feat: implement Seek, Read and ReadAt

file.go

@@ -2,6 +2,7 @@ package gormfs
 
 import (
 	"errors"
+	"io"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -14,6 +15,7 @@ type aferoFile struct {
 	db   *gorm.DB
 	name string
 	flag int
+	head int64
 }
 
 var _ afero.File = (*aferoFile)(nil)
@@ -52,7 +54,15 @@ func (af *aferoFile) Stat() (fs.FileInfo, error) {
 }
 
 func (af *aferoFile) Seek(offset int64, whence int) (int64, error) {
-	return -1, errors.New("aferoFile.Seek not implemented")
+	switch whence {
+	case io.SeekStart:
+		af.head = offset
+	case io.SeekCurrent:
+		af.head += offset
+	case io.SeekEnd:
+		af.head = af.Size() + offset
+	}
+	return af.head, nil
 }
 
 func (af *aferoFile) Readdirnames(count int) ([]string, error) {
@@ -64,11 +74,31 @@ func (af *aferoFile) Readdir(count int) ([]fs.FileInfo, error) {
 }
 
 func (af *aferoFile) ReadAt(p []byte, off int64) (int, error) {
-	return -1, errors.New("aferoFile.ReadAt not implemented")
+	f, err := getFile(af.db, af.name)
+	if err != nil {
+		return 0, err
+	}
+
+	if off >= int64(len(f.Data)) {
+		return 0, io.EOF
+	}
+
+	return copy(p, f.Data[off:]), nil
 }
 
 func (af *aferoFile) Read(p []byte) (int, error) {
-	return -1, errors.New("aferoFile.Read not implemented")
+	f, err := getFile(af.db, af.name)
+	if err != nil {
+		return 0, err
+	}
+
+	if af.head >= int64(len(f.Data)) {
+		return 0, io.EOF
+	}
+
+	n := copy(p, f.Data[af.head:])
+	af.head += int64(n)
+	return n, nil
 }
 
 func (af *aferoFile) Name() string {

fs.go

@@ -14,6 +14,7 @@ import (
 )
 
 // FIXME: set File.Mode, File.ATime, File.User and File.Group correctly
+// FIXME: handle flag correctly
 
 type GormFs struct {
 	db *gorm.DB
@@ -29,7 +30,7 @@ func NewGormFs(db *gorm.DB) (*GormFs, error) {
 var _ afero.Fs = (*GormFs)(nil)
 
 func (fs *GormFs) Chmod(name string, mode os.FileMode) error {
-	f, err := fs.get(name)
+	f, err := getFile(fs.db, name)
 	if err != nil {
 		return err
 	}
@@ -39,7 +40,7 @@ func (fs *GormFs) Chmod(name string, mode os.FileMode) error {
 }
 
 func (fs *GormFs) Chown(name string, uid, gid int) error {
-	f, err := fs.get(name)
+	f, err := getFile(fs.db, name)
 	if err != nil {
 		return err
 	}
@@ -50,7 +51,7 @@ func (fs *GormFs) Chown(name string, uid, gid int) error {
 }
 
 func (fs *GormFs) Chtimes(name string, atime time.Time, mtime time.Time) error {
-	f, err := fs.get(name)
+	f, err := getFile(fs.db, name)
 	if err != nil {
 		return err
 	}
@@ -179,11 +180,3 @@ func (fs *GormFs) exists(name string) bool {
 	}
 	return fs.db.Where("name = ?", name).Limit(1).Find(&File{}).RowsAffected != 0
 }
-
-func (fs *GormFs) get(name string) (*File, error) {
-	var f File
-	if err := fs.db.Where("name = ?", name).Limit(1).Find(&f).Error; err != nil {
-		return nil, err
-	}
-	return &f, nil
-}

models.go

@@ -13,6 +13,7 @@ type File struct {
 	IsDir bool
 	User  int
 	Group int
+	Data  []byte
 }
 
 var allModels = []interface{}{&File{}}

utils.go

@@ -0,0 +1,11 @@
+package gormfs
+
+import "gorm.io/gorm"
+
+func getFile(db *gorm.DB, name string) (*File, error) {
+	var f File
+	if err := db.Where("name = ?", name).Limit(1).Find(&f).Error; err != nil {
+		return nil, err
+	}
+	return &f, nil
+}