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
42static Elf *
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
85Elf *
86elf_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