source/smbd/notify_kernel.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 3.0
   4    change notify handling - linux kernel based implementation
   5    Copyright (C) Andrew Tridgell 2000
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 #if HAVE_KERNEL_CHANGE_NOTIFY
  25
  26 extern int DEBUGLEVEL;
  27 static VOLATILE SIG_ATOMIC_T fd_pending;
  28 static VOLATILE SIG_ATOMIC_T signals_received;
  29 static VOLATILE SIG_ATOMIC_T signals_processed;
  30
  31 #ifndef DN_ACCESS
  32 #define DN_ACCESS       0x00000001      /* File accessed in directory */
  33 #define DN_MODIFY       0x00000002      /* File modified in directory */
  34 #define DN_CREATE       0x00000004      /* File created in directory */
  35 #define DN_DELETE       0x00000008      /* File removed from directory */
  36 #define DN_RENAME       0x00000010      /* File renamed in directory */
  37 #define DN_ATTRIB       0x00000020      /* File changed attribute */
  38 #define DN_MULTISHOT    0x80000000      /* Don't remove notifier */
  39 #endif
  40
  41
  42 #ifndef RT_SIGNAL_NOTIFY
  43 #define RT_SIGNAL_NOTIFY 34
  44 #endif
  45
  46 #ifndef F_SETSIG
  47 #define F_SETSIG 10
  48 #endif
  49
  50 #ifndef F_NOTIFY
  51 #define F_NOTIFY 1026
  52 #endif
  53
  54 /****************************************************************************
  55  This is the structure to keep the information needed to
  56  determine if a directory has changed.
  57 *****************************************************************************/
  58 struct change_data {
  59         int directory_handle;
  60 };
  61
  62 /****************************************************************************
  63 the signal handler for change notify
  64 *****************************************************************************/
  65 static void signal_handler(int sig, siginfo_t *info, void *unused)
  66 {
  67         BlockSignals(True, sig);
  68         fd_pending = (SIG_ATOMIC_T)info->si_fd;
  69         signals_received++;
  70         sys_select_signal();
  71 }
  72
  73
  74
  75 /****************************************************************************
  76  Check if a change notify should be issued.
  77  time non-zero means timeout check (used for hash). Ignore this (async method
  78  where time is zero will be used instead).
  79 *****************************************************************************/
  80 static BOOL kernel_check_notify(connection_struct *conn, uint16 vuid, char *path, uint32 flags, void *datap, time_t t)
  81 {
  82         struct change_data *data = (struct change_data *)datap;
  83
  84         if (t)
  85                 return False;
  86
  87         if (data->directory_handle != (int)fd_pending) return False;
  88
  89         DEBUG(3,("kernel change notify on %s fd=%d\n", path, (int)fd_pending));
  90
  91         close((int)fd_pending);
  92         fd_pending = (SIG_ATOMIC_T)-1;
  93         data->directory_handle = -1;
  94         signals_processed++;
  95         BlockSignals(False, RT_SIGNAL_NOTIFY);
  96         return True;
  97 }
  98
  99 /****************************************************************************
 100 remove a change notify data structure
 101 *****************************************************************************/
 102 static void kernel_remove_notify(void *datap)
 103 {
 104         struct change_data *data = (struct change_data *)datap;
 105         int fd = data->directory_handle;
 106         if (fd != -1) {
 107                 if (fd == (int)fd_pending) {
 108                         fd_pending = (SIG_ATOMIC_T)-1;
 109                         signals_processed++;
 110                         BlockSignals(False, RT_SIGNAL_NOTIFY);
 111                 }
 112                 close(fd);
 113         }
 114         free(data);
 115         DEBUG(3,("removed kernel change notify fd=%d\n", fd));
 116 }
 117
 118
 119 /****************************************************************************
 120 register a change notify request
 121 *****************************************************************************/
 122 static void *kernel_register_notify(connection_struct *conn, char *path, uint32 flags)
 123 {
 124         struct change_data data;
 125         int fd;
 126         unsigned long kernel_flags;
 127
 128         fd = dos_open(path, O_RDONLY, 0);
 129
 130         if (fd == -1) {
 131                 DEBUG(3,("Failed to open directory %s for change notify\n", path));
 132                 return NULL;
 133         }
 134
 135         if (fcntl(fd, F_SETSIG, RT_SIGNAL_NOTIFY) == -1) {
 136                 DEBUG(3,("Failed to set signal handler for change notify\n"));
 137                 return NULL;
 138         }
 139
 140         kernel_flags = DN_CREATE|DN_DELETE|DN_RENAME; /* creation/deletion changes everything! */
 141         if (flags & FILE_NOTIFY_CHANGE_FILE)        kernel_flags |= DN_MODIFY;
 142         if (flags & FILE_NOTIFY_CHANGE_DIR_NAME)    kernel_flags |= DN_RENAME|DN_DELETE;
 143         if (flags & FILE_NOTIFY_CHANGE_ATTRIBUTES)  kernel_flags |= DN_ATTRIB;
 144         if (flags & FILE_NOTIFY_CHANGE_SIZE)        kernel_flags |= DN_MODIFY;
 145         if (flags & FILE_NOTIFY_CHANGE_LAST_WRITE)  kernel_flags |= DN_MODIFY;
 146         if (flags & FILE_NOTIFY_CHANGE_LAST_ACCESS) kernel_flags |= DN_ACCESS;
 147         if (flags & FILE_NOTIFY_CHANGE_CREATION)    kernel_flags |= DN_CREATE;
 148         if (flags & FILE_NOTIFY_CHANGE_SECURITY)    kernel_flags |= DN_ATTRIB;
 149         if (flags & FILE_NOTIFY_CHANGE_EA)          kernel_flags |= DN_ATTRIB;
 150         if (flags & FILE_NOTIFY_CHANGE_FILE_NAME)   kernel_flags |= DN_RENAME|DN_DELETE;
 151
 152         if (fcntl(fd, F_NOTIFY, kernel_flags) == -1) {
 153                 DEBUG(3,("Failed to set async flag for change notify\n"));
 154                 return NULL;
 155         }
 156
 157         data.directory_handle = fd;
 158
 159         DEBUG(3,("kernel change notify on %s (ntflags=0x%x flags=0x%x) fd=%d\n",
 160                  path, (int)flags, (int)kernel_flags, fd));
 161
 162         return (void *)memdup(&data, sizeof(data));
 163 }
 164
 165 /****************************************************************************
 166 see if the kernel supports change notify
 167 ****************************************************************************/
 168 static BOOL kernel_notify_available(void)
 169 {
 170         int fd, ret;
 171         fd = open("/tmp", O_RDONLY);
 172         if (fd == -1) return False; /* uggh! */
 173         ret = fcntl(fd, F_NOTIFY, 0);
 174         close(fd);
 175         return ret == 0;
 176 }
 177
 178
 179 /****************************************************************************
 180 setup kernel based change notify
 181 ****************************************************************************/
 182 struct cnotify_fns *kernel_notify_init(void)
 183 {
 184         static struct cnotify_fns cnotify;
 185         struct sigaction act;
 186
 187         act.sa_handler = NULL;
 188         act.sa_sigaction = signal_handler;
 189         act.sa_flags = SA_SIGINFO;
 190         if (sigaction(RT_SIGNAL_NOTIFY, &act, NULL) != 0) {
 191                 DEBUG(0,("Failed to setup RT_SIGNAL_NOTIFY handler\n"));
 192                 return NULL;
 193         }
 194
 195         if (!kernel_notify_available()) return NULL;
 196
 197         cnotify.register_notify = kernel_register_notify;
 198         cnotify.check_notify = kernel_check_notify;
 199         cnotify.remove_notify = kernel_remove_notify;
 200         cnotify.select_time = -1;
 201
 202         return &cnotify;
 203 }
 204
 205
 206 #else
 207  void notify_kernel_dummy(void) {}
 208 #endif /* HAVE_KERNEL_CHANGE_NOTIFY */