common/utils/utils.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 <fcntl.h>
  38 #include <unistd.h>
  39 #include <string.h>
  40 #include <sys/types.h>
  41
  42 #ifdef HAVE_SYS_SOCKET_H
  43 #include <sys/socket.h>
  44 #endif
  45
  46 #ifdef HAVE_SYS_WAIT_H
  47 #include <sys/wait.h>
  48 #endif
  49
  50 #include <nbdkit-plugin.h>
  51
  52 #include "windows-compat.h"
  53
  54 #ifndef WIN32
  55
  56 /* Convert exit status to nbd_error.  If the exit status was nonzero
  57  * or another failure then -1 is returned.
  58  */
  59 int
  60 exit_status_to_nbd_error (int status, const char *cmd)
  61 {
  62   if (WIFEXITED (status) && WEXITSTATUS (status) != 0) {
  63     nbdkit_error ("%s: command failed with exit code %d",
  64                   cmd, WEXITSTATUS (status));
  65     return -1;
  66   }
  67   else if (WIFSIGNALED (status)) {
  68     nbdkit_error ("%s: command was killed by signal %d",
  69                   cmd, WTERMSIG (status));
  70     return -1;
  71   }
  72   else if (WIFSTOPPED (status)) {
  73     nbdkit_error ("%s: command was stopped by signal %d",
  74                   cmd, WSTOPSIG (status));
  75     return -1;
  76   }
  77
  78   return 0;
  79 }
  80
  81 #else /* WIN32 */
  82
  83 /* This assumes we're using Win32 system().  See:
  84  * https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/system-wsystem?view=vs-2019
  85  */
  86 int
  87 exit_status_to_nbd_error (int status, const char *cmd)
  88 {
  89   if (status == 0)
  90     return 0;
  91
  92   nbdkit_error ("%s: command failed: errno = %d", cmd, errno);
  93   return -1;
  94 }
  95
  96 #endif /* WIN32 */
  97
  98 #ifndef WIN32
  99
 100 /* Set the FD_CLOEXEC flag on the given fd, if it is non-negative.
 101  * On failure, close fd and return -1; on success, return fd.
 102  *
 103  * Note that this function should ONLY be used on platforms that lack
 104  * atomic CLOEXEC support during fd creation (such as Haiku in 2019);
 105  * when using it as a fallback path, you must also consider how to
 106  * prevent fd leaks to plugins that want to fork().
 107  */
 108 int
 109 set_cloexec (int fd)
 110 {
 111 #if (defined SOCK_CLOEXEC && defined HAVE_MKOSTEMP && defined HAVE_PIPE2 && \
 112      defined HAVE_ACCEPT4)
 113   nbdkit_error ("prefer creating fds with CLOEXEC atomically set");
 114   close (fd);
 115   errno = EBADF;
 116   return -1;
 117 #else
 118 # if !defined __APPLE__ && \
 119      (defined SOCK_CLOEXEC || defined HAVE_MKOSTEMP || defined HAVE_PIPE2 || \
 120       defined HAVE_ACCEPT4)
 121 # error "Unexpected: your system has incomplete atomic CLOEXEC support"
 122 # endif
 123   int f;
 124   int err;
 125
 126   if (fd == -1)
 127     return -1;
 128
 129   f = fcntl (fd, F_GETFD);
 130   if (f == -1 || fcntl (fd, F_SETFD, f | FD_CLOEXEC) == -1) {
 131     err = errno;
 132     nbdkit_error ("fcntl: %m");
 133     close (fd);
 134     errno = err;
 135     return -1;
 136   }
 137   return fd;
 138 #endif
 139 }
 140
 141 #else /* WIN32 */
 142
 143 int
 144 set_cloexec (int fd)
 145 {
 146   return fd;
 147 }
 148
 149 #endif /* WIN32 */
 150
 151 #ifndef WIN32
 152
 153 /* Set the O_NONBLOCK flag on the given fd, if it is non-negative.
 154  * On failure, close fd and return -1; on success, return fd.
 155  */
 156 int
 157 set_nonblock (int fd)
 158 {
 159   int f;
 160   int err;
 161
 162   if (fd == -1)
 163     return -1;
 164
 165   f = fcntl (fd, F_GETFL);
 166   if (f == -1 || fcntl (fd, F_SETFL, f | O_NONBLOCK) == -1) {
 167     err = errno;
 168     nbdkit_error ("fcntl: %m");
 169     close (fd);
 170     errno = err;
 171     return -1;
 172   }
 173   return fd;
 174 }
 175
 176 #else /* WIN32 */
 177
 178 int
 179 set_nonblock (int fd)
 180 {
 181   return fd;
 182 }
 183
 184 #endif /* WIN32 */
 185
 186 #ifndef WIN32
 187
 188 char *
 189 make_temporary_directory (void)
 190 {
 191   char template[] = "/tmp/nbdkitXXXXXX";
 192
 193   if (mkdtemp (template) == NULL)
 194     return NULL;
 195
 196   return strdup (template);
 197 }
 198
 199 #else /* WIN32 */
 200
 201 char *
 202 make_temporary_directory (void)
 203 {
 204   char tmppath[MAX_PATH];
 205   char tmpname[MAX_PATH];
 206   DWORD ret;
 207
 208   ret = GetTempPath (MAX_PATH, tmppath);
 209   if (ret > MAX_PATH || ret == 0) {
 210     fprintf (stderr, "mkdtemp: GetTempPath: %lu\n", GetLastError ());
 211     return NULL;
 212   }
 213
 214   ret = GetTempFileName (tmppath, TEXT ("nbdkit"), 0, tmpname);
 215   if (!ret) {
 216     fprintf (stderr, "mkdtemp: GetTempFileName: %lu\n", GetLastError ());
 217     return NULL;
 218   }
 219
 220   /* The above function actually creates the file, so we must remove
 221    * it before creating the directory.  Not ideal because it leaves a
 222    * small window for exploitation (XXX).
 223    */
 224   unlink (tmpname);
 225
 226   if (mkdir (tmpname) == -1) {
 227     fprintf (stderr, "mkdtemp: mkdir: %s: %lu\n", tmpname, GetLastError ());
 228     return NULL;
 229   }
 230
 231   return strdup (tmpname);
 232 }
 233
 234 #endif /* WIN32 */