Modify the NaCl_page_alloc_hint function to use VirtualQuery to check

src/trusted/service_runtime/arch/x86_32/sel_addrspace_x86_32.c

 /*
  * Copyright 2009 The Native Client Authors.  All rights reserved.
  * Use of this source code is governed by a BSD-style license that can
  * be found in the LICENSE file.
  */
 
 #include "native_client/src/include/nacl_platform.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/src/trusted/service_runtime/sel_memory.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
 
 
 NaClErrorCode NaClAllocateSpace(void **mem, size_t addrsp_size) {
   int result;
 
   CHECK(NULL != mem);
 
 #ifdef NACL_SANDBOX_FIXED_AT_ZERO
   /*
    * When creating a zero-based sandbox, we do not allocate the first 64K of
    * pages beneath the trampolines, because -- on Linux at least -- we cannot.
    * Instead, we allocate starting at the trampolines, and then coerce the
    * out parameter.
    */
   addrsp_size -= NACL_TRAMPOLINE_START;
   *mem = (void *) NACL_TRAMPOLINE_START;
   result = NaCl_page_alloc_at_addr(mem, addrsp_size);
   *mem = 0;
+#elif NACL_WINDOWS && NACL_BUILD_SUBARCH == 32
+  /*
+   * On 32 bit Windows, a 1 gigabyte block of address space is reserved before
+   * starting up this process to make sure we can create the sandbox. Look for
+   * this pre-reserved block and if found, pass its address to the page
+   * allocation function.
+   */
+  if (0 == NaCl_find_prereserved_sandbox_memory(mem, addrsp_size)) {
+    result = NaCl_page_alloc_at_addr(mem, addrsp_size);
+  } else {
+    result = NaCl_page_alloc(mem, addrsp_size);
+  }
 #else
   result = NaCl_page_alloc(mem, addrsp_size);
 #endif
 
   if (0 != result) {
     NaClLog(2,
         "NaClAllocateSpace: NaCl_page_alloc 0x%08"NACL_PRIxPTR
         " failed\n",
         (uintptr_t) *mem);
     return LOAD_NO_MEMORY;
@@ skipping 33 matching lines @@
                     NACL_SYSCALL_START_ADDR >> NACL_PAGESHIFT,
                     PROT_NONE,
                     (struct NaClMemObj *) NULL)) {
     NaClLog(LOG_ERROR, ("NaClMemoryProtection: NaClVmmapAdd failed"
                         " (NULL pointer guard page)\n"));
     return LOAD_MPROTECT_FAIL;
   }
 
   return LOAD_OK;
 }