plugins/iso/iso.c

   1 /* nbdkit
   2  * Copyright (C) 2018-2020 Red Hat Inc.
   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 <sys/types.h>
  40 #include <sys/stat.h>
  41
  42 #include <nbdkit-plugin.h>
  43
  44 #include "cleanup.h"
  45 #include "string-vector.h"
  46 #include "utils.h"
  47
  48 /* List of directories parsed from the command line. */
  49 static string_vector dirs = empty_vector;
  50
  51 /* xorriso or genisoimage or mkisofs program, picked at compile time,
  52  * but can be overridden at run time.
  53  */
  54 static const char *isoprog = ISOPROG;
  55
  56 /* Extra parameters for isoprog. */
  57 static const char *params = NULL;
  58
  59 /* The temporary ISO. */
  60 static int fd = -1;
  61
  62 /* Construct the temporary ISO. */
  63 static int
  64 make_iso (void)
  65 {
  66   const char *tmpdir;
  67   CLEANUP_FREE char *template = NULL;
  68   CLEANUP_FREE char *command = NULL;
  69   size_t command_len = 0;
  70   FILE *fp;
  71   size_t i;
  72   int r;
  73
  74   /* Path for temporary file. */
  75   tmpdir = getenv ("TMPDIR");
  76   if (tmpdir == NULL)
  77     tmpdir = LARGE_TMPDIR;
  78   if (asprintf (&template, "%s/isoXXXXXX", tmpdir) == -1) {
  79     nbdkit_error ("asprintf: %m");
  80     return -1;
  81   }
  82
  83   fd = mkstemp (template);
  84   if (fd == -1) {
  85     nbdkit_error ("mkstemp: %s: %m", template);
  86     return -1;
  87   }
  88   unlink (template);
  89
  90   /* Construct the isoprog command. */
  91   fp = open_memstream (&command, &command_len);
  92   if (fp == NULL) {
  93     nbdkit_error ("open_memstream: %m");
  94     return -1;
  95   }
  96
  97   shell_quote (isoprog, fp);
  98 #if ISOPROG_IS_XORRISO
  99   /* This is necessary to make xorriso command line parsing behave
 100    * like mkisofs.
 101    */
 102   fprintf (fp, " -as mkisofs");
 103 #endif
 104   fprintf (fp, " -quiet");
 105   if (params)
 106     fprintf (fp, " %s", params);
 107   for (i = 0; i < dirs.len; ++i) {
 108     fputc (' ', fp);
 109     shell_quote (dirs.ptr[i], fp);
 110   }
 111   /* Redirect output to the temporary file. */
 112   fprintf (fp, " >&%d", fd);
 113
 114   if (fclose (fp) == EOF) {
 115     nbdkit_error ("memstream failed: %m");
 116     return -1;
 117   }
 118
 119   /* Run the command. */
 120   nbdkit_debug ("%s", command);
 121   r = system (command);
 122   if (exit_status_to_nbd_error (r, isoprog) == -1)
 123     return -1;
 124
 125   return 0;
 126 }
 127
 128 static void
 129 iso_unload (void)
 130 {
 131   string_vector_iter (&dirs, (void *) free);
 132   free (dirs.ptr);
 133
 134   if (fd >= 0)
 135     close (fd);
 136 }
 137
 138 static int
 139 iso_config (const char *key, const char *value)
 140 {
 141   char *dir;
 142
 143   if (strcmp (key, "dir") == 0) {
 144     dir = nbdkit_realpath (value);
 145     if (dir == NULL)
 146       return -1;
 147
 148     if (string_vector_append (&dirs, dir) == -1) {
 149       nbdkit_error ("realloc: %m");
 150       free (dir);
 151       return -1;
 152     }
 153   }
 154   else if (strcmp (key, "params") == 0) {
 155     params = value;
 156   }
 157   else if (strcmp (key, "prog") == 0) {
 158     isoprog = value;
 159   }
 160   else {
 161     nbdkit_error ("unknown parameter '%s'", key);
 162     return -1;
 163   }
 164
 165   return 0;
 166 }
 167
 168 static int
 169 iso_config_complete (void)
 170 {
 171   if (dirs.len == 0) {
 172     nbdkit_error ("you must supply the dir=<DIRECTORY> parameter "
 173                   "after the plugin name on the command line");
 174     return -1;
 175   }
 176
 177   return 0;
 178 }
 179
 180 #define iso_config_help \
 181   "dir=<DIRECTORY>     (required) The directory to serve.\n" \
 182   "params='<PARAMS>'              Extra parameters to pass.\n" \
 183   "prog=<ISOPROG>                 The program used to make ISOs." \
 184
 185 static void
 186 iso_dump_plugin (void)
 187 {
 188   printf ("iso_prog=%s\n", ISOPROG);
 189 }
 190
 191 static int
 192 iso_get_ready (void)
 193 {
 194   return make_iso ();
 195 }
 196
 197 static void *
 198 iso_open (int readonly)
 199 {
 200   return NBDKIT_HANDLE_NOT_NEEDED;
 201 }
 202
 203 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
 204
 205 /* Get the file size. */
 206 static int64_t
 207 iso_get_size (void *handle)
 208 {
 209   struct stat statbuf;
 210
 211   if (fstat (fd, &statbuf) == -1) {
 212     nbdkit_error ("fstat: %m");
 213     return -1;
 214   }
 215
 216   return statbuf.st_size;
 217 }
 218
 219 /* Serves the same data over multiple connections. */
 220 static int
 221 iso_can_multi_conn (void *handle)
 222 {
 223   return 1;
 224 }
 225
 226 static int
 227 iso_can_cache (void *handle)
 228 {
 229   /* Let nbdkit call pread to populate the file system cache. */
 230   return NBDKIT_CACHE_EMULATE;
 231 }
 232
 233 /* Read data from the file. */
 234 static int
 235 iso_pread (void *handle, void *buf, uint32_t count, uint64_t offset)
 236 {
 237   while (count > 0) {
 238     ssize_t r = pread (fd, buf, count, offset);
 239     if (r == -1) {
 240       nbdkit_error ("pread: %m");
 241       return -1;
 242     }
 243     if (r == 0) {
 244       nbdkit_error ("pread: unexpected end of file");
 245       return -1;
 246     }
 247     buf += r;
 248     count -= r;
 249     offset += r;
 250   }
 251
 252   return 0;
 253 }
 254
 255 static struct nbdkit_plugin plugin = {
 256   .name              = "iso",
 257   .longname          = "nbdkit iso plugin",
 258   .version           = PACKAGE_VERSION,
 259   .unload            = iso_unload,
 260   .config            = iso_config,
 261   .config_complete   = iso_config_complete,
 262   .config_help       = iso_config_help,
 263   .magic_config_key  = "dir",
 264   .dump_plugin       = iso_dump_plugin,
 265   .get_ready         = iso_get_ready,
 266   .open              = iso_open,
 267   .get_size          = iso_get_size,
 268   .can_multi_conn    = iso_can_multi_conn,
 269   .can_cache         = iso_can_cache,
 270   .pread             = iso_pread,
 271   .errno_is_preserved = 1,
 272 };
 273
 274 NBDKIT_REGISTER_PLUGIN(plugin)