sysdeps/unix/sysv/linux/pwrite.c

   1 /* Copyright (C) 1997, 1998, 1999, 2000, 2002 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <endian.h>
  23 #include <unistd.h>
  24
  25 #include <sysdep.h>
  26 #include <sys/syscall.h>
  27 #include <bp-checks.h>
  28
  29 #include "kernel-features.h"
  30
  31 #if defined __NR_pwrite || __ASSUME_PWRITE_SYSCALL > 0
  32
  33 /* The order of hi, lo depends on endianness.  */
  34 extern ssize_t __syscall_pwrite (int fd, const void *__unbounded buf, size_t count,
  35                                  off_t offset_hi, off_t offset_lo);
  36
  37 # if __ASSUME_PWRITE_SYSCALL == 0
  38 static ssize_t __emulate_pwrite (int fd, const void *buf, size_t count,
  39                                  off_t offset) internal_function;
  40 # endif
  41
  42
  43 ssize_t
  44 __libc_pwrite (fd, buf, count, offset)
  45      int fd;
  46      const void *buf;
  47      size_t count;
  48      off_t offset;
  49 {
  50   ssize_t result;
  51
  52   /* First try the syscall.  */
  53   assert (sizeof (offset) == 4);
  54   result = INLINE_SYSCALL (pwrite, 5, fd, CHECK_N (buf, count), count,
  55                            __LONG_LONG_PAIR (offset >> 31, offset));
  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