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
28#include <sys/types.h>
29#include <errno.h>
30#include <sys/mman.h>
31#include <sys/stat.h>
32
33#include <ar.h>
34#include <ctype.h>
35#include "libelf.h"
36
37#include "_libelf.h"
38
39static Elf *
40_libelf_open_object(int fd, Elf_Cmd c)
41{
42        Elf *e;
43        void *m;
44        struct stat sb;
45
46        /*
47         * 'Raw' files are always mapped with 'PROT_READ'.  At
48         * elf_update(3) time for files opened with ELF_C_RDWR the
49         * mapping is unmapped, file data is written to using write(2)
50         * and then the raw data is immediately mapped back in.
51         */
52        if (fstat(fd, &sb) < 0) {
53                LIBELF_SET_ERROR(IO, errno);
54                return (NULL);
55        }
56
57        m = NULL;
58        if ((m = mmap(NULL, (size_t) sb.st_size, PROT_READ, MAP_PRIVATE, fd,
59            (off_t) 0)) == MAP_FAILED) {
60                LIBELF_SET_ERROR(IO, errno);
61                return (NULL);
62        }
63
64        if ((e = elf_memory(m, (size_t) sb.st_size)) == NULL) {
65                (void) munmap(m, (size_t) sb.st_size);
66                return (NULL);
67        }
68
69        e->e_flags |= LIBELF_F_MMAP;
70        e->e_fd = fd;
71        e->e_cmd = c;
72
73        if (c == ELF_C_RDWR && e->e_kind == ELF_K_AR) {
74                (void) elf_end(e);
75                LIBELF_SET_ERROR(ARGUMENT, 0);
76                return (NULL);
77        }
78
79        return (e);
80}
81
82Elf *
83elf_begin(int fd, Elf_Cmd c, Elf *a)
84{
85        Elf *e;
86
87        e = NULL;
88
89        if (LIBELF_PRIVATE(version) == EV_NONE) {
90                LIBELF_SET_ERROR(SEQUENCE, 0);
91                return (NULL);
92        }
93
94        switch (c) {
95        case ELF_C_NULL:
96                return (NULL);
97
98        case ELF_C_WRITE:
99
100                if (a != NULL) { /* not allowed for ar(1) archives. */
101                        LIBELF_SET_ERROR(ARGUMENT, 0);
102                        return (NULL);
103                }
104
105                /*
106                 * Check writeability of `fd' immediately and fail if
107                 * not writeable.
108                 */
109                if (ftruncate(fd, (off_t) 0) < 0) {
110                        LIBELF_SET_ERROR(IO, errno);
111                        return (NULL);
112                }
113
114                if ((e = _libelf_allocate_elf()) != NULL) {
115                        _libelf_init_elf(e, ELF_K_ELF);
116                        e->e_byteorder = LIBELF_PRIVATE(byteorder);
117                        e->e_fd = fd;
118                        e->e_cmd = c;
119                }
120                return (e);
121
122        case ELF_C_RDWR:
123                if (a != NULL) { /* not allowed for ar(1) archives. */
124                        LIBELF_SET_ERROR(ARGUMENT, 0);
125                        return (NULL);
126                }
127                /*FALLTHROUGH*/
128        case ELF_C_READ:
129                /*
130                 * Descriptor `a' could be for a regular ELF file, or
131                 * for an ar(1) archive.
132                 */
133                if (a && (a->e_fd != fd || c != a->e_cmd)) {
134                        LIBELF_SET_ERROR(ARGUMENT, 0);
135                        return (NULL);
136                }
137
138                break;
139
140        default:
141                LIBELF_SET_ERROR(ARGUMENT, 0);
142                return (NULL);
143
144        }
145
146        if (a == NULL)
147                e = _libelf_open_object(fd, c);
148        else if (a->e_kind == ELF_K_AR)
149                e = _libelf_ar_open_member(fd, c, a);
150        else
151                (e = a)->e_activations++;
152
153        return (e);
154}
155