From f67994a77d5bcd7877bf229bfda48e8338f36893 Mon Sep 17 00:00:00 2001
From: Dmitrii Okunev <xaionaro@fb.com>
Date: Fri, 31 Jan 2020 20:40:03 +0000
Subject: [PATCH] uefi: Do not copy if not necessary

Removed extra copies. It reduces memory consumption,
improves performances and simplifies the result.

ITS: https://github.com/linuxboot/fiano/issues/304

Signed-off-by: Dmitrii Okunev <xaionaro@fb.com>
---
 pkg/uefi/biosregion.go     | 3 +--
 pkg/uefi/file.go           | 6 ++----
 pkg/uefi/firmwarevolume.go | 5 +----
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/pkg/uefi/biosregion.go b/pkg/uefi/biosregion.go
index 13be3b52..71fe2032 100644
--- a/pkg/uefi/biosregion.go
+++ b/pkg/uefi/biosregion.go
@@ -85,8 +85,7 @@ func NewBIOSRegion(buf []byte, r *FlashRegion, _ FlashRegionType) (Region, error
 	var absOffset uint64
 
 	// Copy the buffer
-	br.buf = make([]byte, len(buf))
-	copy(br.buf, buf)
+	br.buf = buf
 
 	for {
 		offset := FindFirmwareVolumeOffset(buf)
diff --git a/pkg/uefi/file.go b/pkg/uefi/file.go
index c0fe9941..3254d537 100644
--- a/pkg/uefi/file.go
+++ b/pkg/uefi/file.go
@@ -416,10 +416,8 @@ func NewFile(buf []byte) (*File, error) {
 		return nil, fmt.Errorf("File size too big! File with GUID: %v has length %v, but is only %v bytes big",
 			f.Header.GUID, f.Header.ExtendedSize, buflen)
 	}
-	// Copy out the buffer.
-	newBuf := buf[:f.Header.ExtendedSize]
-	f.buf = make([]byte, f.Header.ExtendedSize)
-	copy(f.buf, newBuf)
+
+	f.buf = buf[:f.Header.ExtendedSize]
 
 	// Special case for NVAR Store stored in raw file
 	if f.Header.Type == FVFileTypeRaw && f.Header.GUID == *NVAR {
diff --git a/pkg/uefi/firmwarevolume.go b/pkg/uefi/firmwarevolume.go
index 9f571062..030b81fe 100644
--- a/pkg/uefi/firmwarevolume.go
+++ b/pkg/uefi/firmwarevolume.go
@@ -259,10 +259,7 @@ func NewFirmwareVolume(data []byte, fvOffset uint64, resizable bool) (*FirmwareV
 	fv.FVType = FVGUIDs[fv.FileSystemGUID]
 	fv.FVOffset = fvOffset
 
-	// copy out the buffer.
-	newBuf := data[:fv.Length]
-	fv.buf = make([]byte, fv.Length)
-	copy(fv.buf, newBuf)
+	fv.buf = data[:fv.Length]
 
 	// Parse the files.
 	// TODO: handle fv data alignment.