struct monitor_entry {
int fd; /* public file descriptor */
char *path; /* path to the monitored file */
- unsigned int events; /* epoll events or zero */
int type; /* MNT_MONITOR_TYPE_* */
+ unsigned int enable : 1;
+
struct list_head ents;
};
struct list_head ents;
};
+static int monitor_enable_entry(struct libmnt_monitor *mn,
+ struct monitor_entry *me, int enable);
+
/**
* mnt_new_monitor:
*
INIT_LIST_HEAD(&me->ents);
list_add_tail(&me->ents, &mn->ents);
+ me->fd = -1;
+
return me;
}
+static struct monitor_entry *monitor_get_entry(struct libmnt_monitor *mn, int type)
+{
+ struct list_head *p;
+
+ assert(mn);
+ assert(type);
+
+ list_for_each(p, &mn->ents) {
+ struct monitor_entry *me;
+
+ me = list_entry(p, struct monitor_entry, ents);
+ if (me->type == type)
+ return me;
+ }
+
+ return NULL;
+}
+
+static struct monitor_entry *monitor_get_entry_by_fd(struct libmnt_monitor *mn, int fd)
+{
+ struct list_head *p;
+
+ assert(mn);
+
+ if (fd < 0)
+ return NULL;
+
+ list_for_each(p, &mn->ents) {
+ struct monitor_entry *me;
+
+ me = list_entry(p, struct monitor_entry, ents);
+ if (me->fd == fd)
+ return me;
+ }
+
+ DBG(MONITOR, ul_debugobj(mn, "failed to get entry for fd=%d", fd));
+ return NULL;
+}
+
+
+
/**
- * mnt_monitor_userspace_get_fd:
- * @mn: monitor pointer
+ * mnt_monitor_enable_userspace:
+ * @mn: monitor
+ * @enable: 0 or 1
* @filename: overwrites default
*
- * The kernel mount tables (/proc/mounts and /proc/self/mountinfo) are possible
- * to monitor by [e]poll(). This function provides the same for userspace mount
- * table.
- *
- * The userspace mount table is originaly /etc/mtab or on systems without mtab
- * it's private libmount utab file.
+ * Enables or disables userspace monitor. If the monitor does not exist and
+ * enable=1 then allocates new resources necessary for the monitor.
*
- * The userspace mount tables are updated by rename(2), this requires that all
- * dictionary with the mount table is monitored. Be careful on systems with
- * regular /etc (see mnt_has_regular_mtab()).
+ * If high-level monitor has been already initialized (by mnt_monitor_get_fd()
+ * or mnt_wait_monitor()) then it's updated according to @enable.
*
- * Use mnt_monitor_userspace_get_events() to get epoll events mask (e.g
- * EPOLLIN, ...).
- *
- * Use mnt_monitor_is_changed() to verify that events on the @fd are really
- * relevant for userspace moutn table.
+ * The @filename is used only first time when you enable the monitor. It's
+ * impossible to have more than one userspace monitor.
*
- * If the change is detected then you can use mnt_table_parse_mtab() to parse
- * the file and mnt_diff_tables() to compare old and new version of the file.
+ * Note that the current implementation of the userspace monitor is based on
+ * inotify. On systems (libc) without inotify_init1() the function return
+ * -ENOSYS. The dependence on inotify is implemenation specific and may be
+ * changed later.
*
- * Returns: <0 on error or file descriptor.
+ * Return: 0 on success and <0 on error
*/
-#ifdef HAVE_INOTIFY_INIT1
-int mnt_monitor_userspace_get_fd(struct libmnt_monitor *mn, const char *filename)
+int mnt_monitor_enable_userspace(struct libmnt_monitor *mn, int enable, const char *filename)
{
struct monitor_entry *me;
- int rc = 0, wd;
- char *dirname, *sep;
+ int rc = 0;
- assert(mn);
+ if (!mn)
+ return -EINVAL;
+
+ me = monitor_get_entry(mn, MNT_MONITOR_TYPE_USERSPACE);
+ if (me)
+ return monitor_enable_entry(mn, me, enable);
+ if (!enable)
+ return 0;
+ DBG(MONITOR, ul_debugobj(mn, "allocate new userspace monitor"));
+
+ /* create a new entry */
+ if (!mnt_has_regular_mtab(&filename, NULL)) /* /etc/mtab */
+ filename = mnt_get_utab_path(); /* /run/mount/utab */
if (!filename) {
- if (!mnt_has_regular_mtab(&filename, NULL)) /* /etc/mtab */
- filename = mnt_get_utab_path(); /* /run/mount/utab */
- if (!filename) {
- DBG(MONITOR, ul_debugobj(mn, "failed to get userspace mount table path"));
- return -EINVAL;
- }
+ DBG(MONITOR, ul_debugobj(mn, "failed to get userspace mount table path"));
+ return -EINVAL;
}
- DBG(MONITOR, ul_debugobj(mn, "new userspace monitor for %s requested", filename));
-
me = monitor_new_entry(mn);
if (!me)
goto err;
if (!me->path)
goto err;
+ DBG(MONITOR, ul_debugobj(mn, "allocate new userspace monitor: OK"));
+ return monitor_enable_entry(mn, me, 1);
+err:
+ rc = -errno;
+ free_monitor_entry(me);
+ return rc;
+}
+
+/**
+ * mnt_monitor_userspace_get_fd:
+ * @mn: monitor pointer
+ *
+ * Returns: file descriptor to previously enabled userspace monitor or <0 on error.
+ */
+#ifdef HAVE_INOTIFY_INIT1
+int mnt_monitor_userspace_get_fd(struct libmnt_monitor *mn)
+{
+ struct monitor_entry *me;
+ int wd, rc;
+ char *dirname, *sep;
+
+ assert(mn);
+
+ me = monitor_get_entry(mn, MNT_MONITOR_TYPE_USERSPACE);
+ if (!me || me->enable == 0) /* not-initialized or disabled */
+ return -EINVAL;
+
+ if (me->fd >= 0)
+ return me->fd; /* already initialized */
+
+ assert(me->path);
+ DBG(MONITOR, ul_debugobj(mn, "open userspace monitor for %s", me->path));
+
dirname = me->path;
sep = stripoff_last_component(dirname); /* add \0 between dir/filename */
if (sep && sep > dirname)
*(sep - 1) = '/'; /* set '/' back to the path */
- me->events = EPOLLIN | EPOLLPRI;
-
DBG(MONITOR, ul_debugobj(mn, "new fd=%d", me->fd));
return me->fd;
err:
- rc = -errno;
- free_monitor_entry(me);
- return rc;
-}
-#else /* HAVE_INOTIFY_INIT1 */
-int mnt_monitor_userspace_get_fd(struct libmnt_monitor *mn __attribute__((unused)),
- const char *filename __attribute__((unused)))
-{
- return -ENOSYS;
+ return -errno;
}
-#endif
-static struct monitor_entry *get_monitor_entry(struct libmnt_monitor *mn, int fd)
+static int monitor_userspace_is_changed(struct libmnt_monitor *mn,
+ struct monitor_entry *me)
{
- struct list_head *p;
+ char wanted[NAME_MAX + 1];
+ char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
+ struct inotify_event *event;
+ char *p;
+ ssize_t r;
+ int rc = 0;
- assert(mn);
+ DBG(MONITOR, ul_debugobj(mn, "checking fd=%d for userspace changes", me->fd));
- if (fd < 0)
- return NULL;
+ p = strrchr(me->path, '/');
+ if (!p)
+ p = me->path;
+ else
+ p++;
+ strncpy(wanted, p, sizeof(wanted) - 1);
+ wanted[sizeof(wanted) - 1] = '\0';
+ rc = 0;
- list_for_each(p, &mn->ents) {
- struct monitor_entry *me;
+ DBG(MONITOR, ul_debugobj(mn, "wanted file: '%s'", wanted));
- me = list_entry(p, struct monitor_entry, ents);
- if (me->fd == fd)
- return me;
+ while ((r = read(me->fd, buf, sizeof(buf))) > 0) {
+ for (p = buf; p < buf + r; ) {
+ event = (struct inotify_event *) p;
+
+ if (strcmp(event->name, wanted) == 0)
+ rc = 1;
+ p += sizeof(struct inotify_event) + event->len;
+ }
+ if (rc)
+ break;
}
- DBG(MONITOR, ul_debugobj(mn, "failed to get entry for fd=%d", fd));
- return NULL;
+ return rc;
}
-/**
- * mnt_monitor_get_events:
- * @mn: monitor
- * @fd: event file descriptor
- * @event: returns epoll event mask
- *
- * Returns: on on success, <0 on error.
- */
-int mnt_monitor_get_events(struct libmnt_monitor *mn, int fd, unsigned int *event)
+#else /* HAVE_INOTIFY_INIT1 */
+int mnt_monitor_enable_userspace(
+ struct libmnt_monitor *mn __attribute__((unused)),
+ int enable __attribute__((unused)),
+ const char *filename __attribute__((unused)))
+{
+ return -ENOSYS;
+}
+int mnt_monitor_userspace_get_fd(
+ struct libmnt_monitor *mn __attribute__((unused)))
+{
+ return -ENOSYS;
+}
+#endif
+
+static int monitor_enable_entry(struct libmnt_monitor *mn,
+ struct monitor_entry *me, int enable)
{
- struct monitor_entry *me = get_monitor_entry(mn, fd);
+ assert(mn);
+ assert(me);
- if (!me || !event)
- return -EINVAL;
- *event = me->events;
+ me->enable = enable ? 1 : 0;
+
+ /* TODO : remove / add me->fd to high-level*/
return 0;
}
*/
const char *mnt_monitor_get_filename(struct libmnt_monitor *mn, int fd)
{
- struct monitor_entry *me = get_monitor_entry(mn, fd);
+ struct monitor_entry *me = monitor_get_entry_by_fd(mn, fd);
if (!me)
return NULL;
*/
int mnt_monitor_is_changed(struct libmnt_monitor *mn, int fd)
{
- struct monitor_entry *me = get_monitor_entry(mn, fd);
+ struct monitor_entry *me = monitor_get_entry_by_fd(mn, fd);
int rc = 0;
if (!me)
return 0;
-
switch (me->type) {
-#ifdef HAVE_INOTIFY_INIT1
case MNT_MONITOR_TYPE_USERSPACE:
- {
- char wanted[NAME_MAX + 1];
- char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
- struct inotify_event *event;
- char *p;
- ssize_t r;
-
- DBG(MONITOR, ul_debugobj(mn, "checking fd=%d for userspace changes", me->fd));
-
- p = strrchr(me->path, '/');
- if (!p)
- p = me->path;
- else
- p++;
- strncpy(wanted, p, sizeof(wanted) - 1);
- wanted[sizeof(wanted) - 1] = '\0';
- rc = 0;
-
- DBG(MONITOR, ul_debugobj(mn, "wanted file: '%s'", wanted));
-
- while ((r = read(me->fd, buf, sizeof(buf))) > 0) {
- for (p = buf; p < buf + r; ) {
- event = (struct inotify_event *) p;
-
- if (strcmp(event->name, wanted) == 0)
- rc = 1;
- p += sizeof(struct inotify_event) + event->len;
- }
- if (rc)
- break;
- }
+ rc = monitor_userspace_is_changed(mn, me);
break;
- }
-#endif
default:
return 0;
}
goto done;
}
- /* monitor userspace mount table changes */
- fd = mnt_monitor_userspace_get_fd(mn, NULL);
+ if (mnt_monitor_enable_userspace(mn, TRUE, NULL)) {
+ warn("failed to initialize userspace monitor");
+ goto done;
+ }
+
+ fd = mnt_monitor_userspace_get_fd(mn);
if (fd < 0) {
- warn("failed to initialize userspace mount table fd");
+ warn("failed to initialize userspace monitor fd");
goto done;
}
goto done;
}
- mnt_monitor_get_events(mn, fd, &ev.events);
+ ev.events = EPOLLPRI | EPOLLIN;
/* set data is necessary only if you want to use epoll for more file
* descriptors, then epoll_wait() returns data associated with the file
int main(int argc, char *argv[])
{
struct libmnt_test tss[] = {
- { "--monitor", test_monitor, "print change" },
+ { "--low-userspace", test_monitor, "tests low-level userspace monitor" },
{ NULL }
};
projects / thirdparty / util-linux.git / commitdiff
