986f076276
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.
109 lines
3.1 KiB
Go
109 lines
3.1 KiB
Go
/*
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Copyright The ocicrypt Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package utils
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import (
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"io"
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)
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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// DelayedReader wraps a io.Reader and allows a client to use the Reader
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// interface. The DelayedReader holds back some buffer to the client
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// so that it can report any error that occurred on the Reader it wraps
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// early to the client while it may still have held some data back.
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type DelayedReader struct {
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reader io.Reader // Reader to Read() bytes from and delay them
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err error // error that occurred on the reader
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buffer []byte // delay buffer
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bufbytes int // number of bytes in the delay buffer to give to Read(); on '0' we return 'EOF' to caller
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bufoff int // offset in the delay buffer to give to Read()
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}
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// NewDelayedReader wraps a io.Reader and allocates a delay buffer of bufsize bytes
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func NewDelayedReader(reader io.Reader, bufsize uint) io.Reader {
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return &DelayedReader{
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reader: reader,
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buffer: make([]byte, bufsize),
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}
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}
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// Read implements the io.Reader interface
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func (dr *DelayedReader) Read(p []byte) (int, error) {
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if dr.err != nil && dr.err != io.EOF {
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return 0, dr.err
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}
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// if we are completely drained, return io.EOF
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if dr.err == io.EOF && dr.bufbytes == 0 {
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return 0, io.EOF
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}
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// only at the beginning we fill our delay buffer in an extra step
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if dr.bufbytes < len(dr.buffer) && dr.err == nil {
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dr.bufbytes, dr.err = FillBuffer(dr.reader, dr.buffer)
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if dr.err != nil && dr.err != io.EOF {
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return 0, dr.err
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}
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}
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// dr.err != nil means we have EOF and can drain the delay buffer
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// otherwise we need to still read from the reader
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var tmpbuf []byte
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tmpbufbytes := 0
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if dr.err == nil {
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tmpbuf = make([]byte, len(p))
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tmpbufbytes, dr.err = FillBuffer(dr.reader, tmpbuf)
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if dr.err != nil && dr.err != io.EOF {
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return 0, dr.err
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}
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}
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// copy out of the delay buffer into 'p'
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tocopy1 := min(len(p), dr.bufbytes)
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c1 := copy(p[:tocopy1], dr.buffer[dr.bufoff:])
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dr.bufoff += c1
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dr.bufbytes -= c1
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c2 := 0
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// can p still hold more data?
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if c1 < len(p) {
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// copy out of the tmpbuf into 'p'
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c2 = copy(p[tocopy1:], tmpbuf[:tmpbufbytes])
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}
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// if tmpbuf holds data we need to hold onto, copy them
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// into the delay buffer
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if tmpbufbytes-c2 > 0 {
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// left-shift the delay buffer and append the tmpbuf's remaining data
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dr.buffer = dr.buffer[dr.bufoff : dr.bufoff+dr.bufbytes]
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dr.buffer = append(dr.buffer, tmpbuf[c2:tmpbufbytes]...)
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dr.bufoff = 0
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dr.bufbytes = len(dr.buffer)
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}
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var err error
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if dr.bufbytes == 0 {
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err = io.EOF
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}
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return c1 + c2, err
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}
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