forked from containerd/containerd
/
httpreadseeker.go
144 lines (118 loc) · 3.3 KB
/
httpreadseeker.go
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/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package docker
import (
"bytes"
"io"
"io/ioutil"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/log"
"github.com/pkg/errors"
)
type httpReadSeeker struct {
size int64
offset int64
rc io.ReadCloser
open func(offset int64) (io.ReadCloser, error)
closed bool
}
func newHTTPReadSeeker(size int64, open func(offset int64) (io.ReadCloser, error)) (io.ReadCloser, error) {
return &httpReadSeeker{
size: size,
open: open,
}, nil
}
func (hrs *httpReadSeeker) Read(p []byte) (n int, err error) {
if hrs.closed {
return 0, io.EOF
}
rd, err := hrs.reader()
if err != nil {
return 0, err
}
n, err = rd.Read(p)
hrs.offset += int64(n)
return
}
func (hrs *httpReadSeeker) Close() error {
if hrs.closed {
return nil
}
hrs.closed = true
if hrs.rc != nil {
return hrs.rc.Close()
}
return nil
}
func (hrs *httpReadSeeker) Seek(offset int64, whence int) (int64, error) {
if hrs.closed {
return 0, errors.Wrap(errdefs.ErrUnavailable, "Fetcher.Seek: closed")
}
abs := hrs.offset
switch whence {
case io.SeekStart:
abs = offset
case io.SeekCurrent:
abs += offset
case io.SeekEnd:
if hrs.size == -1 {
return 0, errors.Wrap(errdefs.ErrUnavailable, "Fetcher.Seek: unknown size, cannot seek from end")
}
abs = hrs.size + offset
default:
return 0, errors.Wrap(errdefs.ErrInvalidArgument, "Fetcher.Seek: invalid whence")
}
if abs < 0 {
return 0, errors.Wrapf(errdefs.ErrInvalidArgument, "Fetcher.Seek: negative offset")
}
if abs != hrs.offset {
if hrs.rc != nil {
if err := hrs.rc.Close(); err != nil {
log.L.WithError(err).Errorf("Fetcher.Seek: failed to close ReadCloser")
}
hrs.rc = nil
}
hrs.offset = abs
}
return hrs.offset, nil
}
func (hrs *httpReadSeeker) reader() (io.Reader, error) {
if hrs.rc != nil {
return hrs.rc, nil
}
if hrs.size == -1 || hrs.offset < hrs.size {
// only try to reopen the body request if we are seeking to a value
// less than the actual size.
if hrs.open == nil {
return nil, errors.Wrapf(errdefs.ErrNotImplemented, "cannot open")
}
rc, err := hrs.open(hrs.offset)
if err != nil {
return nil, errors.Wrapf(err, "httpReaderSeeker: failed open")
}
if hrs.rc != nil {
if err := hrs.rc.Close(); err != nil {
log.L.WithError(err).Errorf("httpReadSeeker: failed to close ReadCloser")
}
}
hrs.rc = rc
} else {
// There is an edge case here where offset == size of the content. If
// we seek, we will probably get an error for content that cannot be
// sought (?). In that case, we should err on committing the content,
// as the length is already satisified but we just return the empty
// reader instead.
hrs.rc = ioutil.NopCloser(bytes.NewReader([]byte{}))
}
return hrs.rc, nil
}