Line data Source code
1 : /* Create new section in output file.
2 : Copyright (C) 2002-2011, 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 <libintl.h>
36 : #include <stdlib.h>
37 : #include <string.h>
38 :
39 : #include <libasmP.h>
40 : #include <libelf.h>
41 : #include <system.h>
42 :
43 :
44 : /* Memory for the default pattern. The type uses a flexible array
45 : which does work well with a static initializer. So we play some
46 : dirty tricks here. */
47 : static const struct
48 : {
49 : struct FillPattern pattern;
50 : char zero;
51 : } xdefault_pattern =
52 : {
53 : .pattern =
54 : {
55 : .len = 1
56 : },
57 : .zero = '\0'
58 : };
59 : const struct FillPattern *__libasm_default_pattern = &xdefault_pattern.pattern;
60 :
61 :
62 : static AsmScn_t *
63 0 : text_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags)
64 : {
65 : /* Buffer where we construct the flag string. */
66 : char flagstr[sizeof (GElf_Xword) * 8 + 5];
67 0 : char *wp = flagstr;
68 0 : const char *typestr = "";
69 :
70 : /* Only write out the flag string if this is the first time the
71 : section is selected. Some assemblers cannot cope with the
72 : .section pseudo-op otherwise. */
73 0 : wp = stpcpy (wp, ", \"");
74 :
75 0 : if (flags & SHF_WRITE)
76 0 : *wp++ = 'w';
77 0 : if (flags & SHF_ALLOC)
78 0 : *wp++ = 'a';
79 0 : if (flags & SHF_EXECINSTR)
80 0 : *wp++ = 'x';
81 0 : if (flags & SHF_MERGE)
82 0 : *wp++ = 'M';
83 0 : if (flags & SHF_STRINGS)
84 0 : *wp++ = 'S';
85 0 : if (flags & SHF_LINK_ORDER)
86 0 : *wp++ = 'L';
87 :
88 0 : *wp++ = '"';
89 :
90 0 : if (type == SHT_PROGBITS)
91 : typestr = ",@progbits";
92 0 : else if (type == SHT_NOBITS)
93 0 : typestr = ",@nobits";
94 :
95 : /* Terminate the string. */
96 0 : *wp = '\0';
97 :
98 0 : fprintf (result->ctx->out.file, "\t.section \"%s\"%s%s\n",
99 0 : result->name, flagstr, typestr);
100 :
101 0 : return result;
102 : }
103 :
104 :
105 : static AsmScn_t *
106 176005 : binary_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags,
107 : size_t scnname_len)
108 : {
109 : GElf_Shdr shdr_mem;
110 : GElf_Shdr *shdr;
111 : Elf_Scn *scn;
112 :
113 : /* The initial subsection has the number zero. */
114 176005 : result->subsection_id = 0;
115 :
116 : /* We start at offset zero. */
117 176005 : result->offset = 0;
118 : /* And generic alignment. */
119 176005 : result->max_align = 1;
120 :
121 : /* No output yet. */
122 176005 : result->content = NULL;
123 :
124 : /* Put the default fill pattern in place. */
125 176005 : result->pattern = (struct FillPattern *) __libasm_default_pattern;
126 :
127 : /* There are no subsections so far. */
128 176005 : result->subnext = NULL;
129 :
130 : /* Add the name to the section header string table. */
131 176005 : result->data.main.strent = dwelf_strtab_add_len (result->ctx->section_strtab,
132 176005 : result->name, scnname_len);
133 176005 : assert (result->data.main.strent != NULL);
134 :
135 : /* Create the new ELF section. */
136 176005 : result->data.main.scn = scn = elf_newscn (result->ctx->out.elf);
137 176005 : if (scn == NULL)
138 : {
139 0 : free (result);
140 0 : __libasm_seterrno (ASM_E_LIBELF);
141 0 : return NULL;
142 : }
143 :
144 : /* Not part of a section group (yet). */
145 176005 : result->data.main.next_in_group = NULL;
146 :
147 : /* Remember the flags. */
148 176005 : shdr = gelf_getshdr (scn, &shdr_mem);
149 :
150 176005 : shdr->sh_flags = flags;
151 176005 : result->type = shdr->sh_type = type;
152 :
153 176005 : (void) gelf_update_shdr (scn, shdr);
154 :
155 176005 : return result;
156 : }
157 :
158 :
159 : AsmScn_t *
160 176005 : asm_newscn (AsmCtx_t *ctx, const char *scnname, GElf_Word type,
161 : GElf_Xword flags)
162 : {
163 176005 : size_t scnname_len = strlen (scnname) + 1;
164 : AsmScn_t *result;
165 :
166 : /* If no context is given there might be an earlier error. */
167 176005 : if (ctx == NULL)
168 : return NULL;
169 :
170 : /* Check whether only flags are set which areselectable by the user. */
171 176005 : if (unlikely ((flags & ~(SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR | SHF_MERGE
172 : | SHF_STRINGS | SHF_LINK_ORDER)) != 0)
173 : /* We allow only two section types: data and data without file
174 : representation. */
175 176005 : || (type != SHT_PROGBITS && unlikely (type != SHT_NOBITS)))
176 : {
177 0 : __libasm_seterrno (ASM_E_INVALID);
178 0 : return NULL;
179 : }
180 :
181 : rwlock_wrlock (ctx->lock);
182 :
183 : /* This is a new section. */
184 176005 : result = (AsmScn_t *) malloc (sizeof (AsmScn_t) + scnname_len);
185 176005 : if (result != NULL)
186 : {
187 : /* Add the name. */
188 352010 : memcpy (result->name, scnname, scnname_len);
189 :
190 : /* Add the reference to the context. */
191 176005 : result->ctx = ctx;
192 :
193 : /* Perform operations according to output mode. */
194 352010 : result = (unlikely (ctx->textp)
195 : ? text_newscn (result, type, flags)
196 176005 : : binary_newscn (result, type, flags, scnname_len));
197 :
198 : /* If everything went well finally add the new section to the hash
199 : table. */
200 176005 : if (result != NULL)
201 : {
202 176005 : result->allnext = ctx->section_list;
203 176005 : ctx->section_list = result;
204 : }
205 : }
206 :
207 : rwlock_unlock (ctx->lock);
208 :
209 : return result;
210 : }
211 : INTDEF(asm_newscn)
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