lsyncd/fsevents.c

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/** fsevents.c from Lsyncd - Live (Mirror) Syncing Demon
*
* License: GPLv2 (see COPYING) or any later version
*
* Authors: Axel Kittenberger <axkibe@gmail.com>
*
* -----------------------------------------------------------------------
*
* Event interface for MacOS 10.5 (Leopard) /dev/fsevents interface.
*
* Special thanks go to Amit Singh and his fslogger demonstration that showed
* how apples /dev/fsevents can be used. http://osxbook.com/software/fslogger/
*
* -- WARNING -- Quoting http://www.osxbook.com/software/fslogger/ --
*
* The interface that fslogger [and thus Lsyncd] uses is private to Apple.
* Currently, there is a caveat regarding the use of this interface by third
* parties (including fslogger [and thus Lsyncd]). While the change
* notification interface supports multiple clients, there is a single kernel
* buffer for holding events that are to be delivered to one or more
* subscribers, with the primary subscriber being Spotlight. Now, the kernel
* must hold events until it has notified all subscribers that are interested
* in them. Since there is a single buffer, a slow subscriber can cause it to
* overflow. If this happens, events will be dropped for all subscribers,
* including Spotlight. Consequently, Spotlight may need to look at the entire
* volume to determine "what changed".
*/
#include "lsyncd.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "bsd/sys/fsevents.h"
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#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
/* the fsevents pseudo-device */
#define DEV_FSEVENTS "/dev/fsevents"
/* buffer for reading from the device */
#define FSEVENT_BUFSIZ 131072
/* limited by MAX_KFS_EVENTS */
#define EVENT_QUEUE_SIZE 4096
#define KFS_NUM_ARGS FSE_MAX_ARGS
/* OS 10.5 structuce */
/* an event argument */
struct kfs_event_arg {
/* argument type */
u_int16_t type;
/* size of argument data that follows this field */
u_int16_t len;
union {
struct vnode *vp;
char *str;
void *ptr;
int32_t int32;
dev_t dev;
ino_t ino;
int32_t mode;
uid_t uid;
gid_t gid;
uint64_t timestamp;
} data;
};
/* OS 10.5 structuce */
/* an event */
struct kfs_event {
/* event type */
int32_t type;
/* pid of the process that performed the operation */
pid_t pid;
/* event arguments */
struct kfs_event_arg args[KFS_NUM_ARGS];
};
/**
* fsevents (cloned) filedescriptor
*/
static int fsevents_fd = -1;
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static const luaL_reg lfseventslib[] = {
{NULL, NULL}
};
static size_t const readbuf_size = 131072;
static char * readbuf = NULL;
/**
* Called when fsevents has something to read
*/
static void
fsevents_ready(lua_State *L, struct observance *obs)
{
if (obs->fd != fsevents_fd) {
logstring("Error", "Internal, fsevents_fd != ob->fd");
exit(-1); // ERRNO
}
while(true) {
ptrdiff_t len;
int err;
len = read (fsevents_fd, readbuf, readbuf_size);
err = errno;
if (len == 0) {
/* nothing more */
break;
}
if (len < 0) {
if (err == EAGAIN) {
/* nothing more inotify */
break;
} else {
printlogf(L, "Error", "Read fail on fsevents");
exit(-1); // ERRNO
}
}
{
int off = 0;
int32_t atype;
uint32_t aflags;
while (off < len && !hup && !term) {
struct kfs_event *event = (struct kfs_event *) &readbuf[off];
off += sizeof(int32_t) + sizeof(pid_t);
if (event->type == FSE_EVENTS_DROPPED) {
logstring("Fsevents", "Events dropped!");
load_runner_func(L, "overflow");
if (lua_pcall(L, 0, 0, -2)) {
exit(-1); // ERRNO
}
lua_pop(L, 1);
hup = 1;
off += sizeof(u_int16_t);
continue;
}
atype = event->type & FSE_TYPE_MASK;
aflags = FSE_GET_FLAGS(event->type);
}
}
}
}
/**
* Called to close/tidy fsevents
*/
static void
fsevents_tidy(struct observance *obs)
{
if (obs->fd != fsevents_fd) {
logstring("Error", "Internal, fsevents_fd != ob->fd");
exit(-1); // ERRNO
}
close(fsevents_fd);
}
/**
* registers fsevents functions.
*/
extern void
register_fsevents(lua_State *L) {
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lua_pushstring(L, "fsevents");
luaL_register(L, "fsevents", lfseventslib);
}
/**
* opens and initalizes fsevents.
*/
extern void
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open_fsevents(lua_State *L)
{
return;
int8_t event_list[] = { // action to take for each event
FSE_REPORT, /* FSE_CREATE_FILE */
FSE_REPORT, /* FSE_DELETE */
FSE_REPORT, /* FSE_STAT_CHANGED */
FSE_REPORT, /* FSE_RENAME */
FSE_REPORT, /* FSE_CONTENT_MODIFIED */
FSE_REPORT, /* FSE_EXCHANGE */
FSE_REPORT, /* FSE_FINDER_INFO_CHANGED */
FSE_REPORT, /* FSE_CREATE_DIR */
FSE_REPORT, /* FSE_CHOWN */
FSE_REPORT, /* FSE_XATTR_MODIFIED */
FSE_REPORT, /* FSE_XATTR_REMOVED */
};
struct fsevent_clone_args fca = {
.event_list = (int8_t *) event_list,
.num_events = sizeof(event_list)/sizeof(int8_t),
.event_queue_depth = EVENT_QUEUE_SIZE,
.fd = &fsevents_fd,
};
int fd = open(DEV_FSEVENTS, O_RDONLY);
if (fd < 0) {
printlogf(L, "Error",
"Cannot access %s monitor! (%d:%s)",
DEV_FSEVENTS, errno, strerror(errno));
exit(-1); // ERRNO
}
if (ioctl(fd, FSEVENTS_CLONE, (char *)&fca) < 0) {
printlogf(L, "Error",
"Cannot control %s monitor! (%d:%s)",
DEV_FSEVENTS, errno, strerror(errno));
exit(-1); // ERRNO
}
/* fd has been cloned, closes access fd */
close(fd);
close_exec_fd(fsevents_fd);
non_block_fd(fsevents_fd);
observe_fd(fsevents_fd, fsevents_ready, NULL, fsevents_tidy, NULL);
}