lib/ftruncate.c

   1 /* ftruncate emulations for native Windows.
   2    Copyright (C) 1992-2018 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <unistd.h>
  21
  22 #if HAVE_CHSIZE
  23 /* A native Windows platform.  */
  24
  25 # include <errno.h>
  26
  27 # if _GL_WINDOWS_64_BIT_OFF_T
  28
  29 /* Large File Support: off_t is 64-bit, but chsize() takes only a 32-bit
  30    argument.  So, define a 64-bit safe SetFileSize function ourselves.  */
  31
  32 /* Ensure that <windows.h> declares GetFileSizeEx.  */
  33 #  undef _WIN32_WINNT
  34 #  define _WIN32_WINNT _WIN32_WINNT_WIN2K
  35
  36 /* Get declarations of the native Windows API functions.  */
  37 #  define WIN32_LEAN_AND_MEAN
  38 #  include <windows.h>
  39
  40 /* Get _get_osfhandle.  */
  41 #  if GNULIB_MSVC_NOTHROW
  42 #   include "msvc-nothrow.h"
  43 #  else
  44 #   include <io.h>
  45 #  endif
  46
  47 static BOOL
  48 SetFileSize (HANDLE h, LONGLONG size)
  49 {
  50   LARGE_INTEGER old_size;
  51
  52   if (!GetFileSizeEx (h, &old_size))
  53     return FALSE;
  54
  55   if (size != old_size.QuadPart)
  56     {
  57       /* Duplicate the handle, so we are free to modify its file position.  */
  58       HANDLE curr_process = GetCurrentProcess ();
  59       HANDLE tmph;
  60
  61       if (!DuplicateHandle (curr_process,           /* SourceProcessHandle */
  62                             h,                      /* SourceHandle */
  63                             curr_process,           /* TargetProcessHandle */
  64                             (PHANDLE) &tmph,        /* TargetHandle */
  65                             (DWORD) 0,              /* DesiredAccess */
  66                             FALSE,                  /* InheritHandle */
  67                             DUPLICATE_SAME_ACCESS)) /* Options */
  68         return FALSE;
  69
  70       if (size < old_size.QuadPart)
  71         {
  72           /* Reduce the size.  */
  73           LONG size_hi = (LONG) (size >> 32);
  74           if (SetFilePointer (tmph, (LONG) size, &size_hi, FILE_BEGIN)
  75               == INVALID_SET_FILE_POINTER
  76               && GetLastError() != NO_ERROR)
  77             {
  78               CloseHandle (tmph);
  79               return FALSE;
  80             }
  81           if (!SetEndOfFile (tmph))
  82             {
  83               CloseHandle (tmph);
  84               return FALSE;
  85             }
  86         }
  87       else
  88         {
  89           /* Increase the size by adding zero bytes at the end.  */
  90           static char zero_bytes[1024];
  91           LONG pos_hi = 0;
  92           LONG pos_lo = SetFilePointer (tmph, (LONG) 0, &pos_hi, FILE_END);
  93           LONGLONG pos;
  94           if (pos_lo == INVALID_SET_FILE_POINTER
  95               && GetLastError() != NO_ERROR)
  96             {
  97               CloseHandle (tmph);
  98               return FALSE;
  99             }
 100           pos = ((LONGLONG) pos_hi << 32) | (ULONGLONG) (ULONG) pos_lo;
 101           while (pos < size)
 102             {
 103               DWORD written;
 104               LONGLONG count = size - pos;
 105               if (count > sizeof (zero_bytes))
 106                 count = sizeof (zero_bytes);
 107               if (!WriteFile (tmph, zero_bytes, (DWORD) count, &written, NULL)
 108                   || written == 0)
 109                 {
 110                   CloseHandle (tmph);
 111                   return FALSE;
 112                 }
 113               pos += (ULONGLONG) (ULONG) written;
 114             }
 115         }
 116       /* Close the handle.  */
 117       CloseHandle (tmph);
 118     }
 119   return TRUE;
 120 }
 121
 122 int
 123 ftruncate (int fd, off_t length)
 124 {
 125   HANDLE handle = (HANDLE) _get_osfhandle (fd);
 126
 127   if (handle == INVALID_HANDLE_VALUE)
 128     {
 129       errno = EBADF;
 130       return -1;
 131     }
 132   if (length < 0)
 133     {
 134       errno = EINVAL;
 135       return -1;
 136     }
 137   if (!SetFileSize (handle, length))
 138     {
 139       switch (GetLastError ())
 140         {
 141         case ERROR_ACCESS_DENIED:
 142           errno = EACCES;
 143           break;
 144         case ERROR_HANDLE_DISK_FULL:
 145         case ERROR_DISK_FULL:
 146         case ERROR_DISK_TOO_FRAGMENTED:
 147           errno = ENOSPC;
 148           break;
 149         default:
 150           errno = EIO;
 151           break;
 152         }
 153       return -1;
 154     }
 155   return 0;
 156 }
 157
 158 # else
 159
 160 #  include <io.h>
 161
 162 #  if HAVE_MSVC_INVALID_PARAMETER_HANDLER
 163 #   include "msvc-inval.h"
 164 static int
 165 chsize_nothrow (int fd, long length)
 166 {
 167   int result;
 168
 169   TRY_MSVC_INVAL
 170     {
 171       result = chsize (fd, length);
 172     }
 173   CATCH_MSVC_INVAL
 174     {
 175       result = -1;
 176       errno = EBADF;
 177     }
 178   DONE_MSVC_INVAL;
 179
 180   return result;
 181 }
 182 #  else
 183 #   define chsize_nothrow chsize
 184 #  endif
 185
 186 int
 187 ftruncate (int fd, off_t length)
 188 {
 189   return chsize_nothrow (fd, length);
 190 }
 191
 192 # endif
 193 #endif