xnu-7195.50.7.100.1.tar.gz

[apple/xnu.git] / tests / bounded_ptr_src / example.malloc.cpp

diff --git a/tests/bounded_ptr_src/example.malloc.cpp b/tests/bounded_ptr_src/example.malloc.cpp
new file mode 100644 (file)
index 0000000..c8a53af
--- /dev/null
+++ b/tests/bounded_ptr_src/example.malloc.cpp
@@ -0,0 +1,75 @@
+//
+// Example of providing a malloc() wrapper that returns a `bounded_ptr`.
+//
+// This test serves as some kind of integration test, ensuring that we're
+// able to convert existing code using raw pointers to using `bounded_ptr`s
+// without too much hassle. This code was lifted from existing code in XNU,
+// and the variable names were changed to make it more generic.
+//
+
+#include <libkern/c++/bounded_ptr.h>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <darwintest.h>
+#include "test_utils.h"
+
+test_bounded_ptr<void>
+bounded_malloc(std::size_t size)
+{
+       void* p = std::malloc(size);
+       void* end = static_cast<char*>(p) + size;
+       test_bounded_ptr<void> with_bounds(p, p, end);
+       return with_bounds;
+}
+
+void
+bounded_free(test_bounded_ptr<void> ptr)
+{
+       std::free(ptr.discard_bounds());
+}
+
+struct SomeType {
+       std::uint32_t idx;
+};
+
+// Pretend that those functions are already part of the code base being
+// transitioned over to `bounded_ptr`s, and we can't change their signature.
+// The purpose of having those functions is to make sure that we're able to
+// integrate into existing code bases with decent ease.
+void
+use(SomeType*)
+{
+}
+void
+require(bool condition)
+{
+       if (!condition) {
+               std::exit(EXIT_FAILURE);
+       }
+}
+
+T_DECL(example_malloc, "bounded_ptr.example.malloc") {
+       test_bounded_ptr<SomeType> array = nullptr;
+       std::uint32_t count = 100;
+       std::uint32_t alloc_size = count * sizeof(SomeType);
+
+       // (1) must use a bounded version of malloc
+       // (2) must use a reinterpret_pointer_cast to go from void* to SomeType*
+       array = libkern::reinterpret_pointer_cast<SomeType>(bounded_malloc(alloc_size));
+
+       require(array != nullptr); // use != nullptr instead of relying on implicit conversion to bool
+       use(array.discard_bounds()); // must manually discard bounds here
+
+       for (std::uint32_t i = 0; i < count; i++) {
+               std::uint32_t& idx = array[i].idx;
+               idx = i;
+               use(&array[idx]);
+       }
+
+       if (array) {
+               bounded_free(array); // must use a bounded version of free
+       }
+
+       T_PASS("bounded_ptr.example.malloc test done");
+}