vendor/github.com/hashicorp/go-getter/get_file_copy.go

   1 package getter
   2
   3 import (
   4         "context"
   5         "io"
   6 )
   7
   8 // readerFunc is syntactic sugar for read interface.
   9 type readerFunc func(p []byte) (n int, err error)
  10
  11 func (rf readerFunc) Read(p []byte) (n int, err error) { return rf(p) }
  12
  13 // Copy is a io.Copy cancellable by context
  14 func Copy(ctx context.Context, dst io.Writer, src io.Reader) (int64, error) {
  15         // Copy will call the Reader and Writer interface multiple time, in order
  16         // to copy by chunk (avoiding loading the whole file in memory).
  17         return io.Copy(dst, readerFunc(func(p []byte) (int, error) {
  18
  19                 select {
  20                 case <-ctx.Done():
  21                         // context has been canceled
  22                         // stop process and propagate "context canceled" error
  23                         return 0, ctx.Err()
  24                 default:
  25                         // otherwise just run default io.Reader implementation
  26                         return src.Read(p)
  27                 }
  28         }))
  29 }