drone/git/api/blob.go

101 lines
2.5 KiB
Go

// Copyright 2023 Harness, Inc.
//
// 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 api
import (
"context"
"fmt"
"io"
"github.com/harness/gitness/errors"
"github.com/harness/gitness/git/sha"
)
type BlobReader struct {
SHA sha.SHA
// Size is the actual size of the blob.
Size int64
// ContentSize is the total number of bytes returned by the Content Reader.
ContentSize int64
// Content contains the (partial) content of the blob.
Content io.ReadCloser
}
// GetBlob returns the blob for the given object sha.
func GetBlob(
ctx context.Context,
repoPath string,
alternateObjectDirs []string,
sha sha.SHA,
sizeLimit int64,
) (*BlobReader, error) {
stdIn, stdOut, cancel := CatFileBatch(ctx, repoPath, alternateObjectDirs)
line := sha.String() + "\n"
_, err := stdIn.Write([]byte(line))
if err != nil {
cancel()
return nil, fmt.Errorf("failed to write blob sha to git stdin: %w", err)
}
output, err := ReadBatchHeaderLine(stdOut)
if err != nil {
cancel()
return nil, processGitErrorf(err, "failed to read cat-file batch line")
}
if !output.SHA.Equal(sha) {
cancel()
return nil, fmt.Errorf("cat-file returned object sha '%s' but expected '%s'", output.SHA, sha)
}
if output.Type != string(GitObjectTypeBlob) {
cancel()
return nil, errors.InvalidArgument(
"cat-file returned object type '%s' but expected '%s'", output.Type, GitObjectTypeBlob)
}
contentSize := output.Size
if sizeLimit > 0 && sizeLimit < contentSize {
contentSize = sizeLimit
}
return &BlobReader{
SHA: sha,
Size: output.Size,
ContentSize: contentSize,
Content: newLimitReaderCloser(stdOut, contentSize, cancel),
}, nil
}
func newLimitReaderCloser(reader io.Reader, limit int64, stop func()) limitReaderCloser {
return limitReaderCloser{
reader: io.LimitReader(reader, limit),
stop: stop,
}
}
type limitReaderCloser struct {
reader io.Reader
stop func()
}
func (l limitReaderCloser) Read(p []byte) (n int, err error) {
return l.reader.Read(p)
}
func (l limitReaderCloser) Close() error {
l.stop()
return nil
}