sysdeps/unix/sysv/linux/futimes.c

   1 /* futimes -- change access and modification times of open file.  Linux version.
   2    Copyright (C) 2002-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sysdep.h>
  21 #include <string.h>
  22 #include <time.h>
  23 #include <utime.h>
  24 #include <sys/time.h>
  25 #include <_itoa.h>
  26 #include <fcntl.h>
  27
  28 #include <kernel-features.h>
  29
  30
  31 #if defined __NR_utimensat && !defined __ASSUME_UTIMENSAT
  32 static int miss_utimensat;
  33 #endif
  34
  35 /* Change the access time of the file associated with FD to TVP[0] and
  36    the modification time of FILE to TVP[1].
  37
  38    Starting with 2.6.22 the Linux kernel has the utimensat syscall which
  39    can be used to implement futimes.  Earlier kernels have no futimes()
  40    syscall so we use the /proc filesystem.  */
  41 int
  42 __futimes (int fd, const struct timeval tvp[2])
  43 {
  44   /* The utimensat system call expects timespec not timeval.  */
  45   struct timespec ts[2];
  46   if (tvp != NULL)
  47     {
  48       if (tvp[0].tv_usec < 0 || tvp[0].tv_usec >= 1000000
  49           || tvp[1].tv_usec < 0 || tvp[1].tv_usec >= 1000000)
  50         {
  51           __set_errno (EINVAL);
  52           return -1;
  53         }
  54
  55       TIMEVAL_TO_TIMESPEC (&tvp[0], &ts[0]);
  56       TIMEVAL_TO_TIMESPEC (&tvp[1], &ts[1]);
  57     }
  58
  59 #ifdef __ASSUME_UTIMENSAT
  60   return INLINE_SYSCALL (utimensat, 4, fd, NULL, tvp ? &ts : NULL, 0);
  61 #else
  62   int result;
  63 # ifdef __NR_utimensat
  64   if (!__builtin_expect (miss_utimensat, 0))
  65     {
  66       result = INLINE_SYSCALL (utimensat, 4, fd, NULL, tvp ? &ts : NULL, 0);
  67       if (__builtin_expect (result, 0) != -1 || errno != ENOSYS)
  68         return result;
  69
  70       miss_utimensat = 1;
  71     }
  72 # endif
  73
  74   static const char selffd[] = "/proc/self/fd/";
  75   char fname[sizeof (selffd) + 3 * sizeof (int)];
  76   fname[sizeof (fname) - 1] = '\0';
  77   char *cp = _itoa_word ((unsigned int) fd, fname + sizeof (fname) - 1, 10, 0);
  78   cp = memcpy (cp - sizeof (selffd) + 1, selffd, sizeof (selffd) - 1);
  79
  80 # ifdef __NR_utimes
  81   result = INLINE_SYSCALL (utimes, 2, cp, tvp);
  82 #  ifndef __ASSUME_UTIMES
  83   if (result == -1 && errno == ENOSYS)
  84 #  endif
  85 # endif
  86     {
  87       /* The utimes() syscall does not exist or is not available in the
  88          used kernel.  Use utime().  For this we have to convert to the
  89          data format utime() expects.  */
  90 # ifndef __ASSUME_UTIMES
  91       struct utimbuf buf;
  92       struct utimbuf *times;
  93
  94       if (tvp != NULL)
  95         {
  96           times = &buf;
  97           buf.actime = tvp[0].tv_sec;
  98           buf.modtime = tvp[1].tv_sec;
  99         }
 100       else
 101         times = NULL;
 102
 103       result = INLINE_SYSCALL (utime, 2, cp, times);
 104 # endif
 105     }
 106
 107   if (result == -1)
 108     /* Check for errors that result from failing to find /proc.
 109        This means we can't do futimes at all, so return ENOSYS
 110        rather than some confusing error.  */
 111     switch (errno)
 112       {
 113       case EACCES:
 114         if (tvp == NULL)  /* Could be a path problem or a file problem.  */
 115           break;
 116         /*FALLTHROUGH*/
 117       case ELOOP:
 118       case ENAMETOOLONG:
 119       case ENOTDIR:
 120         __set_errno (ENOSYS);
 121         break;
 122
 123       case ENOENT:
 124         /* Validate the file descriptor by letting fcntl set errno to
 125            EBADF if it's bogus.  Otherwise it's a /proc issue.  */
 126 # if !defined __NR_fcntl && defined __NR_fcntl64
 127 #  define __NR_fcntl __NR_fcntl64
 128 # endif
 129         if (INLINE_SYSCALL (fcntl, 3, fd, F_GETFD, 0) != -1)
 130           __set_errno (ENOSYS);
 131         break;
 132       }
 133
 134   return result;
 135 #endif
 136 }
 137 weak_alias (__futimes, futimes)