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: src/lib/libarchive/archive_read_open_fd.c,v 1.13 2007/06/26 03:06:48 kientzle Exp $"); 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_STDLIB_H 36 #include <stdlib.h> 37 #endif 38 #ifdef HAVE_STRING_H 39 #include <string.h> 40 #endif 41 #ifdef HAVE_UNISTD_H 42 #include <unistd.h> 43 #endif 44 45 #include "archive.h" 46 47 struct read_fd_data { 48 int fd; 49 size_t block_size; 50 char can_skip; 51 void *buffer; 52 }; 53 54 static int file_close(struct archive *, void *); 55 static ssize_t file_read(struct archive *, void *, const void **buff); 56 #if ARCHIVE_API_VERSION < 2 57 static ssize_t file_skip(struct archive *, void *, size_t request); 58 #else 59 static off_t file_skip(struct archive *, void *, off_t request); 60 #endif 61 62 int 63 archive_read_open_fd(struct archive *a, int fd, size_t block_size) 64 { 65 struct stat st; 66 struct read_fd_data *mine; 67 void *b; 68 69 if (fstat(fd, &st) != 0) { 70 archive_set_error(a, errno, "Can't stat fd %d", fd); 71 return (ARCHIVE_FATAL); 72 } 73 74 mine = (struct read_fd_data *)malloc(sizeof(*mine)); 75 b = malloc(block_size); 76 if (mine == NULL || b == NULL) { 77 archive_set_error(a, ENOMEM, "No memory"); 78 free(mine); 79 free(b); 80 return (ARCHIVE_FATAL); 81 } 82 mine->block_size = block_size; 83 mine->buffer = b; 84 mine->fd = fd; 85 /* 86 * Skip support is a performance optimization for anything 87 * that supports lseek(). On FreeBSD, only regular files and 88 * raw disk devices support lseek() and there's no portable 89 * way to determine if a device is a raw disk device, so we 90 * only enable this optimization for regular files. 91 */ 92 if (S_ISREG(st.st_mode)) { 93 archive_read_extract_set_skip_file(a, st.st_dev, st.st_ino); 94 mine->can_skip = 1; 95 } else 96 mine->can_skip = 0; 97 98 return (archive_read_open2(a, mine, 99 NULL, file_read, file_skip, file_close)); 100 } 101 102 static ssize_t 103 file_read(struct archive *a, void *client_data, const void **buff) 104 { 105 struct read_fd_data *mine = (struct read_fd_data *)client_data; 106 ssize_t bytes_read; 107 108 *buff = mine->buffer; 109 bytes_read = read(mine->fd, mine->buffer, mine->block_size); 110 if (bytes_read < 0) { 111 archive_set_error(a, errno, "Error reading fd %d", mine->fd); 112 } 113 return (bytes_read); 114 } 115 116 #if ARCHIVE_API_VERSION < 2 117 static ssize_t 118 file_skip(struct archive *a, void *client_data, size_t request) 119 #else 120 static off_t 121 file_skip(struct archive *a, void *client_data, off_t request) 122 #endif 123 { 124 struct read_fd_data *mine = (struct read_fd_data *)client_data; 125 off_t old_offset, new_offset; 126 127 if (!mine->can_skip) 128 return (0); 129 130 /* Reduce request to the next smallest multiple of block_size */ 131 request = (request / mine->block_size) * mine->block_size; 132 if (request == 0) 133 return (0); 134 135 /* 136 * Hurray for lazy evaluation: if the first lseek fails, the second 137 * one will not be executed. 138 */ 139 if (((old_offset = lseek(mine->fd, 0, SEEK_CUR)) < 0) || 140 ((new_offset = lseek(mine->fd, request, SEEK_CUR)) < 0)) 141 { 142 /* If seek failed once, it will probably fail again. */ 143 mine->can_skip = 0; 144 145 if (errno == ESPIPE) 146 { 147 /* 148 * Failure to lseek() can be caused by the file 149 * descriptor pointing to a pipe, socket or FIFO. 150 * Return 0 here, so the compression layer will use 151 * read()s instead to advance the file descriptor. 152 * It's slower of course, but works as well. 153 */ 154 return (0); 155 } 156 /* 157 * There's been an error other than ESPIPE. This is most 158 * likely caused by a programmer error (too large request) 159 * or a corrupted archive file. 160 */ 161 archive_set_error(a, errno, "Error seeking"); 162 return (-1); 163 } 164 return (new_offset - old_offset); 165 } 166 167 static int 168 file_close(struct archive *a, void *client_data) 169 { 170 struct read_fd_data *mine = (struct read_fd_data *)client_data; 171 172 (void)a; /* UNUSED */ 173 free(mine->buffer); 174 free(mine); 175 return (ARCHIVE_OK); 176 } 177