1 files changed, 46 insertions, 0 deletions
diff --git a/tests/src/test_preload.c b/tests/src/test_preload.c
new file mode 100644
index 0000000..0ded605
--- /dev/null
+++ b/tests/src/test_preload.c
@@ -0,0 +1,46 @@
+/**
+ * @file   main.c
+ * @brief  Smoke test — call malloc once and print the returned pointer.
+ *
+ * Uses write(2) instead of printf to avoid stdio calling malloc
+ * internally, which would pollute output under LD_PRELOAD.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+
+/** @brief Write the hex representation of @p ptr to stdout. */
+static void
+_s_put_ptr (void *ptr)
+{
+  const char hex[] = "0123456789abcdef";
+  char buf[20];
+  unsigned long v = (unsigned long)ptr;
+  int i;
+
+  if (!ptr)
+    {
+      write (1, "(nil)", 5);
+      return;
+    }
+  i = (int)sizeof (buf);
+  while (v)
+    {
+      buf[--i] = hex[v % 16];
+      v /= 16;
+    }
+  buf[--i] = 'x';
+  buf[--i] = '0';
+  write (1, buf + i, (size_t)(sizeof (buf) - i));
+}
+
+int
+main (void)
+{
+  void *p = malloc (42);
+  write (1, "malloc(42) = ", 13);
+  _s_put_ptr (p);
+  write (1, "\n", 1);
+  free (p);
+  return (0);
+}