Squashed 'third_party/elfutils/' content from commit 555e15e

Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libelf/elf_next.c b/libelf/elf_next.c
new file mode 100644
index 0000000..6edafd2
--- /dev/null
+++ b/libelf/elf_next.c
@@ -0,0 +1,72 @@
+/* Advance in archive to next element.
+   Copyright (C) 1998-2009, 2015 Red Hat, Inc.
+   This file is part of elfutils.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 1998.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <assert.h>
+#include <libelf.h>
+#include <stddef.h>
+
+#include "libelfP.h"
+
+
+Elf_Cmd
+elf_next (Elf *elf)
+{
+  Elf *parent;
+  Elf_Cmd ret;
+
+  /* Be gratious, the specs demand it.  */
+  if (elf == NULL || elf->parent == NULL)
+    return ELF_C_NULL;
+
+  /* We can be sure the parent is an archive.  */
+  parent = elf->parent;
+  assert (parent->kind == ELF_K_AR);
+
+  rwlock_wrlock (parent->lock);
+
+  /* Now advance the offset.  */
+  parent->state.ar.offset += (sizeof (struct ar_hdr)
+			      + ((parent->state.ar.elf_ar_hdr.ar_size + 1)
+				 & ~1l));
+
+  /* Get the next archive header.  */
+  ret = __libelf_next_arhdr_wrlock (parent) != 0 ? ELF_C_NULL : elf->cmd;
+
+  /* If necessary, mark the archive header as unusable.  */
+  if (ret == ELF_C_NULL)
+    parent->state.ar.elf_ar_hdr.ar_name = NULL;
+
+  rwlock_unlock (parent->lock);
+
+  return ret;
+}