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samba-mirror/source3/smbd/notify_fam.c

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/*
* FAM file notification support.
*
* Copyright (c) James Peach 2005
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "includes.h"
#ifdef HAVE_FAM_CHANGE_NOTIFY
#include <fam.h>
/* NOTE: There are multiple versions of FAM floating around the net, each with
* slight differences from the original SGI FAM implementation. In this file,
* we rely only on the SGI features and do not assume any extensions. For
* example, we do not look at FAMErrno, because it is not set by the original
* implementation.
*
* Random FAM links:
* http://oss.sgi.com/projects/fam/
* http://savannah.nongnu.org/projects/fam/
* http://sourceforge.net/projects/bsdfam/
*/
struct fam_req_info
{
FAMRequest req;
int generation;
enum FAMCodes code;
enum
{
/* We are waiting for an event. */
FAM_REQ_MONITORING,
/* An event has been receive, but we haven't been able to send it back
* to the client yet. It is stashed in the code member.
*/
FAM_REQ_FIRED
} state;
};
/* Don't initialise this until the first register request. We want a single
* FAM connection for each worker smbd. If we allow the master (parent) smbd to
* open a FAM connection, multiple processes talking on the same socket will
* undoubtedly create havoc.
*/
static FAMConnection global_fc;
static int global_fc_generation;
#define FAM_TRACE 8
#define FAM_TRACE_LOW 10
#define FAM_EVENT_DRAIN ((uint32_t)(-1))
static void * fam_register_notify(connection_struct * conn,
char * path,
uint32 flags);
static BOOL fam_check_notify(connection_struct * conn,
uint16_t vuid,
char * path,
uint32_t flags,
void * data,
time_t when);
static void fam_remove_notify(void * data);
static struct cnotify_fns global_fam_notify =
{
fam_register_notify,
fam_check_notify,
fam_remove_notify,
-1,
-1
};
/* Turn a FAM event code into a string. Don't rely on specific code values,
* because that might not work across all flavours of FAM.
*/
static const char *
fam_event_str(enum FAMCodes code)
{
static struct { enum FAMCodes code; const char * name; } evstr[] =
{
{ FAMChanged, "FAMChanged"},
{ FAMDeleted, "FAMDeleted"},
{ FAMStartExecuting, "FAMStartExecuting"},
{ FAMStopExecuting, "FAMStopExecuting"},
{ FAMCreated, "FAMCreated"},
{ FAMMoved, "FAMMoved"},
{ FAMAcknowledge, "FAMAcknowledge"},
{ FAMExists, "FAMExists"},
{ FAMEndExist, "FAMEndExist"}
};
int i;
for (i = 0; i < ARRAY_SIZE(evstr); ++i) {
if (code == evstr[i].code)
return(evstr[i].name);
}
return("<unknown>");
}
static BOOL
fam_check_reconnect(void)
{
if (FAMCONNECTION_GETFD(&global_fc) < 0) {
fstring name;
global_fc_generation++;
snprintf(name, sizeof(name), "smbd (%lu)", (unsigned long)sys_getpid());
if (FAMOpen2(&global_fc, name) < 0) {
DEBUG(0, ("failed to connect to FAM service\n"));
return(False);
}
}
global_fam_notify.notification_fd = FAMCONNECTION_GETFD(&global_fc);
return(True);
}
static BOOL
fam_monitor_path(connection_struct * conn,
struct fam_req_info * info,
const char * path,
uint32 flags)
{
SMB_STRUCT_STAT st;
pstring fullpath;
DEBUG(FAM_TRACE, ("requesting FAM notifications for '%s'\n", path));
/* FAM needs an absolute pathname. */
/* It would be better to use reduce_name() here, but reduce_name does not
* actually return the reduced result. How utterly un-useful.
*/
pstrcpy(fullpath, path);
if (!canonicalize_path(conn, fullpath)) {
DEBUG(0, ("failed to canonicalize path '%s'\n", path));
return(False);
}
if (*fullpath != '/') {
DEBUG(0, ("canonicalized path '%s' into `%s`\n", path, fullpath));
DEBUGADD(0, ("but expected an absolute path\n"));
return(False);
}
if (SMB_VFS_STAT(conn, path, &st) < 0) {
DEBUG(0, ("stat of '%s' failed: %s\n", path, strerror(errno)));
return(False);
}
/* Start monitoring this file or directory. We hand the state structure to
* both the caller and the FAM library so we can match up the caller's
* status requests with FAM notifications.
*/
if (S_ISDIR(st.st_mode)) {
FAMMonitorDirectory(&global_fc, fullpath, &(info->req), info);
} else {
FAMMonitorFile(&global_fc, fullpath, &(info->req), info);
}
/* Grr. On IRIX, neither of the monitor functions return a status. */
/* We will stay in initialising state until we see the FAMendExist message
* for this file.
*/
info->state = FAM_REQ_MONITORING;
info->generation = global_fc_generation;
return(True);
}
static BOOL
fam_handle_event(enum FAMCodes code, uint32 flags)
{
#define F_CHANGE_MASK (FILE_NOTIFY_CHANGE_FILE | \
FILE_NOTIFY_CHANGE_ATTRIBUTES | \
FILE_NOTIFY_CHANGE_SIZE | \
FILE_NOTIFY_CHANGE_LAST_WRITE | \
FILE_NOTIFY_CHANGE_LAST_ACCESS | \
FILE_NOTIFY_CHANGE_CREATION | \
FILE_NOTIFY_CHANGE_EA | \
FILE_NOTIFY_CHANGE_SECURITY)
#define F_DELETE_MASK (FILE_NOTIFY_CHANGE_FILE_NAME | \
FILE_NOTIFY_CHANGE_DIR_NAME)
#define F_CREATE_MASK (FILE_NOTIFY_CHANGE_FILE_NAME | \
FILE_NOTIFY_CHANGE_DIR_NAME)
switch (code) {
case FAMChanged:
if (flags & F_CHANGE_MASK)
return(True);
break;
case FAMDeleted:
if (flags & F_DELETE_MASK)
return(True);
break;
case FAMCreated:
if (flags & F_CREATE_MASK)
return(True);
break;
default:
/* Ignore anything else. */
break;
}
return(False);
#undef F_CHANGE_MASK
#undef F_DELETE_MASK
#undef F_CREATE_MASK
}
static BOOL
fam_pump_events(struct fam_req_info * info, uint32_t flags)
{
FAMEvent ev;
for (;;) {
/* If we are draining the event queue we must keep going until we find
* the correct FAMAcknowledge event or the connection drops. Otherwise
* we should stop when there are no more events pending.
*/
if (flags != FAM_EVENT_DRAIN && !FAMPending(&global_fc)) {
break;
}
if (FAMNextEvent(&global_fc, &ev) < 0) {
DEBUG(0, ("failed to fetch pending FAM event\n"));
DEBUGADD(0, ("resetting FAM connection\n"));
FAMClose(&global_fc);
FAMCONNECTION_GETFD(&global_fc) = -1;
return(False);
}
DEBUG(FAM_TRACE_LOW, ("FAM event %s on '%s' for request %d\n",
fam_event_str(ev.code), ev.filename, ev.fr.reqnum));
switch (ev.code) {
case FAMAcknowledge:
/* FAM generates an ACK event when we cancel a monitor. We need
* this to know when it is safe to free out request state
* structure.
*/
if (info->generation == global_fc_generation &&
info->req.reqnum == ev.fr.reqnum &&
flags == FAM_EVENT_DRAIN) {
return(True);
}
case FAMEndExist:
case FAMExists:
/* Ignore these. FAM sends these enumeration events when we
* start monitoring. If we are monitoring a directory, we will
* get a FAMExists event for each directory entry.
*/
/* TODO: we might be able to use these to implement recursive
* monitoring of entire subtrees.
*/
case FAMMoved:
/* These events never happen. A move or rename shows up as a
* create/delete pair.
*/
case FAMStartExecuting:
case FAMStopExecuting:
/* We might get these, but we just don't care. */
break;
case FAMChanged:
case FAMDeleted:
case FAMCreated:
if (info->generation != global_fc_generation) {
/* Ignore this; the req number can't be matched. */
break;
}
if (info->req.reqnum == ev.fr.reqnum) {
/* This is the event the caller was interested in. */
DEBUG(FAM_TRACE, ("handling FAM %s event on '%s'\n",
fam_event_str(ev.code), ev.filename));
/* Ignore events if we are draining this request. */
if (flags != FAM_EVENT_DRAIN) {
return(fam_handle_event(ev.code, flags));
}
break;
} else {
/* Caller doesn't want this event. Stash the result so we
* can come back to it. Unfortunately, FAM doesn't
* guarantee to give us back evinfo.
*/
struct fam_req_info * evinfo =
(struct fam_req_info *)ev.userdata;
if (evinfo) {
DEBUG(FAM_TRACE, ("storing FAM %s event for winter\n",
fam_event_str(ev.code)));
evinfo->state = FAM_REQ_FIRED;
evinfo->code = ev.code;
} else {
DEBUG(2, ("received FAM %s notification for %s, "
"but userdata was unexpectedly NULL\n",
fam_event_str(ev.code), ev.filename));
}
break;
}
default:
DEBUG(0, ("ignoring unknown FAM event code %d for `%s`\n",
ev.code, ev.filename));
}
}
/* No more notifications pending. */
return(False);
}
static BOOL
fam_test_connection(void)
{
FAMConnection fc;
/* On IRIX FAMOpen2 leaks 960 bytes in 48 blocks. It's a deliberate leak
* in the library and there's nothing we can do about it here.
*/
if (FAMOpen2(&fc, "smbd probe") < 0)
return(False);
FAMClose(&fc);
return(True);
}
/* ------------------------------------------------------------------------- */
static void *
fam_register_notify(connection_struct * conn,
char * path,
uint32 flags)
{
struct fam_req_info * info;
if (!fam_check_reconnect()) {
return(False);
}
if ((info = SMB_MALLOC_P(struct fam_req_info)) == NULL) {
DEBUG(0, ("malloc of %d bytes failed\n", sizeof(struct fam_req_info)));
return(NULL);
}
if (fam_monitor_path(conn, info, path, flags)) {
return(info);
} else {
SAFE_FREE(info);
return(NULL);
}
}
static BOOL
fam_check_notify(connection_struct * conn,
uint16_t vuid,
char * path,
uint32_t flags,
void * data,
time_t when)
{
struct fam_req_info * info;
info = (struct fam_req_info *)data;
SMB_ASSERT(info != NULL);
DEBUG(10, ("checking FAM events for `%s`\n", path));
if (info->state == FAM_REQ_FIRED) {
DEBUG(FAM_TRACE, ("handling previously fired FAM %s event\n",
fam_event_str(info->code)));
info->state = FAM_REQ_MONITORING;
return(fam_handle_event(info->code, flags));
}
if (!fam_check_reconnect()) {
return(False);
}
if (info->generation != global_fc_generation) {
DEBUG(FAM_TRACE, ("reapplying stale FAM monitor to %s\n", path));
fam_monitor_path(conn, info, path, flags);
return(False);
}
return(fam_pump_events(info, flags));
}
static void
fam_remove_notify(void * data)
{
struct fam_req_info * info;
if ((info = (struct fam_req_info *)data) == NULL)
return;
/* No need to reconnect. If the FAM connection is gone, there's no need to
* cancel and we can safely let FAMCancelMonitor fail. If it we
* reconnected, then the generation check will stop us cancelling the wrong
* request.
*/
if (info->generation == global_fc_generation) {
DEBUG(FAM_TRACE, ("removing FAM notification for request %d\n",
info->req.reqnum));
FAMCancelMonitor(&global_fc, &(info->req));
/* Soak up all events until the FAMAcknowledge. We can't free
* our request state until we are sure there are no more events in
* flight.
*/
fam_pump_events(info, FAM_EVENT_DRAIN);
}
SAFE_FREE(info);
}
struct cnotify_fns * fam_notify_init(void)
{
FAMCONNECTION_GETFD(&global_fc) = -1;
if (!fam_test_connection()) {
DEBUG(0, ("FAM file change notifications not available\n"));
return(NULL);
}
DEBUG(FAM_TRACE, ("enabling FAM change notifications\n"));
return &global_fam_notify;
}
#endif /* HAVE_FAM_CHANGE_NOTIFY */