mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-08 20:55:01 +00:00
67 lines
1.8 KiB
Go
67 lines
1.8 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package fs
|
|
|
|
import "io"
|
|
|
|
// ReadFileFS is the interface implemented by a file system
|
|
// that provides an optimized implementation of ReadFile.
|
|
type ReadFileFS interface {
|
|
FS
|
|
|
|
// ReadFile reads the named file and returns its contents.
|
|
// A successful call returns a nil error, not io.EOF.
|
|
// (Because ReadFile reads the whole file, the expected EOF
|
|
// from the final Read is not treated as an error to be reported.)
|
|
//
|
|
// The caller is permitted to modify the returned byte slice.
|
|
// This method should return a copy of the underlying data.
|
|
ReadFile(name string) ([]byte, error)
|
|
}
|
|
|
|
// ReadFile reads the named file from the file system fs and returns its contents.
|
|
// A successful call returns a nil error, not io.EOF.
|
|
// (Because ReadFile reads the whole file, the expected EOF
|
|
// from the final Read is not treated as an error to be reported.)
|
|
//
|
|
// If fs implements ReadFileFS, ReadFile calls fs.ReadFile.
|
|
// Otherwise ReadFile calls fs.Open and uses Read and Close
|
|
// on the returned file.
|
|
func ReadFile(fsys FS, name string) ([]byte, error) {
|
|
if fsys, ok := fsys.(ReadFileFS); ok {
|
|
return fsys.ReadFile(name)
|
|
}
|
|
|
|
file, err := fsys.Open(name)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer file.Close()
|
|
|
|
var size int
|
|
if info, err := file.Stat(); err == nil {
|
|
size64 := info.Size()
|
|
if int64(int(size64)) == size64 {
|
|
size = int(size64)
|
|
}
|
|
}
|
|
|
|
data := make([]byte, 0, size+1)
|
|
for {
|
|
if len(data) >= cap(data) {
|
|
d := append(data[:cap(data)], 0)
|
|
data = d[:len(data)]
|
|
}
|
|
n, err := file.Read(data[len(data):cap(data)])
|
|
data = data[:len(data)+n]
|
|
if err != nil {
|
|
if err == io.EOF {
|
|
err = nil
|
|
}
|
|
return data, err
|
|
}
|
|
}
|
|
}
|