1 files changed, 14 insertions, 0 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 7f0a74ca834..7c671e25cfc 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -850,6 +850,20 @@ xlispstrdup (Lisp_Object string)
   return memcpy (xmalloc (size), SSDATA (string), size);
 }
 
+/* Assign to *PTR a copy of STRING, freeing any storage *PTR formerly
+   pointed to.  If STRING is null, assign it without copying anything.
+   Allocate before freeing, to avoid a dangling pointer if allocation
+   fails.  */
+
+void
+dupstring (char **ptr, char const *string)
+{
+  char *old = *ptr;
+  *ptr = string ? xstrdup (string) : 0;
+  xfree (old);
+}
+
+
 /* Like putenv, but (1) use the equivalent of xmalloc and (2) the
    argument is a const pointer.  */