1/* Create descriptor for assembling.
2   Copyright (C) 2002 Red Hat, Inc.
3   This file is part of elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <assert.h>
35#include <errno.h>
36#include <stdio.h>
37#include <stdio_ext.h>
38#include <stdlib.h>
39#include <string.h>
40#include <unistd.h>
41
42#include <gelf.h>
43#include "libasmP.h"
44#include <system.h>
45
46
47static AsmCtx_t *
48prepare_text_output (AsmCtx_t *result)
49{
50  if (result->fd == -1)
51    result->out.file = stdout;
52  else
53    {
54      result->out.file = fdopen (result->fd, "a");
55      if (result->out.file == NULL)
56	{
57	  close (result->fd);
58	  free (result);
59	  result = NULL;
60	}
61
62      __fsetlocking (result->out.file, FSETLOCKING_BYCALLER);
63    }
64
65  return result;
66}
67
68
69static AsmCtx_t *
70prepare_binary_output (AsmCtx_t *result, Ebl *ebl)
71{
72  GElf_Ehdr *ehdr;
73  GElf_Ehdr ehdr_mem;
74
75  /* Create the ELF descriptor for the file.  */
76  result->out.elf = elf_begin (result->fd, ELF_C_WRITE_MMAP, NULL);
77  if (result->out.elf == NULL)
78    {
79    err_libelf:
80      unlink (result->tmp_fname);
81      close (result->fd);
82      free (result);
83      __libasm_seterrno (ASM_E_LIBELF);
84      return NULL;
85    }
86
87  /* Create the ELF header for the output file.  */
88  int class = ebl_get_elfclass (ebl);
89  if (gelf_newehdr (result->out.elf, class) == 0)
90    goto err_libelf;
91
92  ehdr = gelf_getehdr (result->out.elf, &ehdr_mem);
93  /* If this failed we are in trouble.  */
94  assert (ehdr != NULL);
95
96  /* We create an object file.  */
97  ehdr->e_type = ET_REL;
98  /* Set the ELF version.  */
99  ehdr->e_version = EV_CURRENT;
100
101  /* Use the machine, class, and endianess values from the Ebl descriptor.  */
102  ehdr->e_machine = ebl_get_elfmachine (ebl);
103  ehdr->e_ident[EI_CLASS] = class;
104  ehdr->e_ident[EI_DATA] = ebl_get_elfdata (ebl);
105
106  memcpy (&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG);
107
108  /* Write the ELF header information back.  */
109  (void) gelf_update_ehdr (result->out.elf, ehdr);
110
111  /* No section so far.  */
112  result->section_list = NULL;
113
114  /* Initialize the hash table.  */
115  asm_symbol_tab_init (&result->symbol_tab, 67);
116  result->nsymbol_tab = 0;
117  /* And the string tables.  */
118  result->section_strtab = ebl_strtabinit (true);
119  result->symbol_strtab = ebl_strtabinit (true);
120
121  /* We have no section groups so far.  */
122  result->groups = NULL;
123  result->ngroups = 0;
124
125  return result;
126}
127
128
129AsmCtx_t *
130asm_begin (const char *fname, Ebl *ebl, bool textp)
131{
132  if (fname == NULL && ! textp)
133    return NULL;
134
135  size_t fname_len = fname != NULL ? strlen (fname) : 0;
136
137  /* Create the file descriptor.  We do not generate the output file
138     right away.  Instead we create a temporary file in the same
139     directory which, if everything goes alright, will replace a
140     possibly existing file with the given name.  */
141  AsmCtx_t *result
142    = (AsmCtx_t *) malloc (sizeof (AsmCtx_t) + 2 * fname_len + 9);
143  if (result == NULL)
144    return NULL;
145
146      /* Initialize the lock.  */
147      rwlock_init (result->lock);
148
149  if (fname != NULL)
150    {
151      /* Create the name of the temporary file.  */
152      result->fname = stpcpy (mempcpy (result->tmp_fname, fname, fname_len),
153			      ".XXXXXX") + 1;
154      memcpy (result->fname, fname, fname_len + 1);
155
156      /* Create the temporary file.  */
157      result->fd = mkstemp (result->tmp_fname);
158      if (result->fd == -1)
159	{
160	  int save_errno = errno;
161	  free (result);
162	  __libasm_seterrno (ASM_E_CANNOT_CREATE);
163	  errno = save_errno;
164	  return NULL;
165	}
166    }
167  else
168    result->fd = -1;
169
170  /* Initialize the counter for temporary symbols.  */
171  result->tempsym_count = 0;
172
173  /* Now we differentiate between textual and binary output.   */
174  result->textp = textp;
175  if (textp)
176    result = prepare_text_output (result);
177  else
178    result = prepare_binary_output (result, ebl);
179
180  return result;
181}
182