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

Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libdwfl/dwfl_getmodules.c b/libdwfl/dwfl_getmodules.c
new file mode 100644
index 0000000..243cb04
--- /dev/null
+++ b/libdwfl/dwfl_getmodules.c
@@ -0,0 +1,96 @@
+/* Iterate through modules.
+   Copyright (C) 2005, 2008 Red Hat, Inc.
+   This file is part of elfutils.
+
+   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 "libdwflP.h"
+
+ptrdiff_t
+dwfl_getmodules (Dwfl *dwfl,
+		 int (*callback) (Dwfl_Module *, void **,
+				  const char *, Dwarf_Addr, void *),
+		 void *arg,
+		 ptrdiff_t offset)
+{
+  if (dwfl == NULL)
+    return -1;
+
+  /* We iterate through the linked list when it's all we have.
+     But continuing from an offset is slow that way.  So when
+     DWFL->lookup_module is populated, we can instead keep our
+     place by jumping directly into the array.  Since the actions
+     of a callback could cause it to get populated, we must
+     choose the style of place-holder when we return an offset,
+     and we encode the choice in the low bits of that value.  */
+
+  Dwfl_Module *m = dwfl->modulelist;
+
+  if ((offset & 3) == 1)
+    {
+      offset >>= 2;
+      for (ptrdiff_t pos = 0; pos < offset; ++pos)
+	if (m == NULL)
+	  return -1;
+	else
+	  m = m->next;
+    }
+  else if (((offset & 3) == 2) && likely (dwfl->lookup_module != NULL))
+    {
+      offset >>= 2;
+
+      if ((size_t) offset - 1 == dwfl->lookup_elts)
+	return 0;
+
+      if (unlikely ((size_t) offset - 1 > dwfl->lookup_elts))
+	return -1;
+
+      m = dwfl->lookup_module[offset - 1];
+      if (unlikely (m == NULL))
+	return -1;
+    }
+  else if (offset != 0)
+    {
+      __libdwfl_seterrno (DWFL_E_BADSTROFF);
+      return -1;
+    }
+
+  while (m != NULL)
+    {
+      int ok = (*callback) (MODCB_ARGS (m), arg);
+      ++offset;
+      m = m->next;
+      if (ok != DWARF_CB_OK)
+	return ((dwfl->lookup_module == NULL) ? ((offset << 2) | 1)
+		: (((m == NULL ? (ptrdiff_t) dwfl->lookup_elts + 1
+		     : m->segment + 1) << 2) | 2));
+    }
+  return 0;
+}
+INTDEF (dwfl_getmodules)