lsyncd/core/userobs.c
2018-04-13 22:55:04 +02:00

222 lines
4.2 KiB
C

/*
| userobs.c from Lsyncd -- the Live (Mirror) Syncing Demon
|
| Allows user Lua scripts to observe file descriptors.
|
| They have to be opened by some other utility tough,
| for example lua-posix.
|
| License: GPLv2 (see COPYING) or any later version
| Authors: Axel Kittenberger <axkibe@gmail.com>
*/
#include "feature.h"
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#define LUA_USE_APICHECK 1
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#include "observe.h"
#include "userobs.h"
/*
| Used to load error handler
*/
extern int callError;
/*
| A user observance became read-ready.
*/
static void
user_obs_ready(
lua_State * L,
int fd,
void * extra
)
{
// 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 );
// pushes 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 );
lua_pop( L, 2 );
}
/*
| A user observance became write-ready
*/
static void
user_obs_writey(
lua_State * L,
int fd,
void * extra
)
{
// 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 );
// pushes the user func
lua_pushnumber( L, fd );
lua_gettable( L, -3 );
// gives the user func the fd
lua_pushnumber( L, fd );
// calls the user function
if( lua_pcall( L, 1, 0, -3 ) ) exit(-1);
lua_pop( L, 2 );
}
/*
| Tidies up a user observance
| FIXME - give the user a chance to do something in that case!
*/
static void
user_obs_tidy(
int fd,
void * extra
)
{
close( fd );
}
/*
| Allows user scripts to observe filedescriptors
|
| Params on Lua stack:
| 1: file descriptor
| 2: function to call when read becomes ready
| 3: function to call when write becomes ready
*/
int
l_observe_fd( lua_State *L )
{
int fd = luaL_checknumber( L, 1 );
bool ready = false;
bool writey = false;
// Stores the user function in the lua registry.
// It uses the address of the cores ready / writey functions
// for the user as key
if( !lua_isnoneornil( L, 2 ) )
{
lua_pushlightuserdata( L, (void *) user_obs_ready );
lua_gettable( L, LUA_REGISTRYINDEX );
if( lua_isnil( L, -1 ) )
{
lua_pop( L, 1 );
lua_newtable( L );
lua_pushlightuserdata( L, (void *) user_obs_ready );
lua_pushvalue( L, -2 );
lua_settable( L, LUA_REGISTRYINDEX );
}
lua_pushnumber( L, fd );
lua_pushvalue( L, 2 );
lua_settable( L, -3 );
lua_pop( L, 1 );
ready = true;
}
if( !lua_isnoneornil( L, 3 ) )
{
lua_pushlightuserdata( L, (void *) user_obs_writey );
lua_gettable (L, LUA_REGISTRYINDEX );
if( lua_isnil(L, -1) )
{
lua_pop ( L, 1 );
lua_newtable ( L );
lua_pushlightuserdata ( L, (void *) user_obs_writey );
lua_pushvalue ( L, -2 );
lua_settable ( L, LUA_REGISTRYINDEX );
}
lua_pushnumber ( L, fd );
lua_pushvalue ( L, 3 );
lua_settable ( L, -3 );
lua_pop ( L, 1 );
writey = true;
}
// tells the core to watch the fd
observe_fd(
fd,
ready ? user_obs_ready : NULL,
writey ? user_obs_writey : NULL,
user_obs_tidy,
NULL
);
return 0;
}
/*
| Removes a user observance
|
| Params on Lua stack:
| 1: exitcode of Lsyncd.
*/
int
l_nonobserve_fd( lua_State *L )
{
int fd = luaL_checknumber( L, 1 );
// removes the read function
lua_pushlightuserdata( L, (void *) user_obs_ready );
lua_gettable( L, LUA_REGISTRYINDEX );
if( !lua_isnil( L, -1 ) )
{
lua_pushnumber ( L, fd );
lua_pushnil ( L );
lua_settable ( L, -2 );
}
lua_pop( L, 1 );
lua_pushlightuserdata( L, (void *) user_obs_writey );
lua_gettable( L, LUA_REGISTRYINDEX );
if ( !lua_isnil( L, -1 ) )
{
lua_pushnumber ( L, fd );
lua_pushnil ( L );
lua_settable ( L, -2 );
}
lua_pop( L, 1 );
nonobserve_fd( fd );
return 0;
}