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package util
import (
"context"
"io"
"os"
"path/filepath"
"github.com/containerd/continuity/fs"
"github.com/moby/buildkit/snapshot"
"github.com/pkg/errors"
"github.com/tonistiigi/fsutil"
fstypes "github.com/tonistiigi/fsutil/types"
)
type ReadRequest struct {
Filename string
Range *FileRange
}
type FileRange struct {
Offset int
Length int
}
func withMount(mount snapshot.Mountable, cb func(string) error) error {
lm := snapshot.LocalMounter(mount)
root, err := lm.Mount()
if err != nil {
return err
}
defer func() {
if lm != nil {
lm.Unmount()
}
}()
if err := cb(root); err != nil {
return err
}
if err := lm.Unmount(); err != nil {
return err
}
lm = nil
return nil
}
func ReadFile(ctx context.Context, mount snapshot.Mountable, req ReadRequest) ([]byte, error) {
var dt []byte
err := withMount(mount, func(root string) error {
fp, err := fs.RootPath(root, req.Filename)
if err != nil {
return errors.WithStack(err)
}
f, err := os.Open(fp)
if err != nil {
// The filename here is internal to the mount, so we can restore
// the request base path for error reporting.
// See os.DirFS.Open for details.
if pe, ok := err.(*os.PathError); ok {
pe.Path = req.Filename
}
return errors.WithStack(err)
}
defer f.Close()
var rdr io.Reader = f
if req.Range != nil {
rdr = io.NewSectionReader(f, int64(req.Range.Offset), int64(req.Range.Length))
}
dt, err = io.ReadAll(rdr)
if err != nil {
return errors.WithStack(err)
}
return nil
})
return dt, err
}
type ReadDirRequest struct {
Path string
IncludePattern string
}
func ReadDir(ctx context.Context, mount snapshot.Mountable, req ReadDirRequest) ([]*fstypes.Stat, error) {
var (
rd []*fstypes.Stat
fo fsutil.FilterOpt
)
if req.IncludePattern != "" {
fo.IncludePatterns = append(fo.IncludePatterns, req.IncludePattern)
}
err := withMount(mount, func(root string) error {
fp, err := fs.RootPath(root, req.Path)
if err != nil {
return errors.WithStack(err)
}
return fsutil.Walk(ctx, fp, &fo, func(path string, info os.FileInfo, err error) error {
if err != nil {
return errors.Wrapf(err, "walking %q", root)
}
stat, ok := info.Sys().(*fstypes.Stat)
if !ok {
// This "can't happen(tm)".
return errors.Errorf("expected a *fsutil.Stat but got %T", info.Sys())
}
rd = append(rd, stat)
if info.IsDir() {
return filepath.SkipDir
}
return nil
})
})
return rd, err
}
func StatFile(ctx context.Context, mount snapshot.Mountable, path string) (*fstypes.Stat, error) {
var st *fstypes.Stat
err := withMount(mount, func(root string) error {
fp, err := fs.RootPath(root, path)
if err != nil {
return errors.WithStack(err)
}
if st, err = fsutil.Stat(fp); err != nil {
// The filename here is internal to the mount, so we can restore
// the request base path for error reporting.
// See os.DirFS.Open for details.
err1 := err
if err := errors.Cause(err); err != nil {
err1 = err
}
if pe, ok := err1.(*os.PathError); ok {
pe.Path = path
}
return errors.WithStack(err)
}
return nil
})
return st, err
}
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