Fix address overflow in trampoline

Allocate memory for storing the trampoline code via mmap() with MAP_32BIT flag
to make sure that it stays withing 2GB range.

Also, add missing calls to subhook_free() in the C test program (C++ calls it
implicitly already via destructor).

1 files changed, 20 insertions, 7 deletions

diff --git a/subhook_windows.c b/subhook_windows.c
index b1f0be6..b934651 100644
--- a/subhook_windows.c
+++ b/subhook_windows.c
@@ -27,12 +27,25 @@
 #include <stddef.h>
 #include <windows.h>
 
-void *subhook_unprotect(void *address, size_t size) {
-  DWORD old;
+#define SUBHOOK_CODE_PROTECT_FLAGS PAGE_EXECUTE_READWRITE
 
-  if (VirtualProtect(address, size, PAGE_EXECUTE_READWRITE, &old) != 0) {
-    return address;
-  } else {
-    return NULL;
-  }
+int subhook_unprotect(void *address, size_t size) {
+  DWORD old_flags;
+  BOOL result = VirtualProtect(address,
+                               size,
+                               SUBHOOK_CODE_PROTECT_FLAGS,
+                               &old_flags);
+  return !result;
+}
+
+void *subhook_alloc_code(size_t size) {
+  return VirtualAlloc(NULL,
+                      size,
+                      MEM_COMMIT | MEM_RESERVE,
+                      SUBHOOK_CODE_PROTECT_FLAGS);
+}
+
+int subhok_free_code(void *address, size_t size) {
+  (void)size;
+  return !VirtualFree(address, 0, MEM_RELEASE);
 }