1 /*-
2 * Copyright (c) 2006,2008-2011 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 <libelf.h>
28
29 #include "_libelf.h"
30
31 ELFTC_VCSID("$Id: elf_begin.c 2364 2011-12-28 17:55:25Z jkoshy $");
32
33 Elf *
elf_begin(int fd,Elf_Cmd c,Elf * a)34 elf_begin(int fd, Elf_Cmd c, Elf *a)
35 {
36 Elf *e;
37
38 e = NULL;
39
40 if (LIBELF_PRIVATE(version) == EV_NONE) {
41 LIBELF_SET_ERROR(SEQUENCE, 0);
42 return (NULL);
43 }
44
45 switch (c) {
46 case ELF_C_NULL:
47 return (NULL);
48
49 case ELF_C_WRITE:
50 /*
51 * The ELF_C_WRITE command is required to ignore the
52 * descriptor passed in.
53 */
54 a = NULL;
55 break;
56
57 case ELF_C_RDWR:
58 if (a != NULL) { /* not allowed for ar(1) archives. */
59 LIBELF_SET_ERROR(ARGUMENT, 0);
60 return (NULL);
61 }
62 /*FALLTHROUGH*/
63 case ELF_C_READ:
64 /*
65 * Descriptor `a' could be for a regular ELF file, or
66 * for an ar(1) archive. If descriptor `a' was opened
67 * using a valid file descriptor, we need to check if
68 * the passed in `fd' value matches the original one.
69 */
70 if (a &&
71 ((a->e_fd != -1 && a->e_fd != fd) || c != a->e_cmd)) {
72 LIBELF_SET_ERROR(ARGUMENT, 0);
73 return (NULL);
74 }
75 break;
76
77 default:
78 LIBELF_SET_ERROR(ARGUMENT, 0);
79 return (NULL);
80
81 }
82
83 if (a == NULL)
84 e = _libelf_open_object(fd, c, 1);
85 else if (a->e_kind == ELF_K_AR)
86 e = _libelf_ar_open_member(a->e_fd, c, a);
87 else
88 (e = a)->e_activations++;
89
90 return (e);
91 }
92