src/lj_err.c

   1 /*
   2 ** Error handling.
   3 ** Copyright (C) 2005-2012 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #define lj_err_c
   7 #define LUA_CORE
   8
   9 #include "lj_obj.h"
  10 #include "lj_err.h"
  11 #include "lj_debug.h"
  12 #include "lj_str.h"
  13 #include "lj_func.h"
  14 #include "lj_state.h"
  15 #include "lj_frame.h"
  16 #include "lj_ff.h"
  17 #include "lj_trace.h"
  18 #include "lj_vm.h"
  19
  20 /*
  21 ** LuaJIT can either use internal or external frame unwinding:
  22 **
  23 ** - Internal frame unwinding (INT) is free-standing and doesn't require
  24 **   any OS or library support.
  25 **
  26 ** - External frame unwinding (EXT) uses the system-provided unwind handler.
  27 **
  28 ** Pros and Cons:
  29 **
  30 ** - EXT requires unwind tables for *all* functions on the C stack between
  31 **   the pcall/catch and the error/throw. This is the default on x64,
  32 **   but needs to be manually enabled on x86/PPC for non-C++ code.
  33 **
  34 ** - INT is faster when actually throwing errors (but this happens rarely).
  35 **   Setting up error handlers is zero-cost in any case.
  36 **
  37 ** - EXT provides full interoperability with C++ exceptions. You can throw
  38 **   Lua errors or C++ exceptions through a mix of Lua frames and C++ frames.
  39 **   C++ destructors are called as needed. C++ exceptions caught by pcall
  40 **   are converted to the string "C++ exception". Lua errors can be caught
  41 **   with catch (...) in C++.
  42 **
  43 ** - INT has only limited support for automatically catching C++ exceptions
  44 **   on POSIX systems using DWARF2 stack unwinding. Other systems may use
  45 **   the wrapper function feature. Lua errors thrown through C++ frames
  46 **   cannot be caught by C++ code and C++ destructors are not run.
  47 **
  48 ** EXT is the default on x64 systems, INT is the default on all other systems.
  49 **
  50 ** EXT can be manually enabled on POSIX systems using GCC and DWARF2 stack
  51 ** unwinding with -DLUAJIT_UNWIND_EXTERNAL. *All* C code must be compiled
  52 ** with -funwind-tables (or -fexceptions). This includes LuaJIT itself (set
  53 ** TARGET_CFLAGS), all of your C/Lua binding code, all loadable C modules
  54 ** and all C libraries that have callbacks which may be used to call back
  55 ** into Lua. C++ code must *not* be compiled with -fno-exceptions.
  56 **
  57 ** EXT cannot be enabled on WIN32 since system exceptions use code-driven SEH.
  58 ** EXT is mandatory on WIN64 since the calling convention has an abundance
  59 ** of callee-saved registers (rbx, rbp, rsi, rdi, r12-r15, xmm6-xmm15).
  60 ** EXT is mandatory on POSIX/x64 since the interpreter doesn't save r12/r13.
  61 */
  62
  63 #if defined(__GNUC__) && (LJ_TARGET_X64 || defined(LUAJIT_UNWIND_EXTERNAL))
  64 #define LJ_UNWIND_EXT   1
  65 #elif LJ_TARGET_X64 && LJ_TARGET_WINDOWS
  66 #define LJ_UNWIND_EXT   1
  67 #endif
  68
  69 /* -- Error messages ------------------------------------------------------ */
  70
  71 /* Error message strings. */
  72 LJ_DATADEF const char *lj_err_allmsg =
  73 #define ERRDEF(name, msg)       msg "\0"
  74 #include "lj_errmsg.h"
  75 ;
  76
  77 /* -- Internal frame unwinding -------------------------------------------- */
  78
  79 /* Unwind Lua stack and move error message to new top. */
  80 LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top)
  81 {
  82   lj_func_closeuv(L, top);
  83   if (top < L->top-1) {
  84     copyTV(L, top, L->top-1);
  85     L->top = top+1;
  86   }
  87   lj_state_relimitstack(L);
  88 }
  89
  90 /* Unwind until stop frame. Optionally cleanup frames. */
  91 static void *err_unwind(lua_State *L, void *stopcf, int errcode)
  92 {
  93   TValue *frame = L->base-1;
  94   void *cf = L->cframe;
  95   while (cf) {
  96     int32_t nres = cframe_nres(cframe_raw(cf));
  97     if (nres < 0) {  /* C frame without Lua frame? */
  98       TValue *top = restorestack(L, -nres);
  99       if (frame < top) {  /* Frame reached? */
 100         if (errcode) {
 101           L->cframe = cframe_prev(cf);
 102           L->base = frame+1;
 103           unwindstack(L, top);
 104         }
 105         return cf;
 106       }
 107     }
 108     if (frame <= tvref(L->stack))
 109       break;
 110     switch (frame_typep(frame)) {
 111     case FRAME_LUA:  /* Lua frame. */
 112     case FRAME_LUAP:
 113       frame = frame_prevl(frame);
 114       break;
 115     case FRAME_C:  /* C frame. */
 116 #if LJ_HASFFI
 117     unwind_c:
 118 #endif
 119 #if LJ_UNWIND_EXT
 120       if (errcode) {
 121         L->cframe = cframe_prev(cf);
 122         L->base = frame_prevd(frame) + 1;
 123         unwindstack(L, frame);
 124       } else if (cf != stopcf) {
 125         cf = cframe_prev(cf);
 126         frame = frame_prevd(frame);
 127         break;
 128       }
 129       return NULL;  /* Continue unwinding. */
 130 #else
 131       UNUSED(stopcf);
 132       cf = cframe_prev(cf);
 133       frame = frame_prevd(frame);
 134       break;
 135 #endif
 136     case FRAME_CP:  /* Protected C frame. */
 137       if (cframe_canyield(cf)) {  /* Resume? */
 138         if (errcode) {
 139           L->cframe = NULL;
 140           L->status = (uint8_t)errcode;
 141         }
 142         return cf;
 143       }
 144       if (errcode) {
 145         L->cframe = cframe_prev(cf);
 146         L->base = frame_prevd(frame) + 1;
 147         unwindstack(L, frame);
 148       }
 149       return cf;
 150     case FRAME_CONT:  /* Continuation frame. */
 151 #if LJ_HASFFI
 152       if ((frame-1)->u32.lo == LJ_CONT_FFI_CALLBACK)
 153         goto unwind_c;
 154 #endif
 155     case FRAME_VARG:  /* Vararg frame. */
 156       frame = frame_prevd(frame);
 157       break;
 158     case FRAME_PCALL:  /* FF pcall() frame. */
 159     case FRAME_PCALLH:  /* FF pcall() frame inside hook. */
 160       if (errcode) {
 161         if (errcode == LUA_YIELD) {
 162           frame = frame_prevd(frame);
 163           break;
 164         }
 165         if (frame_typep(frame) == FRAME_PCALL)
 166           hook_leave(G(L));
 167         L->cframe = cf;
 168         L->base = frame_prevd(frame) + 1;
 169         unwindstack(L, L->base);
 170       }
 171       return (void *)((intptr_t)cf | CFRAME_UNWIND_FF);
 172     }
 173   }
 174   /* No C frame. */
 175   if (errcode) {
 176     L->cframe = NULL;
 177     L->base = tvref(L->stack)+1;
 178     unwindstack(L, L->base);
 179     if (G(L)->panic)
 180       G(L)->panic(L);
 181     exit(EXIT_FAILURE);
 182   }
 183   return L;  /* Anything non-NULL will do. */
 184 }
 185
 186 /* -- External frame unwinding -------------------------------------------- */
 187
 188 #if defined(__GNUC__) && !defined(LUAJIT_NO_UNWIND)
 189
 190 #ifdef __clang__
 191 /* http://llvm.org/bugs/show_bug.cgi?id=8703 */
 192 #define __unwind_word__ word
 193 #endif
 194
 195 #include <unwind.h>
 196
 197 #if !LJ_TARGET_ARM
 198
 199 #define LJ_UEXCLASS             0x4c55414a49543200ULL   /* LUAJIT2\0 */
 200 #define LJ_UEXCLASS_MAKE(c)     (LJ_UEXCLASS | (uint64_t)(c))
 201 #define LJ_UEXCLASS_CHECK(cl)   (((cl) ^ LJ_UEXCLASS) <= 0xff)
 202 #define LJ_UEXCLASS_ERRCODE(cl) ((int)((cl) & 0xff))
 203
 204 /* DWARF2 personality handler referenced from interpreter .eh_frame. */
 205 LJ_FUNCA int lj_err_unwind_dwarf(int version, _Unwind_Action actions,
 206   uint64_t uexclass, struct _Unwind_Exception *uex,
 207   struct _Unwind_Context *ctx)
 208 {
 209   void *cf;
 210   lua_State *L;
 211   if (version != 1)
 212     return _URC_FATAL_PHASE1_ERROR;
 213   UNUSED(uexclass);
 214   cf = (void *)_Unwind_GetCFA(ctx);
 215   L = cframe_L(cf);
 216   if ((actions & _UA_SEARCH_PHASE)) {
 217 #if LJ_UNWIND_EXT
 218     if (err_unwind(L, cf, 0) == NULL)
 219       return _URC_CONTINUE_UNWIND;
 220 #endif
 221     if (!LJ_UEXCLASS_CHECK(uexclass)) {
 222       setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
 223     }
 224     return _URC_HANDLER_FOUND;
 225   }
 226   if ((actions & _UA_CLEANUP_PHASE)) {
 227     int errcode;
 228     if (LJ_UEXCLASS_CHECK(uexclass)) {
 229       errcode = LJ_UEXCLASS_ERRCODE(uexclass);
 230     } else {
 231       if ((actions & _UA_HANDLER_FRAME))
 232         _Unwind_DeleteException(uex);
 233       errcode = LUA_ERRRUN;
 234     }
 235 #if LJ_UNWIND_EXT
 236     cf = err_unwind(L, cf, errcode);
 237     if ((actions & _UA_FORCE_UNWIND)) {
 238       return _URC_CONTINUE_UNWIND;
 239     } else if (cf) {
 240       _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
 241       _Unwind_SetIP(ctx, (uintptr_t)(cframe_unwind_ff(cf) ?
 242                                      lj_vm_unwind_ff_eh :
 243                                      lj_vm_unwind_c_eh));
 244       return _URC_INSTALL_CONTEXT;
 245     }
 246 #if LJ_TARGET_X86ORX64
 247     else if ((actions & _UA_HANDLER_FRAME)) {
 248       /* Workaround for ancient libgcc bug. Still present in RHEL 5.5. :-/
 249       ** Real fix: http://gcc.gnu.org/viewcvs/trunk/gcc/unwind-dw2.c?r1=121165&r2=124837&pathrev=153877&diff_format=h
 250       */
 251       _Unwind_SetGR(ctx, LJ_TARGET_EHRETREG, errcode);
 252       _Unwind_SetIP(ctx, (uintptr_t)lj_vm_unwind_rethrow);
 253       return _URC_INSTALL_CONTEXT;
 254     }
 255 #endif
 256 #else
 257     /* This is not the proper way to escape from the unwinder. We get away with
 258     ** it on x86/PPC because the interpreter restores all callee-saved regs.
 259     */
 260     lj_err_throw(L, errcode);
 261 #endif
 262   }
 263   return _URC_CONTINUE_UNWIND;
 264 }
 265
 266 #if LJ_UNWIND_EXT
 267 #if LJ_TARGET_OSX || defined(__OpenBSD__)
 268 /* Sorry, no thread safety for OSX. Complain to Apple, not me. */
 269 static struct _Unwind_Exception static_uex;
 270 #else
 271 static __thread struct _Unwind_Exception static_uex;
 272 #endif
 273
 274 /* Raise DWARF2 exception. */
 275 static void err_raise_ext(int errcode)
 276 {
 277   static_uex.exception_class = LJ_UEXCLASS_MAKE(errcode);
 278   static_uex.exception_cleanup = NULL;
 279   _Unwind_RaiseException(&static_uex);
 280 }
 281 #endif
 282
 283 #else
 284
 285 /* ARM unwinder personality handler referenced from interpreter .ARM.extab. */
 286 LJ_FUNCA _Unwind_Reason_Code lj_err_unwind_arm(_Unwind_State state,
 287                                                _Unwind_Control_Block *ucb,
 288                                                _Unwind_Context *ctx)
 289 {
 290   void *cf = (void *)_Unwind_GetGR(ctx, 13);
 291   lua_State *L = cframe_L(cf);
 292   if ((state & _US_ACTION_MASK) == _US_VIRTUAL_UNWIND_FRAME) {
 293     setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
 294     return _URC_HANDLER_FOUND;
 295   }
 296   if ((state&(_US_ACTION_MASK|_US_FORCE_UNWIND)) == _US_UNWIND_FRAME_STARTING) {
 297     _Unwind_DeleteException(ucb);
 298     _Unwind_SetGR(ctx, 15, (_Unwind_Word)(void *)lj_err_throw);
 299     _Unwind_SetGR(ctx, 0, (_Unwind_Word)L);
 300     _Unwind_SetGR(ctx, 1, (_Unwind_Word)LUA_ERRRUN);
 301     return _URC_INSTALL_CONTEXT;
 302   }
 303   if (__gnu_unwind_frame(ucb, ctx) != _URC_OK)
 304     return _URC_FAILURE;
 305   return _URC_CONTINUE_UNWIND;
 306 }
 307
 308 #endif
 309
 310 #elif LJ_TARGET_X64 && LJ_TARGET_WINDOWS
 311
 312 /*
 313 ** Someone in Redmond owes me several days of my life. A lot of this is
 314 ** undocumented or just plain wrong on MSDN. Some of it can be gathered
 315 ** from 3rd party docs or must be found by trial-and-error. They really
 316 ** don't want you to write your own language-specific exception handler
 317 ** or to interact gracefully with MSVC. :-(
 318 **
 319 ** Apparently MSVC doesn't call C++ destructors for foreign exceptions
 320 ** unless you compile your C++ code with /EHa. Unfortunately this means
 321 ** catch (...) also catches things like access violations. The use of
 322 ** _set_se_translator doesn't really help, because it requires /EHa, too.
 323 */
 324
 325 #define WIN32_LEAN_AND_MEAN
 326 #include <windows.h>
 327
 328 /* Taken from: http://www.nynaeve.net/?p=99 */
 329 typedef struct UndocumentedDispatcherContext {
 330   ULONG64 ControlPc;
 331   ULONG64 ImageBase;
 332   PRUNTIME_FUNCTION FunctionEntry;
 333   ULONG64 EstablisherFrame;
 334   ULONG64 TargetIp;
 335   PCONTEXT ContextRecord;
 336   PEXCEPTION_ROUTINE LanguageHandler;
 337   PVOID HandlerData;
 338   PUNWIND_HISTORY_TABLE HistoryTable;
 339   ULONG ScopeIndex;
 340   ULONG Fill0;
 341 } UndocumentedDispatcherContext;
 342
 343 #ifdef _MSC_VER
 344 /* Another wild guess. */
 345 extern __DestructExceptionObject(EXCEPTION_RECORD *rec, int nothrow);
 346 #endif
 347
 348 #define LJ_MSVC_EXCODE          ((DWORD)0xe06d7363)
 349
 350 #define LJ_EXCODE               ((DWORD)0xe24c4a00)
 351 #define LJ_EXCODE_MAKE(c)       (LJ_EXCODE | (DWORD)(c))
 352 #define LJ_EXCODE_CHECK(cl)     (((cl) ^ LJ_EXCODE) <= 0xff)
 353 #define LJ_EXCODE_ERRCODE(cl)   ((int)((cl) & 0xff))
 354
 355 /* Win64 exception handler for interpreter frame. */
 356 LJ_FUNCA EXCEPTION_DISPOSITION lj_err_unwind_win64(EXCEPTION_RECORD *rec,
 357   void *cf, CONTEXT *ctx, UndocumentedDispatcherContext *dispatch)
 358 {
 359   lua_State *L = cframe_L(cf);
 360   int errcode = LJ_EXCODE_CHECK(rec->ExceptionCode) ?
 361                 LJ_EXCODE_ERRCODE(rec->ExceptionCode) : LUA_ERRRUN;
 362   if ((rec->ExceptionFlags & 6)) {  /* EH_UNWINDING|EH_EXIT_UNWIND */
 363     /* Unwind internal frames. */
 364     err_unwind(L, cf, errcode);
 365   } else {
 366     void *cf2 = err_unwind(L, cf, 0);
 367     if (cf2) {  /* We catch it, so start unwinding the upper frames. */
 368       if (rec->ExceptionCode == LJ_MSVC_EXCODE) {
 369 #ifdef _MSC_VER
 370         __DestructExceptionObject(rec, 1);
 371 #endif
 372         setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRCPP));
 373       } else if (!LJ_EXCODE_CHECK(rec->ExceptionCode)) {
 374         /* Don't catch access violations etc. */
 375         return ExceptionContinueSearch;
 376       }
 377       /* Unwind the stack and call all handlers for all lower C frames
 378       ** (including ourselves) again with EH_UNWINDING set. Then set
 379       ** rsp = cf, rax = errcode and jump to the specified target.
 380       */
 381       RtlUnwindEx(cf, (void *)((cframe_unwind_ff(cf2) && errcode != LUA_YIELD) ?
 382                                lj_vm_unwind_ff_eh :
 383                                lj_vm_unwind_c_eh),
 384                   rec, (void *)errcode, ctx, dispatch->HistoryTable);
 385       /* RtlUnwindEx should never return. */
 386     }
 387   }
 388   return ExceptionContinueSearch;
 389 }
 390
 391 /* Raise Windows exception. */
 392 static void err_raise_ext(int errcode)
 393 {
 394   RaiseException(LJ_EXCODE_MAKE(errcode), 1 /* EH_NONCONTINUABLE */, 0, NULL);
 395 }
 396
 397 #endif
 398
 399 /* -- Error handling ------------------------------------------------------ */
 400
 401 /* Throw error. Find catch frame, unwind stack and continue. */
 402 LJ_NOINLINE void LJ_FASTCALL lj_err_throw(lua_State *L, int errcode)
 403 {
 404   global_State *g = G(L);
 405   lj_trace_abort(g);
 406   setgcrefnull(g->jit_L);
 407   L->status = 0;
 408 #if LJ_UNWIND_EXT
 409   err_raise_ext(errcode);
 410   /*
 411   ** A return from this function signals a corrupt C stack that cannot be
 412   ** unwound. We have no choice but to call the panic function and exit.
 413   **
 414   ** Usually this is caused by a C function without unwind information.
 415   ** This should never happen on x64, but may happen if you've manually
 416   ** enabled LUAJIT_UNWIND_EXTERNAL and forgot to recompile *every*
 417   ** non-C++ file with -funwind-tables.
 418   */
 419   if (G(L)->panic)
 420     G(L)->panic(L);
 421 #else
 422   {
 423     void *cf = err_unwind(L, NULL, errcode);
 424     if (cframe_unwind_ff(cf))
 425       lj_vm_unwind_ff(cframe_raw(cf));
 426     else
 427       lj_vm_unwind_c(cframe_raw(cf), errcode);
 428   }
 429 #endif
 430   exit(EXIT_FAILURE);
 431 }
 432
 433 /* Return string object for error message. */
 434 LJ_NOINLINE GCstr *lj_err_str(lua_State *L, ErrMsg em)
 435 {
 436   return lj_str_newz(L, err2msg(em));
 437 }
 438
 439 /* Out-of-memory error. */
 440 LJ_NOINLINE void lj_err_mem(lua_State *L)
 441 {
 442   if (L->status == LUA_ERRERR+1)  /* Don't touch the stack during lua_open. */
 443     lj_vm_unwind_c(L->cframe, LUA_ERRMEM);
 444   L->top = L->base;
 445   setstrV(L, L->top++, lj_err_str(L, LJ_ERR_ERRMEM));
 446   lj_err_throw(L, LUA_ERRMEM);
 447 }
 448
 449 /* Find error function for runtime errors. Requires an extra stack traversal. */
 450 static ptrdiff_t finderrfunc(lua_State *L)
 451 {
 452   cTValue *frame = L->base-1, *bot = tvref(L->stack);
 453   void *cf = L->cframe;
 454   while (frame > bot) {
 455     lua_assert(cf != NULL);
 456     while (cframe_nres(cframe_raw(cf)) < 0) {  /* cframe without frame? */
 457       if (frame >= restorestack(L, -cframe_nres(cf)))
 458         break;
 459       if (cframe_errfunc(cf) >= 0)  /* Error handler not inherited (-1)? */
 460         return cframe_errfunc(cf);
 461       cf = cframe_prev(cf);  /* Else unwind cframe and continue searching. */
 462       if (cf == NULL)
 463         return 0;
 464     }
 465     switch (frame_typep(frame)) {
 466     case FRAME_LUA:
 467     case FRAME_LUAP:
 468       frame = frame_prevl(frame);
 469       break;
 470     case FRAME_C:
 471       cf = cframe_prev(cf);
 472       /* fallthrough */
 473     case FRAME_CONT:
 474 #if LJ_HASFFI
 475       if ((frame-1)->u32.lo == LJ_CONT_FFI_CALLBACK)
 476         cf = cframe_prev(cf);
 477 #endif
 478     case FRAME_VARG:
 479       frame = frame_prevd(frame);
 480       break;
 481     case FRAME_CP:
 482       if (cframe_canyield(cf)) return 0;
 483       if (cframe_errfunc(cf) >= 0)
 484         return cframe_errfunc(cf);
 485       frame = frame_prevd(frame);
 486       break;
 487     case FRAME_PCALL:
 488     case FRAME_PCALLH:
 489       if (frame_ftsz(frame) >= (ptrdiff_t)(2*sizeof(TValue)))  /* xpcall? */
 490         return savestack(L, frame-1);  /* Point to xpcall's errorfunc. */
 491       return 0;
 492     default:
 493       lua_assert(0);
 494       return 0;
 495     }
 496   }
 497   return 0;
 498 }
 499
 500 /* Runtime error. */
 501 LJ_NOINLINE void lj_err_run(lua_State *L)
 502 {
 503   ptrdiff_t ef = finderrfunc(L);
 504   if (ef) {
 505     TValue *errfunc = restorestack(L, ef);
 506     TValue *top = L->top;
 507     lj_trace_abort(G(L));
 508     if (!tvisfunc(errfunc) || L->status == LUA_ERRERR) {
 509       setstrV(L, top-1, lj_err_str(L, LJ_ERR_ERRERR));
 510       lj_err_throw(L, LUA_ERRERR);
 511     }
 512     L->status = LUA_ERRERR;
 513     copyTV(L, top, top-1);
 514     copyTV(L, top-1, errfunc);
 515     L->top = top+1;
 516     lj_vm_call(L, top, 1+1);  /* Stack: |errfunc|msg| -> |msg| */
 517   }
 518   lj_err_throw(L, LUA_ERRRUN);
 519 }
 520
 521 /* Formatted runtime error message. */
 522 LJ_NORET LJ_NOINLINE static void err_msgv(lua_State *L, ErrMsg em, ...)
 523 {
 524   const char *msg;
 525   va_list argp;
 526   va_start(argp, em);
 527   if (curr_funcisL(L)) L->top = curr_topL(L);
 528   msg = lj_str_pushvf(L, err2msg(em), argp);
 529   va_end(argp);
 530   lj_debug_addloc(L, msg, L->base-1, NULL);
 531   lj_err_run(L);
 532 }
 533
 534 /* Non-vararg variant for better calling conventions. */
 535 LJ_NOINLINE void lj_err_msg(lua_State *L, ErrMsg em)
 536 {
 537   err_msgv(L, em);
 538 }
 539
 540 /* Lexer error. */
 541 LJ_NOINLINE void lj_err_lex(lua_State *L, GCstr *src, const char *tok,
 542                             BCLine line, ErrMsg em, va_list argp)
 543 {
 544   char buff[LUA_IDSIZE];
 545   const char *msg;
 546   lj_debug_shortname(buff, src);
 547   msg = lj_str_pushvf(L, err2msg(em), argp);
 548   msg = lj_str_pushf(L, "%s:%d: %s", buff, line, msg);
 549   if (tok)
 550     lj_str_pushf(L, err2msg(LJ_ERR_XNEAR), msg, tok);
 551   lj_err_throw(L, LUA_ERRSYNTAX);
 552 }
 553
 554 /* Typecheck error for operands. */
 555 LJ_NOINLINE void lj_err_optype(lua_State *L, cTValue *o, ErrMsg opm)
 556 {
 557   const char *tname = typename(o);
 558   const char *opname = err2msg(opm);
 559   if (curr_funcisL(L)) {
 560     GCproto *pt = curr_proto(L);
 561     const BCIns *pc = cframe_Lpc(L) - 1;
 562     const char *oname = NULL;
 563     const char *kind = lj_debug_slotname(pt, pc, (BCReg)(o-L->base), &oname);
 564     if (kind)
 565       err_msgv(L, LJ_ERR_BADOPRT, opname, kind, oname, tname);
 566   }
 567   err_msgv(L, LJ_ERR_BADOPRV, opname, tname);
 568 }
 569
 570 /* Typecheck error for ordered comparisons. */
 571 LJ_NOINLINE void lj_err_comp(lua_State *L, cTValue *o1, cTValue *o2)
 572 {
 573   const char *t1 = typename(o1);
 574   const char *t2 = typename(o2);
 575   err_msgv(L, t1 == t2 ? LJ_ERR_BADCMPV : LJ_ERR_BADCMPT, t1, t2);
 576   /* This assumes the two "boolean" entries are commoned by the C compiler. */
 577 }
 578
 579 /* Typecheck error for __call. */
 580 LJ_NOINLINE void lj_err_optype_call(lua_State *L, TValue *o)
 581 {
 582   /* Gross hack if lua_[p]call or pcall/xpcall fail for a non-callable object:
 583   ** L->base still points to the caller. So add a dummy frame with L instead
 584   ** of a function. See lua_getstack().
 585   */
 586   const BCIns *pc = cframe_Lpc(L);
 587   if (((ptrdiff_t)pc & FRAME_TYPE) != FRAME_LUA) {
 588     const char *tname = typename(o);
 589     setframe_pc(o, pc);
 590     setframe_gc(o, obj2gco(L));
 591     L->top = L->base = o+1;
 592     err_msgv(L, LJ_ERR_BADCALL, tname);
 593   }
 594   lj_err_optype(L, o, LJ_ERR_OPCALL);
 595 }
 596
 597 /* Error in context of caller. */
 598 LJ_NOINLINE void lj_err_callermsg(lua_State *L, const char *msg)
 599 {
 600   TValue *frame = L->base-1;
 601   TValue *pframe = NULL;
 602   if (frame_islua(frame)) {
 603     pframe = frame_prevl(frame);
 604   } else if (frame_iscont(frame)) {
 605 #if LJ_HASFFI
 606     if ((frame-1)->u32.lo == LJ_CONT_FFI_CALLBACK) {
 607       pframe = frame;
 608       frame = NULL;
 609     } else
 610 #endif
 611     {
 612       pframe = frame_prevd(frame);
 613 #if LJ_HASFFI
 614       /* Remove frame for FFI metamethods. */
 615       if (frame_func(frame)->c.ffid >= FF_ffi_meta___index &&
 616           frame_func(frame)->c.ffid <= FF_ffi_meta___tostring) {
 617         L->base = pframe+1;
 618         L->top = frame;
 619       }
 620 #endif
 621     }
 622   }
 623   lj_debug_addloc(L, msg, pframe, frame);
 624   lj_err_run(L);
 625 }
 626
 627 /* Formatted error in context of caller. */
 628 LJ_NOINLINE void lj_err_callerv(lua_State *L, ErrMsg em, ...)
 629 {
 630   const char *msg;
 631   va_list argp;
 632   va_start(argp, em);
 633   msg = lj_str_pushvf(L, err2msg(em), argp);
 634   va_end(argp);
 635   lj_err_callermsg(L, msg);
 636 }
 637
 638 /* Error in context of caller. */
 639 LJ_NOINLINE void lj_err_caller(lua_State *L, ErrMsg em)
 640 {
 641   lj_err_callermsg(L, err2msg(em));
 642 }
 643
 644 /* Argument error message. */
 645 LJ_NORET LJ_NOINLINE static void err_argmsg(lua_State *L, int narg,
 646                                             const char *msg)
 647 {
 648   const char *fname = "?";
 649   const char *ftype = lj_debug_funcname(L, L->base - 1, &fname);
 650   if (narg < 0 && narg > LUA_REGISTRYINDEX)
 651     narg = (int)(L->top - L->base) + narg + 1;
 652   if (ftype && ftype[3] == 'h' && --narg == 0)  /* Check for "method". */
 653     msg = lj_str_pushf(L, err2msg(LJ_ERR_BADSELF), fname, msg);
 654   else
 655     msg = lj_str_pushf(L, err2msg(LJ_ERR_BADARG), narg, fname, msg);
 656   lj_err_callermsg(L, msg);
 657 }
 658
 659 /* Formatted argument error. */
 660 LJ_NOINLINE void lj_err_argv(lua_State *L, int narg, ErrMsg em, ...)
 661 {
 662   const char *msg;
 663   va_list argp;
 664   va_start(argp, em);
 665   msg = lj_str_pushvf(L, err2msg(em), argp);
 666   va_end(argp);
 667   err_argmsg(L, narg, msg);
 668 }
 669
 670 /* Argument error. */
 671 LJ_NOINLINE void lj_err_arg(lua_State *L, int narg, ErrMsg em)
 672 {
 673   err_argmsg(L, narg, err2msg(em));
 674 }
 675
 676 /* Typecheck error for arguments. */
 677 LJ_NOINLINE void lj_err_argtype(lua_State *L, int narg, const char *xname)
 678 {
 679   TValue *o = narg < 0 ? L->top + narg : L->base + narg-1;
 680   const char *tname = o < L->top ? typename(o) : lj_obj_typename[0];
 681   const char *msg = lj_str_pushf(L, err2msg(LJ_ERR_BADTYPE), xname, tname);
 682   err_argmsg(L, narg, msg);
 683 }
 684
 685 /* Typecheck error for arguments. */
 686 LJ_NOINLINE void lj_err_argt(lua_State *L, int narg, int tt)
 687 {
 688   lj_err_argtype(L, narg, lj_obj_typename[tt+1]);
 689 }
 690
 691 /* -- Public error handling API ------------------------------------------- */
 692
 693 LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
 694 {
 695   lua_CFunction old = G(L)->panic;
 696   G(L)->panic = panicf;
 697   return old;
 698 }
 699
 700 /* Forwarders for the public API (C calling convention and no LJ_NORET). */
 701 LUA_API int lua_error(lua_State *L)
 702 {
 703   lj_err_run(L);
 704   return 0;  /* unreachable */
 705 }
 706
 707 LUALIB_API int luaL_argerror(lua_State *L, int narg, const char *msg)
 708 {
 709   err_argmsg(L, narg, msg);
 710   return 0;  /* unreachable */
 711 }
 712
 713 LUALIB_API int luaL_typerror(lua_State *L, int narg, const char *xname)
 714 {
 715   lj_err_argtype(L, narg, xname);
 716   return 0;  /* unreachable */
 717 }
 718
 719 LUALIB_API void luaL_where(lua_State *L, int level)
 720 {
 721   int size;
 722   cTValue *frame = lj_debug_frame(L, level, &size);
 723   lj_debug_addloc(L, "", frame, size ? frame+size : NULL);
 724 }
 725
 726 LUALIB_API int luaL_error(lua_State *L, const char *fmt, ...)
 727 {
 728   const char *msg;
 729   va_list argp;
 730   va_start(argp, fmt);
 731   msg = lj_str_pushvf(L, fmt, argp);
 732   va_end(argp);
 733   lj_err_callermsg(L, msg);
 734   return 0;  /* unreachable */
 735 }
 736