Tests: Add tests for posix_memalign(3) and aligned_alloc(3)

Author: https://github.com/petelliott
Commit: https://github.com/SerenityOS/serenity/commit/420f78ca8b
Pull-request: https://github.com/SerenityOS/serenity/pull/13915
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/gmta ✅
Reviewed-by: https://github.com/kennethmyhra

Tests/LibC/CMakeLists.txt

@@ -10,6 +10,7 @@ set(TEST_SOURCES
     TestLibCString.cpp
     TestLibCTime.cpp
     TestMalloc.cpp
+    TestMemalign.cpp
     TestMemmem.cpp
     TestMkDir.cpp
     TestQsort.cpp

Tests/LibC/TestMemalign.cpp

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2022, Peter Elliott <pelliott@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <LibC/mallocdefs.h>
+#include <stdlib.h>
+
+static constexpr size_t runs = 5000;
+static constexpr size_t ptrs_per_run = 20;
+
+static size_t random_alignment()
+{
+    return 1 << (rand() % 16);
+}
+
+static size_t random_size()
+{
+    int r = rand() % num_size_classes;
+    if (r == num_size_classes - 1) {
+        return rand() % (1 << 17);
+    }
+
+    return size_classes[r] + (rand() % (size_classes[r + 1] - size_classes[r]));
+}
+
+static bool is_aligned(void* ptr, size_t align)
+{
+    return (reinterpret_cast<uintptr_t>(ptr) & (align - 1)) == 0;
+}
+
+TEST_CASE(posix_memalign_fuzz)
+{
+    EXPECT_NO_CRASH("posix_memalign should not crash under regular use", [] {
+        for (size_t i = 0; i < runs; ++i) {
+            size_t align = random_alignment();
+            size_t size = random_size();
+
+            for (size_t j = 0; j < 2; ++j) {
+                void* ptrs[ptrs_per_run];
+
+                for (size_t k = 0; k < ptrs_per_run; ++k) {
+                    EXPECT_EQ(posix_memalign(&(ptrs[k]), align, size), 0);
+                    EXPECT(is_aligned(ptrs[k], align));
+                }
+                for (size_t k = 0; k < ptrs_per_run; ++k) {
+                    free(ptrs[k]);
+                }
+            }
+        }
+
+        return Test::Crash::Failure::DidNotCrash;
+    });
+}
+
+TEST_CASE(posix_memalign_not_power2)
+{
+    char secret_ptr[0];
+    void* memptr = secret_ptr;
+    EXPECT_EQ(posix_memalign(&memptr, 7, 256), EINVAL);
+    EXPECT_EQ(memptr, secret_ptr);
+}
+
+TEST_CASE(aligned_alloc_fuzz)
+{
+    EXPECT_NO_CRASH("aligned_alloc should not crash under regular use", [] {
+        for (size_t i = 0; i < runs; ++i) {
+            size_t align = random_alignment();
+            size_t size = random_size();
+
+            for (size_t j = 0; j < 2; ++j) {
+                void* ptrs[ptrs_per_run];
+
+                for (size_t k = 0; k < ptrs_per_run; ++k) {
+                    ptrs[k] = aligned_alloc(align, size);
+                    EXPECT(ptrs[k]);
+                    EXPECT(is_aligned(ptrs[k], align));
+                }
+                for (size_t k = 0; k < ptrs_per_run; ++k) {
+                    free(ptrs[k]);
+                }
+            }
+        }
+
+        return Test::Crash::Failure::DidNotCrash;
+    });
+}
+
+TEST_CASE(aligned_alloc_not_power2)
+{
+#ifdef __clang__
+#    pragma clang diagnostic push
+#    pragma clang diagnostic ignored "-Wnon-power-of-two-alignment"
+#endif
+    EXPECT_EQ(aligned_alloc(7, 256), nullptr);
+    EXPECT_EQ(errno, EINVAL);
+#ifdef __clang__
+#    pragma clang diagnostic pop
+#endif
+}