Add an implementation of mifki's sizecheck library (tested on Linux)

CMakeLists.txt

@@ -540,3 +540,9 @@ endif()
 
 # Store old build arch
 set(DFHACK_BUILD_ARCH_PREV "${DFHACK_BUILD_ARCH}" CACHE STRING "Previous build architecture" FORCE)
+
+option(BUILD_SIZECHECK "Build the sizecheck library, for research" OFF)
+if(BUILD_SIZECHECK)
+    add_subdirectory(depends/sizecheck)
+    add_dependencies(dfhack sizecheck)
+endif()

depends/sizecheck/CMakeLists.txt

@@ -0,0 +1,6 @@
+project(sizecheck)
+add_library(sizecheck SHARED sizecheck.cpp)
+ide_folder(sizecheck "Depends")
+install(TARGETS sizecheck
+    LIBRARY DESTINATION ${DFHACK_LIBRARY_DESTINATION}
+    RUNTIME DESTINATION ${DFHACK_LIBRARY_DESTINATION})

depends/sizecheck/sizecheck.cpp

@@ -0,0 +1,43 @@
+// adapted from https://github.com/mifki/df-sizecheck/blob/master/b.cpp
+// usage:
+// linux: PRELOAD_LIB=hack/libsizecheck.so ./dfhack
+
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <memory>
+
+using namespace std;
+
+const uint32_t MAGIC = 0xdfdf4ac8;
+
+void* alloc(size_t n) {
+    void* addr;
+    if (posix_memalign(&addr, 32, n + 16) != 0) {
+        return addr;
+    }
+    memset(addr, 0, 16);
+    *(size_t*)addr = n;
+    *(uint32_t*)((uint8_t*)addr + 8) = MAGIC;
+    return (uint8_t*)addr + 16;
+}
+
+void dealloc(void* addr) {
+    if (intptr_t(addr) % 32 == 16 && *(size_t*)((uint8_t*)addr - 8) == MAGIC) {
+        addr = (void*)((uint8_t*)addr - 16);
+    }
+    free(addr);
+}
+
+void* operator new (size_t n, const nothrow_t& tag) {
+    return alloc(n);
+}
+
+void* operator new (size_t n) {
+    return alloc(n);
+}
+
+void operator delete (void* addr) {
+    return dealloc(addr);
+}

plugins/devel/memview.cpp

@@ -117,7 +117,7 @@ void Deinit()
 size_t detect_size(void *addr) {
     size_t *size = (size_t*)((char*)addr - 16);
     int32_t *tag = (int32_t*)((char*)addr - 8);
-    if (isAddr(size, memdata.ranges) && *tag == 0x11223344) {
+    if (isAddr(size, memdata.ranges) && (*tag == 0x11223344 || *tag == 0xdfdf4ac8)) {
         return *size;
     }
     // default