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 #include <unistd.h>
41
42 #include <gelf.h>
43 #include "libasmP.h"
44 #include <system.h>
45
46
47 static AsmCtx_t *
prepare_text_output(AsmCtx_t * result)48 prepare_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 else
62 __fsetlocking (result->out.file, FSETLOCKING_BYCALLER);
63 }
64
65 return result;
66 }
67
68
69 static AsmCtx_t *
prepare_binary_output(AsmCtx_t * result,Ebl * ebl)70 prepare_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 endianness 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 = dwelf_strtab_init (true);
119 result->symbol_strtab = dwelf_strtab_init (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
129 AsmCtx_t *
asm_begin(const char * fname,Ebl * ebl,bool textp)130 asm_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 = malloc (sizeof (AsmCtx_t) + 2 * fname_len + 9);
142 if (result == NULL)
143 return NULL;
144
145 /* Initialize the lock. */
146 rwlock_init (result->lock);
147
148 if (fname != NULL)
149 {
150 /* Create the name of the temporary file. */
151 result->fname = stpcpy (mempcpy (result->tmp_fname, fname, fname_len),
152 ".XXXXXX") + 1;
153 memcpy (result->fname, fname, fname_len + 1);
154
155 /* Create the temporary file. */
156 result->fd = mkstemp (result->tmp_fname);
157 if (result->fd == -1)
158 {
159 int save_errno = errno;
160 free (result);
161 __libasm_seterrno (ASM_E_CANNOT_CREATE);
162 errno = save_errno;
163 return NULL;
164 }
165 }
166 else
167 result->fd = -1;
168
169 /* Initialize the counter for temporary symbols. */
170 result->tempsym_count = 0;
171
172 /* Now we differentiate between textual and binary output. */
173 result->textp = textp;
174 if (textp)
175 result = prepare_text_output (result);
176 else
177 result = prepare_binary_output (result, ebl);
178
179 return result;
180 }
181