From 2d306dbe9c77d588945bd8984b23ed1245e8aaa0 Mon Sep 17 00:00:00 2001
From: Steven Watanabe <steven@providere-consulting.com>
Date: Wed, 24 Apr 2019 16:31:31 -0600
Subject: [PATCH] Fix errors reported by ubsan.  (memcpy w/ nullptr).

---
 src/engine/function.cpp | 20 ++++++++++++--------
 src/engine/strings.cpp  |  3 ++-
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/engine/function.cpp b/src/engine/function.cpp
index 886c1c65e..8996f2705 100644
--- a/src/engine/function.cpp
+++ b/src/engine/function.cpp
@@ -1537,8 +1537,9 @@ static JAM_FUNCTION * compile_to_function( compiler * c )
     memcpy( result->code, c->code->data, c->code->size * sizeof( instruction ) );
 
     result->constants = (OBJECT**)BJAM_MALLOC( c->constants->size * sizeof( OBJECT * ) );
-    memcpy( result->constants, c->constants->data, c->constants->size * sizeof(
-        OBJECT * ) );
+    if ( c->constants->size != 0 )
+        memcpy( result->constants, c->constants->data,
+                c->constants->size * sizeof( OBJECT * ) );
     result->num_constants = c->constants->size;
 
     result->num_subfunctions = c->rules->size;
@@ -1555,8 +1556,9 @@ static JAM_FUNCTION * compile_to_function( compiler * c )
     }
 
     result->actions = (SUBACTION*)BJAM_MALLOC( c->actions->size * sizeof( SUBACTION ) );
-    memcpy( result->actions, c->actions->data, c->actions->size * sizeof(
-        SUBACTION ) );
+    if ( c->actions->size != 0 )
+        memcpy( result->actions, c->actions->data,
+                c->actions->size * sizeof( SUBACTION ) );
     result->num_subactions = c->actions->size;
 
     result->generic = 0;
@@ -3417,8 +3419,9 @@ static struct arg_list arg_compile_impl( struct argument_compiler * c,
     }
     result.size = c->args->size;
     result.args = (struct argument*)BJAM_MALLOC( c->args->size * sizeof( struct argument ) );
-    memcpy( result.args, c->args->data, c->args->size * sizeof( struct argument
-        ) );
+    if ( c->args->size != 0 )
+        memcpy( result.args, c->args->data,
+                c->args->size * sizeof( struct argument ) );
     return result;
 }
 
@@ -3515,8 +3518,9 @@ static struct arg_list * arg_list_compile_builtin( char const * * args,
         }
         *num_arguments = c->args->size;
         result = (struct arg_list *)BJAM_MALLOC( c->args->size * sizeof( struct arg_list ) );
-        memcpy( result, c->args->data, c->args->size * sizeof( struct arg_list )
-            );
+        if ( c->args->size != 0 )
+            memcpy( result, c->args->data,
+                    c->args->size * sizeof( struct arg_list ) );
         argument_list_compiler_free( c );
         return result;
     }
diff --git a/src/engine/strings.cpp b/src/engine/strings.cpp
index fae3b2d45..4e4e0b8da 100644
--- a/src/engine/strings.cpp
+++ b/src/engine/strings.cpp
@@ -148,7 +148,8 @@ void string_append_range( string * self, char const * start, char const * finish
 
     maybe_reserve( self, new_size );
 
-    memcpy( self->value + self->size, start, rhs_size );
+    if ( start != finish )
+        memcpy( self->value + self->size, start, rhs_size );
     self->size = new_size;
     self->value[ new_size ] = 0;