+++ /dev/null
-package afero
-
-import (
- "io"
- "os"
- "path/filepath"
- "syscall"
-)
-
-// The UnionFile implements the afero.File interface and will be returned
-// when reading a directory present at least in the overlay or opening a file
-// for writing.
-//
-// The calls to
-// Readdir() and Readdirnames() merge the file os.FileInfo / names from the
-// base and the overlay - for files present in both layers, only those
-// from the overlay will be used.
-//
-// When opening files for writing (Create() / OpenFile() with the right flags)
-// the operations will be done in both layers, starting with the overlay. A
-// successful read in the overlay will move the cursor position in the base layer
-// by the number of bytes read.
-type UnionFile struct {
- base File
- layer File
- off int
- files []os.FileInfo
-}
-
-func (f *UnionFile) Close() error {
- // first close base, so we have a newer timestamp in the overlay. If we'd close
- // the overlay first, we'd get a cacheStale the next time we access this file
- // -> cache would be useless ;-)
- if f.base != nil {
- f.base.Close()
- }
- if f.layer != nil {
- return f.layer.Close()
- }
- return BADFD
-}
-
-func (f *UnionFile) Read(s []byte) (int, error) {
- if f.layer != nil {
- n, err := f.layer.Read(s)
- if (err == nil || err == io.EOF) && f.base != nil {
- // advance the file position also in the base file, the next
- // call may be a write at this position (or a seek with SEEK_CUR)
- if _, seekErr := f.base.Seek(int64(n), os.SEEK_CUR); seekErr != nil {
- // only overwrite err in case the seek fails: we need to
- // report an eventual io.EOF to the caller
- err = seekErr
- }
- }
- return n, err
- }
- if f.base != nil {
- return f.base.Read(s)
- }
- return 0, BADFD
-}
-
-func (f *UnionFile) ReadAt(s []byte, o int64) (int, error) {
- if f.layer != nil {
- n, err := f.layer.ReadAt(s, o)
- if (err == nil || err == io.EOF) && f.base != nil {
- _, err = f.base.Seek(o+int64(n), os.SEEK_SET)
- }
- return n, err
- }
- if f.base != nil {
- return f.base.ReadAt(s, o)
- }
- return 0, BADFD
-}
-
-func (f *UnionFile) Seek(o int64, w int) (pos int64, err error) {
- if f.layer != nil {
- pos, err = f.layer.Seek(o, w)
- if (err == nil || err == io.EOF) && f.base != nil {
- _, err = f.base.Seek(o, w)
- }
- return pos, err
- }
- if f.base != nil {
- return f.base.Seek(o, w)
- }
- return 0, BADFD
-}
-
-func (f *UnionFile) Write(s []byte) (n int, err error) {
- if f.layer != nil {
- n, err = f.layer.Write(s)
- if err == nil && f.base != nil { // hmm, do we have fixed size files where a write may hit the EOF mark?
- _, err = f.base.Write(s)
- }
- return n, err
- }
- if f.base != nil {
- return f.base.Write(s)
- }
- return 0, BADFD
-}
-
-func (f *UnionFile) WriteAt(s []byte, o int64) (n int, err error) {
- if f.layer != nil {
- n, err = f.layer.WriteAt(s, o)
- if err == nil && f.base != nil {
- _, err = f.base.WriteAt(s, o)
- }
- return n, err
- }
- if f.base != nil {
- return f.base.WriteAt(s, o)
- }
- return 0, BADFD
-}
-
-func (f *UnionFile) Name() string {
- if f.layer != nil {
- return f.layer.Name()
- }
- return f.base.Name()
-}
-
-// Readdir will weave the two directories together and
-// return a single view of the overlayed directories
-func (f *UnionFile) Readdir(c int) (ofi []os.FileInfo, err error) {
- if f.off == 0 {
- var files = make(map[string]os.FileInfo)
- var rfi []os.FileInfo
- if f.layer != nil {
- rfi, err = f.layer.Readdir(-1)
- if err != nil {
- return nil, err
- }
- for _, fi := range rfi {
- files[fi.Name()] = fi
- }
- }
-
- if f.base != nil {
- rfi, err = f.base.Readdir(-1)
- if err != nil {
- return nil, err
- }
- for _, fi := range rfi {
- if _, exists := files[fi.Name()]; !exists {
- files[fi.Name()] = fi
- }
- }
- }
- for _, fi := range files {
- f.files = append(f.files, fi)
- }
- }
- if c == -1 {
- return f.files[f.off:], nil
- }
- defer func() { f.off += c }()
- return f.files[f.off:c], nil
-}
-
-func (f *UnionFile) Readdirnames(c int) ([]string, error) {
- rfi, err := f.Readdir(c)
- if err != nil {
- return nil, err
- }
- var names []string
- for _, fi := range rfi {
- names = append(names, fi.Name())
- }
- return names, nil
-}
-
-func (f *UnionFile) Stat() (os.FileInfo, error) {
- if f.layer != nil {
- return f.layer.Stat()
- }
- if f.base != nil {
- return f.base.Stat()
- }
- return nil, BADFD
-}
-
-func (f *UnionFile) Sync() (err error) {
- if f.layer != nil {
- err = f.layer.Sync()
- if err == nil && f.base != nil {
- err = f.base.Sync()
- }
- return err
- }
- if f.base != nil {
- return f.base.Sync()
- }
- return BADFD
-}
-
-func (f *UnionFile) Truncate(s int64) (err error) {
- if f.layer != nil {
- err = f.layer.Truncate(s)
- if err == nil && f.base != nil {
- err = f.base.Truncate(s)
- }
- return err
- }
- if f.base != nil {
- return f.base.Truncate(s)
- }
- return BADFD
-}
-
-func (f *UnionFile) WriteString(s string) (n int, err error) {
- if f.layer != nil {
- n, err = f.layer.WriteString(s)
- if err == nil && f.base != nil {
- _, err = f.base.WriteString(s)
- }
- return n, err
- }
- if f.base != nil {
- return f.base.WriteString(s)
- }
- return 0, BADFD
-}
-
-func copyToLayer(base Fs, layer Fs, name string) error {
- bfh, err := base.Open(name)
- if err != nil {
- return err
- }
- defer bfh.Close()
-
- // First make sure the directory exists
- exists, err := Exists(layer, filepath.Dir(name))
- if err != nil {
- return err
- }
- if !exists {
- err = layer.MkdirAll(filepath.Dir(name), 0777) // FIXME?
- if err != nil {
- return err
- }
- }
-
- // Create the file on the overlay
- lfh, err := layer.Create(name)
- if err != nil {
- return err
- }
- n, err := io.Copy(lfh, bfh)
- if err != nil {
- // If anything fails, clean up the file
- layer.Remove(name)
- lfh.Close()
- return err
- }
-
- bfi, err := bfh.Stat()
- if err != nil || bfi.Size() != n {
- layer.Remove(name)
- lfh.Close()
- return syscall.EIO
- }
-
- err = lfh.Close()
- if err != nil {
- layer.Remove(name)
- lfh.Close()
- return err
- }
- return layer.Chtimes(name, bfi.ModTime(), bfi.ModTime())
-}
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