lutimes.c

glibc 库, 不仅可以学习使用库函数,还可以学习函数的具体实现,是提高功力的好资料

/* Change access and/or modification date of file.  Do not follow symbolic
   links.
   Copyright (C) 2007 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <fcntl.h>
#include <time.h>
#include <sys/time.h>
#include <sysdep.h>
#include <kernel-features.h>


int
lutimes (const char *file, const struct timeval tvp[2])
{
#ifdef __NR_utimensat
  /* The system call espects timespec, not timeval.  */
  struct timespec ts[2];
  if (tvp != NULL)
    {
      if (tvp[0].tv_usec < 0 || tvp[0].tv_usec >= 1000000
          || tvp[1].tv_usec < 0 || tvp[1].tv_usec >= 1000000)
	{
	  __set_errno (EINVAL);
	  return -1;
	}

      TIMEVAL_TO_TIMESPEC (&tvp[0], &ts[0]);
      TIMEVAL_TO_TIMESPEC (&tvp[1], &ts[1]);
    }

  return INLINE_SYSCALL (utimensat, 4, AT_FDCWD, file, tvp ? ts : NULL,
  			 AT_SYMLINK_NOFOLLOW);
#else
  __set_errno (ENOSYS);
  return -1;
#endif
}

#ifndef __NR_utimensat
stub_warning (lutimes)
# include <stub-tag.h>
#endif