common/replacements/pwrite.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 /* Replacement for pwrite for platforms which lack this function. */
  34
  35 #include <config.h>
  36
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <assert.h>
  40 #include <errno.h>
  41
  42 #ifndef HAVE_PWRITE
  43
  44 #include "pwrite.h"
  45
  46 #ifdef WIN32
  47
  48 /* Replacement pwrite for Win32. */
  49
  50 #include "nbdkit-plugin.h"
  51 #include <windows.h>
  52
  53 ssize_t
  54 pwrite (int fd, const void *buf, size_t count, off_t offset)
  55 {
  56   DWORD r;
  57   OVERLAPPED ovl;
  58   HANDLE h;
  59
  60   memset (&ovl, 0, sizeof ovl);
  61   /* Seriously WTF Windows? */
  62   ovl.Offset = offset & 0xffffffff;
  63   ovl.OffsetHigh = offset >> 32;
  64
  65   h = (HANDLE) _get_osfhandle (fd);
  66   if (h == INVALID_HANDLE_VALUE) {
  67     nbdkit_debug ("ReadFile: bad handle");
  68     errno = EIO;
  69     return -1;
  70   }
  71
  72   /* XXX Will fail weirdly if count is larger than 32 bits. */
  73   if (!WriteFile (h, buf, count, &r, &ovl)) {
  74     nbdkit_debug ("WriteFile: error %d", GetLastError ());
  75     errno = EIO;
  76     return -1;
  77   }
  78
  79   return r;
  80 }
  81
  82 #else /* !WIN32 */
  83 #error "no replacement pwrite is available on this platform"
  84 #endif
  85
  86 #endif /* !HAVE_PWRITE */