elftc_copyfile.c revision 276371 
1/*-
2 * Copyright (c) 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 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/types.h>
28#include <sys/stat.h>
29
30#include <stdlib.h>
31#include <unistd.h>
32
33#include "libelftc.h"
34#include "_libelftc.h"
35
36#if	ELFTC_HAVE_MMAP
37#include <sys/mman.h>
38#endif
39
40ELFTC_VCSID("$Id: elftc_copyfile.c 2981 2014-02-01 02:41:13Z jkoshy $");
41
42/*
43 * Copy the contents referenced by 'ifd' to 'ofd'.  Returns 0 on
44 * success and -1 on error.
45 */
46
47int
48elftc_copyfile(int ifd, int ofd)
49{
50	int buf_mmapped;
51	struct stat sb;
52	char *b, *buf;
53	ssize_t nw;
54	size_t n;
55
56	/* Determine the input file's size. */
57	if (fstat(ifd, &sb) < 0)
58		return (-1);
59
60	/* Skip files without content. */
61	if (sb.st_size == 0)
62		return (0);
63
64	buf = NULL;
65	buf_mmapped = 0;
66
67#if	ELFTC_HAVE_MMAP
68	/*
69	 * Prefer mmap() if it is available.
70	 */
71	buf = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, ifd, (off_t) 0);
72	if (buf != MAP_FAILED)
73		buf_mmapped = 1;
74	else
75		buf = NULL;
76#endif
77
78	/*
79	 * If mmap() is not available, or if the mmap() operation
80	 * failed, allocate a buffer, and read in input data.
81	 */
82	if (buf_mmapped == false) {
83		if ((buf = malloc(sb.st_size)) == NULL)
84			return (-1);
85		if (read(ifd, buf, sb.st_size) != sb.st_size) {
86			free(buf);
87			return (-1);
88		}
89	}
90
91	/*
92	 * Write data to the output file descriptor.
93	 */
94	for (n = sb.st_size, b = buf; n > 0; n -= nw, b += nw)
95		if ((nw = write(ofd, b, n)) <= 0)
96			break;
97
98	/* Release the input buffer. */
99#if	ELFTC_HAVE_MMAP
100	if (buf_mmapped && munmap(buf, sb.st_size) < 0)
101		return (-1);
102#endif
103
104	if (!buf_mmapped)
105		free(buf);
106
107	return (n > 0 ? -1 : 0);
108}
109
110