plugins/floppy/floppy.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * 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  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40
  41 #include <nbdkit-plugin.h>
  42
  43 #include "regions.h"
  44
  45 #include "virtual-floppy.h"
  46
  47 /* Directory. */
  48 static char *dir = NULL;
  49
  50 /* Volume label. */
  51 static const char *label = "NBDKITFLOPY";
  52
  53 /* Filesystem size. */
  54 static uint64_t size = 0;
  55
  56 /* Virtual floppy. */
  57 static struct virtual_floppy floppy;
  58
  59 static void
  60 floppy_load (void)
  61 {
  62   init_virtual_floppy (&floppy);
  63 }
  64
  65 static void
  66 floppy_unload (void)
  67 {
  68   free (dir);
  69   free_virtual_floppy (&floppy);
  70 }
  71
  72 static int
  73 floppy_config (const char *key, const char *value)
  74 {
  75   int64_t r;
  76
  77   if (strcmp (key, "dir") == 0) {
  78     if (dir != NULL) {
  79       /* TODO: Support merging of multiple directories, like iso plugin. */
  80       nbdkit_error ("dir=<DIRECTORY> must only be set once");
  81       return -1;
  82     }
  83     dir = nbdkit_realpath (value);
  84     if (dir == NULL)
  85       return -1;
  86   }
  87   else if (strcmp (key, "label") == 0) {
  88     label = value;
  89   }
  90   else if (strcmp (key, "size") == 0) {
  91     r = nbdkit_parse_size (value);
  92     if (r == -1)
  93       return -1;
  94     size = r;
  95   }
  96   else {
  97     nbdkit_error ("unknown parameter '%s'", key);
  98     return -1;
  99   }
 100
 101   return 0;
 102 }
 103
 104 static int
 105 floppy_config_complete (void)
 106 {
 107   if (dir == NULL) {
 108     nbdkit_error ("you must supply the dir=<DIRECTORY> parameter "
 109                   "after the plugin name on the command line");
 110     return -1;
 111   }
 112
 113   return 0;
 114 }
 115
 116 #define floppy_config_help \
 117   "dir=<DIRECTORY>     (required) The directory to serve\n" \
 118   "label=<LABEL>                  The volume label\n" \
 119   "size=<SIZE>                    Optional total disk size"
 120
 121 static int
 122 floppy_get_ready (void)
 123 {
 124   return create_virtual_floppy (dir, label, size, &floppy);
 125 }
 126
 127 static void *
 128 floppy_open (int readonly)
 129 {
 130   return NBDKIT_HANDLE_NOT_NEEDED;
 131 }
 132
 133 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
 134
 135 /* Get the file size. */
 136 static int64_t
 137 floppy_get_size (void *handle)
 138 {
 139   return virtual_size (&floppy.regions);
 140 }
 141
 142 /* Serves the same data over multiple connections. */
 143 static int
 144 floppy_can_multi_conn (void *handle)
 145 {
 146   return 1;
 147 }
 148
 149 /* Cache. */
 150 static int
 151 floppy_can_cache (void *handle)
 152 {
 153   /* Let nbdkit call pread to populate the file system cache. */
 154   return NBDKIT_CACHE_EMULATE;
 155 }
 156
 157 /* Read data from the file. */
 158 static int
 159 floppy_pread (void *handle, void *buf, uint32_t count, uint64_t offset)
 160 {
 161   while (count > 0) {
 162     const struct region *region = find_region (&floppy.regions, offset);
 163     size_t i, len;
 164     const char *host_path;
 165     int fd;
 166     ssize_t r;
 167
 168     /* Length to end of region. */
 169     len = region->end - offset + 1;
 170     if (len > count)
 171       len = count;
 172
 173     switch (region->type) {
 174     case region_file:
 175       i = region->u.i;
 176       assert (i < floppy.files.len);
 177       host_path = floppy.files.ptr[i].host_path;
 178       fd = open (host_path, O_RDONLY|O_CLOEXEC);
 179       if (fd == -1) {
 180         nbdkit_error ("open: %s: %m", host_path);
 181         return -1;
 182       }
 183       r = pread (fd, buf, len, offset - region->start);
 184       if (r == -1) {
 185         nbdkit_error ("pread: %s: %m", host_path);
 186         close (fd);
 187         return -1;
 188       }
 189       if (r == 0) {
 190         nbdkit_error ("pread: %s: unexpected end of file", host_path);
 191         close (fd);
 192         return -1;
 193       }
 194       close (fd);
 195       len = r;
 196       break;
 197
 198     case region_data:
 199       memcpy (buf, &region->u.data[offset - region->start], len);
 200       break;
 201
 202     case region_zero:
 203       memset (buf, 0, len);
 204       break;
 205     }
 206
 207     count -= len;
 208     buf += len;
 209     offset += len;
 210   }
 211
 212   return 0;
 213 }
 214
 215 static struct nbdkit_plugin plugin = {
 216   .name              = "floppy",
 217   .longname          = "nbdkit floppy plugin",
 218   .version           = PACKAGE_VERSION,
 219   .load              = floppy_load,
 220   .unload            = floppy_unload,
 221   .config            = floppy_config,
 222   .config_complete   = floppy_config_complete,
 223   .config_help       = floppy_config_help,
 224   .magic_config_key  = "dir",
 225   .get_ready         = floppy_get_ready,
 226   .open              = floppy_open,
 227   .get_size          = floppy_get_size,
 228   .can_multi_conn    = floppy_can_multi_conn,
 229   .can_cache         = floppy_can_cache,
 230   .pread             = floppy_pread,
 231   .errno_is_preserved = 1,
 232 };
 233
 234 NBDKIT_REGISTER_PLUGIN (plugin)