archive_read_open_fd.c revision 228753 
1/*-
2 * Copyright (c) 2003-2007 Tim Kientzle
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(S) ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "archive_platform.h"
27__FBSDID("$FreeBSD: head/lib/libarchive/archive_read_open_fd.c 201103 2009-12-28 03:13:49Z kientzle $");
28
29#ifdef HAVE_SYS_STAT_H
30#include <sys/stat.h>
31#endif
32#ifdef HAVE_ERRNO_H
33#include <errno.h>
34#endif
35#ifdef HAVE_FCNTL_H
36#include <fcntl.h>
37#endif
38#ifdef HAVE_IO_H
39#include <io.h>
40#endif
41#ifdef HAVE_STDLIB_H
42#include <stdlib.h>
43#endif
44#ifdef HAVE_STRING_H
45#include <string.h>
46#endif
47#ifdef HAVE_UNISTD_H
48#include <unistd.h>
49#endif
50
51#include "archive.h"
52
53struct read_fd_data {
54	int	 fd;
55	size_t	 block_size;
56	char	 can_skip;
57	void	*buffer;
58};
59
60static int	file_close(struct archive *, void *);
61static ssize_t	file_read(struct archive *, void *, const void **buff);
62#if ARCHIVE_API_VERSION < 2
63static ssize_t	file_skip(struct archive *, void *, size_t request);
64#else
65static off_t	file_skip(struct archive *, void *, off_t request);
66#endif
67
68int
69archive_read_open_fd(struct archive *a, int fd, size_t block_size)
70{
71	struct stat st;
72	struct read_fd_data *mine;
73	void *b;
74
75	archive_clear_error(a);
76	if (fstat(fd, &st) != 0) {
77		archive_set_error(a, errno, "Can't stat fd %d", fd);
78		return (ARCHIVE_FATAL);
79	}
80
81	mine = (struct read_fd_data *)malloc(sizeof(*mine));
82	b = malloc(block_size);
83	if (mine == NULL || b == NULL) {
84		archive_set_error(a, ENOMEM, "No memory");
85		free(mine);
86		free(b);
87		return (ARCHIVE_FATAL);
88	}
89	mine->block_size = block_size;
90	mine->buffer = b;
91	mine->fd = fd;
92	/*
93	 * Skip support is a performance optimization for anything
94	 * that supports lseek().  On FreeBSD, only regular files and
95	 * raw disk devices support lseek() and there's no portable
96	 * way to determine if a device is a raw disk device, so we
97	 * only enable this optimization for regular files.
98	 */
99	if (S_ISREG(st.st_mode)) {
100		archive_read_extract_set_skip_file(a, st.st_dev, st.st_ino);
101		mine->can_skip = 1;
102	} else
103		mine->can_skip = 0;
104#if defined(__CYGWIN__) || defined(_WIN32)
105	setmode(mine->fd, O_BINARY);
106#endif
107
108	return (archive_read_open2(a, mine,
109		NULL, file_read, file_skip, file_close));
110}
111
112static ssize_t
113file_read(struct archive *a, void *client_data, const void **buff)
114{
115	struct read_fd_data *mine = (struct read_fd_data *)client_data;
116	ssize_t bytes_read;
117
118	*buff = mine->buffer;
119	for (;;) {
120		bytes_read = read(mine->fd, mine->buffer, mine->block_size);
121		if (bytes_read < 0) {
122			if (errno == EINTR)
123				continue;
124			archive_set_error(a, errno, "Error reading fd %d", mine->fd);
125		}
126		return (bytes_read);
127	}
128}
129
130#if ARCHIVE_API_VERSION < 2
131static ssize_t
132file_skip(struct archive *a, void *client_data, size_t request)
133#else
134static off_t
135file_skip(struct archive *a, void *client_data, off_t request)
136#endif
137{
138	struct read_fd_data *mine = (struct read_fd_data *)client_data;
139	off_t old_offset, new_offset;
140
141	if (!mine->can_skip)
142		return (0);
143
144	/* Reduce request to the next smallest multiple of block_size */
145	request = (request / mine->block_size) * mine->block_size;
146	if (request == 0)
147		return (0);
148
149	/*
150	 * Hurray for lazy evaluation: if the first lseek fails, the second
151	 * one will not be executed.
152	 */
153	if (((old_offset = lseek(mine->fd, 0, SEEK_CUR)) < 0) ||
154	    ((new_offset = lseek(mine->fd, request, SEEK_CUR)) < 0))
155	{
156		/* If seek failed once, it will probably fail again. */
157		mine->can_skip = 0;
158
159		if (errno == ESPIPE)
160		{
161			/*
162			 * Failure to lseek() can be caused by the file
163			 * descriptor pointing to a pipe, socket or FIFO.
164			 * Return 0 here, so the compression layer will use
165			 * read()s instead to advance the file descriptor.
166			 * It's slower of course, but works as well.
167			 */
168			return (0);
169		}
170		/*
171		 * There's been an error other than ESPIPE. This is most
172		 * likely caused by a programmer error (too large request)
173		 * or a corrupted archive file.
174		 */
175		archive_set_error(a, errno, "Error seeking");
176		return (-1);
177	}
178	return (new_offset - old_offset);
179}
180
181static int
182file_close(struct archive *a, void *client_data)
183{
184	struct read_fd_data *mine = (struct read_fd_data *)client_data;
185
186	(void)a; /* UNUSED */
187	free(mine->buffer);
188	free(mine);
189	return (ARCHIVE_OK);
190}
191