1/* Return string pointer from string section.
2   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2008, 2009 Red Hat, Inc.
3   This file is part of elfutils.
4   Contributed by Ulrich Drepper <drepper@redhat.com>, 1998.
5
6   This file is free software; you can redistribute it and/or modify
7   it under the terms of either
8
9     * the GNU Lesser General Public License as published by the Free
10       Software Foundation; either version 3 of the License, or (at
11       your option) any later version
12
13   or
14
15     * the GNU General Public License as published by the Free
16       Software Foundation; either version 2 of the License, or (at
17       your option) any later version
18
19   or both in parallel, as here.
20
21   elfutils is distributed in the hope that it will be useful, but
22   WITHOUT ANY WARRANTY; without even the implied warranty of
23   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
24   General Public License for more details.
25
26   You should have received copies of the GNU General Public License and
27   the GNU Lesser General Public License along with this program.  If
28   not, see <http://www.gnu.org/licenses/>.  */
29
30#ifdef HAVE_CONFIG_H
31# include <config.h>
32#endif
33
34#include <libelf.h>
35#include <stddef.h>
36
37#include "libelfP.h"
38
39
40char *
41elf_strptr (elf, idx, offset)
42     Elf *elf;
43     size_t idx;
44     size_t offset;
45{
46  if (elf == NULL)
47    return NULL;
48
49  if (elf->kind != ELF_K_ELF)
50    {
51      __libelf_seterrno (ELF_E_INVALID_HANDLE);
52      return NULL;
53    }
54
55  rwlock_rdlock (elf->lock);
56
57  char *result = NULL;
58  Elf_Scn *strscn;
59
60  /* Find the section in the list.  */
61  Elf_ScnList *runp = (elf->class == ELFCLASS32
62		       || (offsetof (struct Elf, state.elf32.scns)
63			   == offsetof (struct Elf, state.elf64.scns))
64		       ? &elf->state.elf32.scns : &elf->state.elf64.scns);
65  while (1)
66    {
67      if (idx < runp->max)
68	{
69	  if (idx < runp->cnt)
70	    strscn = &runp->data[idx];
71	  else
72	    {
73	      __libelf_seterrno (ELF_E_INVALID_INDEX);
74	      goto out;
75	    }
76	  break;
77	}
78
79      idx -= runp->max;
80
81      runp = runp->next;
82      if (runp == NULL)
83	{
84	  __libelf_seterrno (ELF_E_INVALID_INDEX);
85	  goto out;
86	}
87    }
88
89  if (elf->class == ELFCLASS32)
90    {
91      if (unlikely (strscn->shdr.e32->sh_type != SHT_STRTAB))
92	{
93	  /* This is no string section.  */
94	  __libelf_seterrno (ELF_E_INVALID_SECTION);
95	  goto out;
96	}
97
98      if (unlikely (offset >= strscn->shdr.e32->sh_size))
99	{
100	  /* The given offset is too big, it is beyond this section.  */
101	  __libelf_seterrno (ELF_E_OFFSET_RANGE);
102	  goto out;
103	}
104    }
105  else
106    {
107      if (unlikely (strscn->shdr.e64->sh_type != SHT_STRTAB))
108	{
109	  /* This is no string section.  */
110	  __libelf_seterrno (ELF_E_INVALID_SECTION);
111	  goto out;
112	}
113
114      if (unlikely (offset >= strscn->shdr.e64->sh_size))
115	{
116	  /* The given offset is too big, it is beyond this section.  */
117	  __libelf_seterrno (ELF_E_OFFSET_RANGE);
118	  goto out;
119	}
120    }
121
122  if (strscn->rawdata_base == NULL && ! strscn->data_read)
123    {
124      rwlock_unlock (elf->lock);
125      rwlock_wrlock (elf->lock);
126      if (strscn->rawdata_base == NULL && ! strscn->data_read
127	/* Read the section data.  */
128	  && __libelf_set_rawdata_wrlock (strscn) != 0)
129	goto out;
130    }
131
132  if (likely (strscn->rawdata_base != NULL))
133    // XXX Is this correct if a file is read and then new data is added
134    // XXX to the string section?  Likely needs to check offset against
135    // XXX size of rawdata_base buffer and then iterate over rest of the
136    // XXX list.
137    result = &strscn->rawdata_base[offset];
138  else
139    {
140      /* This is a file which is currently created.  Use the list of
141	 data blocks.  */
142      struct Elf_Data_List *dl = &strscn->data_list;
143      while (dl != NULL)
144	{
145	  if (offset >= (size_t) dl->data.d.d_off
146	      && offset < dl->data.d.d_off + dl->data.d.d_size)
147	    {
148	      result = (char *) dl->data.d.d_buf + (offset - dl->data.d.d_off);
149	      break;
150	    }
151
152	  dl = dl->next;
153	}
154    }
155
156 out:
157  rwlock_unlock (elf->lock);
158
159  return result;
160}
161INTDEF(elf_strptr)
162