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/**
* inotify.c from Lsyncd - Live (Mirror) Syncing Demon
*
* License: GPLv2 (see COPYING) or any later version
*
* Authors: Axel Kittenberger <axkibe@gmail.com>
*
* -----------------------------------------------------------------------
*
* Event interface for Lsyncd to Linux´ inotify.
*/
#include "lsyncd.h"
#ifndef HAVE_SYS_INOTIFY_H
# error Missing <sys/inotify.h>; supply kernel-headers and rerun configure.
#endif
#include <sys/stat.h>
#include <sys/times.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/inotify.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <math.h>
#include <time.h>
#include <unistd.h>
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
/*-----------------------------------------------------------------------------
* Event types.
*/
static const char * ATTRIB = "Attrib";
static const char * MODIFY = "Modify";
static const char * CREATE = "Create";
static const char * DELETE = "Delete";
static const char * MOVE = "Move";
/**
* The inotify file descriptor.
*/
static int inotify_fd = -1;
/**
* Standard inotify events to listen to.
*/
static const uint32_t standard_event_mask =
IN_ATTRIB | IN_CLOSE_WRITE | IN_CREATE |
IN_DELETE | IN_DELETE_SELF | IN_MOVED_FROM |
IN_MOVED_TO | IN_DONT_FOLLOW | IN_ONLYDIR;
/**
* Adds an inotify watch
*
* @param dir (Lua stack) path to directory
* @param inotifyMode (Lua stack) path to directory
* @return (Lua stack) numeric watch descriptor
*/
static int
l_addwatch(lua_State *L)
{
const char *path = luaL_checkstring(L, 1);
const char *imode = luaL_checkstring(L, 2);
uint32_t mask = standard_event_mask;
if (*imode) {
if (!strcmp(imode, "Modify")) {
/* act on modify instead of closeWrite */
mask |= IN_MODIFY;
mask &= ~IN_CLOSE_WRITE;
} else if (!strcmp(imode, "CloseWrite")) {
/* default */
} else if (!strcmp(imode, "CloseWrite or Modify")) {
/* acts on modify and closeWrite */
mask |= IN_MODIFY;
} else if (!strcmp(imode, "CloseWrite after Modify")) {
/* might be done in future */
printlogf(L, "Error",
"'CloseWrite after Modify' not implemented.");
exit(-1); // ERRNO
} else {
printlogf(L, "Error",
"'%s' not a valid inotfiyMode.", imode);
exit(-1); // ERRNO
}
}
int wd = inotify_add_watch(inotify_fd, path, mask);
if (wd < 0) {
if (errno == ENOSPC) {
printlogf(L, "Error",
"Terminating since out of inotify watches.");
printlogf(L, "Error",
"Consider increasing /proc/sys/fs/inotify/max_user_watches");
exit(-1); // ERRNO.
}
printlogf(L, "Inotify", "addwatch(%s)->%d; err=%d:%s", path, wd,
errno, strerror(errno));
} else {
printlogf(L, "Inotify", "addwatch(%s)->%d", path, wd);
}
lua_pushinteger(L, wd);
return 1;
}
/**
* Removes an inotify watch
*
* @param dir (Lua stack) numeric watch descriptor
* @return nil
*/
static int
l_rmwatch(lua_State *L)
{
int wd = luaL_checkinteger(L, 1);
inotify_rm_watch(inotify_fd, wd);
printlogf(L, "Inotify", "rmwatch()<-%d", wd);
return 0;
}
/**
* Cores inotify functions.
*/
static const luaL_reg linotfylib[] = {
{"addwatch", l_addwatch },
{"rmwatch", l_rmwatch },
{NULL, NULL}
};
/**
* Buffer for MOVE_FROM events.
* Lsyncd buffers MOVE_FROM events to check if
* they are followed by MOVE_TO events with identical cookie
* then they are condensed into one move event to be sent to the
* runner
*/
static struct inotify_event * move_event_buf = NULL;
/**
* Memory allocated for move_event_buf
*/
static size_t move_event_buf_size = 0;
/**
* true if the buffer is used.
*/
static bool move_event = false;
/**
* Handles an inotify event.
*/
static void
handle_event(lua_State *L,
struct inotify_event *event)
{
const char *event_type = NULL;
/* used to execute two events in case of unmatched MOVE_FROM buffer */
struct inotify_event *after_buf = NULL;
if (event && (IN_Q_OVERFLOW & event->mask)) {
/* and overflow happened, tells the runner */
load_runner_func(L, "overflow");
if (lua_pcall(L, 0, 0, -2)) {
exit(-1); // ERRNO
}
lua_pop(L, 1);
hup = 1;
return;
}
/* cancel on ignored or resetting */
if (event && (IN_IGNORED & event->mask)) {
return;
}
if (event && event->len == 0) {
/* sometimes inotify sends such strange events,
* (e.g. when touching a dir */
return;
}
if (event == NULL) {
/* a buffered MOVE_FROM is not followed by anything,
thus it is unary */
event = move_event_buf;
event_type = "Delete";
move_event = false;
} else if (move_event &&
( !(IN_MOVED_TO & event->mask) ||
event->cookie != move_event_buf->cookie) ) {
/* there is a MOVE_FROM event in the buffer and this is not the match
* continue in this function iteration to handle the buffer instead */
logstring("Inotify", "icore, changing unary MOVE_FROM into DELETE")
after_buf = event;
event = move_event_buf;
event_type = "Delete";
move_event = false;
} else if ( move_event &&
(IN_MOVED_TO & event->mask) &&
event->cookie == move_event_buf->cookie ) {
/* this is indeed a matched move */
event_type = "Move";
move_event = false;
} else if (IN_MOVED_FROM & event->mask) {
/* just the MOVE_FROM, buffers this event, and wait if next event is
* a matching MOVED_TO of this was an unary move out of the watched
* tree. */
size_t el = sizeof(struct inotify_event) + event->len;
if (move_event_buf_size < el) {
move_event_buf_size = el;
move_event_buf = s_realloc(move_event_buf, el);
}
memcpy(move_event_buf, event, el);
move_event = true;
return;
} else if (IN_MOVED_TO & event->mask) {
/* must be an unary move-to */
event_type = CREATE;
} else if (IN_ATTRIB & event->mask) {
/* just attrib change */
event_type = ATTRIB;
} else if (IN_CLOSE_WRITE & event->mask) {
/* closed after written something */
event_type = MODIFY;
} else if (IN_CREATE & event->mask) {
/* a new file */
event_type = CREATE;
} else if (IN_DELETE & event->mask) {
/* rm'ed */
event_type = DELETE;
} else {
logstring("Inotify", "icore, skipped some inotify event.");
return;
}
/* and hands over to runner */
load_runner_func(L, "inotifyEvent");
if (!event_type) {
logstring("Error", "Internal: unknown event in handle_event()");
exit(-1); // ERRNO
}
lua_pushstring(L, event_type);
if (event_type != MOVE) {
lua_pushnumber(L, event->wd);
} else {
lua_pushnumber(L, move_event_buf->wd);
}
lua_pushboolean(L, (event->mask & IN_ISDIR) != 0);
l_now(L);
if (event_type == MOVE) {
lua_pushstring(L, move_event_buf->name);
lua_pushnumber(L, event->wd);
lua_pushstring(L, event->name);
} else {
lua_pushstring(L, event->name);
lua_pushnil(L);
lua_pushnil(L);
}
if (lua_pcall(L, 7, 0, -9)) {
exit(-1); // ERRNO
}
lua_pop(L, 1);
/* if there is a buffered event executes it */
if (after_buf) {
logstring("Inotify", "icore, handling buffered event.");
handle_event(L, after_buf);
}
}
/**
* buffer to read inotify events into
*/
static size_t readbuf_size = 2048;
static char * readbuf = NULL;
/**
* Called by function pointer from when the inotify file descriptor
* became ready. Reads it contents and forward all received events
* to the runner.
*/
static void
inotify_ready(lua_State *L, struct observance *obs)
{
if (obs->fd != inotify_fd) {
logstring("Error", "Internal, inotify_fd != ob->fd");
exit(-1); // ERRNO
}
while(true) {
ptrdiff_t len;
int err;
do {
len = read (inotify_fd, readbuf, readbuf_size);
err = errno;
if (len < 0 && err == EINVAL) {
/* kernel > 2.6.21 indicates that way that way that
* the buffer was too small to fit a filename.
* double its size and try again. When using a lower
* kernel and a filename > 2KB appears lsyncd
* will fail. (but does a 2KB filename really happen?)
*/
readbuf_size *= 2;
readbuf = s_realloc(readbuf, readbuf_size);
}
} while(len < 0 && err == EINVAL);
if (len == 0) {
/* nothing more inotify */
break;
}
if (len < 0) {
if (err == EAGAIN) {
/* nothing more inotify */
break;
} else {
printlogf(L, "Error", "Read fail on inotify");
exit(-1); // ERRNO
}
}
{
int i = 0;
while (i < len && !hup && !term) {
struct inotify_event *event =
(struct inotify_event *) &readbuf[i];
handle_event(L, event);
i += sizeof(struct inotify_event) + event->len;
}
}
if (!move_event) {
/* give it a pause if not endangering splitting a move */
break;
}
}
/* checks if there is an unary MOVE_FROM left in the buffer */
if (move_event) {
logstring("Inotify", "icore, handling unary move from.");
handle_event(L, NULL);
}
}
/**
* registers inotify functions.
*/
extern void
register_inotify(lua_State *L)
{
lua_pushstring(L, "inotify");
luaL_register(L, "inotify", linotfylib);
}
/**
* closes inotify
*/
static void
inotify_tidy(struct observance *obs)
{
if (obs->fd != inotify_fd) {
logstring("Error", "Internal, inotify_fd != ob->fd");
exit(-1); // ERRNO
}
close(inotify_fd);
free(readbuf);
readbuf = NULL;
}
/**
* opens and initalizes inotify.
*/
extern void
open_inotify(lua_State *L)
{
if (readbuf) {
logstring("Error",
"internal fail, inotify readbuf!=NULL in open_inotify()")
exit(-1); // ERRNO
}
readbuf = s_malloc(readbuf_size);
inotify_fd = inotify_init();
if (inotify_fd < 0) {
printlogf(L, "Error",
"Cannot access inotify monitor! (%d:%s)",
errno, strerror(errno));
exit(-1); // ERRNO
}
printlogf(L, "Inotify", "inotify fd = %d", inotify_fd);
close_exec_fd(inotify_fd);
non_block_fd(inotify_fd);
observe_fd(inotify_fd, inotify_ready, NULL, inotify_tidy, NULL);
}