lib/utime.c

   1 /* Copyright (C) 1998, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   2
   3    This program is free software; you can redistribute it and/or modify it
   4    under the terms of the GNU General Public License as published by the
   5    Free Software Foundation; either version 2, or (at your option) any
   6    later version.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12
  13    You should have received a copy of the GNU General Public License
  14    along with this program; if not, write to the Free Software Foundation,
  15    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  16
  17 /* derived from a function in touch.c */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22 #undef utime
  23
  24 #include <sys/types.h>
  25
  26 #ifdef HAVE_UTIME_H
  27 # include <utime.h>
  28 #endif
  29
  30 #if !HAVE_UTIMES_NULL
  31 # include <sys/stat.h>
  32 # include <fcntl.h>
  33 #endif
  34
  35 #include <unistd.h>
  36 #include <errno.h>
  37
  38 #include "full-write.h"
  39 #include "safe-read.h"
  40
  41 /* Some systems (even some that do have <utime.h>) don't declare this
  42    structure anywhere.  */
  43 #ifndef HAVE_STRUCT_UTIMBUF
  44 struct utimbuf
  45 {
  46   long actime;
  47   long modtime;
  48 };
  49 #endif
  50
  51 /* Emulate utime (file, NULL) for systems (like 4.3BSD) that do not
  52    interpret it to set the access and modification times of FILE to
  53    the current time.  Return 0 if successful, -1 if not. */
  54
  55 static int
  56 utime_null (const char *file)
  57 {
  58 #if HAVE_UTIMES_NULL
  59   return utimes (file, 0);
  60 #else
  61   int fd;
  62   char c;
  63   int status = 0;
  64   struct stat st;
  65   int saved_errno = 0;
  66
  67   fd = open (file, O_RDWR);
  68   if (fd < 0
  69       || fstat (fd, &st) < 0
  70       || safe_read (fd, &c, sizeof c) == SAFE_READ_ERROR
  71       || lseek (fd, (off_t) 0, SEEK_SET) < 0
  72       || full_write (fd, &c, sizeof c) != sizeof c
  73       /* Maybe do this -- it's necessary on SunOS 4.1.3 with some combination
  74          of patches, but that system doesn't use this code: it has utimes.
  75          || fsync (fd) < 0
  76       */
  77       || (st.st_size == 0 && ftruncate (fd, st.st_size) < 0))
  78     {
  79       saved_errno = errno;
  80       status = -1;
  81     }
  82
  83   if (0 <= fd)
  84     {
  85       if (close (fd) < 0)
  86         status = -1;
  87
  88       /* If there was a prior failure, use the saved errno value.
  89          But if the only failure was in the close, don't change errno.  */
  90       if (saved_errno)
  91         errno = saved_errno;
  92     }
  93
  94   return status;
  95 #endif
  96 }
  97
  98 int
  99 rpl_utime (const char *file, const struct utimbuf *times)
 100 {
 101   if (times)
 102     return utime (file, times);
 103
 104   return utime_null (file);
 105 }