1/* Find a named variable or parameter within given scopes.
2   Copyright (C) 2005-2009 Red Hat, Inc.
3   This file is part of elfutils.
4
5   This file is free software; you can redistribute it and/or modify
6   it under the terms of either
7
8     * the GNU Lesser General Public License as published by the Free
9       Software Foundation; either version 3 of the License, or (at
10       your option) any later version
11
12   or
13
14     * the GNU General Public License as published by the Free
15       Software Foundation; either version 2 of the License, or (at
16       your option) any later version
17
18   or both in parallel, as here.
19
20   elfutils is distributed in the hope that it will be useful, but
21   WITHOUT ANY WARRANTY; without even the implied warranty of
22   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
23   General Public License for more details.
24
25   You should have received copies of the GNU General Public License and
26   the GNU Lesser General Public License along with this program.  If
27   not, see <http://www.gnu.org/licenses/>.  */
28
29#ifdef HAVE_CONFIG_H
30# include <config.h>
31#endif
32
33#include <stdbool.h>
34#include <string.h>
35#include "libdwP.h"
36#include <dwarf.h>
37
38
39/* Find the containing CU's files.  */
40static int
41getfiles (Dwarf_Die *die, Dwarf_Files **files)
42{
43  return INTUSE(dwarf_getsrcfiles) (&CUDIE (die->cu), files, NULL);
44}
45
46/* Fetch an attribute that should have a constant integer form.  */
47static int
48getattr (Dwarf_Die *die, int search_name, Dwarf_Word *value)
49{
50  Dwarf_Attribute attr_mem;
51  return INTUSE(dwarf_formudata) (INTUSE(dwarf_attr) (die, search_name,
52						      &attr_mem), value);
53}
54
55/* Search SCOPES[0..NSCOPES-1] for a variable called NAME.
56   Ignore the first SKIP_SHADOWS scopes that match the name.
57   If MATCH_FILE is not null, accept only declaration in that source file;
58   if MATCH_LINENO or MATCH_LINECOL are also nonzero, accept only declaration
59   at that line and column.
60
61   If successful, fill in *RESULT with the DIE of the variable found,
62   and return N where SCOPES[N] is the scope defining the variable.
63   Return -1 for errors or -2 for no matching variable found.  */
64
65int
66dwarf_getscopevar (Dwarf_Die *scopes, int nscopes,
67		   const char *name, int skip_shadows,
68		   const char *match_file, int match_lineno, int match_linecol,
69		   Dwarf_Die *result)
70{
71  /* Match against the given file name.  */
72  size_t match_file_len = match_file == NULL ? 0 : strlen (match_file);
73  bool lastfile_matches = false;
74  const char *lastfile = NULL;
75  inline bool file_matches (Dwarf_Files *files, size_t idx)
76    {
77      if (idx >= files->nfiles)
78	return false;
79
80      const char *file = files->info[idx].name;
81      if (file != lastfile)
82	{
83	  size_t len = strlen (file);
84	  lastfile_matches = (len >= match_file_len
85			      && !memcmp (match_file, file, match_file_len)
86			      && (len == match_file_len
87				  || file[len - match_file_len - 1] == '/'));
88	}
89      return lastfile_matches;
90    }
91
92  /* Start with the innermost scope and move out.  */
93  for (int out = 0; out < nscopes; ++out)
94    if (INTUSE(dwarf_haschildren) (&scopes[out]))
95      {
96	if (INTUSE(dwarf_child) (&scopes[out], result) != 0)
97	  return -1;
98	do
99	  {
100	    switch (INTUSE(dwarf_tag) (result))
101	      {
102	      case DW_TAG_variable:
103	      case DW_TAG_formal_parameter:
104		break;
105
106	      default:
107		continue;
108	      }
109
110	    /* Only get here for a variable or parameter.  Check the name.  */
111	    const char *diename = INTUSE(dwarf_diename) (result);
112	    if (diename != NULL && !strcmp (name, diename))
113	      {
114		/* We have a matching name.  */
115
116		if (skip_shadows > 0)
117		  {
118		    /* Punt this scope for the one it shadows.  */
119		    --skip_shadows;
120		    break;
121		  }
122
123		if (match_file != NULL)
124		  {
125		    /* Check its decl_file.  */
126
127		    Dwarf_Word i;
128		    Dwarf_Files *files;
129		    if (getattr (result, DW_AT_decl_file, &i) != 0
130			|| getfiles (&scopes[out], &files) != 0)
131		      break;
132
133		    if (!file_matches (files, i))
134		      break;
135
136		    if (match_lineno > 0
137			&& (getattr (result, DW_AT_decl_line, &i) != 0
138			    || (int) i != match_lineno))
139		      break;
140		    if (match_linecol > 0
141			&& (getattr (result, DW_AT_decl_column, &i) != 0
142			    || (int) i != match_linecol))
143		      break;
144		  }
145
146		/* We have a winner!  */
147		return out;
148	      }
149	  }
150	while (INTUSE(dwarf_siblingof) (result, result) == 0);
151      }
152
153  return -2;
154}
155