forked from lug/matterbridge
Add vendor files for spf13/viper
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Wim
253
vendor/github.com/spf13/afero/copyOnWriteFs.go
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vendored
Normal file
253
vendor/github.com/spf13/afero/copyOnWriteFs.go
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vendored
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package afero
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import (
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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"time"
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)
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// The CopyOnWriteFs is a union filesystem: a read only base file system with
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// a possibly writeable layer on top. Changes to the file system will only
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// be made in the overlay: Changing an existing file in the base layer which
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// is not present in the overlay will copy the file to the overlay ("changing"
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// includes also calls to e.g. Chtimes() and Chmod()).
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//
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// Reading directories is currently only supported via Open(), not OpenFile().
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type CopyOnWriteFs struct {
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base Fs
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layer Fs
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}
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func NewCopyOnWriteFs(base Fs, layer Fs) Fs {
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return &CopyOnWriteFs{base: base, layer: layer}
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}
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// Returns true if the file is not in the overlay
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func (u *CopyOnWriteFs) isBaseFile(name string) (bool, error) {
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if _, err := u.layer.Stat(name); err == nil {
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return false, nil
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}
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_, err := u.base.Stat(name)
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if err != nil {
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if oerr, ok := err.(*os.PathError); ok {
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if oerr.Err == os.ErrNotExist || oerr.Err == syscall.ENOENT || oerr.Err == syscall.ENOTDIR {
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return false, nil
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}
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}
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if err == syscall.ENOENT {
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return false, nil
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}
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}
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return true, err
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}
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func (u *CopyOnWriteFs) copyToLayer(name string) error {
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return copyToLayer(u.base, u.layer, name)
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}
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func (u *CopyOnWriteFs) Chtimes(name string, atime, mtime time.Time) error {
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b, err := u.isBaseFile(name)
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if err != nil {
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return err
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}
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if b {
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if err := u.copyToLayer(name); err != nil {
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return err
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}
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}
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return u.layer.Chtimes(name, atime, mtime)
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}
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func (u *CopyOnWriteFs) Chmod(name string, mode os.FileMode) error {
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b, err := u.isBaseFile(name)
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if err != nil {
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return err
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}
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if b {
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if err := u.copyToLayer(name); err != nil {
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return err
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}
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}
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return u.layer.Chmod(name, mode)
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}
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func (u *CopyOnWriteFs) Stat(name string) (os.FileInfo, error) {
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fi, err := u.layer.Stat(name)
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if err != nil {
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origErr := err
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if e, ok := err.(*os.PathError); ok {
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err = e.Err
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}
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if err == os.ErrNotExist || err == syscall.ENOENT || err == syscall.ENOTDIR {
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return u.base.Stat(name)
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}
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return nil, origErr
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}
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return fi, nil
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}
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// Renaming files present only in the base layer is not permitted
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func (u *CopyOnWriteFs) Rename(oldname, newname string) error {
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b, err := u.isBaseFile(oldname)
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if err != nil {
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return err
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}
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if b {
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return syscall.EPERM
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}
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return u.layer.Rename(oldname, newname)
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}
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// Removing files present only in the base layer is not permitted. If
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// a file is present in the base layer and the overlay, only the overlay
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// will be removed.
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func (u *CopyOnWriteFs) Remove(name string) error {
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err := u.layer.Remove(name)
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switch err {
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case syscall.ENOENT:
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_, err = u.base.Stat(name)
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if err == nil {
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return syscall.EPERM
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}
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return syscall.ENOENT
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default:
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return err
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}
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}
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func (u *CopyOnWriteFs) RemoveAll(name string) error {
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err := u.layer.RemoveAll(name)
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switch err {
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case syscall.ENOENT:
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_, err = u.base.Stat(name)
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if err == nil {
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return syscall.EPERM
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}
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return syscall.ENOENT
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default:
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return err
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}
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}
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func (u *CopyOnWriteFs) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
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b, err := u.isBaseFile(name)
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if err != nil {
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return nil, err
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}
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if flag&(os.O_WRONLY|os.O_RDWR|os.O_APPEND|os.O_CREATE|os.O_TRUNC) != 0 {
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if b {
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if err = u.copyToLayer(name); err != nil {
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return nil, err
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}
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return u.layer.OpenFile(name, flag, perm)
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}
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dir := filepath.Dir(name)
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isaDir, err := IsDir(u.base, dir)
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if err != nil && !os.IsNotExist(err) {
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return nil, err
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}
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if isaDir {
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if err = u.layer.MkdirAll(dir, 0777); err != nil {
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return nil, err
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}
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return u.layer.OpenFile(name, flag, perm)
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}
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isaDir, err = IsDir(u.layer, dir)
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if err != nil {
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return nil, err
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}
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if isaDir {
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return u.layer.OpenFile(name, flag, perm)
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}
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return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOTDIR} // ...or os.ErrNotExist?
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}
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if b {
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return u.base.OpenFile(name, flag, perm)
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}
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return u.layer.OpenFile(name, flag, perm)
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}
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// This function handles the 9 different possibilities caused
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// by the union which are the intersection of the following...
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// layer: doesn't exist, exists as a file, and exists as a directory
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// base: doesn't exist, exists as a file, and exists as a directory
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func (u *CopyOnWriteFs) Open(name string) (File, error) {
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// Since the overlay overrides the base we check that first
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b, err := u.isBaseFile(name)
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if err != nil {
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return nil, err
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}
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// If overlay doesn't exist, return the base (base state irrelevant)
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if b {
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return u.base.Open(name)
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}
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// If overlay is a file, return it (base state irrelevant)
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dir, err := IsDir(u.layer, name)
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if err != nil {
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return nil, err
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}
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if !dir {
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return u.layer.Open(name)
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}
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// Overlay is a directory, base state now matters.
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// Base state has 3 states to check but 2 outcomes:
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// A. It's a file or non-readable in the base (return just the overlay)
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// B. It's an accessible directory in the base (return a UnionFile)
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// If base is file or nonreadable, return overlay
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dir, err = IsDir(u.base, name)
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if !dir || err != nil {
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return u.layer.Open(name)
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}
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// Both base & layer are directories
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// Return union file (if opens are without error)
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bfile, bErr := u.base.Open(name)
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lfile, lErr := u.layer.Open(name)
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// If either have errors at this point something is very wrong. Return nil and the errors
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if bErr != nil || lErr != nil {
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return nil, fmt.Errorf("BaseErr: %v\nOverlayErr: %v", bErr, lErr)
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}
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return &UnionFile{base: bfile, layer: lfile}, nil
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}
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func (u *CopyOnWriteFs) Mkdir(name string, perm os.FileMode) error {
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dir, err := IsDir(u.base, name)
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if err != nil {
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return u.layer.MkdirAll(name, perm)
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}
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if dir {
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return syscall.EEXIST
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}
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return u.layer.MkdirAll(name, perm)
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}
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func (u *CopyOnWriteFs) Name() string {
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return "CopyOnWriteFs"
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}
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func (u *CopyOnWriteFs) MkdirAll(name string, perm os.FileMode) error {
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dir, err := IsDir(u.base, name)
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if err != nil {
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return u.layer.MkdirAll(name, perm)
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}
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if dir {
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return syscall.EEXIST
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}
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return u.layer.MkdirAll(name, perm)
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}
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func (u *CopyOnWriteFs) Create(name string) (File, error) {
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return u.OpenFile(name, os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0666)
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}
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