reduce memory usage in metacache reader (#12334)

pkg/ioutil/read_file.go

@@ -15,11 +15,6 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-// Forked from golang.org/pkg/os.ReadFile with NOATIME support.
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the https://golang.org/LICENSE file.
-
 package ioutil
 
 import (
@@ -40,36 +35,5 @@ func ReadFile(name string) ([]byte, error) {
 	}
 	defer f.Close()
 
-	var size int
-	if info, err := f.Stat(); err == nil {
-		size64 := info.Size()
-		if int64(int(size64)) == size64 {
-			size = int(size64)
-		}
-	}
-	size++ // one byte for final read at EOF
-
-	// If a file claims a small size, read at least 512 bytes.
-	// In particular, files in Linux's /proc claim size 0 but
-	// then do not work right if read in small pieces,
-	// so an initial read of 1 byte would not work correctly.
-	if size < 512 {
-		size = 512
-	}
-
-	data := make([]byte, 0, size)
-	for {
-		if len(data) >= cap(data) {
-			d := append(data[:cap(data)], 0)
-			data = d[:len(data)]
-		}
-		n, err := f.Read(data[len(data):cap(data)])
-		data = data[:len(data)+n]
-		if err != nil {
-			if err == io.EOF {
-				err = nil
-			}
-			return data, err
-		}
-	}
+	return io.ReadAll(f)
 }

pkg/ioutil/wait_pipe.go

@@ -15,11 +15,6 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-// Forked from golang.org/pkg/os.ReadFile with NOATIME support.
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the https://golang.org/LICENSE file.
-
 package ioutil
 
 import (