1/* Find a named variable or parameter within given scopes.
2   Copyright (C) 2005-2009 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4
5   Red Hat elfutils is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by the
7   Free Software Foundation; version 2 of the License.
8
9   Red Hat elfutils is distributed in the hope that it will be useful, but
10   WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License along
15   with Red Hat elfutils; if not, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18   In addition, as a special exception, Red Hat, Inc. gives You the
19   additional right to link the code of Red Hat elfutils with code licensed
20   under any Open Source Initiative certified open source license
21   (http://www.opensource.org/licenses/index.php) which requires the
22   distribution of source code with any binary distribution and to
23   distribute linked combinations of the two.  Non-GPL Code permitted under
24   this exception must only link to the code of Red Hat elfutils through
25   those well defined interfaces identified in the file named EXCEPTION
26   found in the source code files (the "Approved Interfaces").  The files
27   of Non-GPL Code may instantiate templates or use macros or inline
28   functions from the Approved Interfaces without causing the resulting
29   work to be covered by the GNU General Public License.  Only Red Hat,
30   Inc. may make changes or additions to the list of Approved Interfaces.
31   Red Hat's grant of this exception is conditioned upon your not adding
32   any new exceptions.  If you wish to add a new Approved Interface or
33   exception, please contact Red Hat.  You must obey the GNU General Public
34   License in all respects for all of the Red Hat elfutils code and other
35   code used in conjunction with Red Hat elfutils except the Non-GPL Code
36   covered by this exception.  If you modify this file, you may extend this
37   exception to your version of the file, but you are not obligated to do
38   so.  If you do not wish to provide this exception without modification,
39   you must delete this exception statement from your version and license
40   this file solely under the GPL without exception.
41
42   Red Hat elfutils is an included package of the Open Invention Network.
43   An included package of the Open Invention Network is a package for which
44   Open Invention Network licensees cross-license their patents.  No patent
45   license is granted, either expressly or impliedly, by designation as an
46   included package.  Should you wish to participate in the Open Invention
47   Network licensing program, please visit www.openinventionnetwork.com
48   <http://www.openinventionnetwork.com>.  */
49
50#ifdef HAVE_CONFIG_H
51# include <config.h>
52#endif
53
54#include <stdbool.h>
55#include <string.h>
56#include "libdwP.h"
57#include <dwarf.h>
58
59
60/* Find the containing CU's files.  */
61static int
62getfiles (Dwarf_Die *die, Dwarf_Files **files)
63{
64  return INTUSE(dwarf_getsrcfiles) (&CUDIE (die->cu), files, NULL);
65}
66
67/* Fetch an attribute that should have a constant integer form.  */
68static int
69getattr (Dwarf_Die *die, int search_name, Dwarf_Word *value)
70{
71  Dwarf_Attribute attr_mem;
72  return INTUSE(dwarf_formudata) (INTUSE(dwarf_attr) (die, search_name,
73						      &attr_mem), value);
74}
75
76/* Search SCOPES[0..NSCOPES-1] for a variable called NAME.
77   Ignore the first SKIP_SHADOWS scopes that match the name.
78   If MATCH_FILE is not null, accept only declaration in that source file;
79   if MATCH_LINENO or MATCH_LINECOL are also nonzero, accept only declaration
80   at that line and column.
81
82   If successful, fill in *RESULT with the DIE of the variable found,
83   and return N where SCOPES[N] is the scope defining the variable.
84   Return -1 for errors or -2 for no matching variable found.  */
85
86int
87dwarf_getscopevar (Dwarf_Die *scopes, int nscopes,
88		   const char *name, int skip_shadows,
89		   const char *match_file, int match_lineno, int match_linecol,
90		   Dwarf_Die *result)
91{
92  /* Match against the given file name.  */
93  size_t match_file_len = match_file == NULL ? 0 : strlen (match_file);
94  bool lastfile_matches = false;
95  const char *lastfile = NULL;
96  inline bool file_matches (Dwarf_Files *files, size_t idx)
97    {
98      if (idx >= files->nfiles)
99	return false;
100
101      const char *file = files->info[idx].name;
102      if (file != lastfile)
103	{
104	  size_t len = strlen (file);
105	  lastfile_matches = (len >= match_file_len
106			      && !memcmp (match_file, file, match_file_len)
107			      && (len == match_file_len
108				  || file[len - match_file_len - 1] == '/'));
109	}
110      return lastfile_matches;
111    }
112
113  /* Start with the innermost scope and move out.  */
114  for (int out = 0; out < nscopes; ++out)
115    if (INTUSE(dwarf_haschildren) (&scopes[out]))
116      {
117	if (INTUSE(dwarf_child) (&scopes[out], result) != 0)
118	  return -1;
119	do
120	  {
121	    switch (INTUSE(dwarf_tag) (result))
122	      {
123	      case DW_TAG_variable:
124	      case DW_TAG_formal_parameter:
125		break;
126
127	      default:
128		continue;
129	      }
130
131	    /* Only get here for a variable or parameter.  Check the name.  */
132	    const char *diename = INTUSE(dwarf_diename) (result);
133	    if (diename != NULL && !strcmp (name, diename))
134	      {
135		/* We have a matching name.  */
136
137		if (skip_shadows > 0)
138		  {
139		    /* Punt this scope for the one it shadows.  */
140		    --skip_shadows;
141		    break;
142		  }
143
144		if (match_file != NULL)
145		  {
146		    /* Check its decl_file.  */
147
148		    Dwarf_Word i;
149		    Dwarf_Files *files;
150		    if (getattr (result, DW_AT_decl_file, &i) != 0
151			|| getfiles (&scopes[out], &files) != 0)
152		      break;
153
154		    if (!file_matches (files, i))
155		      break;
156
157		    if (match_lineno > 0
158			&& (getattr (result, DW_AT_decl_line, &i) != 0
159			    || (int) i != match_lineno))
160		      break;
161		    if (match_linecol > 0
162			&& (getattr (result, DW_AT_decl_column, &i) != 0
163			    || (int) i != match_linecol))
164		      break;
165		  }
166
167		/* We have a winner!  */
168		return out;
169	      }
170	  }
171	while (INTUSE(dwarf_siblingof) (result, result) == 0);
172      }
173
174  return -2;
175}
176