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;
+  const size_t kOneGb = 0x40000000;

[Brad Chen, 2011/08/16 01:21:49]

I'm used to 'b' meaning 'bit'. I'd rather see kOneGB here. Some folks find (1 <<
30) more readable than 0x40000000; your call.

[bbudge, 2011/08/16 19:46:22]

Done.

 
   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_ARCH_CPU_32_BITS

[Mark Seaborn, 2011/08/16 17:34:10]

Can you use "NACL_BUILD_SUBARCH == 64" rather than "NACL_ARCH_CPU_32_BITS", for
consistency?  No-one is using the latter.

[bbudge, 2011/08/16 19:46:22]

Done.

+  /*
+   * On 32 bit Windows XP, a 1Gb region of address space is reserved before
+   * starting up this process to make sure we can get a contiguous block. Look
+   * for it now.
+   */
+  if (0 == NaCl_find_sandbox_memory(mem, kOneGb))

[Mark Seaborn, 2011/08/16 17:34:10]

Nit: I'd use curly brackets for this 'if'.

[bbudge, 2011/08/16 19:46:22]

Done.

+    result = NaCl_page_alloc_at_addr(mem, addrsp_size);

[Brad Chen, 2011/08/16 01:21:49]

I don't understand how mem gets initialized in this case.

[bbudge, 2011/08/16 17:21:02]

It's obscure, but the 'mem' parameter gets filled in by the call to
NaCl_find_sandbox_memory if the pre-reserved region is found. Then the call to
NaCl_page_alloc_at_addr tries to use that address.

[Brad Chen, 2011/08/16 17:28:38]

Nit: A brief comment before the call to NaCl_page_alloc_at_addr might be
helpful.
On 2011/08/16 17:21:02, bbudge1 wrote:

[bbudge, 2011/08/16 19:46:22]

Done. (I expanded the comment for the whole case)

+  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;
 }