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samba-mirror/source3/smbd/notify_inotify.c

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/*
Unix SMB/CIFS implementation.
Copyright (C) Andrew Tridgell 2006
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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 3 of the License, or
(at your option) any later version.
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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.
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You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
notify implementation using inotify
*/
#include "includes.h"
#include "../librpc/gen_ndr/notify.h"
#include "smbd/smbd.h"
#include "lib/util/sys_rw_data.h"
#include <sys/inotify.h>
/* glibc < 2.5 headers don't have these defines */
#ifndef IN_ONLYDIR
#define IN_ONLYDIR 0x01000000
#endif
#ifndef IN_MASK_ADD
#define IN_MASK_ADD 0x20000000
#endif
struct inotify_private {
struct sys_notify_context *ctx;
int fd;
struct inotify_watch_context *watches;
};
struct inotify_watch_context {
struct inotify_watch_context *next, *prev;
struct inotify_private *in;
int wd;
void (*callback)(struct sys_notify_context *ctx,
void *private_data,
struct notify_event *ev,
uint32_t filter);
void *private_data;
uint32_t mask; /* the inotify mask */
uint32_t filter; /* the windows completion filter */
const char *path;
};
/*
map from a change notify mask to a inotify mask. Remove any bits
which we can handle
*/
static const struct {
uint32_t notify_mask;
uint32_t inotify_mask;
} inotify_mapping[] = {
{FILE_NOTIFY_CHANGE_FILE_NAME, IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
{FILE_NOTIFY_CHANGE_DIR_NAME, IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},
{FILE_NOTIFY_CHANGE_ATTRIBUTES, IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},
{FILE_NOTIFY_CHANGE_LAST_WRITE, IN_ATTRIB},
{FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},
{FILE_NOTIFY_CHANGE_EA, IN_ATTRIB},
{FILE_NOTIFY_CHANGE_SECURITY, IN_ATTRIB}
};
static uint32_t inotify_map(uint32_t *filter)
{
size_t i;
uint32_t out=0;
for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {
if (inotify_mapping[i].notify_mask & *filter) {
out |= inotify_mapping[i].inotify_mask;
*filter &= ~inotify_mapping[i].notify_mask;
}
}
return out;
}
/*
* Map inotify mask back to filter. This returns all filters that
* could have created the inotify watch.
*/
static uint32_t inotify_map_mask_to_filter(uint32_t mask)
{
size_t i;
uint32_t filter = 0;
for (i = 0; i < ARRAY_SIZE(inotify_mapping); i++) {
if (inotify_mapping[i].inotify_mask & mask) {
filter |= inotify_mapping[i].notify_mask;
}
}
if (mask & IN_ISDIR) {
filter &= ~FILE_NOTIFY_CHANGE_FILE_NAME;
} else {
filter &= ~FILE_NOTIFY_CHANGE_DIR_NAME;
}
return filter;
}
/*
destroy the inotify private context
*/
static int inotify_destructor(struct inotify_private *in)
{
close(in->fd);
return 0;
}
/*
see if a particular event from inotify really does match a requested
notify event in SMB
*/
static bool filter_match(struct inotify_watch_context *w,
struct inotify_event *e)
{
bool ok;
DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",
e->mask, w->mask, w->filter));
if ((e->mask & w->mask) == 0) {
/* this happens because inotify_add_watch() coalesces watches on the same
path, oring their masks together */
return False;
}
/* SMB separates the filters for files and directories */
if (e->mask & IN_ISDIR) {
ok = ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) != 0);
return ok;
}
if ((e->mask & IN_ATTRIB) &&
(w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|
FILE_NOTIFY_CHANGE_LAST_WRITE|
FILE_NOTIFY_CHANGE_LAST_ACCESS|
FILE_NOTIFY_CHANGE_EA|
FILE_NOTIFY_CHANGE_SECURITY))) {
return True;
}
if ((e->mask & IN_MODIFY) &&
(w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {
return True;
}
ok = ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) != 0);
return ok;
}
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/*
dispatch one inotify event
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the cookies are used to correctly handle renames
*/
static void inotify_dispatch(struct inotify_private *in,
struct inotify_event *e,
int prev_wd,
uint32_t prev_cookie,
struct inotify_event *e2)
{
struct inotify_watch_context *w, *next;
struct notify_event ne;
uint32_t filter;
DEBUG(10, ("inotify_dispatch called with mask=%x, name=[%s]\n",
e->mask, e->len ? e->name : ""));
/* ignore extraneous events, such as unmount and IN_IGNORED events */
if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|
IN_MOVED_FROM|IN_MOVED_TO)) == 0) {
return;
}
/* map the inotify mask to a action. This gets complicated for
renames */
if (e->mask & IN_CREATE) {
ne.action = NOTIFY_ACTION_ADDED;
} else if (e->mask & IN_DELETE) {
ne.action = NOTIFY_ACTION_REMOVED;
} else if (e->mask & IN_MOVED_FROM) {
if (e2 != NULL && e2->cookie == e->cookie &&
e2->wd == e->wd) {
ne.action = NOTIFY_ACTION_OLD_NAME;
} else {
ne.action = NOTIFY_ACTION_REMOVED;
}
} else if (e->mask & IN_MOVED_TO) {
if ((e->cookie == prev_cookie) && (e->wd == prev_wd)) {
ne.action = NOTIFY_ACTION_NEW_NAME;
} else {
ne.action = NOTIFY_ACTION_ADDED;
}
} else {
ne.action = NOTIFY_ACTION_MODIFIED;
}
ne.path = e->name;
filter = inotify_map_mask_to_filter(e->mask);
DBG_DEBUG("ne.action = %d, ne.path = %s, filter = %d\n",
ne.action, ne.path, filter);
/* find any watches that have this watch descriptor */
for (w=in->watches;w;w=next) {
next = w->next;
if (w->wd == e->wd && filter_match(w, e)) {
ne.dir = w->path;
w->callback(in->ctx, w->private_data, &ne, filter);
}
}
if ((ne.action == NOTIFY_ACTION_NEW_NAME) &&
((e->mask & IN_ISDIR) == 0)) {
/*
* SMB expects a file rename to generate three events, two for
* the rename and the other for a modify of the
* destination. Strange!
*/
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ne.action = NOTIFY_ACTION_MODIFIED;
e->mask = IN_ATTRIB;
for (w=in->watches;w;w=next) {
next = w->next;
if (w->wd == e->wd && filter_match(w, e) &&
!(w->filter & FILE_NOTIFY_CHANGE_CREATION)) {
ne.dir = w->path;
w->callback(in->ctx, w->private_data, &ne,
filter);
}
}
}
}
/*
called when the kernel has some events for us
*/
static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,
uint16_t flags, void *private_data)
{
struct inotify_private *in = talloc_get_type(private_data,
struct inotify_private);
int bufsize = 0;
struct inotify_event *e0, *e;
uint32_t prev_cookie=0;
int prev_wd = -1;
ssize_t ret;
/*
we must use FIONREAD as we cannot predict the length of the
filenames, and thus can't know how much to allocate
otherwise
*/
if (ioctl(in->fd, FIONREAD, &bufsize) != 0 ||
bufsize == 0) {
DEBUG(0,("No data on inotify fd?!\n"));
TALLOC_FREE(fde);
return;
}
e0 = e = (struct inotify_event *)TALLOC_SIZE(in, bufsize + 1);
if (e == NULL) return;
((uint8_t *)e)[bufsize] = '\0';
ret = read_data(in->fd, e0, bufsize);
if (ret != bufsize) {
DEBUG(0, ("Failed to read all inotify data - %s\n",
strerror(errno)));
talloc_free(e0);
/* the inotify fd will now be out of sync,
* can't keep reading data off it */
TALLOC_FREE(fde);
return;
}
/* we can get more than one event in the buffer */
while (e && (bufsize >= sizeof(*e))) {
struct inotify_event *e2 = NULL;
bufsize -= e->len + sizeof(*e);
if (bufsize >= sizeof(*e)) {
e2 = (struct inotify_event *)(e->len + sizeof(*e) + (char *)e);
}
inotify_dispatch(in, e, prev_wd, prev_cookie, e2);
prev_wd = e->wd;
prev_cookie = e->cookie;
e = e2;
}
talloc_free(e0);
}
/*
setup the inotify handle - called the first time a watch is added on
this context
*/
static int inotify_setup(struct sys_notify_context *ctx)
{
struct inotify_private *in;
struct tevent_fd *fde;
in = talloc(ctx, struct inotify_private);
if (in == NULL) {
return ENOMEM;
}
in->fd = inotify_init();
if (in->fd == -1) {
int ret = errno;
DEBUG(0, ("Failed to init inotify - %s\n", strerror(ret)));
talloc_free(in);
return ret;
}
in->ctx = ctx;
in->watches = NULL;
ctx->private_data = in;
talloc_set_destructor(in, inotify_destructor);
/* add a event waiting for the inotify fd to be readable */
fde = tevent_add_fd(ctx->ev, in, in->fd, TEVENT_FD_READ,
inotify_handler, in);
if (fde == NULL) {
ctx->private_data = NULL;
TALLOC_FREE(in);
return ENOMEM;
}
return 0;
}
/*
destroy a watch
*/
static int watch_destructor(struct inotify_watch_context *w)
{
struct inotify_private *in = w->in;
int wd = w->wd;
DLIST_REMOVE(w->in->watches, w);
for (w=in->watches;w;w=w->next) {
if (w->wd == wd) {
/*
* Another inotify_watch_context listens on this path,
* leave the kernel level watch in place
*/
return 0;
}
}
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DEBUG(10, ("Deleting inotify watch %d\n", wd));
if (inotify_rm_watch(in->fd, wd) == -1) {
DEBUG(1, ("inotify_rm_watch returned %s\n", strerror(errno)));
}
return 0;
}
/*
add a watch. The watch is removed when the caller calls
talloc_free() on *handle
*/
int inotify_watch(TALLOC_CTX *mem_ctx,
struct sys_notify_context *ctx,
const char *path,
uint32_t *filter,
uint32_t *subdir_filter,
void (*callback)(struct sys_notify_context *ctx,
void *private_data,
struct notify_event *ev,
uint32_t filter),
void *private_data,
void *handle_p)
{
struct inotify_private *in;
uint32_t mask;
struct inotify_watch_context *w;
uint32_t orig_filter = *filter;
void **handle = (void **)handle_p;
/* maybe setup the inotify fd */
if (ctx->private_data == NULL) {
int ret;
ret = inotify_setup(ctx);
if (ret != 0) {
return ret;
}
}
in = talloc_get_type(ctx->private_data, struct inotify_private);
mask = inotify_map(filter);
if (mask == 0) {
/* this filter can't be handled by inotify */
return EINVAL;
}
/* using IN_MASK_ADD allows us to cope with inotify() returning the same
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watch descriptor for multiple watches on the same path */
mask |= (IN_MASK_ADD | IN_ONLYDIR);
w = talloc(mem_ctx, struct inotify_watch_context);
if (w == NULL) {
*filter = orig_filter;
return ENOMEM;
}
w->in = in;
w->callback = callback;
w->private_data = private_data;
w->mask = mask;
w->filter = orig_filter;
w->path = talloc_strdup(w, path);
if (w->path == NULL) {
*filter = orig_filter;
TALLOC_FREE(w);
return ENOMEM;
}
/* get a new watch descriptor for this path */
w->wd = inotify_add_watch(in->fd, path, mask);
if (w->wd == -1) {
int err = errno;
*filter = orig_filter;
TALLOC_FREE(w);
DEBUG(1, ("inotify_add_watch returned %s\n", strerror(err)));
return err;
}
DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",
path, mask, w->wd));
(*handle) = w;
DLIST_ADD(in->watches, w);
/* the caller frees the handle to stop watching */
talloc_set_destructor(w, watch_destructor);
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return 0;
}