ref: b2f339168bf5b666f96067daf4de4c9f07f51c92
dir: /src/luaform.c/
/*
* luafile - file formats in Lua.
*
* Copyright 2006-2007 Reuben Thomas
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, write to the Free Software
* Foundation, Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301,
* USA. */
#include "st_i.h"
#include <string.h>
#include <lua.h>
#include <lauxlib.h>
/* Private data */
typedef struct luafile {
lua_State *L; /* Lua state */
int readref; /* reference to read method */
int writeref; /* reference to write method */
int seekref; /* reference to seek method */
} *lua_t;
assert_static(sizeof(struct luafile) <= ST_MAX_FILE_PRIVSIZE,
/* else */ skel_PRIVSIZE_too_big);
/*
* Get the given method, checking that it is a function
*/
static bool get_method(lua_State *L, const char *lua_script, const char *meth, int *ref)
{
int ty;
lua_getfield(L, -1, meth);
if ((ty = lua_type(L, -1)) == LUA_TNIL) {
st_fail("Lua script %s does not have a %s method", lua_script, meth);
lua_pop(L, 1);
return false;
} else if (ty != LUA_TFUNCTION) {
st_fail("Lua script %s's %s method is not a function", lua_script, meth);
lua_pop(L, 1);
return false;
}
*ref = luaL_ref(L, LUA_REGISTRYINDEX);
return true;
}
/*
* Set up Lua state and read script.
*/
static int lua_start(ft_t ft)
{
lua_t lua = (lua_t)ft->priv;
int ret;
lua->L = st_lua_new();
if (!ft->signal.lua_script) {
st_fail("no Lua script given");
return ST_EOF;
} else if ((ret = luaL_loadfile(lua->L, ft->signal.lua_script)) != 0) {
st_fail("cannot load Lua script %s: error %d", ft->signal.lua_script, ret);
return ST_EOF;
} else if ((ret = lua_pcall(lua->L, 0, 1, 0)) != 0) {
st_fail("cannot get methods from Lua script %s: error %d", ft->signal.lua_script, ret);
return ST_EOF;
} else if (lua_type(lua->L, -1) != LUA_TTABLE) {
st_fail("Lua script %s did not return a table", ft->signal.lua_script);
return ST_EOF;
} else if (!get_method(lua->L, ft->signal.lua_script, "read", &lua->readref) ||
!get_method(lua->L, ft->signal.lua_script, "write", &lua->writeref) ||
!get_method(lua->L, ft->signal.lua_script, "seek", &lua->seekref))
return ST_EOF;
lua_pop(lua->L, 1); /* Discard function */
return ST_SUCCESS;
}
/*
* Read up to len samples of type st_sample_t from file into buf[].
* Return number of samples read.
*/
static st_size_t lua_read(ft_t ft, st_sample_t *buf, st_size_t len)
{
lua_t lua = (lua_t)ft->priv;
st_sample_t_array_t inarr;
st_size_t done;
int ret;
inarr.size = len;
inarr.data = buf;
lua_rawgeti(lua->L, LUA_REGISTRYINDEX, lua->readref);
st_lua_pushfile(lua->L, ft->fp);
st_lua_pusharray(lua->L, inarr);
if ((ret = lua_pcall(lua->L, 2, 1, 0)) != 0)
st_fail("error in Lua script's read method: %d", ret);
done = lua_tointeger(lua->L, -1);
lua_pop(lua->L, 1);
return done;
}
/*
* Write len samples of type st_sample_t from buf[] to file.
* Return number of samples written.
*/
static st_size_t lua_write(ft_t ft, const st_sample_t *buf, st_size_t len)
{
lua_t lua = (lua_t)ft->priv;
st_sample_t_array_t outarr;
st_size_t done;
int ret;
outarr.size = len;
outarr.data = (st_sample_t *)buf;
lua_rawgeti(lua->L, LUA_REGISTRYINDEX, lua->writeref);
st_lua_pushfile(lua->L, ft->fp);
st_lua_pusharray(lua->L, outarr);
if ((ret = lua_pcall(lua->L, 2, 1, 0)) != 0)
st_fail("error in Lua script's write method: %d", ret);
done = lua_tointeger(lua->L, -1);
lua_pop(lua->L, 1);
return done;
}
/*
* Clean up state.
*/
static int lua_stop(ft_t ft)
{
lua_t lua = (lua_t)ft->priv;
lua_close(lua->L);
return ST_SUCCESS;
}
/* Seek relative to current position. */
static int lua_seek(ft_t ft, st_size_t offset)
{
lua_t lua = (lua_t)ft->priv;
int ret;
st_size_t done;
lua_rawgeti(lua->L, LUA_REGISTRYINDEX, lua->seekref);
st_lua_pushfile(lua->L, ft->fp);
lua_pushinteger(lua->L, offset);
if ((ret = lua_pcall(lua->L, 2, 1, 0)) != 0)
st_fail("error in Lua script's seek method: %d", ret);
done = lua_toboolean(lua->L, -1);
lua_pop(lua->L, 1);
return done;
}
/* Format file suffixes */
static const char *lua_names[] = {
"lua",
NULL
};
/* Format descriptor */
static st_format_t st_lua_format = {
lua_names,
NULL,
0,
lua_start,
lua_read,
lua_stop,
lua_start,
lua_write,
lua_stop,
lua_seek
};
/*
* Function returning effect descriptor. This should be the only
* externally visible object.
*/
const st_format_t *st_lua_format_fn(void)
{
return &st_lua_format;
}