container: add support for uploading to registries

Add a new generic container registry client via a new `container`
package. Use this to create a command line utility as well as a
new upload target for container registries.

The code uses the github.com/containers/* project and packages to
interact with container registires that is also used by skopeo,
podman et al. One if the dependencies is `proglottis/gpgme` that
is using cgo to bind libgpgme, so we have to add the corresponding
devel package to the BuildRequires as well as installing it on CI.

Checks will follow later via an integration test.

vendor/github.com/containers/storage/pkg/ioutils/buffer.go

@@ -0,0 +1,51 @@
+package ioutils
+
+import (
+	"errors"
+	"io"
+)
+
+var errBufferFull = errors.New("buffer is full")
+
+type fixedBuffer struct {
+	buf      []byte
+	pos      int
+	lastRead int
+}
+
+func (b *fixedBuffer) Write(p []byte) (int, error) {
+	n := copy(b.buf[b.pos:cap(b.buf)], p)
+	b.pos += n
+
+	if n < len(p) {
+		if b.pos == cap(b.buf) {
+			return n, errBufferFull
+		}
+		return n, io.ErrShortWrite
+	}
+	return n, nil
+}
+
+func (b *fixedBuffer) Read(p []byte) (int, error) {
+	n := copy(p, b.buf[b.lastRead:b.pos])
+	b.lastRead += n
+	return n, nil
+}
+
+func (b *fixedBuffer) Len() int {
+	return b.pos - b.lastRead
+}
+
+func (b *fixedBuffer) Cap() int {
+	return cap(b.buf)
+}
+
+func (b *fixedBuffer) Reset() {
+	b.pos = 0
+	b.lastRead = 0
+	b.buf = b.buf[:0]
+}
+
+func (b *fixedBuffer) String() string {
+	return string(b.buf[b.lastRead:b.pos])
+}

vendor/github.com/containers/storage/pkg/ioutils/bytespipe.go

@@ -0,0 +1,186 @@
+package ioutils
+
+import (
+	"errors"
+	"io"
+	"sync"
+)
+
+// maxCap is the highest capacity to use in byte slices that buffer data.
+const maxCap = 1e6
+
+// minCap is the lowest capacity to use in byte slices that buffer data
+const minCap = 64
+
+// blockThreshold is the minimum number of bytes in the buffer which will cause
+// a write to BytesPipe to block when allocating a new slice.
+const blockThreshold = 1e6
+
+var (
+	// ErrClosed is returned when Write is called on a closed BytesPipe.
+	ErrClosed = errors.New("write to closed BytesPipe")
+
+	bufPools     = make(map[int]*sync.Pool)
+	bufPoolsLock sync.Mutex
+)
+
+// BytesPipe is io.ReadWriteCloser which works similarly to pipe(queue).
+// All written data may be read at most once. Also, BytesPipe allocates
+// and releases new byte slices to adjust to current needs, so the buffer
+// won't be overgrown after peak loads.
+type BytesPipe struct {
+	mu       sync.Mutex
+	wait     *sync.Cond
+	buf      []*fixedBuffer
+	bufLen   int
+	closeErr error // error to return from next Read. set to nil if not closed.
+}
+
+// NewBytesPipe creates new BytesPipe, initialized by specified slice.
+// If buf is nil, then it will be initialized with slice which cap is 64.
+// buf will be adjusted in a way that len(buf) == 0, cap(buf) == cap(buf).
+func NewBytesPipe() *BytesPipe {
+	bp := &BytesPipe{}
+	bp.buf = append(bp.buf, getBuffer(minCap))
+	bp.wait = sync.NewCond(&bp.mu)
+	return bp
+}
+
+// Write writes p to BytesPipe.
+// It can allocate new []byte slices in a process of writing.
+func (bp *BytesPipe) Write(p []byte) (int, error) {
+	bp.mu.Lock()
+
+	written := 0
+loop0:
+	for {
+		if bp.closeErr != nil {
+			bp.mu.Unlock()
+			return written, ErrClosed
+		}
+
+		if len(bp.buf) == 0 {
+			bp.buf = append(bp.buf, getBuffer(64))
+		}
+		// get the last buffer
+		b := bp.buf[len(bp.buf)-1]
+
+		n, err := b.Write(p)
+		written += n
+		bp.bufLen += n
+
+		// errBufferFull is an error we expect to get if the buffer is full
+		if err != nil && err != errBufferFull {
+			bp.wait.Broadcast()
+			bp.mu.Unlock()
+			return written, err
+		}
+
+		// if there was enough room to write all then break
+		if len(p) == n {
+			break
+		}
+
+		// more data: write to the next slice
+		p = p[n:]
+
+		// make sure the buffer doesn't grow too big from this write
+		for bp.bufLen >= blockThreshold {
+			bp.wait.Wait()
+			if bp.closeErr != nil {
+				continue loop0
+			}
+		}
+
+		// add new byte slice to the buffers slice and continue writing
+		nextCap := b.Cap() * 2
+		if nextCap > maxCap {
+			nextCap = maxCap
+		}
+		bp.buf = append(bp.buf, getBuffer(nextCap))
+	}
+	bp.wait.Broadcast()
+	bp.mu.Unlock()
+	return written, nil
+}
+
+// CloseWithError causes further reads from a BytesPipe to return immediately.
+func (bp *BytesPipe) CloseWithError(err error) error {
+	bp.mu.Lock()
+	if err != nil {
+		bp.closeErr = err
+	} else {
+		bp.closeErr = io.EOF
+	}
+	bp.wait.Broadcast()
+	bp.mu.Unlock()
+	return nil
+}
+
+// Close causes further reads from a BytesPipe to return immediately.
+func (bp *BytesPipe) Close() error {
+	return bp.CloseWithError(nil)
+}
+
+// Read reads bytes from BytesPipe.
+// Data could be read only once.
+func (bp *BytesPipe) Read(p []byte) (n int, err error) {
+	bp.mu.Lock()
+	if bp.bufLen == 0 {
+		if bp.closeErr != nil {
+			bp.mu.Unlock()
+			return 0, bp.closeErr
+		}
+		bp.wait.Wait()
+		if bp.bufLen == 0 && bp.closeErr != nil {
+			err := bp.closeErr
+			bp.mu.Unlock()
+			return 0, err
+		}
+	}
+
+	for bp.bufLen > 0 {
+		b := bp.buf[0]
+		read, _ := b.Read(p) // ignore error since fixedBuffer doesn't really return an error
+		n += read
+		bp.bufLen -= read
+
+		if b.Len() == 0 {
+			// it's empty so return it to the pool and move to the next one
+			returnBuffer(b)
+			bp.buf[0] = nil
+			bp.buf = bp.buf[1:]
+		}
+
+		if len(p) == read {
+			break
+		}
+
+		p = p[read:]
+	}
+
+	bp.wait.Broadcast()
+	bp.mu.Unlock()
+	return
+}
+
+func returnBuffer(b *fixedBuffer) {
+	b.Reset()
+	bufPoolsLock.Lock()
+	pool := bufPools[b.Cap()]
+	bufPoolsLock.Unlock()
+	if pool != nil {
+		pool.Put(b)
+	}
+}
+
+func getBuffer(size int) *fixedBuffer {
+	bufPoolsLock.Lock()
+	pool, ok := bufPools[size]
+	if !ok {
+		pool = &sync.Pool{New: func() interface{} { return &fixedBuffer{buf: make([]byte, 0, size)} }}
+		bufPools[size] = pool
+	}
+	bufPoolsLock.Unlock()
+	return pool.Get().(*fixedBuffer)
+}

vendor/github.com/containers/storage/pkg/ioutils/fswriters.go

@@ -0,0 +1,195 @@
+package ioutils
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// AtomicFileWriterOptions specifies options for creating the atomic file writer.
+type AtomicFileWriterOptions struct {
+	// NoSync specifies whether the sync call must be skipped for the file.
+	// If NoSync is not specified, the file is synced to the
+	// storage after it has been written and before it is moved to
+	// the specified path.
+	NoSync bool
+}
+
+var defaultWriterOptions AtomicFileWriterOptions = AtomicFileWriterOptions{}
+
+// SetDefaultOptions overrides the default options used when creating an
+// atomic file writer.
+func SetDefaultOptions(opts AtomicFileWriterOptions) {
+	defaultWriterOptions = opts
+}
+
+// NewAtomicFileWriterWithOpts returns WriteCloser so that writing to it writes to a
+// temporary file and closing it atomically changes the temporary file to
+// destination path. Writing and closing concurrently is not allowed.
+func NewAtomicFileWriterWithOpts(filename string, perm os.FileMode, opts *AtomicFileWriterOptions) (io.WriteCloser, error) {
+	f, err := ioutil.TempFile(filepath.Dir(filename), ".tmp-"+filepath.Base(filename))
+	if err != nil {
+		return nil, err
+	}
+	if opts == nil {
+		opts = &defaultWriterOptions
+	}
+	abspath, err := filepath.Abs(filename)
+	if err != nil {
+		return nil, err
+	}
+	return &atomicFileWriter{
+		f:      f,
+		fn:     abspath,
+		perm:   perm,
+		noSync: opts.NoSync,
+	}, nil
+}
+
+// NewAtomicFileWriter returns WriteCloser so that writing to it writes to a
+// temporary file and closing it atomically changes the temporary file to
+// destination path. Writing and closing concurrently is not allowed.
+func NewAtomicFileWriter(filename string, perm os.FileMode) (io.WriteCloser, error) {
+	return NewAtomicFileWriterWithOpts(filename, perm, nil)
+}
+
+// AtomicWriteFile atomically writes data to a file named by filename.
+func AtomicWriteFile(filename string, data []byte, perm os.FileMode) error {
+	f, err := NewAtomicFileWriter(filename, perm)
+	if err != nil {
+		return err
+	}
+	n, err := f.Write(data)
+	if err == nil && n < len(data) {
+		err = io.ErrShortWrite
+		f.(*atomicFileWriter).writeErr = err
+	}
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+	return err
+}
+
+type atomicFileWriter struct {
+	f        *os.File
+	fn       string
+	writeErr error
+	perm     os.FileMode
+	noSync   bool
+}
+
+func (w *atomicFileWriter) Write(dt []byte) (int, error) {
+	n, err := w.f.Write(dt)
+	if err != nil {
+		w.writeErr = err
+	}
+	return n, err
+}
+
+func (w *atomicFileWriter) Close() (retErr error) {
+	defer func() {
+		if retErr != nil || w.writeErr != nil {
+			os.Remove(w.f.Name())
+		}
+	}()
+	if !w.noSync {
+		if err := fdatasync(w.f); err != nil {
+			w.f.Close()
+			return err
+		}
+	}
+	if err := w.f.Close(); err != nil {
+		return err
+	}
+	if err := os.Chmod(w.f.Name(), w.perm); err != nil {
+		return err
+	}
+	if w.writeErr == nil {
+		return os.Rename(w.f.Name(), w.fn)
+	}
+	return nil
+}
+
+// AtomicWriteSet is used to atomically write a set
+// of files and ensure they are visible at the same time.
+// Must be committed to a new directory.
+type AtomicWriteSet struct {
+	root string
+}
+
+// NewAtomicWriteSet creates a new atomic write set to
+// atomically create a set of files. The given directory
+// is used as the base directory for storing files before
+// commit. If no temporary directory is given the system
+// default is used.
+func NewAtomicWriteSet(tmpDir string) (*AtomicWriteSet, error) {
+	td, err := ioutil.TempDir(tmpDir, "write-set-")
+	if err != nil {
+		return nil, err
+	}
+
+	return &AtomicWriteSet{
+		root: td,
+	}, nil
+}
+
+// WriteFile writes a file to the set, guaranteeing the file
+// has been synced.
+func (ws *AtomicWriteSet) WriteFile(filename string, data []byte, perm os.FileMode) error {
+	f, err := ws.FileWriter(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	n, err := f.Write(data)
+	if err == nil && n < len(data) {
+		err = io.ErrShortWrite
+	}
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+	return err
+}
+
+type syncFileCloser struct {
+	*os.File
+}
+
+func (w syncFileCloser) Close() error {
+	if !defaultWriterOptions.NoSync {
+		return w.File.Close()
+	}
+	err := fdatasync(w.File)
+	if err1 := w.File.Close(); err == nil {
+		err = err1
+	}
+	return err
+}
+
+// FileWriter opens a file writer inside the set. The file
+// should be synced and closed before calling commit.
+func (ws *AtomicWriteSet) FileWriter(name string, flag int, perm os.FileMode) (io.WriteCloser, error) {
+	f, err := os.OpenFile(filepath.Join(ws.root, name), flag, perm)
+	if err != nil {
+		return nil, err
+	}
+	return syncFileCloser{f}, nil
+}
+
+// Cancel cancels the set and removes all temporary data
+// created in the set.
+func (ws *AtomicWriteSet) Cancel() error {
+	return os.RemoveAll(ws.root)
+}
+
+// Commit moves all created files to the target directory. The
+// target directory must not exist and the parent of the target
+// directory must exist.
+func (ws *AtomicWriteSet) Commit(target string) error {
+	return os.Rename(ws.root, target)
+}
+
+// String returns the location the set is writing to.
+func (ws *AtomicWriteSet) String() string {
+	return ws.root
+}

vendor/github.com/containers/storage/pkg/ioutils/fswriters_linux.go

@@ -0,0 +1,11 @@
+package ioutils
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func fdatasync(f *os.File) error {
+	return unix.Fdatasync(int(f.Fd()))
+}

vendor/github.com/containers/storage/pkg/ioutils/fswriters_unsupported.go

@@ -0,0 +1,11 @@
+// +build !linux
+
+package ioutils
+
+import (
+	"os"
+)
+
+func fdatasync(f *os.File) error {
+	return f.Sync()
+}

vendor/github.com/containers/storage/pkg/ioutils/readers.go

@@ -0,0 +1,171 @@
+package ioutils
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"io"
+
+	"golang.org/x/net/context"
+)
+
+type readCloserWrapper struct {
+	io.Reader
+	closer func() error
+}
+
+func (r *readCloserWrapper) Close() error {
+	return r.closer()
+}
+
+type readWriteToCloserWrapper struct {
+	io.Reader
+	io.WriterTo
+	closer func() error
+}
+
+func (r *readWriteToCloserWrapper) Close() error {
+	return r.closer()
+}
+
+// NewReadCloserWrapper returns a new io.ReadCloser.
+func NewReadCloserWrapper(r io.Reader, closer func() error) io.ReadCloser {
+	if wt, ok := r.(io.WriterTo); ok {
+		return &readWriteToCloserWrapper{
+			Reader:   r,
+			WriterTo: wt,
+			closer:   closer,
+		}
+	}
+	return &readCloserWrapper{
+		Reader: r,
+		closer: closer,
+	}
+}
+
+type readerErrWrapper struct {
+	reader io.Reader
+	closer func()
+}
+
+func (r *readerErrWrapper) Read(p []byte) (int, error) {
+	n, err := r.reader.Read(p)
+	if err != nil {
+		r.closer()
+	}
+	return n, err
+}
+
+// NewReaderErrWrapper returns a new io.Reader.
+func NewReaderErrWrapper(r io.Reader, closer func()) io.Reader {
+	return &readerErrWrapper{
+		reader: r,
+		closer: closer,
+	}
+}
+
+// HashData returns the sha256 sum of src.
+func HashData(src io.Reader) (string, error) {
+	h := sha256.New()
+	if _, err := io.Copy(h, src); err != nil {
+		return "", err
+	}
+	return "sha256:" + hex.EncodeToString(h.Sum(nil)), nil
+}
+
+// OnEOFReader wraps an io.ReadCloser and a function
+// the function will run at the end of file or close the file.
+type OnEOFReader struct {
+	Rc io.ReadCloser
+	Fn func()
+}
+
+func (r *OnEOFReader) Read(p []byte) (n int, err error) {
+	n, err = r.Rc.Read(p)
+	if err == io.EOF {
+		r.runFunc()
+	}
+	return
+}
+
+// Close closes the file and run the function.
+func (r *OnEOFReader) Close() error {
+	err := r.Rc.Close()
+	r.runFunc()
+	return err
+}
+
+func (r *OnEOFReader) runFunc() {
+	if fn := r.Fn; fn != nil {
+		fn()
+		r.Fn = nil
+	}
+}
+
+// cancelReadCloser wraps an io.ReadCloser with a context for cancelling read
+// operations.
+type cancelReadCloser struct {
+	cancel func()
+	pR     *io.PipeReader // Stream to read from
+	pW     *io.PipeWriter
+}
+
+// NewCancelReadCloser creates a wrapper that closes the ReadCloser when the
+// context is cancelled. The returned io.ReadCloser must be closed when it is
+// no longer needed.
+func NewCancelReadCloser(ctx context.Context, in io.ReadCloser) io.ReadCloser {
+	pR, pW := io.Pipe()
+
+	// Create a context used to signal when the pipe is closed
+	doneCtx, cancel := context.WithCancel(context.Background())
+
+	p := &cancelReadCloser{
+		cancel: cancel,
+		pR:     pR,
+		pW:     pW,
+	}
+
+	go func() {
+		_, err := io.Copy(pW, in)
+		select {
+		case <-ctx.Done():
+			// If the context was closed, p.closeWithError
+			// was already called. Calling it again would
+			// change the error that Read returns.
+		default:
+			p.closeWithError(err)
+		}
+		in.Close()
+	}()
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				p.closeWithError(ctx.Err())
+			case <-doneCtx.Done():
+				return
+			}
+		}
+	}()
+
+	return p
+}
+
+// Read wraps the Read method of the pipe that provides data from the wrapped
+// ReadCloser.
+func (p *cancelReadCloser) Read(buf []byte) (n int, err error) {
+	return p.pR.Read(buf)
+}
+
+// closeWithError closes the wrapper and its underlying reader. It will
+// cause future calls to Read to return err.
+func (p *cancelReadCloser) closeWithError(err error) {
+	p.pW.CloseWithError(err)
+	p.cancel()
+}
+
+// Close closes the wrapper its underlying reader. It will cause
+// future calls to Read to return io.EOF.
+func (p *cancelReadCloser) Close() error {
+	p.closeWithError(io.EOF)
+	return nil
+}

vendor/github.com/containers/storage/pkg/ioutils/temp_unix.go

@@ -0,0 +1,10 @@
+// +build !windows
+
+package ioutils
+
+import "io/ioutil"
+
+// TempDir on Unix systems is equivalent to ioutil.TempDir.
+func TempDir(dir, prefix string) (string, error) {
+	return ioutil.TempDir(dir, prefix)
+}

vendor/github.com/containers/storage/pkg/ioutils/temp_windows.go

@@ -0,0 +1,18 @@
+// +build windows
+
+package ioutils
+
+import (
+	"io/ioutil"
+
+	"github.com/containers/storage/pkg/longpath"
+)
+
+// TempDir is the equivalent of ioutil.TempDir, except that the result is in Windows longpath format.
+func TempDir(dir, prefix string) (string, error) {
+	tempDir, err := ioutil.TempDir(dir, prefix)
+	if err != nil {
+		return "", err
+	}
+	return longpath.AddPrefix(tempDir), nil
+}

vendor/github.com/containers/storage/pkg/ioutils/writeflusher.go

@@ -0,0 +1,92 @@
+package ioutils
+
+import (
+	"io"
+	"sync"
+)
+
+// WriteFlusher wraps the Write and Flush operation ensuring that every write
+// is a flush. In addition, the Close method can be called to intercept
+// Read/Write calls if the targets lifecycle has already ended.
+type WriteFlusher struct {
+	w           io.Writer
+	flusher     flusher
+	flushed     chan struct{}
+	flushedOnce sync.Once
+	closed      chan struct{}
+	closeLock   sync.Mutex
+}
+
+type flusher interface {
+	Flush()
+}
+
+var errWriteFlusherClosed = io.EOF
+
+func (wf *WriteFlusher) Write(b []byte) (n int, err error) {
+	select {
+	case <-wf.closed:
+		return 0, errWriteFlusherClosed
+	default:
+	}
+
+	n, err = wf.w.Write(b)
+	wf.Flush() // every write is a flush.
+	return n, err
+}
+
+// Flush the stream immediately.
+func (wf *WriteFlusher) Flush() {
+	select {
+	case <-wf.closed:
+		return
+	default:
+	}
+
+	wf.flushedOnce.Do(func() {
+		close(wf.flushed)
+	})
+	wf.flusher.Flush()
+}
+
+// Flushed returns the state of flushed.
+// If it's flushed, return true, or else it return false.
+func (wf *WriteFlusher) Flushed() bool {
+	// BUG(stevvooe): Remove this method. Its use is inherently racy. Seems to
+	// be used to detect whether or a response code has been issued or not.
+	// Another hook should be used instead.
+	var flushed bool
+	select {
+	case <-wf.flushed:
+		flushed = true
+	default:
+	}
+	return flushed
+}
+
+// Close closes the write flusher, disallowing any further writes to the
+// target. After the flusher is closed, all calls to write or flush will
+// result in an error.
+func (wf *WriteFlusher) Close() error {
+	wf.closeLock.Lock()
+	defer wf.closeLock.Unlock()
+
+	select {
+	case <-wf.closed:
+		return errWriteFlusherClosed
+	default:
+		close(wf.closed)
+	}
+	return nil
+}
+
+// NewWriteFlusher returns a new WriteFlusher.
+func NewWriteFlusher(w io.Writer) *WriteFlusher {
+	var fl flusher
+	if f, ok := w.(flusher); ok {
+		fl = f
+	} else {
+		fl = &NopFlusher{}
+	}
+	return &WriteFlusher{w: w, flusher: fl, closed: make(chan struct{}), flushed: make(chan struct{})}
+}

vendor/github.com/containers/storage/pkg/ioutils/writers.go

@@ -0,0 +1,66 @@
+package ioutils
+
+import "io"
+
+// NopWriter represents a type which write operation is nop.
+type NopWriter struct{}
+
+func (*NopWriter) Write(buf []byte) (int, error) {
+	return len(buf), nil
+}
+
+type nopWriteCloser struct {
+	io.Writer
+}
+
+func (w *nopWriteCloser) Close() error { return nil }
+
+// NopWriteCloser returns a nopWriteCloser.
+func NopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w}
+}
+
+// NopFlusher represents a type which flush operation is nop.
+type NopFlusher struct{}
+
+// Flush is a nop operation.
+func (f *NopFlusher) Flush() {}
+
+type writeCloserWrapper struct {
+	io.Writer
+	closer func() error
+}
+
+func (r *writeCloserWrapper) Close() error {
+	return r.closer()
+}
+
+// NewWriteCloserWrapper returns a new io.WriteCloser.
+func NewWriteCloserWrapper(r io.Writer, closer func() error) io.WriteCloser {
+	return &writeCloserWrapper{
+		Writer: r,
+		closer: closer,
+	}
+}
+
+// WriteCounter wraps a concrete io.Writer and hold a count of the number
+// of bytes written to the writer during a "session".
+// This can be convenient when write return is masked
+// (e.g., json.Encoder.Encode())
+type WriteCounter struct {
+	Count  int64
+	Writer io.Writer
+}
+
+// NewWriteCounter returns a new WriteCounter.
+func NewWriteCounter(w io.Writer) *WriteCounter {
+	return &WriteCounter{
+		Writer: w,
+	}
+}
+
+func (wc *WriteCounter) Write(p []byte) (count int, err error) {
+	count, err = wc.Writer.Write(p)
+	wc.Count += int64(count)
+	return
+}