implemented os file interface acstraction

pkg/provider/interface.go

@@ -0,0 +1,45 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package provider
+
+import (
+	"io/fs"
+	"os"
+)
+
+type FS interface {
+	Stat(string) (fs.FileInfo, error)
+	Remove(string) error
+	Open(string) (File, error)
+	OpenFile(string, int, os.FileMode) (File, error)
+	MkdirAll(string, os.FileMode) error
+	Root() string
+	Fstat(uintptr) (int64, error)
+}
+
+type walk struct {
+	fs FS
+}
+
+func (w *walk) Open(p string) (fs.File, error) {
+	return w.fs.Open(p)
+}
+
+func WalkFS(fs FS) fs.FS {
+	return &walk{fs}
+}
+
+type File interface {
+	Name() string
+	Stat() (fs.FileInfo, error)
+	Truncate(int64) error
+	Sync() error
+	Fd() uintptr
+	ReadDir(int) ([]fs.DirEntry, error)
+	Read([]byte) (int, error)
+	ReadAt([]byte, int64) (int, error)
+	WriteAt([]byte, int64) (int, error)
+	Seek(int64, int) (int64, error)
+	Readdir(int) ([]fs.FileInfo, error)
+	Close() error
+}

pkg/provider/mount/mount.go

@@ -0,0 +1,57 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package mount
+
+import (
+	"cachefs/pkg/provider"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+)
+
+var _ provider.FS = (*FS)(nil)
+
+type FS struct {
+	root string
+}
+
+func NewFS(root string) *FS {
+	return &FS{root}
+}
+
+func (fs *FS) path(p string) string {
+	return filepath.Join(fs.root, filepath.FromSlash(path.Clean("/"+p)))
+}
+
+func (fs *FS) Stat(p string) (fs.FileInfo, error) {
+	return os.Stat(fs.path(p))
+}
+
+func (fs *FS) Remove(p string) error {
+	return os.Remove(fs.path(p))
+}
+
+func (fs *FS) Open(p string) (provider.File, error) {
+	return os.Open(fs.path(p))
+}
+
+func (fs *FS) OpenFile(p string, flags int, mode os.FileMode) (provider.File, error) {
+	return os.OpenFile(fs.path(p), flags, mode)
+}
+
+func (fs *FS) MkdirAll(p string, mode os.FileMode) error {
+	return os.MkdirAll(fs.path(p), mode)
+}
+
+func (fs *FS) Root() string {
+	return fs.root
+}
+
+func (fs *FS) Fstat(fd uintptr) (int64, error) {
+	var stat unix.Stat_t
+	err := unix.Fstat(int(fd), &stat)
+	return stat.Blocks, err
+}

pkg/provider/parse/parse.go

@@ -0,0 +1,34 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package parse
+
+import (
+	"cachefs/pkg/provider"
+	"cachefs/pkg/provider/mount"
+	"errors"
+	"fmt"
+	neturl "net/url"
+	"path/filepath"
+)
+
+var (
+	ErrPathNotAbsolute   = errors.New("path is not absolute")
+	ErrUnsupportedScheme = errors.New("unsupported scheme")
+)
+
+func FS(url string) (provider.FS, error) {
+	u, err := neturl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+	if !filepath.IsAbs(u.Path) {
+		return nil, ErrPathNotAbsolute
+	}
+	switch u.Scheme {
+	case "file":
+		return mount.NewFS(u.Path), nil
+		//case "sftp":
+		//	return sftp.FS(u.Path), nil
+	}
+	return nil, fmt.Errorf("%w: %s", ErrUnsupportedScheme, u.Scheme)
+}

pkg/provider/sftp/sftp.go

@@ -0,0 +1,5 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package sftp
+
+// github.com/pkg/sftp