1 /* Create descriptor for assembling.
2 Copyright (C) 2002, 2016 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
41 #include <gelf.h>
42 #include "libasmP.h"
43
44
45 static AsmCtx_t *
prepare_text_output(AsmCtx_t * result)46 prepare_text_output (AsmCtx_t *result)
47 {
48 if (result->fd == -1)
49 result->out.file = stdout;
50 else
51 {
52 result->out.file = fdopen (result->fd, "a");
53 if (result->out.file == NULL)
54 {
55 close (result->fd);
56 free (result);
57 result = NULL;
58 }
59 else
60 __fsetlocking (result->out.file, FSETLOCKING_BYCALLER);
61 }
62
63 return result;
64 }
65
66
67 static AsmCtx_t *
prepare_binary_output(AsmCtx_t * result,Ebl * ebl)68 prepare_binary_output (AsmCtx_t *result, Ebl *ebl)
69 {
70 GElf_Ehdr *ehdr;
71 GElf_Ehdr ehdr_mem;
72
73 /* Create the ELF descriptor for the file. */
74 result->out.elf = elf_begin (result->fd, ELF_C_WRITE_MMAP, NULL);
75 if (result->out.elf == NULL)
76 {
77 err_libelf:
78 unlink (result->tmp_fname);
79 close (result->fd);
80 free (result);
81 __libasm_seterrno (ASM_E_LIBELF);
82 return NULL;
83 }
84
85 /* Create the ELF header for the output file. */
86 int class = ebl_get_elfclass (ebl);
87 if (gelf_newehdr (result->out.elf, class) == 0)
88 goto err_libelf;
89
90 ehdr = gelf_getehdr (result->out.elf, &ehdr_mem);
91 /* If this failed we are in trouble. */
92 assert (ehdr != NULL);
93
94 /* We create an object file. */
95 ehdr->e_type = ET_REL;
96 /* Set the ELF version. */
97 ehdr->e_version = EV_CURRENT;
98
99 /* Use the machine, class, and endianness values from the Ebl descriptor. */
100 ehdr->e_machine = ebl_get_elfmachine (ebl);
101 ehdr->e_ident[EI_CLASS] = class;
102 ehdr->e_ident[EI_DATA] = ebl_get_elfdata (ebl);
103
104 memcpy (&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG);
105
106 /* Write the ELF header information back. */
107 (void) gelf_update_ehdr (result->out.elf, ehdr);
108
109 /* No section so far. */
110 result->section_list = NULL;
111
112 /* Initialize the hash table. */
113 asm_symbol_tab_init (&result->symbol_tab, 67);
114 result->nsymbol_tab = 0;
115 /* And the string tables. */
116 result->section_strtab = dwelf_strtab_init (true);
117 result->symbol_strtab = dwelf_strtab_init (true);
118
119 /* We have no section groups so far. */
120 result->groups = NULL;
121 result->ngroups = 0;
122
123 return result;
124 }
125
126
127 AsmCtx_t *
asm_begin(const char * fname,Ebl * ebl,bool textp)128 asm_begin (const char *fname, Ebl *ebl, bool textp)
129 {
130 if (fname == NULL && ! textp)
131 return NULL;
132
133 size_t fname_len = fname != NULL ? strlen (fname) : 0;
134
135 /* Create the file descriptor. We do not generate the output file
136 right away. Instead we create a temporary file in the same
137 directory which, if everything goes alright, will replace a
138 possibly existing file with the given name. */
139 AsmCtx_t *result = malloc (sizeof (AsmCtx_t) + 2 * fname_len + 9);
140 if (result == NULL)
141 return NULL;
142
143 /* Initialize the lock. */
144 rwlock_init (result->lock);
145
146 if (fname != NULL)
147 {
148 /* Create the name of the temporary file. */
149 result->fname = stpcpy (mempcpy (result->tmp_fname, fname, fname_len),
150 ".XXXXXX") + 1;
151 memcpy (result->fname, fname, fname_len + 1);
152
153 /* Create the temporary file. */
154 result->fd = mkstemp (result->tmp_fname);
155 if (result->fd == -1)
156 {
157 int save_errno = errno;
158 free (result);
159 __libasm_seterrno (ASM_E_CANNOT_CREATE);
160 errno = save_errno;
161 return NULL;
162 }
163 }
164 else
165 result->fd = -1;
166
167 /* Initialize the counter for temporary symbols. */
168 result->tempsym_count = 0;
169
170 /* Now we differentiate between textual and binary output. */
171 result->textp = textp;
172 if (textp)
173 result = prepare_text_output (result);
174 else
175 result = prepare_binary_output (result, ebl);
176
177 return result;
178 }
179