteMode")
-
 	if f.readOpReader != nil || f.readOpWriter != nil {
 		if err := f.closeWithoutLocking(); err != nil {
 			return err
@@ -253,15 +251,18 @@ func (f *File) enterWriteMode() error {
 			}
 		}
 
-		// TODO: Don't do this if O_APPEND is set
+		if f.flags.truncate {
 			if err := f.writeBuf.Truncate(0); err != nil {
 				return err
 			}
+		}
 
+		if !f.flags.append {
 			if _, err := f.writeBuf.Seek(0, io.SeekStart); err != nil {
 				return err
 			}
 		}
+	}
 
 	return nil
 }

internal/fs/filesystem.go

@@ -32,6 +32,7 @@ type FileSystem struct {
 
 	compressionLevel       string
 	getFileBuffer          func() (WriteCache, func() error, error)
+	relaxedReadPermissions bool
 
 	onHeader func(hdr *models.Header)
 }
@@ -44,6 +45,7 @@ func NewFileSystem(
 
 	compressionLevel string,
 	getFileBuffer func() (WriteCache, func() error, error),
+	ignorePermissionFlags bool,
 
 	onHeader func(hdr *models.Header),
 ) afero.Fs {
@@ -55,6 +57,7 @@ func NewFileSystem(
 
 		compressionLevel:       compressionLevel,
 		getFileBuffer:          getFileBuffer,
+		relaxedReadPermissions: ignorePermissionFlags,
 
 		onHeader: onHeader,
 	}
@@ -196,6 +199,11 @@ func (f *FileSystem) OpenFile(name string, flag int, perm os.FileMode) (afero.Fi
 		flags.write = true
 	}
 
+	if flags.write && !flags.read && f.relaxedReadPermissions {
+		flags.read = true
+		flags.write = true
+	}
+
 	if flag&os.O_APPEND != 0 {
 		flags.append = true
 	}