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// Copyright 2017, the Blazer 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 b2
import (
"bytes"
"crypto/sha1"
"errors"
"fmt"
"hash"
"io"
"io/ioutil"
"os"
"strings"
"sync"
)
type readResetter interface {
Read([]byte) (int, error)
Reset() error
}
type resetter struct {
rs io.ReadSeeker
}
func (r resetter) Read(p []byte) (int, error) { return r.rs.Read(p) }
func (r resetter) Reset() error { _, err := r.rs.Seek(0, 0); return err }
func newResetter(p []byte) readResetter { return resetter{rs: bytes.NewReader(p)} }
type writeBuffer interface {
io.Writer
Len() int
Reader() (readResetter, error)
Hash() string // sha1 or whatever it is
Close() error
}
// nonBuffer doesn't buffer anything, but passes values directly from the
// source readseeker. Many nonBuffers can point at different parts of the same
// underlying source, and be accessed by multiple goroutines simultaneously.
func newNonBuffer(rs io.ReaderAt, offset, size int64) writeBuffer {
return &nonBuffer{
r: io.NewSectionReader(rs, offset, size),
size: int(size),
hsh: sha1.New(),
}
}
type nonBuffer struct {
r *io.SectionReader
size int
hsh hash.Hash
isEOF bool
buf *strings.Reader
}
func (nb *nonBuffer) Len() int { return nb.size + 40 }
func (nb *nonBuffer) Hash() string { return "hex_digits_at_end" }
func (nb *nonBuffer) Close() error { return nil }
func (nb *nonBuffer) Reader() (readResetter, error) { return nb, nil }
func (nb *nonBuffer) Write([]byte) (int, error) { return 0, errors.New("writes not supported") }
func (nb *nonBuffer) Read(p []byte) (int, error) {
if nb.isEOF {
return nb.buf.Read(p)
}
n, err := io.TeeReader(nb.r, nb.hsh).Read(p)
if err == io.EOF {
err = nil
nb.isEOF = true
nb.buf = strings.NewReader(fmt.Sprintf("%x", nb.hsh.Sum(nil)))
}
return n, err
}
func (nb *nonBuffer) Reset() error {
nb.hsh.Reset()
nb.isEOF = false
_, err := nb.r.Seek(0, 0)
return err
}
type memoryBuffer struct {
buf *bytes.Buffer
hsh hash.Hash
w io.Writer
mux sync.Mutex
}
var bufpool *sync.Pool
func init() {
bufpool = &sync.Pool{}
bufpool.New = func() interface{} { return &bytes.Buffer{} }
}
func newMemoryBuffer() *memoryBuffer {
mb := &memoryBuffer{
hsh: sha1.New(),
}
mb.buf = bufpool.Get().(*bytes.Buffer)
mb.w = io.MultiWriter(mb.hsh, mb.buf)
return mb
}
func (mb *memoryBuffer) Write(p []byte) (int, error) { return mb.w.Write(p) }
func (mb *memoryBuffer) Len() int { return mb.buf.Len() }
func (mb *memoryBuffer) Reader() (readResetter, error) { return newResetter(mb.buf.Bytes()), nil }
func (mb *memoryBuffer) Hash() string { return fmt.Sprintf("%x", mb.hsh.Sum(nil)) }
func (mb *memoryBuffer) Close() error {
mb.mux.Lock()
defer mb.mux.Unlock()
if mb.buf == nil {
return nil
}
mb.buf.Truncate(0)
bufpool.Put(mb.buf)
mb.buf = nil
return nil
}
type fileBuffer struct {
f *os.File
hsh hash.Hash
w io.Writer
s int
}
func newFileBuffer(loc string) (*fileBuffer, error) {
f, err := ioutil.TempFile(loc, "blazer")
if err != nil {
return nil, err
}
fb := &fileBuffer{
f: f,
hsh: sha1.New(),
}
fb.w = io.MultiWriter(fb.f, fb.hsh)
return fb, nil
}
func (fb *fileBuffer) Write(p []byte) (int, error) {
n, err := fb.w.Write(p)
fb.s += n
return n, err
}
func (fb *fileBuffer) Len() int { return fb.s }
func (fb *fileBuffer) Hash() string { return fmt.Sprintf("%x", fb.hsh.Sum(nil)) }
func (fb *fileBuffer) Reader() (readResetter, error) {
if _, err := fb.f.Seek(0, 0); err != nil {
return nil, err
}
return &fr{f: fb.f}, nil
}
func (fb *fileBuffer) Close() error {
fb.f.Close()
return os.Remove(fb.f.Name())
}
// wraps *os.File so that the http package doesn't see it as an io.Closer
type fr struct {
f *os.File
}
func (r *fr) Read(p []byte) (int, error) { return r.f.Read(p) }
func (r *fr) Reset() error { _, err := r.f.Seek(0, 0); return err }
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