Remove failure for bad mmap address hints.

src/trusted/service_runtime/sys_memory.c

 /*
  * Copyright (c) 2013 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/trusted/service_runtime/sys_memory.h"
 
 #include <errno.h>
 #include <string.h>
@@ skipping 311 matching lines @@
   } else if (0 != (prot & NACL_ABI_PROT_EXEC)) {
     map_result = -NACL_ABI_EINVAL;
     goto cleanup;
   }
 
   /*
    * Starting address must be aligned to worst-case allocation
    * granularity.  (Windows.)
    */
   if (!NaClIsAllocPageMultiple(usraddr)) {
-    NaClLog(2, "NaClSysMmap: address not allocation granularity aligned\n");
-    map_result = -NACL_ABI_EINVAL;
-    goto cleanup;
+    if (NACL_ABI_MAP_FIXED & flags) {

[Mark Seaborn, 2015/07/30 15:20:14]

Nit: use "(NACL_ABI_MAP_FIXED & flags) != 0"

NaCl style is not to implicitly convert to boolean.

[Sean Klein, 2015/07/30 16:04:29]

Done.

+      NaClLog(2, "NaClSysMmap: address not allocation granularity aligned\n");
+      map_result = -NACL_ABI_EINVAL;

[Mark Seaborn, 2015/07/30 15:20:14]

Is there a test case covering this code path?

[Sean Klein, 2015/07/30 16:04:29]

There is now (added to mem_test.cc).

+      goto cleanup;
+    } else {
+      /* Ignore the hint, as we do not need it. */

[Mark Seaborn, 2015/07/30 15:20:14]

So we use the hint if it's aligned but ignore it otherwise?

Why not just round the hint down to page size alignment when MAP_FIXED isn't
passed?  What does Linux do?

[Sean Klein, 2015/07/30 16:04:29]

Linux rounds the address to a minimum value, and then forces alignment -- I will
match the alignment behavior here.

+      NaClLog(2, "NaClSysMmap: ignoring misaligned hint address\n");
+      usraddr = 0;
+    }
   }
   /*
    * Offset should be non-negative (nacl_abi_off_t is signed).  This
    * condition is caught when the file is stat'd and checked, and
    * offset is ignored for anonymous mappings.
    */
   if (offset < 0) {
     NaClLog(1,  /* application bug */
             "NaClSysMmap: negative file offset: %"NACL_PRId64"\n",
             (int64_t) offset);
@@ skipping 1023 matching lines @@
                         size_t                length,
                         int                   prot) {
   struct NaClApp  *nap = natp->nap;
 
   NaClLog(3, "Entered NaClSysMprotect(0x%08"NACL_PRIxPTR", "
           "0x%08"NACL_PRIxPTR", 0x%"NACL_PRIxS", 0x%x)\n",
           (uintptr_t) natp, (uintptr_t) start, length, prot);
 
   return NaClSysMprotectInternal(nap, start, length, prot);
 }