mpv/player/lua.c

#include <assert.h>
#include <string.h>

#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

#include "talloc.h"

#include "common/common.h"
#include "options/m_property.h"
#include "common/msg.h"
#include "options/m_option.h"
#include "input/input.h"
#include "options/path.h"
#include "bstr/bstr.h"
#include "osdep/timer.h"
#include "sub/osd.h"
#include "core.h"
#include "command.h"
#include "lua.h"

// List of builtin modules and their contents as strings.
// All these are generated from player/lua/*.lua
static const char *builtin_lua_scripts[][2] = {
    {"mp.defaults",
#   include "player/lua/defaults.inc"
    },
    {"mp.assdraw",
#   include "player/lua/assdraw.inc"
    },
    {"@osc",
#   include "player/lua/osc.inc"
    },
    {0}
};

// Represents a loaded script. Each has its own Lua state.
struct script_ctx {
    const char *name;
    lua_State *state;
    struct mp_log *log;
    struct MPContext *mpctx;
};

struct lua_ctx {
    struct script_ctx **scripts;
    int num_scripts;
};

static struct script_ctx *find_script(struct lua_ctx *lctx, const char *name)
{
    for (int n = 0; n < lctx->num_scripts; n++) {
        if (strcmp(lctx->scripts[n]->name, name) == 0)
            return lctx->scripts[n];
    }
    return NULL;
}

static struct script_ctx *get_ctx(lua_State *L)
{
    lua_getfield(L, LUA_REGISTRYINDEX, "ctx");
    struct script_ctx *ctx = lua_touserdata(L, -1);
    lua_pop(L, 1);
    assert(ctx);
    return ctx;
}

static struct MPContext *get_mpctx(lua_State *L)
{
    return get_ctx(L)->mpctx;
}

static int wrap_cpcall(lua_State *L)
{
    lua_CFunction fn = lua_touserdata(L, -1);
    lua_pop(L, 1);
    return fn(L);
}

// Call the given function fn under a Lua error handler (similar to lua_cpcall).
// Pass the given number of args from the Lua stack to fn.
// Returns 0 (and empty stack) on success.
// Returns LUA_ERR[RUN|MEM|ERR] otherwise, with the error value on the stack.
static int mp_cpcall(lua_State *L, lua_CFunction fn, int args)
{
    // Don't use lua_pushcfunction() - it allocates memory on Lua 5.1.
    // Instead, emulate C closures by making wrap_cpcall call fn.
    lua_pushlightuserdata(L, fn); // args... fn
    // Will always succeed if mp_lua_init() set it up correctly.
    lua_getfield(L, LUA_REGISTRYINDEX, "wrap_cpcall"); // args... fn wrap_cpcall
    lua_insert(L, -(args + 2)); // wrap_cpcall args... fn
    return lua_pcall(L, args + 1, 0, 0);
}

static void report_error(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    const char *err = lua_tostring(L, -1);
    MP_WARN(mpctx, "Error: %s\n", err ? err : "[unknown]");
    lua_pop(L, 1);
}

static void add_functions(struct script_ctx *ctx);

static char *script_name_from_filename(void *talloc_ctx, struct lua_ctx *lctx,
                                       const char *fname)
{
    fname = mp_basename(fname);
    if (fname[0] == '@')
        fname += 1;
    char *name = talloc_strdup(talloc_ctx, fname);
    // Drop .lua extension
    char *dot = strrchr(name, '.');
    if (dot)
        *dot = '\0';
    // Turn it into a safe identifier - this is used with e.g. dispatching
    // input via: "send scriptname ..."
    for (int n = 0; name[n]; n++) {
        char c = name[n];
        if (!(c >= 'A' && c <= 'Z') && !(c >= 'a' && c <= 'z') &&
            !(c >= '0' && c <= '9'))
            name[n] = '_';
    }
    // Make unique (stupid but simple)
    while (find_script(lctx, name))
        name = talloc_strdup_append(name, "_");
    return name;
}

static int load_file(struct script_ctx *ctx, const char *fname)
{
    int r = 0;
    lua_State *L = ctx->state;
    if (luaL_loadfile(L, fname) || lua_pcall(L, 0, 0, 0)) {
        report_error(L);
        r = -1;
    }
    assert(lua_gettop(L) == 0);
    return r;
}

static int load_builtin(lua_State *L)
{
    const char *name = luaL_checkstring(L, 1);
    for (int n = 0; builtin_lua_scripts[n][0]; n++) {
        if (strcmp(name, builtin_lua_scripts[n][0]) == 0) {
            if (luaL_loadstring(L, builtin_lua_scripts[n][1]))
                lua_error(L);
            lua_call(L, 0, 1);
            return 1;
        }
    }
    return 0;
}

// Execute "require " .. name
static bool require(lua_State *L, const char *name)
{
    char buf[80];
    // Lazy, but better than calling the "require" function manually
    snprintf(buf, sizeof(buf), "require '%s'", name);
    if (luaL_loadstring(L, buf) || lua_pcall(L, 0, 0, 0)) {
        report_error(L);
        return false;
    }
    return true;
}

static void mp_lua_load_script(struct MPContext *mpctx, const char *fname)
{
    struct lua_ctx *lctx = mpctx->lua_ctx;
    struct script_ctx *ctx = talloc_ptrtype(NULL, ctx);
    *ctx = (struct script_ctx) {
        .mpctx = mpctx,
        .name = script_name_from_filename(ctx, lctx, fname),
    };
    char *log_name = talloc_asprintf(ctx, "lua/%s", ctx->name);
    ctx->log = mp_log_new(ctx, mpctx->log, log_name);

    lua_State *L = ctx->state = luaL_newstate();
    if (!L)
        goto error_out;

    // used by get_ctx()
    lua_pushlightuserdata(L, ctx); // ctx
    lua_setfield(L, LUA_REGISTRYINDEX, "ctx"); // -

    lua_pushcfunction(L, wrap_cpcall); // closure
    lua_setfield(L, LUA_REGISTRYINDEX, "wrap_cpcall"); // -

    luaL_openlibs(L);

    lua_newtable(L); // mp
    lua_pushvalue(L, -1); // mp mp
    lua_setglobal(L, "mp"); // mp

    add_functions(ctx); // mp

    lua_pushstring(L, ctx->name); // mp name
    lua_setfield(L, -2, "script_name"); // mp

    lua_pop(L, 1); // -

    // Add a preloader for each builtin Lua module
    lua_getglobal(L, "package"); // package
    assert(lua_type(L, -1) == LUA_TTABLE);
    lua_getfield(L, -1, "preload"); // package preload
    assert(lua_type(L, -1) == LUA_TTABLE);
    for (int n = 0; builtin_lua_scripts[n][0]; n++) {
        lua_pushcfunction(L, load_builtin); // package preload load_builtin
        lua_setfield(L, -2, builtin_lua_scripts[n][0]);
    }
    lua_pop(L, 2); // -

    assert(lua_gettop(L) == 0);

    if (!require(L, "mp.defaults")) {
        report_error(L);
        goto error_out;
    }

    assert(lua_gettop(L) == 0);

    if (fname[0] == '@') {
        if (!require(L, fname))
            goto error_out;
    } else {
        if (load_file(ctx, fname) < 0)
            goto error_out;
    }

    MP_TARRAY_APPEND(lctx, lctx->scripts, lctx->num_scripts, ctx);
    return;

error_out:
    if (ctx->state)
        lua_close(ctx->state);
    talloc_free(ctx);
}

static void kill_script(struct script_ctx *ctx)
{
    if (!ctx)
        return;
    struct lua_ctx *lctx = ctx->mpctx->lua_ctx;
    lua_close(ctx->state);
    for (int n = 0; n < lctx->num_scripts; n++) {
        if (lctx->scripts[n] == ctx) {
            MP_TARRAY_REMOVE_AT(lctx->scripts, lctx->num_scripts, n);
            break;
        }
    }
    talloc_free(ctx);
}

static const char *log_level[] = {
    [MSGL_FATAL] = "fatal",
    [MSGL_ERR] = "error",
    [MSGL_WARN] = "warn",
    [MSGL_INFO] = "info",
    [MSGL_V] = "verbose",
    [MSGL_DBG2] = "debug",
};

static int script_log(lua_State *L)
{
    struct script_ctx *ctx = get_ctx(L);

    const char *level = luaL_checkstring(L, 1);
    int msgl = -1;
    for (int n = 0; n < MP_ARRAY_SIZE(log_level); n++) {
        if (log_level[n] && strcasecmp(log_level[n], level) == 0) {
            msgl = n;
            break;
        }
    }
    if (msgl < 0)
        luaL_error(L, "Invalid log level '%s'", level);

    int last = lua_gettop(L);
    lua_getglobal(L, "tostring"); // args... tostring
    for (int i = 2; i <= last; i++) {
        lua_pushvalue(L, -1); // args... tostring tostring
        lua_pushvalue(L, i); // args... tostring tostring args[i]
        lua_call(L, 1, 1); // args... tostring str
        const char *s = lua_tostring(L, -1);
        if (s == NULL)
            return luaL_error(L, "Invalid argument");
        mp_msg_log(ctx->log, msgl, "%s%s", s, i > 0 ? " " : "");
        lua_pop(L, 1);  // args... tostring
    }
    mp_msg_log(ctx->log, msgl, "\n");

    return 0;
}

static int script_find_config_file(lua_State *L)
{
    const char *s = luaL_checkstring(L, 1);
    char *path = mp_find_user_config_file(s);
    if (path) {
        lua_pushstring(L, path);
    } else {
        lua_pushnil(L);
    }
    talloc_free(path);
    return 1;
}

static int run_event(lua_State *L)
{
    lua_getglobal(L, "mp_event"); // name arg mp_event
    if (lua_isnil(L, -1))
        return 0;
    lua_insert(L, -3); // mp_event name arg
    lua_call(L, 2, 0);
    return 0;
}

void mp_lua_event(struct MPContext *mpctx, const char *name, const char *arg)
{
    // There is no proper subscription mechanism yet, so all scripts get it.
    struct lua_ctx *lctx = mpctx->lua_ctx;
    for (int n = 0; n < lctx->num_scripts; n++) {
        struct script_ctx *ctx = lctx->scripts[n];
        lua_State *L = ctx->state;
        lua_pushstring(L, name);
        if (arg) {
            lua_pushstring(L, arg);
        } else {
            lua_pushnil(L);
        }
        if (mp_cpcall(L, run_event, 2) != 0)
            report_error(L);
    }
}

static int run_script_dispatch(lua_State *L)
{
    int id = lua_tointeger(L, 1);
    const char *event = lua_tostring(L, 2);
    lua_getglobal(L, "mp_script_dispatch");
    if (lua_isnil(L, -1))
        return 0;
    lua_pushinteger(L, id);
    lua_pushstring(L, event);
    lua_call(L, 2, 0);
    return 0;
}

void mp_lua_script_dispatch(struct MPContext *mpctx, char *script_name,
                            int id, char *event)
{
    struct script_ctx *ctx = find_script(mpctx->lua_ctx, script_name);
    if (!ctx) {
        MP_VERBOSE(mpctx, "Can't find script '%s' when handling input.\n",
                   script_name);
        return;
    }
    lua_State *L = ctx->state;
    lua_pushinteger(L, id);
    lua_pushstring(L, event);
    if (mp_cpcall(L, run_script_dispatch, 2) != 0)
        report_error(L);
}

static int script_send_command(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    const char *s = luaL_checkstring(L, 1);

    mp_cmd_t *cmd = mp_input_parse_cmd(mpctx->input, bstr0((char*)s), "<lua>");
    if (!cmd)
        luaL_error(L, "error parsing command");
    mp_input_queue_cmd(mpctx->input, cmd);

    return 0;
}

static int script_property_list(lua_State *L)
{
    const struct m_option *props = mp_get_property_list();
    lua_newtable(L);
    for (int i = 0; props[i].name; i++) {
        lua_pushinteger(L, i + 1);
        lua_pushstring(L, props[i].name);
        lua_settable(L, -3);
    }
    return 1;
}

static int script_property_string(lua_State *L)
{
    const struct m_option *props = mp_get_property_list();
    struct MPContext *mpctx = get_mpctx(L);
    const char *name = luaL_checkstring(L, 1);
    int type = lua_tointeger(L, lua_upvalueindex(1))
               ? M_PROPERTY_PRINT : M_PROPERTY_GET_STRING;

    char *result = NULL;
    if (m_property_do(props, name, type, &result, mpctx) >= 0 && result) {
        lua_pushstring(L, result);
        talloc_free(result);
        return 1;
    }
    if (type == M_PROPERTY_PRINT) {
        lua_pushstring(L, "");
        return 1;
    }
    return 0;
}

static int script_set_osd_ass(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    int res_x = luaL_checkinteger(L, 1);
    int res_y = luaL_checkinteger(L, 2);
    const char *text = luaL_checkstring(L, 3);
    if (!mpctx->osd->external ||
        strcmp(mpctx->osd->external, text) != 0 ||
        mpctx->osd->external_res_x != res_x ||
        mpctx->osd->external_res_y != res_y)
    {
        talloc_free(mpctx->osd->external);
        mpctx->osd->external = talloc_strdup(mpctx->osd, text);
        mpctx->osd->external_res_x = res_x;
        mpctx->osd->external_res_y = res_y;
        osd_changed(mpctx->osd, OSDTYPE_EXTERNAL);
    }
    return 0;
}

static int script_get_osd_resolution(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    int w, h;
    osd_object_get_resolution(mpctx->osd, mpctx->osd->objs[OSDTYPE_EXTERNAL],
                              &w, &h);
    lua_pushnumber(L, w);
    lua_pushnumber(L, h);
    return 2;
}

static int script_get_screen_size(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    struct osd_object *obj = mpctx->osd->objs[OSDTYPE_EXTERNAL];
    double aspect = 1.0 * obj->vo_res.w / MPMAX(obj->vo_res.h, 1) /
                    obj->vo_res.display_par;
    lua_pushnumber(L, obj->vo_res.w);
    lua_pushnumber(L, obj->vo_res.h);
    lua_pushnumber(L, aspect);
    return 3;
}

static int script_get_mouse_pos(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    int px, py;
    mp_input_get_mouse_pos(mpctx->input, &px, &py);
    double sw, sh;
    osd_object_get_scale_factor(mpctx->osd, mpctx->osd->objs[OSDTYPE_EXTERNAL],
                                &sw, &sh);
    lua_pushnumber(L, px * sw);
    lua_pushnumber(L, py * sh);
    return 2;
}

static int script_get_timer(lua_State *L)
{
    lua_pushnumber(L, mp_time_sec());
    return 1;
}

static int script_get_chapter_list(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    lua_newtable(L); // list
    int num = get_chapter_count(mpctx);
    for (int n = 0; n < num; n++) {
        double time = chapter_start_time(mpctx, n);
        char *name = chapter_display_name(mpctx, n);
        lua_newtable(L); // list ch
        lua_pushnumber(L, time); // list ch time
        lua_setfield(L, -2, "time"); // list ch
        lua_pushstring(L, name); // list ch name
        lua_setfield(L, -2, "name"); // list ch
        lua_pushinteger(L, n + 1); // list ch n1
        lua_insert(L, -2); // list n1 ch
        lua_settable(L, -3); // list
        talloc_free(name);
    }
    return 1;
}

static const char *stream_type(enum stream_type t)
{
    switch (t) {
    case STREAM_VIDEO: return "video";
    case STREAM_AUDIO: return "audio";
    case STREAM_SUB:   return "sub";
    default:           return "unknown";
    }
}

static int script_get_track_list(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    lua_newtable(L); // list
    for (int n = 0; n < mpctx->num_tracks; n++) {
        struct track *track = mpctx->tracks[n];
        lua_newtable(L); // list track

        lua_pushstring(L, stream_type(track->type));
        lua_setfield(L, -2, "type");
        lua_pushinteger(L, track->user_tid);
        lua_setfield(L, -2, "id");
        lua_pushboolean(L, track->default_track);
        lua_setfield(L, -2, "default");
        lua_pushboolean(L, track->attached_picture);
        lua_setfield(L, -2, "attached_picture");
        if (track->lang) {
            lua_pushstring(L, track->lang);
            lua_setfield(L, -2, "language");
        }
        if (track->title) {
            lua_pushstring(L, track->title);
            lua_setfield(L, -2, "title");
        }
        lua_pushboolean(L, track->is_external);
        lua_setfield(L, -2, "external");
        if (track->external_filename) {
            lua_pushstring(L, track->external_filename);
            lua_setfield(L, -2, "external_filename");
        }
        lua_pushboolean(L, track->auto_loaded);
        lua_setfield(L, -2, "auto_loaded");

        lua_pushinteger(L, n + 1); // list track n1
        lua_insert(L, -2); // list n1 track
        lua_settable(L, -3); // list
    }
    return 1;
}

static int script_input_define_section(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    char *section = (char *)luaL_checkstring(L, 1);
    char *contents = (char *)luaL_checkstring(L, 2);
    mp_input_define_section(mpctx->input, section, "<script>", contents, true);
    return 0;
}

static int script_input_enable_section(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    char *section = (char *)luaL_checkstring(L, 1);
    char *sflags = (char *)luaL_optstring(L, 2, "");
    bstr bflags = bstr0(sflags);
    int flags = 0;
    while (bflags.len) {
        bstr val;
        bstr_split_tok(bflags, "|", &val, &bflags);
        if (bstr_equals0(val, "allow-hide-cursor")) {
            flags |= MP_INPUT_ALLOW_HIDE_CURSOR;
        } else if (bstr_equals0(val, "allow-vo-dragging")) {
            flags |= MP_INPUT_ALLOW_VO_DRAGGING;
        } else if (bstr_equals0(val, "exclusive")) {
            flags |= MP_INPUT_EXCLUSIVE;
        } else {
            luaL_error(L, "invalid flag: '%.*s'", BSTR_P(val));
        }
    }
    mp_input_enable_section(mpctx->input, section, flags);
    return 0;
}

static int script_input_disable_section(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);
    char *section = (char *)luaL_checkstring(L, 1);
    mp_input_disable_section(mpctx->input, section);
    return 0;
}

static int script_input_set_section_mouse_area(lua_State *L)
{
    struct MPContext *mpctx = get_mpctx(L);

    double sw, sh;
    struct osd_object *obj = mpctx->osd->objs[OSDTYPE_EXTERNAL];
    osd_object_get_scale_factor(mpctx->osd, obj, &sw, &sh);

    char *section = (char *)luaL_checkstring(L, 1);
    int x0 = luaL_checkinteger(L, 2) / sw;
    int y0 = luaL_checkinteger(L, 3) / sh;
    int x1 = luaL_checkinteger(L, 4) / sw;
    int y1 = luaL_checkinteger(L, 5) / sh;
    mp_input_set_section_mouse_area(mpctx->input, section, x0, y0, x1, y1);
    return 0;
}

static int script_format_time(lua_State *L)
{
    double t = luaL_checknumber(L, 1);
    const char *fmt = luaL_optstring(L, 2, "%H:%M:%S");
    char *r = mp_format_time_fmt(fmt, t);
    if (!r)
        luaL_error(L, "Invalid time format string '%s'", fmt);
    lua_pushstring(L, r);
    talloc_free(r);
    return 1;
}

struct fn_entry {
    const char *name;
    int (*fn)(lua_State *L);
};

#define FN_ENTRY(name) {#name, script_ ## name}

static struct fn_entry fn_list[] = {
    FN_ENTRY(log),
    FN_ENTRY(find_config_file),
    FN_ENTRY(send_command),
    FN_ENTRY(property_list),
    FN_ENTRY(set_osd_ass),
    FN_ENTRY(get_osd_resolution),
    FN_ENTRY(get_screen_size),
    FN_ENTRY(get_mouse_pos),
    FN_ENTRY(get_timer),
    FN_ENTRY(get_chapter_list),
    FN_ENTRY(get_track_list),
    FN_ENTRY(input_define_section),
    FN_ENTRY(input_enable_section),
    FN_ENTRY(input_disable_section),
    FN_ENTRY(input_set_section_mouse_area),
    FN_ENTRY(format_time),
};

// On stack: mp table
static void add_functions(struct script_ctx *ctx)
{
    lua_State *L = ctx->state;

    for (int n = 0; n < MP_ARRAY_SIZE(fn_list); n++) {
        lua_pushcfunction(L, fn_list[n].fn);
        lua_setfield(L, -2, fn_list[n].name);
    }

    lua_pushinteger(L, 0);
    lua_pushcclosure(L, script_property_string, 1);
    lua_setfield(L, -2, "property_get");

    lua_pushinteger(L, 1);
    lua_pushcclosure(L, script_property_string, 1);
    lua_setfield(L, -2, "property_get_string");
}

void mp_lua_init(struct MPContext *mpctx)
{
    mpctx->lua_ctx = talloc_zero(NULL, struct lua_ctx);
    // Load scripts from options
    if (mpctx->opts->lua_load_osc)
        mp_lua_load_script(mpctx, "@osc");
    char **files = mpctx->opts->lua_files;
    for (int n = 0; files && files[n]; n++) {
        if (files[n][0])
            mp_lua_load_script(mpctx, files[n]);
    }
}

void mp_lua_uninit(struct MPContext *mpctx)
{
    if (mpctx->lua_ctx) {
        while (mpctx->lua_ctx->num_scripts)
            kill_script(mpctx->lua_ctx->scripts[0]);
        talloc_free(mpctx->lua_ctx);
        mpctx->lua_ctx = NULL;
    }
}