forgejo_backup/modules/util/io.go
oliverpool 31ad7c9353 blob: GetBlobContent: reduce allocations (#8223)
See #8222 for context.

## git.Blob.NewTruncatedReader

This introduce a new `NewTruncatedReader` method to return a blob-reader which silently truncates when the limit is reached (io.EOF will be returned).
Since the actual size is also returned `GetBlobContent` can pre-allocate a `[]byte` of the full-size (min of the asked size and the actual size) and call `io.ReadFull(rc, buf)` (instead of `util.ReadWithLimit(dataRc, int(limit))` which is convoluted and not used anywhere else).

### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.

### Documentation

- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [x] I do not want this change to show in the release notes.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8223
Reviewed-by: Lucas <sclu1034@noreply.codeberg.org>
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: oliverpool <git@olivier.pfad.fr>
Co-committed-by: oliverpool <git@olivier.pfad.fr>
2025-06-19 18:36:12 +02:00

41 lines
923 B
Go

// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package util
import (
"errors"
"io"
)
// ReadAtMost reads at most len(buf) bytes from r into buf.
// It returns the number of bytes copied. n is only less than len(buf) if r provides fewer bytes.
// If EOF or ErrUnexpectedEOF occurs while reading, err will be nil.
func ReadAtMost(r io.Reader, buf []byte) (n int, err error) {
n, err = io.ReadFull(r, buf)
if err == io.EOF || err == io.ErrUnexpectedEOF {
err = nil
}
return n, err
}
// ErrNotEmpty is an error reported when there is a non-empty reader
var ErrNotEmpty = errors.New("not-empty")
// IsEmptyReader reads a reader and ensures it is empty
func IsEmptyReader(r io.Reader) (err error) {
var buf [1]byte
for {
n, err := r.Read(buf[:])
if err != nil {
if err == io.EOF {
return nil
}
return err
}
if n > 0 {
return ErrNotEmpty
}
}
}