plumbing: format/packfile, prevent large objects from being read into memory completely (#303)v5.4.0

This PR adds code to prevent large objects from being read into memory from packfiles or the filesystem.

Objects greater than 1Mb are now no longer directly stored in the cache
or read completely into memory.

Signed-off-by: Andrew Thornton <art27@cantab.net>

1 files changed, 22 insertions, 0 deletions

diff --git a/utils/ioutil/common.go b/utils/ioutil/common.go
index b52e85a..a0e79a2 100644
--- a/utils/ioutil/common.go
+++ b/utils/ioutil/common.go
@@ -55,6 +55,28 @@ func NewReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
 	return &readCloser{Reader: r, closer: c}
 }
 
+type readCloserCloser struct {
+	io.ReadCloser
+	closer func() error
+}
+
+func (r *readCloserCloser) Close() (err error) {
+	defer func() {
+		if err == nil {
+			err = r.closer()
+			return
+		}
+		_ = r.closer()
+	}()
+	return r.ReadCloser.Close()
+}
+
+// NewReadCloserWithCloser creates an `io.ReadCloser` with the given `io.ReaderCloser` and
+// `io.Closer` that ensures that the closer is closed on close
+func NewReadCloserWithCloser(r io.ReadCloser, c func() error) io.ReadCloser {
+	return &readCloserCloser{ReadCloser: r, closer: c}
+}
+
 type writeCloser struct {
 	io.Writer
 	closer io.Closer