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
55static inline int
56file_matches (const char *lastfile,
57              size_t match_file_len, const char *match_file,
58              Dwarf_Files *files, size_t idx,
59              bool *lastfile_matches)
60{
61  if (idx >= files->nfiles)
62    return false;
63  const char *file = files->info[idx].name;
64  if (file != lastfile)
65    {
66      size_t len = strlen (file);
67      *lastfile_matches = (len >= match_file_len
68                          && !memcmp (match_file, file, match_file_len)
69                          && (len == match_file_len
70                              || file[len - match_file_len - 1] == '/'));
71    }
72  return *lastfile_matches;
73}
74
75/* Search SCOPES[0..NSCOPES-1] for a variable called NAME.
76   Ignore the first SKIP_SHADOWS scopes that match the name.
77   If MATCH_FILE is not null, accept only declaration in that source file;
78   if MATCH_LINENO or MATCH_LINECOL are also nonzero, accept only declaration
79   at that line and column.
80
81   If successful, fill in *RESULT with the DIE of the variable found,
82   and return N where SCOPES[N] is the scope defining the variable.
83   Return -1 for errors or -2 for no matching variable found.  */
84
85int
86dwarf_getscopevar (Dwarf_Die *scopes, int nscopes,
87		   const char *name, int skip_shadows,
88		   const char *match_file, int match_lineno, int match_linecol,
89		   Dwarf_Die *result)
90{
91  /* Match against the given file name.  */
92  size_t match_file_len = match_file == NULL ? 0 : strlen (match_file);
93  bool lastfile_matches = false;
94  const char *lastfile = NULL;
95
96  /* Start with the innermost scope and move out.  */
97  for (int out = 0; out < nscopes; ++out)
98    if (INTUSE(dwarf_haschildren) (&scopes[out]))
99      {
100	if (INTUSE(dwarf_child) (&scopes[out], result) != 0)
101	  return -1;
102	do
103	  {
104	    switch (INTUSE(dwarf_tag) (result))
105	      {
106	      case DW_TAG_variable:
107	      case DW_TAG_formal_parameter:
108		break;
109
110	      default:
111		continue;
112	      }
113
114	    /* Only get here for a variable or parameter.  Check the name.  */
115	    const char *diename = INTUSE(dwarf_diename) (result);
116	    if (diename != NULL && !strcmp (name, diename))
117	      {
118		/* We have a matching name.  */
119
120		if (skip_shadows > 0)
121		  {
122		    /* Punt this scope for the one it shadows.  */
123		    --skip_shadows;
124		    break;
125		  }
126
127		if (match_file != NULL)
128		  {
129		    /* Check its decl_file.  */
130
131		    Dwarf_Word i;
132		    Dwarf_Files *files;
133		    if (getattr (result, DW_AT_decl_file, &i) != 0
134			|| getfiles (&scopes[out], &files) != 0)
135		      break;
136
137		    if (!file_matches (lastfile, match_file_len, match_file,
138		                       files, i, &lastfile_matches))
139		      break;
140
141		    if (match_lineno > 0
142			&& (getattr (result, DW_AT_decl_line, &i) != 0
143			    || (int) i != match_lineno))
144		      break;
145		    if (match_linecol > 0
146			&& (getattr (result, DW_AT_decl_column, &i) != 0
147			    || (int) i != match_linecol))
148		      break;
149		  }
150
151		/* We have a winner!  */
152		return out;
153	      }
154	  }
155	while (INTUSE(dwarf_siblingof) (result, result) == 0);
156      }
157
158  return -2;
159}
160