contrib/libarchive-2/libarchive/archive_read_open_fd.c

   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 int      file_open(struct archive *, void *);
  56 static ssize_t  file_read(struct archive *, void *, const void **buff);
  57 #if ARCHIVE_API_VERSION < 2
  58 static ssize_t  file_skip(struct archive *, void *, size_t request);
  59 #else
  60 static off_t    file_skip(struct archive *, void *, off_t request);
  61 #endif
  62
  63 int
  64 archive_read_open_fd(struct archive *a, int fd, size_t block_size)
  65 {
  66         struct read_fd_data *mine;
  67
  68         mine = (struct read_fd_data *)malloc(sizeof(*mine));
  69         if (mine == NULL) {
  70                 archive_set_error(a, ENOMEM, "No memory");
  71                 return (ARCHIVE_FATAL);
  72         }
  73         mine->block_size = block_size;
  74         mine->buffer = malloc(mine->block_size);
  75         if (mine->buffer == NULL) {
  76                 archive_set_error(a, ENOMEM, "No memory");
  77                 free(mine);
  78                 return (ARCHIVE_FATAL);
  79         }
  80         mine->fd = fd;
  81         /* lseek() hardly ever works, so disable it by default.  See below. */
  82         mine->can_skip = 0;
  83         return (archive_read_open2(a, mine, file_open, file_read, file_skip, file_close));
  84 }
  85
  86 static int
  87 file_open(struct archive *a, void *client_data)
  88 {
  89         struct read_fd_data *mine = (struct read_fd_data *)client_data;
  90         struct stat st;
  91
  92         if (fstat(mine->fd, &st) != 0) {
  93                 archive_set_error(a, errno, "Can't stat fd %d", mine->fd);
  94                 return (ARCHIVE_FATAL);
  95         }
  96
  97         if (S_ISREG(st.st_mode)) {
  98                 archive_read_extract_set_skip_file(a, st.st_dev, st.st_ino);
  99                 /*
 100                  * Enabling skip here is a performance optimization for
 101                  * anything that supports lseek().  On FreeBSD, only
 102                  * regular files and raw disk devices support lseek() and
 103                  * there's no portable way to determine if a device is
 104                  * a raw disk device, so we only enable this optimization
 105                  * for regular files.
 106                  */
 107                 mine->can_skip = 1;
 108         }
 109         return (ARCHIVE_OK);
 110 }
 111
 112 static ssize_t
 113 file_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         bytes_read = read(mine->fd, mine->buffer, mine->block_size);
 120         if (bytes_read < 0) {
 121                 archive_set_error(a, errno, "Error reading fd %d", mine->fd);
 122         }
 123         return (bytes_read);
 124 }
 125
 126 #if ARCHIVE_API_VERSION < 2
 127 static ssize_t
 128 file_skip(struct archive *a, void *client_data, size_t request)
 129 #else
 130 static off_t
 131 file_skip(struct archive *a, void *client_data, off_t request)
 132 #endif
 133 {
 134         struct read_fd_data *mine = (struct read_fd_data *)client_data;
 135         off_t old_offset, new_offset;
 136
 137         if (!mine->can_skip)
 138                 return (0);
 139
 140         /* Reduce request to the next smallest multiple of block_size */
 141         request = (request / mine->block_size) * mine->block_size;
 142         if (request == 0)
 143                 return (0);
 144
 145         /*
 146          * Hurray for lazy evaluation: if the first lseek fails, the second
 147          * one will not be executed.
 148          */
 149         if (((old_offset = lseek(mine->fd, 0, SEEK_CUR)) < 0) ||
 150             ((new_offset = lseek(mine->fd, request, SEEK_CUR)) < 0))
 151         {
 152                 /* If seek failed once, it will probably fail again. */
 153                 mine->can_skip = 0;
 154
 155                 if (errno == ESPIPE)
 156                 {
 157                         /*
 158                          * Failure to lseek() can be caused by the file
 159                          * descriptor pointing to a pipe, socket or FIFO.
 160                          * Return 0 here, so the compression layer will use
 161                          * read()s instead to advance the file descriptor.
 162                          * It's slower of course, but works as well.
 163                          */
 164                         return (0);
 165                 }
 166                 /*
 167                  * There's been an error other than ESPIPE. This is most
 168                  * likely caused by a programmer error (too large request)
 169                  * or a corrupted archive file.
 170                  */
 171                 archive_set_error(a, errno, "Error seeking");
 172                 return (-1);
 173         }
 174         return (new_offset - old_offset);
 175 }
 176
 177 static int
 178 file_close(struct archive *a, void *client_data)
 179 {
 180         struct read_fd_data *mine = (struct read_fd_data *)client_data;
 181
 182         (void)a; /* UNUSED */
 183         if (mine->buffer != NULL)
 184                 free(mine->buffer);
 185         free(mine);
 186         return (ARCHIVE_OK);
 187 }