bugfix: handle absolute and relative paths as expected (#31)

* chore: ignore .vscode folder

* feat: handle absolute and relative paths as expected

Previous behavior would take the absolute or relative path and
expand the directory structure onto the receiver. This is not what
one expects when for instance sending files using the absolute path
"portal send /home/zinokader/data/somefile.txt", which previously would
actually try to recreate the same directory structure "/home/zinokader..."
on the receiver end.

Now, we handle absolute paths by sending the last directory or file
(and its subfiles/subdirectories), this means "/home/zinokader/folder"
will just send and expand "folder" and all of its contents on the receiving end.

.gitignore

@@ -23,3 +23,4 @@
 # misc
 .DS_Store
 dist/
+.vscode

internal/file/file.go

@@ -141,11 +141,17 @@ func FilesTotalSize(files []*os.File) (int64, error) {
 	return size, nil
 }
 
-// addToTarArchive adds a file/folder to a tar archive. This function handles symlinks by replacing
-// them with the files that they point to
+// addToTarArchive adds a file/folder to a tar archive.
+// Handles symlinks by replacing them with the files that they point to.
 func addToTarArchive(tw *tar.Writer, file *os.File) error {
-	return filepath.Walk(file.Name(), func(path string, fi os.FileInfo, err error) error {
+	var absoluteBase string
+	absPath, err := filepath.Abs(file.Name())
+	if err != nil {
+		return err
+	}
+	absoluteBase = filepath.Dir(absPath)
 
+	return filepath.Walk(file.Name(), func(path string, fi os.FileInfo, err error) error {
 		if (fi.Mode() & os.ModeSymlink) == os.ModeSymlink {
 			// read path that the symlink is pointing to
 			var link string
@@ -165,7 +171,15 @@ func addToTarArchive(tw *tar.Writer, file *os.File) error {
 		if e != nil {
 			return err
 		}
-		header.Name = filepath.ToSlash(path)
+
+		// use absolute paths to handle both relative and absolute input paths identically
+		targetPath, err := filepath.Abs(path)
+		if err != nil {
+			return err
+		}
+		// remove the absolute root from the filename, leaving only the desired filename
+		header.Name = filepath.ToSlash(strings.TrimPrefix(targetPath, absoluteBase))
+		header.Name = strings.TrimPrefix(header.Name, string(os.PathSeparator))
 
 		if err := tw.WriteHeader(header); err != nil {
 			return err