sysdeps/unix/sysv/linux/pwrite.c

   1 /* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <endian.h>
  22 #include <unistd.h>
  23
  24 #include <sysdep.h>
  25 #include <sys/syscall.h>
  26
  27 #include "kernel-features.h"
  28
  29 #if defined __NR_pwrite || __ASSUME_PWRITE_SYSCALL > 0
  30
  31 /* The order of hi, lo depends on endianness.  */
  32 extern ssize_t __syscall_pwrite (int fd, const void *buf, size_t count,
  33                                  off_t offset_hi, off_t offset_lo);
  34
  35 # if __ASSUME_PWRITE_SYSCALL == 0
  36 static ssize_t __emulate_pwrite (int fd, const void *buf, size_t count,
  37                                  off_t offset) internal_function;
  38 # endif
  39
  40
  41 ssize_t
  42 __libc_pwrite (fd, buf, count, offset)
  43      int fd;
  44      const void *buf;
  45      size_t count;
  46      off_t offset;
  47 {
  48   ssize_t result;
  49
  50   /* First try the syscall.  */
  51 # if __BYTE_ORDER == __LITTLE_ENDIAN
  52   result = INLINE_SYSCALL (pwrite, 5, fd, buf, count, offset, 0);
  53 # elif __BYTE_ORDER == __BIG_ENDIAN
  54   result = INLINE_SYSCALL (pwrite, 5, fd, buf, count, 0, offset);
  55 # endif
  56 # if __ASSUME_PWRITE_SYSCALL == 0
  57   if (result == -1 && errno == ENOSYS)
  58     /* No system call available.  Use the emulation.  */
  59     result = __emulate_pwrite (fd, buf, count, offset);
  60 # endif
  61
  62   return result;
  63 }
  64
  65 strong_alias (__libc_pwrite, __pwrite)
  66 weak_alias (__libc_pwrite, pwrite)
  67
  68 # define __libc_pwrite(fd, buf, count, offset) \
  69      static internal_function __emulate_pwrite (fd, buf, count, offset)
  70 #endif
  71
  72 #if __ASSUME_PWRITE_SYSCALL == 0
  73 # include <sysdeps/posix/pwrite.c>
  74 #endif