From 0ec12657f46b28ab427490de3d6fd7ac4a63d93a Mon Sep 17 00:00:00 2001
From: lethosor <lethosor@gmail.com>
Date: Tue, 18 Feb 2020 00:31:49 -0500
Subject: [PATCH] sizecheck: add MALLOC_PERTURB_ support on non-Linux

---
 depends/sizecheck/sizecheck.cpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/depends/sizecheck/sizecheck.cpp b/depends/sizecheck/sizecheck.cpp
index 5bb5a665c..6366edd68 100644
--- a/depends/sizecheck/sizecheck.cpp
+++ b/depends/sizecheck/sizecheck.cpp
@@ -11,8 +11,22 @@
 using namespace std;
 
 const uint32_t MAGIC = 0xdfdf4ac8;
+bool initialized = false;
+int perturb = -1;
+
+void init() {
+#ifndef _LINUX
+    if (getenv("MALLOC_PERTURB_")) {
+        perturb = atoi(getenv("MALLOC_PERTURB_"));
+    }
+#endif
+    initialized = true;
+}
 
 void* alloc(size_t n) {
+    if (!initialized) {
+        init();
+    }
     void* addr;
     if (posix_memalign(&addr, 32, n + 16) != 0) {
         return addr;
@@ -20,12 +34,19 @@ void* alloc(size_t n) {
     memset(addr, 0, 16);
     *(size_t*)addr = n;
     *(uint32_t*)((uint8_t*)addr + 8) = MAGIC;
+    if (perturb > 0) {
+        memset((uint8_t*)addr + 16, ~(perturb & 0xff), n);
+    }
     return (uint8_t*)addr + 16;
 }
 
 void dealloc(void* addr) {
+    if (!initialized) {
+        init();
+    }
     if (uintptr_t(addr) % 32 == 16 && *(uint32_t*)((uint8_t*)addr - 8) == MAGIC) {
         addr = (void*)((uint8_t*)addr - 16);
+        memset((uint8_t*)addr + 16, perturb & 0xff, *(size_t*)addr);
     }
     free(addr);
 }