UltraGrid plugin: opt to use memmove instead of memcpy

client/ultragrid/ultragrid.cpp

@@ -344,6 +344,12 @@ void cesnet_set_render_buffer_rgba(unsigned char *rgba, int width, int height)
 bool copy_data(struct cesnet_shm *cesnet_shm,
     unsigned char *y, unsigned char *u, unsigned char *v, int width, int height)
 {
+  void *(*copy_fn)(void *dest, const void *src, size_t n) = memcpy;
+
+  if (getenv("MEMMOVE_INSTEAD_MEMCPY")) {
+    copy_fn = memmove;
+  }
+
 #  if !defined WITH_CLIENT_CUDA
   if (cesnet_shm->use_gpu) {
     fprintf(stderr, "CUDA support not compiled in! Use 'uv -t shm' to use standard SHM.\n");
@@ -386,26 +392,26 @@ bool copy_data(struct cesnet_shm *cesnet_shm,
     } else {
       // Y
       for (int i = 0; i < height; ++i) {
-	memcpy(out1_y, y, width);
+	copy_fn(out1_y, y, width);
 	out1_y += width;
 	y += width;
-	memcpy(out2_y, y, width);
+	copy_fn(out2_y, y, width);
 	out2_y += width;
 	y += width;
       }
       // U V
       for (int i = 0; i < height / 2; ++i) {
-	memcpy(out1_u, u, width / 2);
+	copy_fn(out1_u, u, width / 2);
 	out1_u += width / 2;
 	u += width / 2;
-	memcpy(out2_u, u, width / 2);
+	copy_fn(out2_u, u, width / 2);
 	out2_u += width / 2;
 	u += width / 2;
 
-	memcpy(out1_v, v, width / 2);
+	copy_fn(out1_v, v, width / 2);
 	out1_v += width / 2;
 	v += width / 2;
-	memcpy(out2_v, v, width / 2);
+	copy_fn(out2_v, v, width / 2);
 	out2_v += width / 2;
 	v += width / 2;
       }
@@ -426,12 +432,12 @@ bool copy_data(struct cesnet_shm *cesnet_shm,
 #  endif
     } else {
       int len = width * height;
-      memcpy(tmp, y, len);
+      copy_fn(tmp, y, len);
       tmp += len;
       len = width * height / 4;
-      memcpy(tmp, u, len);
+      copy_fn(tmp, u, len);
       tmp += len;
-      memcpy(tmp, v, len);
+      copy_fn(tmp, v, len);
     }
   }
   return true;