sd_event_add_inotify
systemd
sd_event_add_inotify
3
sd_event_add_inotify
sd_event_source_get_inotify_mask
sd_event_inotify_handler_t
Add an "inotify" file system inode event source to an event loop
#include <systemd/sd-event.h>
typedef struct sd_event_source sd_event_source;
typedef int (*sd_event_inotify_handler_t)
sd_event_source *s
const struct inotify_event *event
void *userdata
int sd_event_add_inotify
sd_event *event
sd_event_source **source
const char *path
uint32_t mask
sd_event_inotify_handler_t handler
void *userdata
int sd_event_source_get_inotify_mask
sd_event_source *source
uint32_t *mask
Description
sd_event_add_inotify() adds a new inotify7 file system inode
event source to an event loop. The event loop object is specified in the event parameter,
the event source object is returned in the source parameter. The path
parameter specifies the path of the file system inode to watch. The handler must reference a
function to call when the inode changes. The handler function will be passed the userdata
pointer, which may be chosen freely by the caller. The handler also receives a pointer to a struct
inotify_event structure containing information about the inode event. The mask
parameter specifies which types of inode events to watch specifically. It must contain an OR-ed combination of
IN_ACCESS, IN_ATTRIB, IN_CLOSE_WRITE, … flags. See
inotify7 for
further information.
If multiple event sources are installed for the same inode the backing inotify watch descriptor is
automatically shared. The mask parameter may contain any flag defined by the inotify API, with the exception of
IN_MASK_ADD.
The handler is enabled continuously (SD_EVENT_ON), but this may be changed with
sd_event_source_set_enabled3. Alternatively,
the IN_ONESHOT mask flag may be used to request SD_EVENT_ONESHOT mode.
If the handler function returns a negative error code, it will be disabled after the invocation, even if the
SD_EVENT_ON mode was requested before.
As a special limitation the priority of inotify event sources may only be altered (see
sd_event_source_set_priority3)
in the time between creation of the event source object with sd_event_add_inotify() and the
beginning of the next event loop iteration. Attempts of changing the priority any later will be refused. Consider
freeing and allocating a new inotify event source to change the priority at that point.
To destroy an event source object use
sd_event_source_unref3, but note
that the event source is only removed from the event loop when all references to the event source are dropped. To
make sure an event source does not fire anymore, even when there's still a reference to it kept, consider disabling
it with
sd_event_source_set_enabled3.
If the second parameter of sd_event_add_inotify() is passed as
NULL no reference to the event source object is returned. In this case the event
source is considered "floating", and will be destroyed implicitly when the event loop itself is
destroyed.
If the handler parameter to sd_event_add_inotify() is
NULL, and the event source fires, this will be considered a request to exit the
event loop. In this case, the userdata parameter, cast to an integer, is passed as
the exit code parameter to
sd_event_exit3.
sd_event_source_get_inotify_mask() retrieves the configured inotify watch mask of an
event source created previously with sd_event_add_inotify(). It takes the event source object
as the source parameter and a pointer to a uint32_t variable to return the mask
in.
Return Value
On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
error code.
Errors
Returned errors may indicate the following problems:
-ENOMEM
Not enough memory to allocate an object.
-EINVAL
An invalid argument has been passed. This includes specifying a mask with
IN_MASK_ADD set.
-ESTALE
The event loop is already terminated.
-ECHILD
The event loop has been created in a different process.
-EDOM
The passed event source is not an inotify process event source.
Examples
A simple program that uses inotify to monitor one or two directories
See Also
systemd1,
sd-event3,
sd_event_new3,
sd_event_now3,
sd_event_add_io3,
sd_event_add_time3,
sd_event_add_signal3,
sd_event_add_defer3,
sd_event_add_child3,
sd_event_source_set_enabled3,
sd_event_source_set_priority3,
sd_event_source_set_userdata3,
sd_event_source_set_description3,
sd_event_source_set_floating3,
waitid2