1 /*-
2 * Copyright (c) 2006 Joseph Koshy
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include <sys/types.h>
31 #include <sys/errno.h>
32 #include <sys/mman.h>
33 #include <sys/stat.h>
34
35 #include <ar.h>
36 #include <ctype.h>
37 #include <libelf.h>
38 #include <unistd.h>
39
40 #include "_libelf.h"
41
42 static Elf *
_libelf_open_object(int fd,Elf_Cmd c)43 _libelf_open_object(int fd, Elf_Cmd c)
44 {
45 Elf *e;
46 void *m;
47 struct stat sb;
48
49 /*
50 * 'Raw' files are always mapped with 'PROT_READ'. At
51 * elf_update(3) time for files opened with ELF_C_RDWR the
52 * mapping is unmapped, file data is written to using write(2)
53 * and then the raw data is immediately mapped back in.
54 */
55 if (fstat(fd, &sb) < 0) {
56 LIBELF_SET_ERROR(IO, errno);
57 return (NULL);
58 }
59
60 m = NULL;
61 if ((m = mmap(NULL, (size_t) sb.st_size, PROT_READ, MAP_PRIVATE, fd,
62 (off_t) 0)) == MAP_FAILED) {
63 LIBELF_SET_ERROR(IO, errno);
64 return (NULL);
65 }
66
67 if ((e = elf_memory(m, (size_t) sb.st_size)) == NULL) {
68 (void) munmap(m, (size_t) sb.st_size);
69 return (NULL);
70 }
71
72 e->e_flags |= LIBELF_F_MMAP;
73 e->e_fd = fd;
74 e->e_cmd = c;
75
76 if (c == ELF_C_RDWR && e->e_kind == ELF_K_AR) {
77 (void) elf_end(e);
78 LIBELF_SET_ERROR(ARGUMENT, 0);
79 return (NULL);
80 }
81
82 return (e);
83 }
84
85 Elf *
elf_begin(int fd,Elf_Cmd c,Elf * a)86 elf_begin(int fd, Elf_Cmd c, Elf *a)
87 {
88 Elf *e;
89
90 e = NULL;
91
92 if (LIBELF_PRIVATE(version) == EV_NONE) {
93 LIBELF_SET_ERROR(SEQUENCE, 0);
94 return (NULL);
95 }
96
97 switch (c) {
98 case ELF_C_NULL:
99 return (NULL);
100
101 case ELF_C_WRITE:
102
103 if (a != NULL) { /* not allowed for ar(1) archives. */
104 LIBELF_SET_ERROR(ARGUMENT, 0);
105 return (NULL);
106 }
107
108 /*
109 * Check writeability of `fd' immediately and fail if
110 * not writeable.
111 */
112 if (ftruncate(fd, (off_t) 0) < 0) {
113 LIBELF_SET_ERROR(IO, errno);
114 return (NULL);
115 }
116
117 if ((e = _libelf_allocate_elf()) != NULL) {
118 _libelf_init_elf(e, ELF_K_ELF);
119 e->e_byteorder = LIBELF_PRIVATE(byteorder);
120 e->e_fd = fd;
121 e->e_cmd = c;
122 }
123 return (e);
124
125 case ELF_C_RDWR:
126 if (a != NULL) { /* not allowed for ar(1) archives. */
127 LIBELF_SET_ERROR(ARGUMENT, 0);
128 return (NULL);
129 }
130 /*FALLTHROUGH*/
131 case ELF_C_READ:
132 /*
133 * Descriptor `a' could be for a regular ELF file, or
134 * for an ar(1) archive. If descriptor `a' was opened
135 * using a valid file descriptor, we need to check if
136 * the passed in `fd' value matches the original one.
137 */
138 if (a &&
139 ((a->e_fd != -1 && a->e_fd != fd) || c != a->e_cmd)) {
140 LIBELF_SET_ERROR(ARGUMENT, 0);
141 return (NULL);
142 }
143 break;
144
145 default:
146 LIBELF_SET_ERROR(ARGUMENT, 0);
147 return (NULL);
148
149 }
150
151 if (a == NULL)
152 e = _libelf_open_object(fd, c);
153 else if (a->e_kind == ELF_K_AR)
154 e = _libelf_ar_open_member(a->e_fd, c, a);
155 else
156 (e = a)->e_activations++;
157
158 return (e);
159 }
160