feat: put selected files in the root of the archive (closes #1065)

fileutils/file.go

@@ -3,6 +3,7 @@ package fileutils
 import (
 	"io"
 	"os"
+	"path"
 	"path/filepath"
 
 	"github.com/spf13/afero"
@@ -50,3 +51,59 @@ func CopyFile(fs afero.Fs, source, dest string) error {
 
 	return nil
 }
+
+// CommonPrefix returns common directory path of provided files
+func CommonPrefix(sep byte, paths ...string) string {
+	// Handle special cases.
+	switch len(paths) {
+	case 0:
+		return ""
+	case 1:
+		return path.Clean(paths[0])
+	}
+
+	// Note, we treat string as []byte, not []rune as is often
+	// done in Go. (And sep as byte, not rune). This is because
+	// most/all supported OS' treat paths as string of non-zero
+	// bytes. A filename may be displayed as a sequence of Unicode
+	// runes (typically encoded as UTF-8) but paths are
+	// not required to be valid UTF-8 or in any normalized form
+	// (e.g. "é" (U+00C9) and "é" (U+0065,U+0301) are different
+	// file names.
+	c := []byte(path.Clean(paths[0]))
+
+	// We add a trailing sep to handle the case where the
+	// common prefix directory is included in the path list
+	// (e.g. /home/user1, /home/user1/foo, /home/user1/bar).
+	// path.Clean will have cleaned off trailing / separators with
+	// the exception of the root directory, "/" (in which case we
+	// make it "//", but this will get fixed up to "/" bellow).
+	c = append(c, sep)
+
+	// Ignore the first path since it's already in c
+	for _, v := range paths[1:] {
+		// Clean up each path before testing it
+		v = path.Clean(v) + string(sep)
+
+		// Find the first non-common byte and truncate c
+		if len(v) < len(c) {
+			c = c[:len(v)]
+		}
+		for i := 0; i < len(c); i++ {
+			if v[i] != c[i] {
+				c = c[:i]
+				break
+			}
+		}
+	}
+
+	// Remove trailing non-separator characters and the final separator
+	for i := len(c) - 1; i >= 0; i-- {
+		if c[i] == sep {
+			c = c[:i]
+			break
+		}
+	}
+
+	return string(c)
+}

fileutils/file_test.go

@@ -0,0 +1,46 @@
+package fileutils
+
+import "testing"
+
+func TestCommonPrefix(t *testing.T) {
+	testCases := map[string]struct {
+		paths []string
+		want  string
+	}{
+		"same lvl": {
+			paths: []string{
+				"/home/user/file1",
+				"/home/user/file2",
+			},
+			want: "/home/user",
+		},
+		"sub folder": {
+			paths: []string{
+				"/home/user/folder",
+				"/home/user/folder/file",
+			},
+			want: "/home/user/folder",
+		},
+		"relative path": {
+			paths: []string{
+				"/home/user/folder",
+				"/home/user/folder/../folder2",
+			},
+			want: "/home/user",
+		},
+		"no common path": {
+			paths: []string{
+				"/home/user/folder",
+				"/etc/file",
+			},
+			want: "",
+		},
+	}
+	for name, tt := range testCases {
+		t.Run(name, func(t *testing.T) {
+			if got := CommonPrefix('/', tt.paths...); got != tt.want {
+				t.Errorf("CommonPrefix() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}