summaryrefslogtreecommitdiff
path: root/indra/llcommon/lua_function.cpp
blob: 07e0c1fac2b5184a0bfaf8ca16969614840e75d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
/**
 * @file   lua_function.cpp
 * @author Nat Goodspeed
 * @date   2024-02-05
 * @brief  Implementation for lua_function.
 * 
 * $LicenseInfo:firstyear=2024&license=viewerlgpl$
 * Copyright (c) 2024, Linden Research, Inc.
 * $/LicenseInfo$
 */

// Precompiled header
#include "linden_common.h"
// associated header
#include "lua_function.h"
// STL headers
// std headers
#include <algorithm>
#include <map>
#include <memory>                   // std::unique_ptr
// external library headers
// other Linden headers
#include "hexdump.h"
#include "llsd.h"
#include "llsdutil.h"
#include "lualistener.h"

namespace
{
    // can't specify free function free() as a unique_ptr deleter
    struct freer
    {
        void operator()(void* ptr){ free(ptr); }
    };
} // anonymous namespace

int lluau::dostring(lua_State* L, const std::string& desc, const std::string& text)
{
    {
        size_t bytecodeSize = 0;
        // The char* returned by luau_compile() must be freed by calling free().
        // Use unique_ptr so the memory will be freed even if luau_load() throws.
        std::unique_ptr<char[], freer> bytecode{
            luau_compile(text.data(), text.length(), nullptr, &bytecodeSize)};
        auto r = luau_load(L, desc.data(), bytecode.get(), bytecodeSize, 0);
        if (r != LUA_OK)
            return r;
    } // free bytecode

    // It's important to pass LUA_MULTRET as the expected number of return
    // values: if we pass any fixed number, we discard any returned values
    // beyond that number.
    return lua_pcall(L, 0, LUA_MULTRET, 0);
}

std::string lua_tostdstring(lua_State* L, int index)
{
    size_t len;
    const char* strval{ lua_tolstring(L, index, &len) };
    return { strval, len };
}

void lua_pushstdstring(lua_State* L, const std::string& str)
{
    luaL_checkstack(L, 1, nullptr);
    lua_pushlstring(L, str.c_str(), str.length());
}

// By analogy with existing lua_tomumble() functions, return an LLSD object
// corresponding to the Lua object at stack index 'index' in state L.
// This function assumes that a Lua caller is fully aware that they're trying
// to call a viewer function. In other words, the caller must specifically
// construct Lua data convertible to LLSD.
//
// For proper error handling, we REQUIRE that the Lua runtime be compiled as
// C++ so errors are raised as C++ exceptions rather than as longjmp() calls:
// http://www.lua.org/manual/5.4/manual.html#4.4
// "Internally, Lua uses the C longjmp facility to handle errors. (Lua will
// use exceptions if you compile it as C++; search for LUAI_THROW in the
// source code for details.)"
// Some blocks within this function construct temporary C++ objects in the
// expectation that these objects will be properly destroyed even if code
// reached by that block raises a Lua error.
LLSD lua_tollsd(lua_State* L, int index)
{
    LL_DEBUGS("Lua") << "lua_tollsd(" << index << ") of " << lua_gettop(L) << " stack entries: "
                     << lua_what(L, index) << LL_ENDL;
    DebugExit log_exit("lua_tollsd()");
    switch (lua_type(L, index))
    {
    case LUA_TNONE:
        // Should LUA_TNONE be an error instead of returning isUndefined()?
    case LUA_TNIL:
        return {};

    case LUA_TBOOLEAN:
        return bool(lua_toboolean(L, index));

    case LUA_TNUMBER:
    {
        // Vanilla Lua supports lua_tointegerx(), which tells the caller
        // whether the number at the specified stack index is or is not an
        // integer. Apparently the function exists but does not work right in
        // Luau: it reports even non-integer numbers as integers.
        // Instead, check if integer truncation leaves the number intact.
        lua_Number  numval{ lua_tonumber(L, index) };
        lua_Integer intval{ narrow(numval) };
        if (lua_Number(intval) == numval)
        {
            return LLSD::Integer(intval);
        }
        else
        {
            return numval;
        }
    }

    case LUA_TSTRING:
        return lua_tostdstring(L, index);

    case LUA_TUSERDATA:
    {
        LLSD::Binary binary(lua_rawlen(L, index));
        std::memcpy(binary.data(), lua_touserdata(L, index), binary.size());
        return binary;
    }

    case LUA_TTABLE:
    {
        // A Lua table correctly constructed to convert to LLSD will have
        // either consecutive integer keys starting at 1, which we represent
        // as an LLSD array (with Lua key 1 at C++ index 0), or will have
        // all string keys.
        //
        // In the belief that Lua table traversal skips "holes," that is, it
        // doesn't report any key/value pair whose value is nil, we allow a
        // table with integer keys >= 1 but with "holes." This produces an
        // LLSD array with isUndefined() entries at unspecified keys. There
        // would be no other way for a Lua caller to construct an
        // isUndefined() LLSD array entry. However, to guard against crazy int
        // keys, we forbid gaps larger than a certain size: crazy int keys
        // could result in a crazy large contiguous LLSD array.
        //
        // Possible looseness could include:
        // - A mix of integer and string keys could produce an LLSD map in
        //   which the integer keys are converted to string. (Key conversion
        //   must be performed in C++, not Lua, to avoid confusing
        //   lua_next().)
        // - However, since in Lua t[0] and t["0"] are distinct table entries,
        //   do not consider converting numeric string keys to int to return
        //   an LLSD array.
        // But until we get more experience with actual Lua scripts in
        // practice, let's say that any deviation is a Lua coding error.
        // An important property of the strict definition above is that most
        // conforming data blobs can make a round trip across the language
        // boundary and still compare equal. A non-conforming data blob would
        // lose that property.
        // Known exceptions to round trip identity:
        // - Empty LLSD map and empty LLSD array convert to empty Lua table.
        //   But empty Lua table converts to isUndefined() LLSD object.
        // - LLSD::Real with integer value returns as LLSD::Integer.
        // - LLSD::UUID, LLSD::Date and LLSD::URI all convert to Lua string,
        //   and so return as LLSD::String.
        // - Lua does not store any table key whose value is nil. An LLSD
        //   array with isUndefined() entries produces a Lua table with
        //   "holes" in the int key sequence; this converts back to an LLSD
        //   array containing corresponding isUndefined() entries -- except
        //   when one or more of the final entries isUndefined(). These are
        //   simply dropped, producing a shorter LLSD array than the original.
        // - For the same reason, any keys in an LLSD map whose value
        //   isUndefined() are simply discarded in the converted Lua table.
        //   This converts back to an LLSD map lacking those keys.
        // - If it's important to preserve the original length of an LLSD
        //   array whose final entries are undefined, or the full set of keys
        //   for an LLSD map some of whose values are undefined, store an
        //   LLSD::emptyArray() or emptyMap() instead. These will be
        //   represented in Lua as empty table, which should convert back to
        //   undefined LLSD. Naturally, though, those won't survive a second
        //   round trip.

        // This is the most important of the luaL_checkstack() calls because a
        // deeply nested Lua structure will enter this case at each level, and
        // we'll need another 2 stack slots to traverse each nested table.
        luaL_checkstack(L, 2, nullptr);
        // BEFORE we push nil to initialize the lua_next() traversal, convert
        // 'index' to absolute! Our caller might have passed a relative index;
        // we do, below: lua_tollsd(L, -1). If 'index' is -1, then when we
        // push nil, what we find at index -1 is nil, not the table!
        index = lua_absindex(L, index);
        LL_DEBUGS("Lua") << "checking for empty table" << LL_ENDL;
        lua_pushnil(L);             // first key
        LL_DEBUGS("Lua") << lua_stack(L) << LL_ENDL;
        if (! lua_next(L, index))
        {
            // it's a table, but the table is empty -- no idea if it should be
            // modeled as empty array or empty map -- return isUndefined(),
            // which can be consumed as either
            LL_DEBUGS("Lua") << "empty table" << LL_ENDL;
            return {};
        }
        // key is at stack index -2, value at index -1
        // from here until lua_next() returns 0, have to lua_pop(2) if we
        // return early
        LuaPopper popper(L, 2);
        // Remember the type of the first key
        auto firstkeytype{ lua_type(L, -2) };
        LL_DEBUGS("Lua") << "table not empty, first key type " << lua_typename(L, firstkeytype)
                         << LL_ENDL;
        switch (firstkeytype)
        {
        case LUA_TNUMBER:
        {
            // First Lua key is a number: try to convert table to LLSD array.
            // This is tricky because we don't know in advance the size of the
            // array. The Lua reference manual says that lua_rawlen() is the
            // same as the length operator '#'; but the length operator states
            // that it might stop at any "hole" in the subject table.
            // Moreover, the Lua next() function (and presumably lua_next())
            // traverses a table in unspecified order, even for numeric keys
            // (emphasized in the doc).
            // Make a preliminary pass over the whole table to validate and to
            // collect keys.
            std::vector<LLSD::Integer> keys;
            // Try to determine the length of the table. If the length
            // operator is truthful, avoid allocations while we grow the keys
            // vector. Even if it's not, we can still grow the vector, albeit
            // a little less efficiently.
            keys.reserve(lua_objlen(L, index));
            do
            {
                auto arraykeytype{ lua_type(L, -2) };
                switch (arraykeytype)
                {
                case LUA_TNUMBER:
                {
                    int isint;
                    lua_Integer intkey{ lua_tointegerx(L, -2, &isint) };
                    if (! isint)
                    {
                        // key isn't an integer - this doesn't fit our LLSD
                        // array constraints
                        return lluau::error(L, "Expected integer array key, got %f instead",
                                            lua_tonumber(L, -2));
                    }
                    if (intkey < 1)
                    {
                        return lluau::error(L, "array key %d out of bounds", int(intkey));
                    }

                    keys.push_back(LLSD::Integer(intkey));
                    break;
                }

                case LUA_TSTRING:
                    // break out strings specially to report the value
                    return lluau::error(L, "Cannot convert string array key '%s' to LLSD",
                                        lua_tostring(L, -2));

                default:
                    return lluau::error(L, "Cannot convert %s array key to LLSD",
                                        lua_typename(L, arraykeytype));
                }

                // remove value, keep key for next iteration
                lua_pop(L, 1);
            } while (lua_next(L, index) != 0);
            popper.disarm();
            // Table keys are all integers: are they reasonable integers?
            // Arbitrary max: may bite us, but more likely to protect us
            size_t array_max{ 10000 };
            if (keys.size() > array_max)
            {
                return lluau::error(L, "Conversion from Lua to LLSD array limited to %d entries",
                                    int(array_max));
            }
            // We know the smallest key is >= 1. Check the largest. We also
            // know the vector is NOT empty, else we wouldn't have gotten here.
            std::sort(keys.begin(), keys.end());
            LLSD::Integer highkey = *keys.rbegin();
            if ((highkey - LLSD::Integer(keys.size())) > 100)
            {
                // Looks like we've gone beyond intentional array gaps into
                // crazy key territory.
                return lluau::error(L, "Gaps in Lua table too large for conversion to LLSD array");
            }
            LL_DEBUGS("Lua") << "collected " << keys.size() << " keys, max " << highkey << LL_ENDL;
            // right away expand the result array to the size we'll need
            LLSD result{ LLSD::emptyArray() };
            result[highkey - 1] = LLSD();
            // Traverse the table again, and this time populate result array.
            lua_pushnil(L);         // first key
            while (lua_next(L, index))
            {
                // key at stack index -2, value at index -1
                // We've already validated lua_tointegerx() for each key.
                auto key{ lua_tointeger(L, -2) };
                LL_DEBUGS("Lua") << "key " << key << ':' << LL_ENDL;
                // Don't forget to subtract 1 from Lua key for LLSD subscript!
                result[LLSD::Integer(key) - 1] = lua_tollsd(L, -1);
                // remove value, keep key for next iteration
                lua_pop(L, 1);
            }
            return result;
        }

        case LUA_TSTRING:
        {
            // First Lua key is a string: try to convert table to LLSD map
            LLSD result{ LLSD::emptyMap() };
            do
            {
                auto mapkeytype{ lua_type(L, -2) };
                if (mapkeytype != LUA_TSTRING)
                {
                    return lluau::error(L, "Cannot convert %s map key to LLSD",
                                        lua_typename(L, mapkeytype));
                }

                auto key{ lua_tostdstring(L, -2) };
                LL_DEBUGS("Lua") << "map key " << std::quoted(key) << ':' << LL_ENDL;
                result[key] = lua_tollsd(L, -1);
                // remove value, keep key for next iteration
                lua_pop(L, 1);
            } while (lua_next(L, index) != 0);
            popper.disarm();
            return result;
        }

        default:
            // First Lua key isn't number or string: sorry
            return lluau::error(L, "Cannot convert %s table key to LLSD",
                                lua_typename(L, firstkeytype));
        }
    }

    default:
        // Other Lua entities (e.g. function, C function, light userdata,
        // thread, userdata) are not convertible to LLSD, indicating a coding
        // error in the caller.
        return lluau::error(L, "Cannot convert type %s to LLSD", luaL_typename(L, index));
    }
}

// By analogy with existing lua_pushmumble() functions, push onto state L's
// stack a Lua object corresponding to the passed LLSD object.
void lua_pushllsd(lua_State* L, const LLSD& data)
{
    // might need 2 slots for array or map
    luaL_checkstack(L, 2, nullptr);
    switch (data.type())
    {
    case LLSD::TypeUndefined:
        lua_pushnil(L);
        break;

    case LLSD::TypeBoolean:
        lua_pushboolean(L, data.asBoolean());
        break;

    case LLSD::TypeInteger:
        lua_pushinteger(L, data.asInteger());
        break;

    case LLSD::TypeReal:
        lua_pushnumber(L, data.asReal());
        break;

    case LLSD::TypeBinary:
    {
        auto binary{ data.asBinary() };
        std::memcpy(lua_newuserdata(L, binary.size()),
                    binary.data(), binary.size());
        break;
    }

    case LLSD::TypeMap:
    {
        // push a new table with space for our non-array keys
        lua_createtable(L, 0, data.size());
        for (const auto& pair: llsd::inMap(data))
        {
            // push value -- so now table is at -2, value at -1
            lua_pushllsd(L, pair.second);
            // pop value, assign to table[key]
            lua_setfield(L, -2, pair.first.c_str());
        }
        break;
    }

    case LLSD::TypeArray:
    {
        // push a new table with space for array entries
        lua_createtable(L, data.size(), 0);
        lua_Integer key{ 0 };
        for (const auto& item: llsd::inArray(data))
        {
            // push new array value: table at -2, value at -1
            lua_pushllsd(L, item);
            // pop value, assign table[key] = value
            lua_rawseti(L, -2, ++key);
        }
        break;
    }

    case LLSD::TypeString:
    case LLSD::TypeUUID:
    case LLSD::TypeDate:
    case LLSD::TypeURI:
    default:
    {
        lua_pushstdstring(L, data.asString());
        break;
    }
    }
}

LuaState::LuaState(script_finished_fn cb):
    mCallback(cb),
    mState(luaL_newstate())
{
    luaL_openlibs(mState);
    LuaFunction::init(mState);
    // Try to make print() write to our log.
    lua_register(mState, "print", LuaFunction::get("print_info"));
}

LuaState::~LuaState()
{
    // Did somebody call listen_events() on this LuaState?
    // That is, is there a LuaListener key in its registry?
    auto keytype{ lua_getfield(mState, LUA_REGISTRYINDEX, "event.listener") };
    if (keytype == LUA_TNUMBER)
    {
        // We do have a LuaListener. Retrieve it.
        int isint;
        auto listener{ LuaListener::getInstance(lua_tointegerx(mState, -1, &isint)) };
        // pop the int "event.listener" key
        lua_pop(mState, 1);
        // if we got a LuaListener instance, destroy it
        // (if (! isint), lua_tointegerx() returned 0, but key 0 might
        // validly designate someone ELSE's LuaListener)
        if (isint && listener)
        {
            auto lptr{ listener.get() };
            listener.reset();
            delete lptr;
        }
    }

    lua_close(mState);

    if (mCallback)
    {
        // mError potentially set by previous checkLua() call(s)
        mCallback(mError);
    }    
}

bool LuaState::checkLua(const std::string& desc, int r)
{
    if (r != LUA_OK)
    {
        mError = lua_tostring(mState, -1);
        lua_pop(mState, 1);

        LL_WARNS() << desc << ": " << mError << LL_ENDL;
        return false;
    }
    return true;
}

std::pair<int, LLSD> LuaState::expr(const std::string& desc, const std::string& text)
{
    if (! checkLua(desc, lluau::dostring(mState, desc, text)))
        return { -1, mError };

    // here we believe there was no error -- did the Lua fragment leave
    // anything on the stack?
    std::pair<int, LLSD> result{ lua_gettop(mState), {} };
    if (! result.first)
        return result;

    // aha, at least one entry on the stack!
    if (result.first == 1)
    {
        result.second = lua_tollsd(mState, 1);
        // pop the result we claimed
        lua_settop(mState, 0);
        return result;
    }

    // multiple entries on the stack
    for (int index = 1; index <= result.first; ++index)
    {
        result.second.append(lua_tollsd(mState, index));
    }
    // pop everything
    lua_settop(mState, 0);
    return result;
}


LuaPopper::~LuaPopper()
{
    if (mCount)
    {
        lua_pop(mState, mCount);
    }
}

LuaFunction::LuaFunction(const std::string_view& name, lua_CFunction function,
                         const std::string_view& helptext)
{
    getRegistry().emplace(name, Registry::mapped_type{ function, helptext });
}

void LuaFunction::init(lua_State* L)
{
    for (const auto& [name, pair]: getRegistry())
    {
        const auto& [funcptr, helptext] = pair;
        lua_register(L, name.c_str(), funcptr);
    }
}

lua_CFunction LuaFunction::get(const std::string& key)
{
    // use find() instead of subscripting to avoid creating an entry for
    // unknown key
    const auto& registry{ getRegistry() };
    auto found{ registry.find(key) };
    return (found == registry.end())? nullptr : found->second.first;
}

LuaFunction::Registry& LuaFunction::getRegistry()
{
    // use a function-local static to ensure it's initialized
    static Registry registry;
    return registry;
}


std::ostream& operator<<(std::ostream& out, const lua_what& self)
{
    switch (lua_type(self.L, self.index))
    {
    case LUA_TNONE:
        // distinguish acceptable but non-valid index
        out << "none";
        break;

    case LUA_TNIL:
        out << "nil";
        break;

    case LUA_TBOOLEAN:
    {
        auto oldflags { out.flags() };
        out << std::boolalpha << lua_toboolean(self.L, self.index);
        out.flags(oldflags);
        break;
    }

    case LUA_TNUMBER:
        out << lua_tonumber(self.L, self.index);
        break;

    case LUA_TSTRING:
        out << std::quoted(lua_tostdstring(self.L, self.index));
        break;

    case LUA_TUSERDATA:
    {
        const S32 maxlen = 20;
        S32 binlen{ lua_rawlen(self.L, self.index) };
        LLSD::Binary binary(std::min(maxlen, binlen));
        std::memcpy(binary.data(), lua_touserdata(self.L, self.index), binary.size());
        out << LL::hexdump(binary);
        if (binlen > maxlen)
        {
            out << "...(" << (binlen - maxlen) << " more)";
        }
        break;
    }

    case LUA_TLIGHTUSERDATA:
        out << lua_touserdata(self.L, self.index);
        break;

    default:
        // anything else, don't bother trying to report value, just type
        out << lua_typename(self.L, lua_type(self.L, self.index));
        break;
    }
    return out;
}

std::ostream& operator<<(std::ostream& out, const lua_stack& self)
{
    const char* sep = "stack: [";
    for (int index = 1; index <= lua_gettop(self.L); ++index)
    {
        out << sep << lua_what(self.L, index);
        sep = ", ";
    }
    out << ']';
    return out;
}

DebugExit::~DebugExit()
{
    LL_DEBUGS("Lua") << "exit " << mName << LL_ENDL;
}