From abf1e0bd405e2be8aad7e494e69242c7f5581ccb Mon Sep 17 00:00:00 2001
From: David Benjamin <davidben@webrtc.org>
Date: Fri, 22 Mar 2024 18:20:09 -0400
Subject: [PATCH] Replace a memcpy with std::copy_n

memcpy has a bug where it doesn't work with empty slices whose pointer
is null. C++ functions in <algorithm> have this bug fixed and, in a good
STL, will specialize down to memcpy or memmove anyway.

This fixes a bunch of UBSan failures in Chromium, such as
https://luci-milo.appspot.com/ui/inv/build-8752767322372882913/test-results?q=RTCEncodedVideoFrameTest.ConstructorCopiesMetadata&sortby=&groupby=

See https://davidben.net/2024/01/15/empty-slices.html

Bug: chromium:40248746
Change-Id: Ibfb9c4d7b44df53766a16e40fabd0a374140d89c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/344260
Auto-Submit: David Benjamin <davidben@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41989}
---
 api/video/encoded_image.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/api/video/encoded_image.cc b/api/video/encoded_image.cc
index 09224c3c49..aad94b12a6 100644
--- a/api/video/encoded_image.cc
+++ b/api/video/encoded_image.cc
@@ -11,7 +11,8 @@
 #include "api/video/encoded_image.h"
 
 #include <stdlib.h>
-#include <string.h>
+
+#include <algorithm>
 
 namespace webrtc {
 
@@ -21,7 +22,7 @@ EncodedImageBuffer::EncodedImageBuffer(size_t size) : size_(size) {
 
 EncodedImageBuffer::EncodedImageBuffer(const uint8_t* data, size_t size)
     : EncodedImageBuffer(size) {
-  memcpy(buffer_, data, size);
+  std::copy_n(data, size, buffer_);
 }
 
 EncodedImageBuffer::~EncodedImageBuffer() {