sysdeps/unix/sysv/linux/futimes.c

   1 /* futimes -- change access and modification times of open file.  Linux version.
   2    Copyright (C) 2002,2003,2005,2006,2007 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <sysdep.h>
  22 #include <string.h>
  23 #include <time.h>
  24 #include <utime.h>
  25 #include <sys/time.h>
  26 #include <stdio-common/_itoa.h>
  27 #include <fcntl.h>
  28
  29 #include <kernel-features.h>
  30
  31
  32 #if defined __NR_utimensat && !defined __ASSUME_UTIMENSAT
  33 static int miss_utimensat;
  34 #endif
  35
  36 /* Change the access time of the file associated with FD to TVP[0] and
  37    the modification time of FILE to TVP[1].
  38
  39    Starting with 2.6.22 the Linux kernel has the utimensat syscall which
  40    can be used to implement futimes.  Earlier kernels have no futimes()
  41    syscall so we use the /proc filesystem.  */
  42 int
  43 __futimes (int fd, const struct timeval tvp[2])
  44 {
  45   /* The utimensat system call expects timespec not timeval.  */
  46   struct timespec ts[2];
  47   if (tvp != NULL)
  48     {
  49       if (tvp[0].tv_usec < 0 || tvp[0].tv_usec >= 1000000
  50           || tvp[1].tv_usec < 0 || tvp[1].tv_usec >= 1000000)
  51         {
  52           __set_errno (EINVAL);
  53           return -1;
  54         }
  55
  56       TIMEVAL_TO_TIMESPEC (&tvp[0], &ts[0]);
  57       TIMEVAL_TO_TIMESPEC (&tvp[1], &ts[1]);
  58     }
  59
  60 #ifdef __ASSUME_UTIMENSAT
  61   return INLINE_SYSCALL (utimensat, 4, fd, NULL, tvp ? &ts : NULL, 0);
  62 #else
  63   int result;
  64 # ifdef __NR_utimensat
  65   if (!__builtin_expect (miss_utimensat, 0))
  66     {
  67       result = INLINE_SYSCALL (utimensat, 4, fd, NULL, tvp ? &ts : NULL, 0);
  68       if (__builtin_expect (result, 0) != -1 || errno != ENOSYS)
  69         return result;
  70
  71       miss_utimensat = 1;
  72     }
  73 # endif
  74
  75   static const char selffd[] = "/proc/self/fd/";
  76   char fname[sizeof (selffd) + 3 * sizeof (int)];
  77   fname[sizeof (fname) - 1] = '\0';
  78   char *cp = _itoa_word ((unsigned int) fd, fname + sizeof (fname) - 1, 10, 0);
  79   cp = memcpy (cp - sizeof (selffd) + 1, selffd, sizeof (selffd) - 1);
  80
  81 # ifdef __NR_utimes
  82   result = INLINE_SYSCALL (utimes, 2, cp, tvp);
  83 #  ifndef __ASSUME_UTIMES
  84   if (result == -1 && errno == ENOSYS)
  85 #  endif
  86 # endif
  87     {
  88       /* The utimes() syscall does not exist or is not available in the
  89          used kernel.  Use utime().  For this we have to convert to the
  90          data format utime() expects.  */
  91 # ifndef __ASSUME_UTIMES
  92       struct utimbuf buf;
  93       struct utimbuf *times;
  94
  95       if (tvp != NULL)
  96         {
  97           times = &buf;
  98           buf.actime = tvp[0].tv_sec + (tvp[0].tv_usec + 500000) / 1000000;
  99           buf.modtime = tvp[1].tv_sec + (tvp[1].tv_usec + 500000) / 1000000;
 100         }
 101       else
 102         times = NULL;
 103
 104       result = INLINE_SYSCALL (utime, 2, cp, times);
 105 # endif
 106     }
 107
 108   if (result == -1)
 109     /* Check for errors that result from failing to find /proc.
 110        This means we can't do futimes at all, so return ENOSYS
 111        rather than some confusing error.  */
 112     switch (errno)
 113       {
 114       case EACCES:
 115         if (tvp == NULL)  /* Could be a path problem or a file problem.  */
 116           break;
 117         /*FALLTHROUGH*/
 118       case ELOOP:
 119       case ENAMETOOLONG:
 120       case ENOTDIR:
 121         __set_errno (ENOSYS);
 122         break;
 123
 124       case ENOENT:
 125         /* Validate the file descriptor by letting fcntl set errno to
 126            EBADF if it's bogus.  Otherwise it's a /proc issue.  */
 127 # if !defined __NR_fcntl && defined __NR_fcntl64
 128 #  define __NR_fcntl __NR_fcntl64
 129 # endif
 130         if (INLINE_SYSCALL (fcntl, 3, fd, F_GETFD, 0) != -1)
 131           __set_errno (ENOSYS);
 132         break;
 133       }
 134
 135   return result;
 136 #endif
 137 }
 138 weak_alias (__futimes, futimes)