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/*
Unix SMB/Netbios implementation.
Version 3.0
change notify handling - linux kernel based implementation
Copyright (C) Andrew Tridgell 2000
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#if HAVE_KERNEL_CHANGE_NOTIFY
#define FD_PENDING_SIZE 20
static SIG_ATOMIC_T fd_pending_array[FD_PENDING_SIZE];
static SIG_ATOMIC_T signals_received;
#ifndef DN_ACCESS
#define DN_ACCESS 0x00000001 /* File accessed in directory */
#define DN_MODIFY 0x00000002 /* File modified in directory */
#define DN_CREATE 0x00000004 /* File created in directory */
#define DN_DELETE 0x00000008 /* File removed from directory */
#define DN_RENAME 0x00000010 /* File renamed in directory */
#define DN_ATTRIB 0x00000020 /* File changed attribute */
#define DN_MULTISHOT 0x80000000 /* Don't remove notifier */
#endif
#ifndef RT_SIGNAL_NOTIFY
#define RT_SIGNAL_NOTIFY (SIGRTMIN+2)
#endif
#ifndef F_SETSIG
#define F_SETSIG 10
#endif
#ifndef F_NOTIFY
#define F_NOTIFY 1026
#endif
/****************************************************************************
This is the structure to keep the information needed to
determine if a directory has changed.
*****************************************************************************/
struct change_data {
int directory_handle;
};
/****************************************************************************
The signal handler for change notify.
The Linux kernel has a bug in that we should be able to block any
further delivery of RT signals until the kernel_check_notify() function
unblocks them, but it seems that any signal mask we're setting here is
being overwritten on exit from this handler. I should create a standalone
test case for the kernel hackers. JRA.
*****************************************************************************/
static void signal_handler(int sig, siginfo_t *info, void *unused)
{
if (signals_received < FD_PENDING_SIZE - 1) {
fd_pending_array[signals_received] = (SIG_ATOMIC_T)info->si_fd;
signals_received++;
} /* Else signal is lost. */
sys_select_signal();
}
/****************************************************************************
Check if a change notify should be issued.
time non-zero means timeout check (used for hash). Ignore this (async method
where time is zero will be used instead).
*****************************************************************************/
static BOOL kernel_check_notify(connection_struct *conn, uint16 vuid, char *path, uint32 flags, void *datap, time_t t)
{
struct change_data *data = (struct change_data *)datap;
int i;
BOOL ret = False;
if (t)
return False;
BlockSignals(True, RT_SIGNAL_NOTIFY);
for (i = 0; i < signals_received; i++) {
if (data->directory_handle == (int)fd_pending_array[i]) {
DEBUG(3,("kernel_check_notify: kernel change notify on %s fd[%d]=%d (signals_received=%d)\n",
path, i, (int)fd_pending_array[i], (int)signals_received ));
close((int)fd_pending_array[i]);
fd_pending_array[i] = (SIG_ATOMIC_T)-1;
if (signals_received - i - 1) {
memmove(CONST_DISCARD(void *, &fd_pending_array[i]),
CONST_DISCARD(void *, &fd_pending_array[i+1]),
sizeof(SIG_ATOMIC_T)*(signals_received-i-1));
}
data->directory_handle = -1;
signals_received--;
ret = True;
break;
}
}
BlockSignals(False, RT_SIGNAL_NOTIFY);
return ret;
}
/****************************************************************************
Remove a change notify data structure.
*****************************************************************************/
static void kernel_remove_notify(void *datap)
{
struct change_data *data = (struct change_data *)datap;
int fd = data->directory_handle;
if (fd != -1) {
int i;
BlockSignals(True, RT_SIGNAL_NOTIFY);
for (i = 0; i < signals_received; i++) {
if (fd == (int)fd_pending_array[i]) {
fd_pending_array[i] = (SIG_ATOMIC_T)-1;
if (signals_received - i - 1) {
memmove(CONST_DISCARD(void *, &fd_pending_array[i]),
CONST_DISCARD(void *, &fd_pending_array[i+1]),
sizeof(SIG_ATOMIC_T)*(signals_received-i-1));
}
data->directory_handle = -1;
signals_received--;
break;
}
}
close(fd);
BlockSignals(False, RT_SIGNAL_NOTIFY);
}
SAFE_FREE(data);
DEBUG(3,("kernel_remove_notify: fd=%d\n", fd));
}
/****************************************************************************
Register a change notify request.
*****************************************************************************/
static void *kernel_register_notify(connection_struct *conn, char *path, uint32 flags)
{
struct change_data data;
int fd;
unsigned long kernel_flags;
fd = sys_open(path,O_RDONLY, 0);
if (fd == -1) {
DEBUG(3,("Failed to open directory %s for change notify\n", path));
return NULL;
}
if (sys_fcntl_long(fd, F_SETSIG, RT_SIGNAL_NOTIFY) == -1) {
DEBUG(3,("Failed to set signal handler for change notify\n"));
return NULL;
}
kernel_flags = DN_CREATE|DN_DELETE|DN_RENAME; /* creation/deletion changes everything! */
if (flags & FILE_NOTIFY_CHANGE_FILE) kernel_flags |= DN_MODIFY;
if (flags & FILE_NOTIFY_CHANGE_DIR_NAME) kernel_flags |= DN_RENAME|DN_DELETE;
if (flags & FILE_NOTIFY_CHANGE_ATTRIBUTES) kernel_flags |= DN_ATTRIB;
if (flags & FILE_NOTIFY_CHANGE_SIZE) kernel_flags |= DN_MODIFY;
if (flags & FILE_NOTIFY_CHANGE_LAST_WRITE) kernel_flags |= DN_MODIFY;
if (flags & FILE_NOTIFY_CHANGE_LAST_ACCESS) kernel_flags |= DN_ACCESS;
if (flags & FILE_NOTIFY_CHANGE_CREATION) kernel_flags |= DN_CREATE;
if (flags & FILE_NOTIFY_CHANGE_SECURITY) kernel_flags |= DN_ATTRIB;
if (flags & FILE_NOTIFY_CHANGE_EA) kernel_flags |= DN_ATTRIB;
if (flags & FILE_NOTIFY_CHANGE_FILE_NAME) kernel_flags |= DN_RENAME|DN_DELETE;
if (sys_fcntl_long(fd, F_NOTIFY, kernel_flags) == -1) {
DEBUG(3,("Failed to set async flag for change notify\n"));
return NULL;
}
data.directory_handle = fd;
DEBUG(3,("kernel change notify on %s (ntflags=0x%x flags=0x%x) fd=%d\n",
path, (int)flags, (int)kernel_flags, fd));
return (void *)memdup(&data, sizeof(data));
}
/****************************************************************************
See if the kernel supports change notify.
****************************************************************************/
static BOOL kernel_notify_available(void)
{
int fd, ret;
fd = open("/tmp", O_RDONLY);
if (fd == -1)
return False; /* uggh! */
ret = sys_fcntl_long(fd, F_NOTIFY, 0);
close(fd);
return ret == 0;
}
/****************************************************************************
Setup kernel based change notify.
****************************************************************************/
struct cnotify_fns *kernel_notify_init(void)
{
static struct cnotify_fns cnotify;
struct sigaction act;
ZERO_STRUCT(act);
act.sa_handler = NULL;
act.sa_sigaction = signal_handler;
act.sa_flags = SA_SIGINFO;
sigemptyset( &act.sa_mask );
if (sigaction(RT_SIGNAL_NOTIFY, &act, NULL) != 0) {
DEBUG(0,("Failed to setup RT_SIGNAL_NOTIFY handler\n"));
return NULL;
}
if (!kernel_notify_available())
return NULL;
cnotify.register_notify = kernel_register_notify;
cnotify.check_notify = kernel_check_notify;
cnotify.remove_notify = kernel_remove_notify;
cnotify.select_time = -1;
/* the signal can start off blocked due to a bug in bash */
BlockSignals(False, RT_SIGNAL_NOTIFY);
return &cnotify;
}
#else
void notify_kernel_dummy(void) {}
#endif /* HAVE_KERNEL_CHANGE_NOTIFY */
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