From 55d05e63e86bad88249d349b2bb57ff8b1126b68 Mon Sep 17 00:00:00 2001
From: Felicitas Pojtinger <felicitas@pojtinger.com>
Date: Mon, 10 Jan 2022 23:43:45 +0100
Subject: [PATCH] fix: Prevent creating directories again if they already exist

---
 internal/fs/file.go       |  3 ---
 pkg/fs/filesystem.go      |  7 ++++-
 pkg/fs/filesystem_test.go | 56 ++++++++++++++++++++++-----------------
 3 files changed, 38 insertions(+), 28 deletions(-)

diff --git a/internal/fs/file.go b/internal/fs/file.go
index 246baff..5b46006 100644
--- a/internal/fs/file.go
+++ b/internal/fs/file.go
@@ -5,7 +5,6 @@ import (
 	"database/sql"
 	"io"
 	"io/fs"
-	"log"
 	"os"
 	"sync"
 
@@ -550,8 +549,6 @@ func (f *File) Write(p []byte) (n int, err error) {
 
 	n, err = f.writeBuf.Write(p)
 	if err != nil {
-		log.Fatal(err)
-
 		return -1, err
 	}
 
diff --git a/pkg/fs/filesystem.go b/pkg/fs/filesystem.go
index a8cff01..86247e6 100644
--- a/pkg/fs/filesystem.go
+++ b/pkg/fs/filesystem.go
@@ -89,7 +89,7 @@ func (f *STFS) Create(name string) (afero.File, error) {
 		return nil, os.ErrPermission
 	}
 
-	return f.OpenFile(name, os.O_CREATE|os.O_RDWR, 0666)
+	return f.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
 }
 
 func (f *STFS) mknodeWithoutLocking(dir bool, name string, perm os.FileMode, overwrite bool, linkname string, initializing bool) error {
@@ -371,6 +371,11 @@ func (f *STFS) OpenFile(name string, flag int, perm os.FileMode) (afero.File, er
 		}
 	}
 
+	// Prevent opening a directory as writable
+	if hdr.Typeflag == tar.TypeDir && (flags.Write || flags.Append || flags.Truncate) {
+		return nil, config.ErrIsDirectory
+	}
+
 	return ifs.NewFile(
 		f.readOps,
 		f.writeOps,
diff --git a/pkg/fs/filesystem_test.go b/pkg/fs/filesystem_test.go
index 6c92b05..df2bac3 100644
--- a/pkg/fs/filesystem_test.go
+++ b/pkg/fs/filesystem_test.go
@@ -635,18 +635,28 @@ var createTests = []struct {
 		createArgs{"/test.txt"},
 		false,
 	},
+	{
+		"Can not create existing directory /",
+		createArgs{"/"},
+		true,
+	},
+	// FIXME: Prevent creating empty directory names
+	// {
+	// 	"Can not create directory ''",
+	// 	createArgs{""},
+	// 	true,
+	// },
+	// {
+	// 	"Can not create directory ' '",
+	// 	createArgs{" "},
+	// 	true,
+	// },
 	// FIXME: STFS can create file in non-existent directory, which should not be possible
 	// {
 	// 	"Can not create /nonexistent/test.txt",
 	// 	createArgs{"/nonexistent/test.txt"},
 	// 	true,
 	// },
-	// FIXME: STFS can create `/` file even if / exists
-	// {
-	// 	"Can create /",
-	// 	createArgs{"/"},
-	// 	true,
-	// },
 }
 
 func TestSTFS_Create(t *testing.T) {
@@ -659,34 +669,32 @@ func TestSTFS_Create(t *testing.T) {
 				return
 			}
 
-			want, err := fs.fs.Stat(tt.args.name)
-			if err != nil {
-				t.Errorf("%v.Stat() error = %v, wantErr %v", fs.fs.Name(), err, tt.wantErr)
+			if !tt.wantErr {
+				want, err := fs.fs.Stat(tt.args.name)
+				if err != nil {
+					t.Errorf("%v.Stat() error = %v, wantErr %v", fs.fs.Name(), err, tt.wantErr)
 
-				return
-			}
+					return
+				}
 
-			if file == nil {
-				if (err != nil) != tt.wantErr {
+				if file == nil {
 					t.Errorf("%v.Create() error = %v, wantErr %v", fs.fs.Name(), err, tt.wantErr)
 
 					return
 				}
 
-				return
-			}
+				got, err := fs.fs.Stat(file.Name())
+				if err != nil {
+					t.Errorf("%v.Stat() error = %v, wantErr %v", fs.fs.Name(), err, tt.wantErr)
 
-			got, err := fs.fs.Stat(file.Name())
-			if err != nil {
-				t.Errorf("%v.Stat() error = %v, wantErr %v", fs.fs.Name(), err, tt.wantErr)
+					return
+				}
 
-				return
-			}
+				if !reflect.DeepEqual(got, want) {
+					t.Errorf("%v.Create().Name() = %v, want %v", fs.fs.Name(), got, want)
 
-			if !reflect.DeepEqual(got, want) {
-				t.Errorf("%v.Create().Name() = %v, want %v", fs.fs.Name(), got, want)
-
-				return
+					return
+				}
 			}
 		})
 	}