malloc: Add scratch_buffer_dupfree

It returns a copy of the buffer up to a defined size.  It will be used
on realpath sync with gnulib.

1 files changed, 24 insertions, 2 deletions

diff --git a/malloc/tst-scratch_buffer.c b/malloc/tst-scratch_buffer.c
index 8ea07e8..6e521c7 100644
--- a/malloc/tst-scratch_buffer.c
+++ b/malloc/tst-scratch_buffer.c
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <array_length.h>
 #include <scratch_buffer.h>
+#include <support/check.h>
+#include <support/support.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
@@ -148,8 +151,27 @@ do_test (void)
 	  && array_size_must_fail (4, ((size_t)-1) / 4)))
 	return 1;
   }
+  {
+    struct scratch_buffer buf;
+    scratch_buffer_init (&buf);
+    memset (buf.data, '@', buf.length);
+
+    size_t sizes[] = { 16, buf.length, buf.length + 16 };
+    for (int i = 0; i < array_length (sizes); i++)
+      {
+        /* The extra size is unitialized through realloc.  */
+        size_t l = sizes[i] > buf.length ? sizes[i] : buf.length;
+        void *r = scratch_buffer_dupfree (&buf, l);
+        void *c = xmalloc (l);
+        memset (c, '@', l);
+        TEST_COMPARE_BLOB (r, l, buf.data, l);
+        free (r);
+        free (c);
+      }
+
+    scratch_buffer_free (&buf);
+  }
   return 0;
 }
 
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
+#include <support/test-driver.c>