Change startup ABI for untrusted code to be C-compatible

src/untrusted/nacl/nacl_irt.c

 /*
  * Copyright (c) 2011 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.
  */
 
 /* TODO(mcgrathr): this should be predefined in all builds,
    but that needs cleaning up scons hooey of nacl_extra_sdk_env vs nacl_env */
 #undef  _GNU_SOURCE
 #define _GNU_SOURCE  /* This makes glibc's unistd.h declare environ.  */
 #include <string.h>
 #include <unistd.h>
 
 #include "native_client/src/include/elf_auxv.h"
 #include "native_client/src/include/elf32.h"
 #include "native_client/src/untrusted/irt/irt_interfaces.h"
 #include "native_client/src/untrusted/nacl/nacl_irt.h"
 
 struct nacl_irt_basic __libnacl_irt_basic;
 struct nacl_irt_file __libnacl_irt_file;
 struct nacl_irt_memory __libnacl_irt_memory;
 struct nacl_irt_dyncode __libnacl_irt_dyncode;
 struct nacl_irt_tls __libnacl_irt_tls;
 struct nacl_irt_blockhook __libnacl_irt_blockhook;
 
 TYPE_nacl_irt_query __nacl_irt_query;
 
 /*
- * TODO(mcgrathr): This extremely stupid function should not exist.
- * If the startup calling sequence were sane, this would be done
- * someplace that has the initial pointer locally rather than stealing
- * it from environ.
- * See http://code.google.com/p/nativeclient/issues/detail?id=651
- */
-static Elf32_auxv_t *find_auxv(void) {
-  /*
-   * This presumes environ has its startup-time value on the stack.
-   */
-  char **ep = environ;
-  while (*ep != NULL)
-    ++ep;
-  return (void *) (ep + 1);
-}
-
-/*
  * Scan the auxv for AT_SYSINFO, which is the pointer to the IRT query function.
  * Stash that for later use.
  */
 static void grok_auxv(const Elf32_auxv_t *auxv) {
   const Elf32_auxv_t *av;
   for (av = auxv; av->a_type != AT_NULL; ++av) {
     if (av->a_type == AT_SYSINFO) {
       __nacl_irt_query = (TYPE_nacl_irt_query) av->a_un.a_val;
     }
   }
 }
 
 #define DO_QUERY(ident, name)                                                 \
   do_irt_query(ident, &__libnacl_irt_##name,                                  \
                sizeof(__libnacl_irt_##name), &nacl_irt_##name)
 
 static void do_irt_query(const char *interface_ident,
                          void *buffer, size_t table_size,
                          const void *fallback) {
   if (NULL == __nacl_irt_query ||
       __nacl_irt_query(interface_ident, buffer, table_size) != table_size) {
     memcpy(buffer, fallback, table_size);
   }
 }
 
 /*
  * Initialize all our IRT function tables using the query function.
  * The query function's address is passed via AT_SYSINFO in auxv.
  */
-void __libnacl_irt_init(void) {
-  grok_auxv(find_auxv());
+void __libnacl_irt_init(Elf32_auxv_t *auxv) {
+  grok_auxv(auxv);
 
   DO_QUERY(NACL_IRT_BASIC_v0_1, basic);
   DO_QUERY(NACL_IRT_FILE_v0_1, file);
   DO_QUERY(NACL_IRT_MEMORY_v0_1, memory);
   DO_QUERY(NACL_IRT_DYNCODE_v0_1, dyncode);
   DO_QUERY(NACL_IRT_TLS_v0_1, tls);
   DO_QUERY(NACL_IRT_BLOCKHOOK_v0_1, blockhook);
 }