3 files changed, 64 insertions, 28 deletions

diff --git a/libc/bionic/getauxval.cpp b/libc/bionic/getauxval.cpp
new file mode 100644
index 000000000..38a05fc21
--- /dev/null
+++ b/libc/bionic/getauxval.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stddef.h>
+#include <sys/cdefs.h>
+#include <sys/auxv.h>
+#include <private/bionic_auxv.h>
+#include <elf.h>
+
+__LIBC_HIDDEN__
+Elf32_auxv_t* __libc_auxv = NULL;
+
+extern "C" unsigned long int getauxval(unsigned long int type) {
+  Elf32_auxv_t* v;
+
+  for (v = __libc_auxv; v->a_type != AT_NULL; v++) {
+    if (v->a_type == type) {
+      return v->a_un.a_val;
+    }
+  }
+
+  return 0;
+}
diff --git a/libc/bionic/libc_init_common.c b/libc/bionic/libc_init_common.c
index fb164f447..86e1eb574 100644
--- a/libc/bionic/libc_init_common.c
+++ b/libc/bionic/libc_init_common.c
@@ -38,6 +38,7 @@
 
 #include <bionic_tls.h>
 #include <errno.h>
+#include <private/bionic_auxv.h>
 
 extern unsigned __get_sp(void);
 extern pid_t gettid(void);
@@ -95,6 +96,15 @@ void __libc_init_common(uintptr_t* elf_data) {
   __progname = argv[0] ? argv[0] : "<unknown>";
   environ = envp;
 
+  // The auxiliary vector is at the end of the environment block
+  while(*envp != NULL) {
+    envp++;
+  }
+  /* The end of the environment block is marked by two NULL pointers */
+  envp++;
+
+  __libc_auxv = (Elf32_auxv_t*) envp;
+
   __system_properties_init(); // Requires 'environ'.
 }
 
diff --git a/libc/bionic/libc_init_static.c b/libc/bionic/libc_init_static.c
index ba7f008e9..bb3a41021 100644
--- a/libc/bionic/libc_init_static.c
+++ b/libc/bionic/libc_init_static.c
@@ -49,6 +49,7 @@
 #include <bionic_tls.h>
 #include <errno.h>
 #include <sys/mman.h>
+#include <sys/auxv.h>
 
 // Returns the address of the page containing address 'x'.
 #define PAGE_START(x)  ((x) & PAGE_MASK)
@@ -65,27 +66,13 @@ static void call_array(void(**list)())
     }
 }
 
-/*
- * Find the value of the AT_* variable passed to us by the kernel.
- */
-static unsigned find_aux(unsigned *vecs, unsigned type) {
-    while (vecs[0]) {
-        if (vecs[0] == type) {
-            return vecs[1];
-        }
-        vecs += 2;
-    }
-
-    return 0; // should never happen
-}
-
-static void apply_gnu_relro(unsigned *vecs) {
+static void apply_gnu_relro() {
     Elf32_Phdr *phdr_start;
-    unsigned phdr_ct;
+    unsigned long int phdr_ct;
     Elf32_Phdr *phdr;
 
-    phdr_start = (Elf32_Phdr *) find_aux(vecs, AT_PHDR);
-    phdr_ct    = find_aux(vecs, AT_PHNUM);
+    phdr_start = (Elf32_Phdr *) getauxval(AT_PHDR);
+    phdr_ct    = getauxval(AT_PHNUM);
 
     for (phdr = phdr_start; phdr < (phdr_start + phdr_ct); phdr++) {
         if (phdr->p_type != PT_GNU_RELRO)
@@ -108,7 +95,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
 {
     int  argc;
     char **argv, **envp;
-    unsigned *vecs;
 
     __libc_init_tls(NULL);
 
@@ -129,14 +115,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
     argv = (char**)(elfdata + 1);
     envp = argv + argc + 1;
 
-    // The auxiliary vector is at the end of the environment block
-    vecs = (unsigned *) envp;
-    while (vecs[0] != 0) {
-        vecs++;
-    }
-    /* The end of the environment block is marked by two NULL pointers */
-    vecs++;
-
     /* The executable may have its own destructors listed in its .fini_array
      * so we need to ensure that these are called when the program exits
      * normally.
@@ -144,6 +122,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
     if (structors->fini_array)
         __cxa_atexit(__libc_fini,structors->fini_array,NULL);
 
-    apply_gnu_relro(vecs);
+    apply_gnu_relro();
     exit(slingshot(argc, argv, envp));
 }