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lsyncd.c
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lsyncd.c
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/**
* lsyncd.c Live (Mirror) Syncing Demon
*
* License: GPLv2 (see COPYING) or any later version
*
* Authors: Axel Kittenberger <axkibe@gmail.com>
*
* -----------------------------------------------------------------------
*
* This is the core. It contains as minimal as possible glues
* to the operating system needed for lsyncd operation. All high-level
* logic is coded (when feasable) into lsyncd.lua
*/
#include "lsyncd.h"
#define SYSLOG_NAMES 1
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/times.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <syslog.h>
#include <math.h>
#include <time.h>
#include <unistd.h>
#define LUA_USE_APICHECK 1
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
/**
* The Lua part of lsyncd if compiled into the binary.
*/
#ifndef LSYNCD_DEFAULT_RUNNER_FILE
extern const char luac_out[];
extern size_t luac_size;
#endif
/**
* Makes sure there is one monitor.
*/
#ifndef LSYNCD_WITH_INOTIFY
#ifndef LSYNCD_WITH_FANOTIFY
#ifndef LSYNCD_WITH_FSEVENTS
# error "need at least one notifcation system. please rerun ./configure"
#endif
#endif
#endif
/**
* All monitors supported by this Lsyncd.
*/
static char *monitors[] = {
#ifdef LSYNCD_WITH_INOTIFY
"inotify",
#endif
#ifdef LSYNCD_WITH_FANOTIFY
"fanotify",
#endif
#ifdef LSYNCD_WITH_FSEVENTS
"fsevents",
#endif
NULL,
};
/**
* configuration parameters
*/
struct settings settings = {
.log_file = NULL,
.log_syslog = false,
.log_ident = NULL,
.log_facility = LOG_USER,
.log_level = LOG_NOTICE,
.nodaemon = false,
};
/**
* configurable names for logging facility
* to be translated to integer value.
*/
//struct {
// const char * c_name;
// int c_val;
//} facilitynames[] = {
// { "auth", LOG_AUTH },
// { "authprive", LOG_AUTHPRIV },
// { "cron", LOG_CRON },
// { "daemon", LOG_DAEMON },
// { "ftp", LOG_FTP },
// { "kern", LOG_KERN },
// { "lpr", LOG_LPR },
// { "mail", LOG_MAIL },
// { "news", LOG_NEWS },
// { "syslog", LOG_SYSLOG },
// { "user", LOG_USER },
// { "uucp", LOG_UUCP },
// { "local0", LOG_LOCAL0 },
// { "local1", LOG_LOCAL1 },
// { "local2", LOG_LOCAL2 },
// { "local3", LOG_LOCAL3 },
// { "local4", LOG_LOCAL4 },
// { "local5", LOG_LOCAL5 },
// { "local6", LOG_LOCAL6 },
// { "local7", LOG_LOCAL7 },
// { NULL, -1 },
//};
/**
* True when lsyncd daemonized itself.
*/
static bool is_daemon = false;
/**
* False after first time Lsyncd started up.
*
* Thus configuration error messages are written to stdout/stderr only on
* first start.
*
* All other resets (HUP or inotify OVERFLOW) run with implictly --insist
* turned on and thus Lsyncd not failing on a not responding target.
*/
static bool first_time = true;
/**
* Set to TERM or HUP in signal handler, when lsyncd should end or reset ASAP.
*/
volatile sig_atomic_t hup = 0;
volatile sig_atomic_t term = 0;
/**
* The kernels clock ticks per second.
*/
static long clocks_per_sec;
/**
* signal handler
*/
void
sig_child(int sig)
{
/* nothing */
}
/**
* signal handler
*/
void
sig_handler(int sig)
{
switch (sig) {
case SIGTERM:
term = 1;
return;
case SIGHUP:
hup = 1;
return;
}
}
/**
* Non glibc builds need a real tms structure for times() call
*/
#ifdef __GLIBC__
static struct tms *dummy_tms = NULL;
#else
static struct tms _dummy_tms;
static struct tms *dummy_tms = &_dummy_tms;
#endif
/*****************************************************************************
* Logging
****************************************************************************/
/**
* A logging category
*/
struct logcat {
char *name;
int priority;
};
/**
* A table of all enabled logging categories.
* Sorted by first letter to have to do less comparisons;
*/
static struct logcat *logcats[26] = {0,};
/**
* Returns the positive priority if category is configured to be logged.
* or -1
*/
extern int
check_logcat(const char *name)
{
struct logcat *lc;
if (name[0] < 'A' || name[0] > 'Z') {
return 99;
}
lc = logcats[name[0]-'A'];
if (!lc) {
return 99;
}
while (lc->name) {
if (!strcmp(lc->name, name)) {
return lc->priority;
}
lc++;
}
return 99;
}
/**
* Adds a logging category
* @return true if OK.
*/
static bool
add_logcat(const char *name, int priority)
{
struct logcat *lc;
if (!strcmp("all", name)) {
settings.log_level = 99;
return true;
}
if (!strcmp("scarce", name)) {
settings.log_level = LOG_WARNING;
return true;
}
/* category must start with capital letter */
if (name[0] < 'A' || name[0] > 'Z') {
return false;
}
if (!logcats[name[0]-'A']) {
/* en empty capital letter */
lc = logcats[name[0]-'A'] = s_calloc(2, sizeof(struct logcat));
} else {
/* length of letter list */
int ll = 0;
/* counts list length */
for(lc = logcats[name[0]-'A']; lc->name; lc++) {
ll++;
}
/* enlarge list */
logcats[name[0]-'A'] =
s_realloc(logcats[name[0]-'A'], (ll + 2) * sizeof(struct logcat));
/* go to list end */
for(lc = logcats[name[0]-'A']; lc->name; lc++) {
if (!strcmp(name, lc->name)) {
/* already there */
return true;
}
}
}
lc->name = s_strdup(name);
lc->priority = priority;
/* terminates the list */
lc[1].name = NULL;
return true;
}
/**
* Logs a string.
*
* Do not call directly, but the macro logstring() in lsyncd.h
*
* @param priorty the priority of the log message
* @param cat the category
* @param message the log message
*/
extern void
logstring0(int priority, const char *cat, const char *message)
{
if (first_time) {
/* lsyncd is in intial configuration.
* thus just print to normal stdout/stderr. */
if (priority >= LOG_ERR) {
fprintf(stderr, "%s: %s\n", cat, message);
} else {
printf("%s: %s\n", cat, message);
}
return;
}
/* writes on console if not daemon */
if (!is_daemon) {
char ct[255];
/* gets current timestamp hour:minute:second */
time_t mtime;
time(&mtime);
strftime(ct, sizeof(ct), "%T", localtime(&mtime));
FILE * flog = priority <= LOG_ERR ? stderr : stdout;
fprintf(flog, "%s %s: %s\n", ct, cat, message);
}
/* writes to file if configured so */
if (settings.log_file) {
FILE * flog = fopen(settings.log_file, "a");
/* gets current timestamp day-time-year */
char * ct;
time_t mtime;
time(&mtime);
ct = ctime(&mtime);
/* cuts trailing linefeed */
ct[strlen(ct) - 1] = 0;
if (flog == NULL) {
fprintf(stderr, "Cannot open logfile [%s]!\n",
settings.log_file);
exit(-1); // ERRNO
}
fprintf(flog, "%s %s: %s\n", ct, cat, message);
fclose(flog);
}
/* sends to syslog if configured so */
if (settings.log_syslog) {
syslog(priority, "%s, %s", cat, message);
}
return;
}
/**
* Lets the core print logmessages comfortably as formated string.
* This uses the lua_State for it easy string buffers only.
*/
extern void
printlogf0(lua_State *L,
int priority,
const char *cat,
const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
lua_pushvfstring(L, fmt, ap);
va_end(ap);
logstring0(priority, cat, luaL_checkstring(L, -1));
lua_pop(L, 1);
return;
}
/*****************************************************************************
* Simple memory management
* TODO: call the garbace collector in case of out of memory.
****************************************************************************/
/**
* "secured" calloc.
*/
extern void *
s_calloc(size_t nmemb, size_t size)
{
void *r = calloc(nmemb, size);
if (r == NULL) {
logstring0(LOG_ERR, "Error", "Out of memory!");
exit(-1); // ERRNO
}
return r;
}
/**
* "secured" malloc. the deamon shall kill itself
* in case of out of memory.
*/
extern void *
s_malloc(size_t size)
{
void *r = malloc(size);
if (r == NULL) {
logstring0(LOG_ERR, "Error", "Out of memory!");
exit(-1); // ERRNO
}
return r;
}
/**
* "secured" realloc.
*/
extern void *
s_realloc(void *ptr, size_t size)
{
void *r = realloc(ptr, size);
if (r == NULL) {
logstring0(LOG_ERR, "Error", "Out of memory!");
exit(-1);
}
return r;
}
/**
* "secured" strdup.
*/
extern char *
s_strdup(const char *src)
{
char *s = strdup(src);
if (s == NULL) {
logstring0(LOG_ERR, "Error", "Out of memory!");
exit(-1); // ERRNO
}
return s;
}
/*****************************************************************************
* Pipes management
****************************************************************************/
/**
* A child process gets text piped longer than on
* write() can manage.
*/
struct pipemsg {
/* message to send */
char *text;
/* length of text */
int tlen;
/* position in message */
int pos;
};
/**
* Called by the core whenever a pipe becomes
* writeable again
*/
static void
pipe_writey(lua_State *L, struct observance *observance)
{
int fd = observance->fd;
struct pipemsg *pm = (struct pipemsg *) observance->extra;
int len = write(fd, pm->text + pm->pos, pm->tlen - pm->pos);
pm->pos += len;
if (len < 0) {
logstring("Normal", "broken pipe.");
nonobserve_fd(fd);
} else if (pm->pos >= pm->tlen) {
logstring("Exec", "finished pipe.");
nonobserve_fd(fd);
}
}
/**
* Called when cleaning up a pipe
*/
static void
pipe_tidy(struct observance *observance)
{
struct pipemsg *pm = (struct pipemsg *) observance->extra;
close(observance->fd);
free(pm->text);
free(pm);
}
/*****************************************************************************
* helper routines.
****************************************************************************/
/**
* Dummy variable whos address is used as the cores index in the lua registry
* to the lua runners function table in the lua registry.
*/
static int runner;
/**
* Dummy variable whos address is used as the cores index n the lua registry
* to the lua runners error handler.
*/
static int callError;
/**
* Sets the close-on-exit flag for an fd
*/
extern void
close_exec_fd(int fd)
{
int flags;
flags = fcntl(fd, F_GETFD);
if (flags == -1) {
logstring("Error", "cannot get descriptor flags!");
exit(-1); // ERRNO
}
flags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, flags) == -1) {
logstring("Error", "cannot set descripptor flags!");
exit(-1); // ERRNO
}
}
/**
* Sets the non-blocking flag for an fd
*/
extern void
non_block_fd(int fd)
{
int flags;
flags = fcntl(fd, F_GETFL);
if (flags == -1) {
logstring("Error", "cannot get status flags!");
exit(-1); // ERRNO
}
flags |= O_NONBLOCK;
if (fcntl(fd, F_SETFL, flags) == -1) {
logstring("Error", "cannot set status flags!");
exit(-1); // ERRNO
}
}
/**
* Writes a pid file.
*/
static void
write_pidfile(lua_State *L, const char *pidfile) {
FILE* f = fopen(pidfile, "w");
if (!f) {
printlogf(L, "Error", "Cannot write pidfile; '%s'", pidfile);
exit(-1); // ERRNO
}
fprintf(f, "%i\n", getpid());
fclose(f);
}
/*****************************************************************************
* Observances
****************************************************************************/
/**
* List of file descriptor watches.
*/
static struct observance * observances = NULL;
static int observances_len = 0;
static int observances_size = 0;
/**
* List of file descriptors to nonobserve.
* While working for the oberver lists, it may
* not be altered, thus nonobserve stores here the
* actions that will be delayed.
*/
static int *nonobservances = NULL;
static int nonobservances_len = 0;
static int nonobservances_size = 0;
/**
* true while the observances list is being handled.
*/
static bool observance_action = false;
/**
* Core watches a filedescriptor to become ready,
* one of read_ready or write_ready may be zero
*/
extern void
observe_fd(int fd,
void (*ready) (lua_State *, struct observance *),
void (*writey)(lua_State *, struct observance *),
void (*tidy) (struct observance *),
void *extra)
{
int pos;
/* looks if the fd is already there as pos or
* stores the position to insert the new fd in pos */
for(pos = 0; pos < observances_len; pos++) {
if (fd <= observances[pos].fd) {
break;
}
}
if (pos < observances_len && observances[pos].fd == fd) {
/* just update an existing observance */
logstring("Masterloop", "updating n fd observance");
observances[pos].ready = ready;
observances[pos].writey = writey;
observances[pos].tidy = tidy;
observances[pos].extra = extra;
return;
}
if (observance_action) {
// TODO
logstring("Error",
"internal, New observances in ready/writey handlers not yet supported");
exit(-1); // ERRNO
}
if (!tidy) {
logstring("Error",
"internal, tidy() in observe_fd() must not be NULL.");
exit(-1); // ERRNO
}
if (observances_len + 1 > observances_size) {
observances_size = observances_len + 1;
observances = s_realloc(observances,
observances_size * sizeof(struct observance));
}
memmove(observances + pos + 1, observances + pos,
(observances_len - pos) * (sizeof(struct observance)));
observances_len++;
observances[pos].fd = fd;
observances[pos].ready = ready;
observances[pos].writey = writey;
observances[pos].tidy = tidy;
observances[pos].extra = extra;
}
/**
* Makes core no longer watch fd.
*/
extern void
nonobserve_fd(int fd)
{
int pos;
if (observance_action) {
/* this function is called through a ready/writey handler
* while the core works through the observance list, thus
* it does not alter the list, but stores this actions
* on a stack
*/
nonobservances_len++;
if (nonobservances_len > nonobservances_size) {
nonobservances_size = nonobservances_len;
nonobservances = s_realloc(nonobservances,
nonobservances_size * sizeof(int));
}
nonobservances[nonobservances_len - 1] = fd;
return;
}
/* looks for the fd */
for(pos = 0; pos < observances_len; pos++) {
if (observances[pos].fd == fd) {
break;
}
}
if (pos >= observances_len) {
logstring("Error",
"internal fail, not observance file descriptor in nonobserve");
exit(-1); //ERRNO
}
/* tidy up the observance */
observances[pos].tidy(observances + pos);
/* and moves the list down */
memmove(observances + pos, observances + pos + 1,
(observances_len - pos) * (sizeof(struct observance)));
observances_len--;
}
/**
* A user observance became read-ready
*/
static void
user_obs_ready(lua_State *L, struct observance *obs)
{
int fd = obs->fd;
/* pushes the ready table on table */
lua_pushlightuserdata(L, (void *) user_obs_ready);
lua_gettable(L, LUA_REGISTRYINDEX);
/* pushes the error handler */
lua_pushlightuserdata(L, (void *) &callError);
lua_gettable(L, LUA_REGISTRYINDEX);
/* pushed the user func */
lua_pushnumber(L, fd);
lua_gettable(L, -3);
/* gives the ufunc the fd */
lua_pushnumber(L, fd);
/* calls the user function */
if (lua_pcall(L, 1, 0, -3)) {
exit(-1); // ERRNO
}
lua_pop(L, 2);
}
/**
* A user observance became write-ready
*/
static void
user_obs_writey(lua_State *L, struct observance *obs)
{
int fd = obs->fd;
/* pushes the writey table on table */
lua_pushlightuserdata(L, (void *) user_obs_writey);
lua_gettable(L, LUA_REGISTRYINDEX);
/* pushes the error handler */
lua_pushlightuserdata(L, (void *) &callError);
lua_gettable(L, LUA_REGISTRYINDEX);
/* pushed the user func */
lua_pushnumber(L, fd);
lua_gettable(L, -3);
/* gives the ufunc the fd */
lua_pushnumber(L, fd);
/* calls the user function */
if (lua_pcall(L, 1, 0, -3)) {
exit(-1); // ERRNO
}
lua_pop(L, 2);
}
/**
* Tidies up a user observance
* TODO - give the user a chance to do something in that case!
*/
static void
user_obs_tidy(struct observance *obs)
{
close(obs->fd);
}
/*****************************************************************************
* Library calls for lsyncd.lua
*
* These are as minimal as possible glues to the operating system needed for
* lsyncd operation.
****************************************************************************/
static void daemonize(lua_State *L);
int l_stackdump(lua_State* L);
/**
* Logs a message.
*
* @param loglevel (Lua stack) loglevel of massage
* @param string (Lua stack) the string to log
*/
static int
l_log(lua_State *L)
{
/* log category */
const char * cat;
/* log message */
const char * message;
/* log priority */
int priority;
cat = luaL_checkstring(L, 1);
priority = check_logcat(cat);
/* skips filtered messages */
if (priority > settings.log_level) {
return 0;
}
{
// replace non string values
int i;
int top = lua_gettop(L);
for (i = 1; i <= top; i++) {
int t = lua_type(L, i);
switch (t) {
case LUA_TTABLE:
lua_pushfstring(L, "(Table: %p)", lua_topointer(L, i));
lua_replace(L, i);
break;
case LUA_TBOOLEAN:
if (lua_toboolean(L, i)) {
lua_pushstring(L, "(true)");
} else {
lua_pushstring(L, "(false)");
}
lua_replace(L, i);
break;
case LUA_TUSERDATA:
{
clock_t *c = (clock_t *)
luaL_checkudata(L, i, "Lsyncd.jiffies");
double d = (*c);
d /= clocks_per_sec;
lua_pushfstring(L, "(Timestamp: %f)", d);
lua_replace(L, i);
break;
}
case LUA_TNIL:
lua_pushstring(L, "(nil)");
lua_replace(L, i);
break;
}
}
}
/* concates if there is more than one string parameter */
lua_concat(L, lua_gettop(L) - 1);
message = luaL_checkstring(L, 2);
logstring0(priority, cat, message);
return 0;
}
/**
* Returns (on Lua stack) the current kernels
* clock state (jiffies)
*/
extern int
l_now(lua_State *L)
{
clock_t *j = lua_newuserdata(L, sizeof(clock_t));
luaL_getmetatable(L, "Lsyncd.jiffies");
lua_setmetatable(L, -2);
*j = times(dummy_tms);
return 1;
}
/**
* Executes a subprocess. Does not wait for it to return.
*
* @param (Lua stack) Path to binary to call
* @params (Lua stack) list of string as arguments
* or "<" in which case the next argument is a string that will be piped
* on stdin. the arguments will follow that one.
*
* @return (Lua stack) the pid on success, 0 on failure.
*/
static int
l_exec(lua_State *L)
{
/* the binary to call */
const char *binary = luaL_checkstring(L, 1);
/* number of arguments */
int argc = lua_gettop(L) - 1;
/* the pid spawned */
pid_t pid;
/* the arguments position in the lua arguments */
int li = 1;
/* the pipe to text */
char const *pipe_text = NULL;
size_t pipe_len = 0;
/* the arguments */
char const **argv;
/* pipe file descriptors */
int pipefd[2];
/* expands tables if there are any */
{
int i;
for(i = 1; i <= lua_gettop(L); i++) {
if (lua_istable(L, i)) {
int tlen;
int it;
/* table is now on top of stack */
lua_checkstack(L, lua_gettop(L) + lua_objlen(L, i) + 1);
lua_pushvalue(L, i);
lua_remove(L, i);
argc--;
tlen = lua_objlen(L, -1);
for (it = 1; it <= tlen; it++) {
lua_pushinteger(L, it);
lua_gettable(L, -2);
lua_insert(L,i);
i++;
argc++;
}
i--;
lua_pop(L, 1);
}
}
}
/* writes a log message, prepares the message only if actually needed. */
if (check_logcat("Exec") <= settings.log_level) {
int i;
lua_checkstack(L, lua_gettop(L) + argc * 3 + 2);
lua_pushvalue(L, 1);
for(i = 1; i <= argc; i++) {
lua_pushstring(L, " [");
lua_pushvalue(L, i + 1);
lua_pushstring(L, "]");
}
lua_concat(L, 3 * argc + 1);
logstring0(LOG_DEBUG, "Exec", luaL_checkstring(L, -1));
lua_pop(L, 1);
}
if (argc >= 2 && !strcmp(luaL_checkstring(L, 2), "<")) {
/* pipes something into stdin */
if (!lua_isstring(L, 3)) {
logstring("Error", "in spawn(), expected a string after pipe '<'");
exit(-1); // ERRNO
}
pipe_text = lua_tolstring(L, 3, &pipe_len);
if (strlen(pipe_text) > 0) {
/* creates the pipe */
if (pipe(pipefd) == -1) {
logstring("Error", "cannot create a pipe!");
exit(-1); // ERRNO
}
/* always close the write end for child processes */
close_exec_fd(pipefd[1]);
/* set the write end on non-blocking */
non_block_fd(pipefd[1]);
} else {
pipe_text = NULL;
}
argc -= 2;
li += 2;
}
{
/* prepares the arguments */
int i;
argv = s_calloc(argc + 2, sizeof(char *));
argv[0] = binary;
for(i = 1; i <= argc; i++) {
argv[i] = luaL_checkstring(L, i + li);
}
argv[i] = NULL;
}
pid = fork();
if (pid == 0) {
/* replaces stdin for pipes */
if (pipe_text) {
dup2(pipefd[0], STDIN_FILENO);
}
// close_exec_fd(pipefd[0]);
/* if lsyncd runs as a daemon and has a logfile it will redirect
stdout/stderr of child processes to the logfile. */
if (is_daemon && settings.log_file) {
if (!freopen(settings.log_file, "a", stdout)) {
printlogf(L, "Error",
"cannot redirect stdout to '%s'.",
settings.log_file);
}
if (!freopen(settings.log_file, "a", stderr)) {
printlogf(L, "Error",
"cannot redirect stderr to '%s'.",
settings.log_file);
}
}
execv(binary, (char **)argv);
/* in a sane world execv does not return! */
printlogf(L, "Error", "Failed executing [%s]!", binary);
exit(-1); // ERRNO
}
if (pipe_text) {
int len;
/* first closes read-end of pipe, this is for child process only */
close(pipefd[0]);
/* start filling the pipe */
len = write(pipefd[1], pipe_text, pipe_len);
if (len < 0) {
logstring("Normal", "immediatly broken pipe.");
close(pipefd[1]);
} else if (len == pipe_len) {
/* usual and best case, the pipe accepted all input -> close */
close(pipefd[1]);
logstring("Exec", "one-sweeped pipe");
} else {
struct pipemsg *pm;
logstring("Exec", "adding pipe observance");
pm = s_calloc(1, sizeof(struct pipemsg));
pm->text = s_calloc(pipe_len + 1, sizeof(char*));
memcpy(pm->text, pipe_text, pipe_len + 1);
pm->tlen = pipe_len;
pm->pos = len;
observe_fd(pipefd[1], NULL, pipe_writey, pipe_tidy, pm);
}
}
free(argv);
lua_pushnumber(L, pid);
return 1;
}
/**
* Converts a relative directory path to an absolute.
*
* @param dir a relative path to directory
* @return absolute path of directory
*/
static int
l_realdir(lua_State *L)
{
luaL_Buffer b;