From a03d1e5016ce2185592e6d27773c91ee53ea6f59 Mon Sep 17 00:00:00 2001
From: Felicitas Pojtinger <felicitas@pojtinger.com>
Date: Mon, 27 Dec 2021 16:48:22 +0100
Subject: [PATCH] feat: Start transfering `open` flags from `FileSystem` to
 `File`

---
 internal/fs/file.go       | 22 +++++++++--
 internal/fs/filesystem.go | 78 +++++++++++++++++++++++++++++----------
 2 files changed, 76 insertions(+), 24 deletions(-)

diff --git a/internal/fs/file.go b/internal/fs/file.go
index a437a66..988b484 100644
--- a/internal/fs/file.go
+++ b/internal/fs/file.go
@@ -33,6 +33,17 @@ type WriteCache interface {
 	Sync() error
 }
 
+type FileFlags struct {
+	readOnly  bool
+	writeOnly bool
+
+	append            bool
+	createIfNotExists bool
+	mostNotExist      bool // If `create` is set, abort if file already exists
+	sync              bool // Sync after each operation
+	truncate          bool
+}
+
 type File struct {
 	afero.File
 
@@ -41,8 +52,9 @@ type File struct {
 
 	metadata config.MetadataConfig
 
-	path string
-	link string
+	path  string
+	link  string
+	flags *FileFlags
 
 	compressionLevel string
 	getFileBuffer    func() (WriteCache, func() error, error)
@@ -69,6 +81,7 @@ func NewFile(
 
 	path string,
 	link string,
+	flags *FileFlags,
 
 	compressionLevel string,
 	getFileBuffer func() (WriteCache, func() error, error),
@@ -84,8 +97,9 @@ func NewFile(
 
 		metadata: metadata,
 
-		path: path,
-		link: link,
+		path:  path,
+		link:  link,
+		flags: flags,
 
 		compressionLevel: compressionLevel,
 		getFileBuffer:    getFileBuffer,
diff --git a/internal/fs/filesystem.go b/internal/fs/filesystem.go
index c86b453..3f27710 100644
--- a/internal/fs/filesystem.go
+++ b/internal/fs/filesystem.go
@@ -176,6 +176,46 @@ func (f *FileSystem) MkdirAll(path string, perm os.FileMode) error {
 func (f *FileSystem) Open(name string) (afero.File, error) {
 	log.Println("FileSystem.Open", name)
 
+	return f.OpenFile(name, os.O_RDWR, os.ModePerm)
+}
+
+func (f *FileSystem) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) {
+	log.Println("FileSystem.OpenFile", name, flag, perm)
+
+	flags := &FileFlags{}
+	if flag&os.O_RDONLY != 0 {
+		flags.readOnly = true
+	}
+
+	if flag&os.O_WRONLY != 0 {
+		flags.writeOnly = true
+	}
+
+	if flag&os.O_RDWR != 0 {
+		flags.readOnly = true
+		flags.writeOnly = true
+	}
+
+	if flag&os.O_APPEND != 0 {
+		flags.append = true
+	}
+
+	if flag&os.O_CREATE != 0 {
+		flags.createIfNotExists = true
+	}
+
+	if flag&os.O_EXCL != 0 {
+		flags.mostNotExist = true
+	}
+
+	if flag&os.O_SYNC != 0 {
+		flags.sync = true
+	}
+
+	if flag&os.O_TRUNC != 0 {
+		flags.truncate = true
+	}
+
 	hdr, err := inventory.Stat(
 		f.metadata,
 
@@ -184,11 +224,24 @@ func (f *FileSystem) Open(name string) (afero.File, error) {
 		f.onHeader,
 	)
 	if err != nil {
-		if err == sql.ErrNoRows {
-			return nil, os.ErrNotExist
-		}
+		if err == sql.ErrNoRows && flags.createIfNotExists {
+			if err := f.mknode(false, name, perm); err != nil {
+				return nil, err
+			}
 
-		panic(err)
+			hdr, err = inventory.Stat(
+				f.metadata,
+
+				name,
+
+				f.onHeader,
+			)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, err
+		}
 	}
 
 	return NewFile(
@@ -199,6 +252,7 @@ func (f *FileSystem) Open(name string) (afero.File, error) {
 
 		hdr.Name,
 		hdr.Linkname,
+		flags,
 
 		f.compressionLevel,
 		f.getFileBuffer,
@@ -210,22 +264,6 @@ func (f *FileSystem) Open(name string) (afero.File, error) {
 	), nil
 }
 
-func (f *FileSystem) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) {
-	log.Println("FileSystem.OpenFile", name, flag, perm)
-
-	if _, err := f.Stat(name); err != nil {
-		if err == os.ErrNotExist && flag&os.O_CREATE != 0 {
-			if err := f.mknode(false, name, perm); err != nil {
-				return nil, err
-			}
-		} else {
-			return nil, err
-		}
-	}
-
-	return f.Open(name)
-}
-
 func (f *FileSystem) Remove(name string) error {
 	log.Println("FileSystem.Remove", name)