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fanotify: send events using read

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Send events to userspace by reading the file descriptor from fanotify_init().
One will get blocks of data which look like:

struct fanotify_event_metadata {
	__u32 event_len;
	__u32 vers;
	__s32 fd;
	__u64 mask;
	__s64 pid;
	__u64 cookie;
} __attribute__ ((packed));

Simple code to retrieve and deal with events is below

	while ((len = read(fan_fd, buf, sizeof(buf))) > 0) {
		struct fanotify_event_metadata *metadata;

		metadata = (void *)buf;
		while(FAN_EVENT_OK(metadata, len)) {
			[PROCESS HERE!!]
			if (metadata->fd >= 0 && close(metadata->fd) != 0)
				goto fail;
			metadata = FAN_EVENT_NEXT(metadata, len);
		}
	}

Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris 2009-12-17 21:24:26 -05:00
parent 2a3edf8604
commit a1014f1023
3 changed files with 245 additions and 4 deletions
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24
include/linux/fanotify.h
View file

@ -51,6 +51,30 @@
*/
#define FAN_ALL_INCOMING_EVENTS (FAN_ALL_EVENTS |\
FAN_EVENT_ON_CHILD)
#define FAN_ALL_OUTGOING_EVENTS (FAN_ALL_EVENTS |\
FAN_Q_OVERFLOW)
#define FANOTIFY_METADATA_VERSION 1
struct fanotify_event_metadata {
__u32 event_len;
__u32 vers;
__s32 fd;
__u64 mask;
} __attribute__ ((packed));
/* Helper functions to deal with fanotify_event_metadata buffers */
#define FAN_EVENT_METADATA_LEN (sizeof(struct fanotify_event_metadata))
#define FAN_EVENT_NEXT(meta, len) ((len) -= (meta)->event_len, \
(struct fanotify_event_metadata*)(((char *)(meta)) + \
(meta)->event_len))
#define FAN_EVENT_OK(meta, len) ((long)(len) >= (long)FAN_EVENT_METADATA_LEN && \
(long)(meta)->event_len >= (long)FAN_EVENT_METADATA_LEN && \
(long)(meta)->event_len <= (long)(len))
#ifdef __KERNEL__
#endif /* __KERNEL__ */