array: Avoid use of memcpy(dest, NULL, 0)

glibc declares memcpy() with the first two arguments (the pointers)
annotated as non-null via an attribute, which results in the undefined
behaviour sanitizer considering it to be UB to pass a null pointer
in the second argument, even if we are copying 0 bytes (and hence not
actually dereferencing the pointer).

This shows up in array-test when run with the undefined behaviour
sanitizer.

Signed-off-by: Simon McVittie <smcv@collabora.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/glib/garray.c b/glib/garray.c
index 2e8dd0b6b..4cbfd1373 100644
--- a/glib/garray.c
+++ b/glib/garray.c
@@ -1146,7 +1146,7 @@ g_ptr_array_copy (GPtrArray *array,
       for (i = 0; i < array->len; i++)
         new_array->pdata[i] = func (array->pdata[i], user_data);
     }
-  else
+  else if (array->len > 0)
     {
       memcpy (new_array->pdata, array->pdata,
               array->len * sizeof (*array->pdata));
@@ -1797,7 +1797,7 @@ g_ptr_array_extend (GPtrArray  *array_to_extend,
         rarray_to_extend->pdata[i + rarray_to_extend->len] =
           func (array->pdata[i], user_data);
     }
-  else
+  else if (array->len > 0)
     {
       memcpy (rarray_to_extend->pdata + rarray_to_extend->len, array->pdata,
               array->len * sizeof (*array->pdata));