Branch data Line data Source code
1 : : /* Update data structures for changes and write them out.
2 : : Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc.
3 : : This file is part of elfutils.
4 : : Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
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 <libelf.h>
35 : : #include <unistd.h>
36 : : #include <sys/mman.h>
37 : : #include <sys/stat.h>
38 : :
39 : : #include "libelfP.h"
40 : :
41 : :
42 : : static off_t
43 : 66 : write_file (Elf *elf, off_t size, int change_bo, size_t shnum)
44 : : {
45 : 66 : int class = elf->class;
46 : :
47 : : /* Check the mode bits now, before modification might change them. */
48 : : struct stat st;
49 [ - + ]: 66 : if (unlikely (fstat (elf->fildes, &st) != 0))
50 : : {
51 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
52 : : return -1;
53 : : }
54 : :
55 : : /* Adjust the size in any case. We do this even if we use `write'.
56 : : We cannot do this if this file is in an archive. We also don't
57 : : do it *now* if we are shortening the file since this would
58 : : prevent programs to use the data of the file in generating the
59 : : new file. We truncate the file later in this case. */
60 [ + - ]: 66 : if (elf->parent == NULL
61 [ + + ]: 66 : && (elf->maximum_size == ~((size_t) 0)
62 [ + - ]: 64 : || (size_t) size > elf->maximum_size)
63 [ - + ]: 66 : && unlikely (ftruncate (elf->fildes, size) != 0))
64 : : {
65 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
66 : : return -1;
67 : : }
68 : :
69 : : /* Try to map the file if this isn't done yet. */
70 [ + + ][ + + ]: 66 : if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)
71 : : {
72 : : #if _MUDFLAP
73 : : /* Mudflap doesn't grok that our mmap'd data is ok. */
74 : : #else
75 : 48 : elf->map_address = mmap (NULL, size, PROT_READ | PROT_WRITE,
76 : : MAP_SHARED, elf->fildes, 0);
77 [ - + ]: 48 : if (unlikely (elf->map_address == MAP_FAILED))
78 : 0 : elf->map_address = NULL;
79 : : #endif
80 : : }
81 : :
82 [ + + ]: 66 : if (elf->map_address != NULL)
83 : : {
84 : : /* The file is mmaped. */
85 [ - + ]: 50 : if ((class == ELFCLASS32
86 : 22 : ? __elf32_updatemmap (elf, change_bo, shnum)
87 [ + + ]: 72 : : __elf64_updatemmap (elf, change_bo, shnum)) != 0)
88 : : /* Some problem while writing. */
89 : 0 : size = -1;
90 : : }
91 : : else
92 : : {
93 : : /* The file is not mmaped. */
94 [ - + ]: 16 : if ((class == ELFCLASS32
95 : 11 : ? __elf32_updatefile (elf, change_bo, shnum)
96 [ + + ]: 27 : : __elf64_updatefile (elf, change_bo, shnum)) != 0)
97 : : /* Some problem while writing. */
98 : 0 : size = -1;
99 : : }
100 : :
101 [ + - ]: 66 : if (size != -1
102 [ + - ]: 66 : && elf->parent == NULL
103 [ + + ]: 66 : && elf->maximum_size != ~((size_t) 0)
104 [ - + ]: 64 : && (size_t) size < elf->maximum_size
105 [ # # ]: 0 : && unlikely (ftruncate (elf->fildes, size) != 0))
106 : : {
107 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
108 : 0 : size = -1;
109 : : }
110 : :
111 : : /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID
112 : : mode bits. So make sure we restore them afterwards if they were set.
113 : : This is not atomic if someone else chmod's the file while we operate. */
114 [ + - ]: 66 : if (size != -1
115 [ - + ]: 66 : && unlikely (st.st_mode & (S_ISUID | S_ISGID))
116 : : /* fchmod ignores the bits we cannot change. */
117 [ # # ]: 0 : && unlikely (fchmod (elf->fildes, st.st_mode) != 0))
118 : : {
119 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
120 : 0 : size = -1;
121 : : }
122 : :
123 [ + - ][ + - ]: 66 : if (size != -1 && elf->parent == NULL)
124 : 66 : elf->maximum_size = size;
125 : :
126 : : return size;
127 : : }
128 : :
129 : :
130 : : off_t
131 : 70 : elf_update (elf, cmd)
132 : : Elf *elf;
133 : : Elf_Cmd cmd;
134 : : {
135 : : size_t shnum;
136 : : off_t size;
137 : 70 : int change_bo = 0;
138 : :
139 [ + + ]: 70 : if (cmd != ELF_C_NULL
140 : 70 : && cmd != ELF_C_WRITE
141 [ - + ]: 9 : && unlikely (cmd != ELF_C_WRITE_MMAP))
142 : : {
143 : 0 : __libelf_seterrno (ELF_E_INVALID_CMD);
144 : : return -1;
145 : : }
146 : :
147 [ + - ]: 70 : if (elf == NULL)
148 : : return -1;
149 : :
150 [ - + ]: 70 : if (elf->kind != ELF_K_ELF)
151 : : {
152 : 0 : __libelf_seterrno (ELF_E_INVALID_HANDLE);
153 : : return -1;
154 : : }
155 : :
156 : : rwlock_wrlock (elf->lock);
157 : :
158 : : /* Make sure we have an ELF header. */
159 [ - + ]: 70 : if (elf->state.elf.ehdr == NULL)
160 : : {
161 : 0 : __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
162 : 0 : size = -1;
163 : 0 : goto out;
164 : : }
165 : :
166 : : /* Determine the number of sections. */
167 : 140 : shnum = (elf->state.elf.scns_last->cnt == 0
168 : : ? 0
169 [ + + ]: 70 : : 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt - 1].index);
170 : :
171 : : /* Update the ELF descriptor. First, place the program header. It
172 : : will come right after the ELF header. The count the size of all
173 : : sections and finally place the section table. */
174 : 140 : size = (elf->class == ELFCLASS32
175 : : ? __elf32_updatenull_wrlock (elf, &change_bo, shnum)
176 [ + + ]: 70 : : __elf64_updatenull_wrlock (elf, &change_bo, shnum));
177 [ + - ]: 70 : if (likely (size != -1)
178 : : /* See whether we actually have to write out the data. */
179 [ + + ]: 70 : && (cmd == ELF_C_WRITE || cmd == ELF_C_WRITE_MMAP))
180 : : {
181 [ + + ]: 66 : if (elf->cmd != ELF_C_RDWR
182 : 66 : && elf->cmd != ELF_C_RDWR_MMAP
183 [ + + ]: 62 : && elf->cmd != ELF_C_WRITE
184 [ - + ]: 48 : && unlikely (elf->cmd != ELF_C_WRITE_MMAP))
185 : : {
186 : 0 : __libelf_seterrno (ELF_E_UPDATE_RO);
187 : 0 : size = -1;
188 : : }
189 [ - + ]: 66 : else if (unlikely (elf->fildes == -1))
190 : : {
191 : : /* We closed the file already. */
192 : 0 : __libelf_seterrno (ELF_E_FD_DISABLED);
193 : 0 : size = -1;
194 : : }
195 : : else
196 : 70 : size = write_file (elf, size, change_bo, shnum);
197 : : }
198 : :
199 : : out:
200 : : rwlock_unlock (elf->lock);
201 : :
202 : : return size;
203 : : }
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