Squashed 'third_party/elfutils/' content from commit 555e15e
Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libdw/dwarf_child.c b/libdw/dwarf_child.c
new file mode 100644
index 0000000..248338e
--- /dev/null
+++ b/libdw/dwarf_child.c
@@ -0,0 +1,165 @@
+/* Return child of current DIE.
+ Copyright (C) 2003-2011, 2014, 2017 Red Hat, Inc.
+ This file is part of elfutils.
+ Written by Ulrich Drepper <drepper@redhat.com>, 2003.
+
+ 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 "libdwP.h"
+#include <string.h>
+
+/* Some arbitrary value not conflicting with any existing code. */
+#define INVALID 0xffffe444
+
+
+unsigned char *
+internal_function
+__libdw_find_attr (Dwarf_Die *die, unsigned int search_name,
+ unsigned int *codep, unsigned int *formp)
+{
+ const unsigned char *readp;
+
+ /* Find the abbreviation entry. */
+ Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, &readp);
+ if (unlikely (abbrevp == DWARF_END_ABBREV))
+ {
+ __libdw_seterrno (DWARF_E_INVALID_DWARF);
+ return NULL;
+ }
+
+ /* Search the name attribute. Attribute has been checked when
+ Dwarf_Abbrev was created, we can read unchecked. */
+ const unsigned char *attrp = abbrevp->attrp;
+ while (1)
+ {
+ /* Get attribute name and form. */
+ unsigned int attr_name;
+ get_uleb128_unchecked (attr_name, attrp);
+
+ unsigned int attr_form;
+ get_uleb128_unchecked (attr_form, attrp);
+
+ /* We can stop if we found the attribute with value zero. */
+ if (attr_name == 0 && attr_form == 0)
+ break;
+
+ /* Is this the name attribute? */
+ if (attr_name == search_name && search_name != INVALID)
+ {
+ if (codep != NULL)
+ *codep = attr_name;
+ if (formp != NULL)
+ *formp = attr_form;
+
+ return (unsigned char *) readp;
+ }
+
+ /* Skip over the rest of this attribute (if there is any). */
+ if (attr_form != 0)
+ {
+ size_t len = __libdw_form_val_len (die->cu, attr_form, readp);
+ if (unlikely (len == (size_t) -1l))
+ {
+ readp = NULL;
+ break;
+ }
+
+ // __libdw_form_val_len will have done a bounds check.
+ readp += len;
+ }
+ }
+
+ // XXX Do we need other values?
+ if (codep != NULL)
+ *codep = INVALID;
+ if (formp != NULL)
+ *formp = INVALID;
+
+ return (unsigned char *) readp;
+}
+
+
+int
+dwarf_child (Dwarf_Die *die, Dwarf_Die *result)
+{
+ /* Ignore previous errors. */
+ if (die == NULL)
+ return -1;
+
+ /* Find the abbreviation entry. */
+ Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, NULL);
+ if (unlikely (abbrevp == DWARF_END_ABBREV))
+ {
+ __libdw_seterrno (DWARF_E_INVALID_DWARF);
+ return -1;
+ }
+
+ /* If there are no children, do not search. */
+ if (! abbrevp->has_children)
+ return 1;
+
+ /* Skip past the last attribute. */
+ void *addr = __libdw_find_attr (die, INVALID, NULL, NULL);
+
+ if (addr == NULL)
+ return -1;
+
+ /* RESULT can be the same as DIE. So preserve what we need. */
+ struct Dwarf_CU *cu = die->cu;
+
+ /* It's kosher (just suboptimal) to have a null entry first thing (7.5.3).
+ So if this starts with ULEB128 of 0 (even with silly encoding of 0),
+ it is a kosher null entry and we do not really have any children. */
+ const unsigned char *code = addr;
+ const unsigned char *endp = cu->endp;
+ while (1)
+ {
+ if (unlikely (code >= endp)) /* Truncated section. */
+ return 1;
+ if (unlikely (*code == 0x80))
+ ++code;
+ else
+ break;
+ }
+ if (unlikely (*code == '\0'))
+ return 1;
+
+ /* Clear the entire DIE structure. This signals we have not yet
+ determined any of the information. */
+ memset (result, '\0', sizeof (Dwarf_Die));
+
+ /* We have the address. */
+ result->addr = addr;
+
+ /* Same CU as the parent. */
+ result->cu = cu;
+
+ return 0;
+}
+INTDEF(dwarf_child)