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94 lines
2.6 KiB
Go

// Copyright 2022 Harness Inc. All rights reserved.
// Use of this source code is governed by the Polyform Free Trial License
// that can be found in the LICENSE.md file for this repository.
package gitea
import (
"bytes"
"context"
"fmt"
"io"
"github.com/harness/gitness/gitrpc/internal/types"
"code.gitea.io/gitea/modules/git"
)
// GetBlob returns the blob for the given object sha.
func (g Adapter) GetBlob(ctx context.Context, repoPath string, sha string, sizeLimit int64) (*types.BlobReader, error) {
// Note: We are avoiding gitea blob implementation, as that is tied to the lifetime of the repository object.
// Instead, we just use the gitea helper methods ourselves.
stdIn, stdOut, cancel := git.CatFileBatch(ctx, repoPath)
_, err := stdIn.Write([]byte(sha + "\n"))
if err != nil {
cancel()
return nil, fmt.Errorf("failed to write blob sha to git stdin: %w", err)
}
objectSHA, objectType, objectSize, err := git.ReadBatchLine(stdOut)
if err != nil {
cancel()
return nil, processGiteaErrorf(err, "failed to read cat-file batch line")
}
if string(objectSHA) != sha {
cancel()
return nil, fmt.Errorf("cat-file returned object sha '%s' but expected '%s'", objectSHA, sha)
}
if objectType != string(git.ObjectBlob) {
cancel()
return nil, fmt.Errorf("cat-file returned object type '%s' but expected '%s'", objectType, git.ObjectBlob)
}
contentSize := objectSize
if sizeLimit > 0 && sizeLimit < contentSize {
contentSize = sizeLimit
}
return &types.BlobReader{
SHA: sha,
Size: objectSize,
ContentSize: contentSize,
Content: &exactLimitReader{
reader: stdOut,
remainingBytes: contentSize,
close: func() error {
// TODO: is there a better (but short) way to clear the buffer?
// gitea is .Discard()'ing elements here until it's empty.
stdOut.Reset(bytes.NewBuffer([]byte{}))
cancel()
return nil
},
},
}, nil
}
// exactLimitReader reads the content of a reader and ensures no more than the specified bytes will be requested from
// the underlaying reader. This is required for readers that don't ensure completion after reading all remaining bytes.
// io.LimitReader doesn't work as it waits for bytes that never come, io.SectionReader would requrie an io.ReaderAt.
type exactLimitReader struct {
reader io.Reader
remainingBytes int64
close func() error
}
func (r *exactLimitReader) Read(p []byte) (int, error) {
if r.remainingBytes <= 0 {
return 0, io.EOF
}
if int64(len(p)) > r.remainingBytes {
p = p[0:r.remainingBytes]
}
n, err := r.reader.Read(p)
r.remainingBytes -= int64(n)
return n, err
}
func (r *exactLimitReader) Close() error {
return r.close()
}