1/* Create new section in output file.
2   Copyright (C) 2002-2011 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2002.
5
6   Red Hat elfutils is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by the
8   Free Software Foundation; version 2 of the License.
9
10   Red Hat elfutils is distributed in the hope that it will be useful, but
11   WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   General Public License for more details.
14
15   You should have received a copy of the GNU General Public License along
16   with Red Hat elfutils; if not, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19   Red Hat elfutils is an included package of the Open Invention Network.
20   An included package of the Open Invention Network is a package for which
21   Open Invention Network licensees cross-license their patents.  No patent
22   license is granted, either expressly or impliedly, by designation as an
23   included package.  Should you wish to participate in the Open Invention
24   Network licensing program, please visit www.openinventionnetwork.com
25   <http://www.openinventionnetwork.com>.  */
26
27#ifdef HAVE_CONFIG_H
28# include <config.h>
29#endif
30
31#include <assert.h>
32#include <error.h>
33#include <libintl.h>
34#include <stdlib.h>
35#include <string.h>
36
37#include <libasmP.h>
38#include <libelf.h>
39#include <system.h>
40
41
42/* Memory for the default pattern.  The type uses a flexible array
43   which does work well with a static initializer.  So we play some
44   dirty tricks here.  */
45static const struct
46{
47  struct FillPattern pattern;
48  char zero;
49} xdefault_pattern =
50  {
51    .pattern =
52    {
53      .len = 1
54    },
55    .zero = '\0'
56  };
57const struct FillPattern *__libasm_default_pattern = &xdefault_pattern.pattern;
58
59
60static AsmScn_t *
61text_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags)
62{
63  /* Buffer where we construct the flag string.  */
64  char flagstr[sizeof (GElf_Xword) * 8 + 5];
65  char *wp = flagstr;
66  const char *typestr = "";
67
68  /* Only write out the flag string if this is the first time the
69     section is selected.  Some assemblers cannot cope with the
70     .section pseudo-op otherwise.  */
71  wp = stpcpy (wp, ", \"");
72
73  if (flags & SHF_WRITE)
74    *wp++ = 'w';
75  if (flags & SHF_ALLOC)
76    *wp++ = 'a';
77  if (flags & SHF_EXECINSTR)
78    *wp++ = 'x';
79  if (flags & SHF_MERGE)
80    *wp++ = 'M';
81  if (flags & SHF_STRINGS)
82    *wp++ = 'S';
83  if (flags & SHF_LINK_ORDER)
84    *wp++ = 'L';
85
86  *wp++ = '"';
87
88  if (type == SHT_PROGBITS)
89    typestr = ",@progbits";
90  else if (type == SHT_NOBITS)
91    typestr = ",@nobits";
92
93  /* Terminate the string.  */
94  *wp = '\0';
95
96  fprintf (result->ctx->out.file, "\t.section \"%s\"%s%s\n",
97	   result->name, flagstr, typestr);
98
99  return result;
100}
101
102
103static AsmScn_t *
104binary_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags,
105	       size_t scnname_len)
106{
107  GElf_Shdr shdr_mem;
108  GElf_Shdr *shdr;
109  Elf_Scn *scn;
110
111  /* The initial subsection has the number zero.  */
112  result->subsection_id = 0;
113
114  /* We start at offset zero.  */
115  result->offset = 0;
116  /* And generic alignment.  */
117  result->max_align = 1;
118
119  /* No output yet.  */
120  result->content = NULL;
121
122  /* Put the default fill pattern in place.  */
123  result->pattern = (struct FillPattern *) __libasm_default_pattern;
124
125  /* There are no subsections so far.  */
126  result->subnext = NULL;
127
128  /* Add the name to the section header string table.  */
129  result->data.main.strent = ebl_strtabadd (result->ctx->section_strtab,
130					    result->name, scnname_len);
131  assert (result->data.main.strent != NULL);
132
133  /* Create the new ELF section.  */
134  result->data.main.scn = scn = elf_newscn (result->ctx->out.elf);
135  if (scn == NULL)
136    {
137      free (result);
138      __libasm_seterrno (ASM_E_LIBELF);
139      return NULL;
140    }
141
142  /* Not part of a section group (yet).  */
143  result->data.main.next_in_group = NULL;
144
145  /* Remember the flags.  */
146  shdr = gelf_getshdr (scn, &shdr_mem);
147
148  shdr->sh_flags = flags;
149  result->type = shdr->sh_type = type;
150
151  (void) gelf_update_shdr (scn, shdr);
152
153  return result;
154}
155
156
157AsmScn_t *
158asm_newscn (ctx, scnname, type, flags)
159     AsmCtx_t *ctx;
160     const char *scnname;
161     GElf_Word type;
162     GElf_Xword flags;
163{
164  size_t scnname_len = strlen (scnname) + 1;
165  AsmScn_t *result;
166
167  /* If no context is given there might be an earlier error.  */
168  if (ctx == NULL)
169    return NULL;
170
171  /* Check whether only flags are set which areselectable by the user.  */
172  if (unlikely ((flags & ~(SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR | SHF_MERGE
173			   | SHF_STRINGS | SHF_LINK_ORDER)) != 0)
174      /* We allow only two section types: data and data without file
175	 representation.  */
176      || (type != SHT_PROGBITS && unlikely (type != SHT_NOBITS)))
177    {
178      __libasm_seterrno (ASM_E_INVALID);
179      return NULL;
180    }
181
182  rwlock_wrlock (ctx->lock);
183
184  /* This is a new section.  */
185  result = (AsmScn_t *) malloc (sizeof (AsmScn_t) + scnname_len);
186  if (result != NULL)
187    {
188      /* Add the name.  */
189      memcpy (result->name, scnname, scnname_len);
190
191      /* Add the reference to the context.  */
192      result->ctx = ctx;
193
194      /* Perform operations according to output mode.  */
195      result = (unlikely (ctx->textp)
196		? text_newscn (result, type, flags)
197		: binary_newscn (result, type, flags, scnname_len));
198
199      /* If everything went well finally add the new section to the hash
200	 table.  */
201      if (result != NULL)
202	{
203	  result->allnext = ctx->section_list;
204	  ctx->section_list = result;
205	}
206    }
207
208  rwlock_unlock (ctx->lock);
209
210  return result;
211}
212INTDEF(asm_newscn)
213