client/deps/liblua/loadlib.c

   1 /*
   2 ** $Id: loadlib.c $
   3 ** Dynamic library loader for Lua
   4 ** See Copyright Notice in lua.h
   5 **
   6 ** This module contains an implementation of loadlib for Unix systems
   7 ** that have dlfcn, an implementation for Windows, and a stub for other
   8 ** systems.
   9 */
  10
  11 #define loadlib_c
  12 #define LUA_LIB
  13
  14 #include "lprefix.h"
  15
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20
  21 #include "lua.h"
  22
  23 #include "lauxlib.h"
  24 #include "lualib.h"
  25
  26
  27 /*
  28 ** LUA_CSUBSEP is the character that replaces dots in submodule names
  29 ** when searching for a C loader.
  30 ** LUA_LSUBSEP is the character that replaces dots in submodule names
  31 ** when searching for a Lua loader.
  32 */
  33 #if !defined(LUA_CSUBSEP)
  34 #define LUA_CSUBSEP             LUA_DIRSEP
  35 #endif
  36
  37 #if !defined(LUA_LSUBSEP)
  38 #define LUA_LSUBSEP             LUA_DIRSEP
  39 #endif
  40
  41
  42 /* prefix for open functions in C libraries */
  43 #define LUA_POF         "luaopen_"
  44
  45 /* separator for open functions in C libraries */
  46 #define LUA_OFSEP       "_"
  47
  48
  49 /*
  50 ** key for table in the registry that keeps handles
  51 ** for all loaded C libraries
  52 */
  53 static const char *const CLIBS = "_CLIBS";
  54
  55 #define LIB_FAIL        "open"
  56
  57
  58 #define setprogdir(L)           ((void)0)
  59
  60
  61 /*
  62 ** Special type equivalent to '(void*)' for functions in gcc
  63 ** (to suppress warnings when converting function pointers)
  64 */
  65 typedef void (*voidf)(void);
  66
  67
  68 /*
  69 ** system-dependent functions
  70 */
  71
  72 /*
  73 ** unload library 'lib'
  74 */
  75 static void lsys_unloadlib(void *lib);
  76
  77 /*
  78 ** load C library in file 'path'. If 'seeglb', load with all names in
  79 ** the library global.
  80 ** Returns the library; in case of error, returns NULL plus an
  81 ** error string in the stack.
  82 */
  83 static void *lsys_load(lua_State *L, const char *path, int seeglb);
  84
  85 /*
  86 ** Try to find a function named 'sym' in library 'lib'.
  87 ** Returns the function; in case of error, returns NULL plus an
  88 ** error string in the stack.
  89 */
  90 static lua_CFunction lsys_sym(lua_State *L, void *lib, const char *sym);
  91
  92
  93
  94
  95 #if defined(LUA_USE_DLOPEN)     /* { */
  96 /*
  97 ** {========================================================================
  98 ** This is an implementation of loadlib based on the dlfcn interface.
  99 ** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
 100 ** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
 101 ** as an emulation layer on top of native functions.
 102 ** =========================================================================
 103 */
 104
 105 #include <dlfcn.h>
 106
 107 /*
 108 ** Macro to convert pointer-to-void* to pointer-to-function. This cast
 109 ** is undefined according to ISO C, but POSIX assumes that it works.
 110 ** (The '__extension__' in gnu compilers is only to avoid warnings.)
 111 */
 112 #if defined(__GNUC__)
 113 #define cast_func(p) (__extension__ (lua_CFunction)(p))
 114 #else
 115 #define cast_func(p) ((lua_CFunction)(p))
 116 #endif
 117
 118
 119 static void lsys_unloadlib(void *lib) {
 120     dlclose(lib);
 121 }
 122
 123
 124 static void *lsys_load(lua_State *L, const char *path, int seeglb) {
 125     void *lib = dlopen(path, RTLD_NOW | (seeglb ? RTLD_GLOBAL : RTLD_LOCAL));
 126     if (l_unlikely(lib == NULL))
 127         lua_pushstring(L, dlerror());
 128     return lib;
 129 }
 130
 131
 132 static lua_CFunction lsys_sym(lua_State *L, void *lib, const char *sym) {
 133     lua_CFunction f = cast_func(dlsym(lib, sym));
 134     if (l_unlikely(f == NULL))
 135         lua_pushstring(L, dlerror());
 136     return f;
 137 }
 138
 139 /* }====================================================== */
 140
 141
 142
 143 #elif defined(LUA_DL_DLL)       /* }{ */
 144 /*
 145 ** {======================================================================
 146 ** This is an implementation of loadlib for Windows using native functions.
 147 ** =======================================================================
 148 */
 149
 150 #include <windows.h>
 151
 152
 153 /*
 154 ** optional flags for LoadLibraryEx
 155 */
 156 #if !defined(LUA_LLE_FLAGS)
 157 #define LUA_LLE_FLAGS   0
 158 #endif
 159
 160
 161 #undef setprogdir
 162
 163
 164 /*
 165 ** Replace in the path (on the top of the stack) any occurrence
 166 ** of LUA_EXEC_DIR with the executable's path.
 167 */
 168 static void setprogdir(lua_State *L) {
 169     char buff[MAX_PATH + 1];
 170     char *lb;
 171     DWORD nsize = sizeof(buff) / sizeof(char);
 172     DWORD n = GetModuleFileNameA(NULL, buff, nsize);  /* get exec. name */
 173     if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
 174         luaL_error(L, "unable to get ModuleFileName");
 175     else {
 176         *lb = '\0';  /* cut name on the last '\\' to get the path */
 177         luaL_gsub(L, lua_tostring(L, -1), LUA_EXEC_DIR, buff);
 178         lua_remove(L, -2);  /* remove original string */
 179     }
 180 }
 181
 182
 183
 184
 185 static void pusherror(lua_State *L) {
 186     int error = GetLastError();
 187     char buffer[128];
 188     if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
 189                        NULL, error, 0, buffer, sizeof(buffer) / sizeof(char), NULL))
 190         lua_pushstring(L, buffer);
 191     else
 192         lua_pushfstring(L, "system error %d\n", error);
 193 }
 194
 195 static void lsys_unloadlib(void *lib) {
 196     FreeLibrary((HMODULE)lib);
 197 }
 198
 199
 200 static void *lsys_load(lua_State *L, const char *path, int seeglb) {
 201     HMODULE lib = LoadLibraryExA(path, NULL, LUA_LLE_FLAGS);
 202     (void)(seeglb);  /* not used: symbols are 'global' by default */
 203     if (lib == NULL) pusherror(L);
 204     return lib;
 205 }
 206
 207
 208 static lua_CFunction lsys_sym(lua_State *L, void *lib, const char *sym) {
 209     lua_CFunction f = (lua_CFunction)(voidf)GetProcAddress((HMODULE)lib, sym);
 210     if (f == NULL) pusherror(L);
 211     return f;
 212 }
 213
 214 /* }====================================================== */
 215
 216
 217 #else                           /* }{ */
 218 /*
 219 ** {======================================================
 220 ** Fallback for other systems
 221 ** =======================================================
 222 */
 223
 224 #undef LIB_FAIL
 225 #define LIB_FAIL        "absent"
 226
 227
 228 #define DLMSG   "dynamic libraries not enabled; check your Lua installation"
 229
 230
 231 static void lsys_unloadlib(void *lib) {
 232     (void)(lib);  /* not used */
 233 }
 234
 235
 236 static void *lsys_load(lua_State *L, const char *path, int seeglb) {
 237     (void)(path);
 238     (void)(seeglb);  /* not used */
 239     lua_pushliteral(L, DLMSG);
 240     return NULL;
 241 }
 242
 243
 244 static lua_CFunction lsys_sym(lua_State *L, void *lib, const char *sym) {
 245     (void)(lib);
 246     (void)(sym);  /* not used */
 247     lua_pushliteral(L, DLMSG);
 248     return NULL;
 249 }
 250
 251 /* }====================================================== */
 252 #endif                          /* } */
 253
 254
 255 /*
 256 ** {==================================================================
 257 ** Set Paths
 258 ** ===================================================================
 259 */
 260
 261 /*
 262 ** LUA_PATH_VAR and LUA_CPATH_VAR are the names of the environment
 263 ** variables that Lua check to set its paths.
 264 */
 265 #if !defined(LUA_PATH_VAR)
 266 #define LUA_PATH_VAR    "LUA_PATH"
 267 #endif
 268
 269 #if !defined(LUA_CPATH_VAR)
 270 #define LUA_CPATH_VAR   "LUA_CPATH"
 271 #endif
 272
 273
 274
 275 /*
 276 ** return registry.LUA_NOENV as a boolean
 277 */
 278 static int noenv(lua_State *L) {
 279     int b;
 280     lua_getfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
 281     b = lua_toboolean(L, -1);
 282     lua_pop(L, 1);  /* remove value */
 283     return b;
 284 }
 285
 286
 287 /*
 288 ** Set a path
 289 */
 290 static void setpath(lua_State *L, const char *fieldname,
 291                     const char *envname,
 292                     const char *dft) {
 293     const char *dftmark;
 294     const char *nver = lua_pushfstring(L, "%s%s", envname, LUA_VERSUFFIX);
 295     const char *path = getenv(nver);  /* try versioned name */
 296     if (path == NULL)  /* no versioned environment variable? */
 297         path = getenv(envname);  /* try unversioned name */
 298     if (path == NULL || noenv(L))  /* no environment variable? */
 299         lua_pushstring(L, dft);  /* use default */
 300     else if ((dftmark = strstr(path, LUA_PATH_SEP LUA_PATH_SEP)) == NULL)
 301         lua_pushstring(L, path);  /* nothing to change */
 302     else {  /* path contains a ";;": insert default path in its place */
 303         size_t len = strlen(path);
 304         luaL_Buffer b;
 305         luaL_buffinit(L, &b);
 306         if (path < dftmark) {  /* is there a prefix before ';;'? */
 307             luaL_addlstring(&b, path, dftmark - path);  /* add it */
 308             luaL_addchar(&b, *LUA_PATH_SEP);
 309         }
 310         luaL_addstring(&b, dft);  /* add default */
 311         if (dftmark < path + len - 2) {  /* is there a suffix after ';;'? */
 312             luaL_addchar(&b, *LUA_PATH_SEP);
 313             luaL_addlstring(&b, dftmark + 2, (path + len - 2) - dftmark);
 314         }
 315         luaL_pushresult(&b);
 316     }
 317     setprogdir(L);
 318     lua_setfield(L, -3, fieldname);  /* package[fieldname] = path value */
 319     lua_pop(L, 1);  /* pop versioned variable name ('nver') */
 320 }
 321
 322 /* }================================================================== */
 323
 324
 325 /*
 326 ** return registry.CLIBS[path]
 327 */
 328 static void *checkclib(lua_State *L, const char *path) {
 329     void *plib;
 330     lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 331     lua_getfield(L, -1, path);
 332     plib = lua_touserdata(L, -1);  /* plib = CLIBS[path] */
 333     lua_pop(L, 2);  /* pop CLIBS table and 'plib' */
 334     return plib;
 335 }
 336
 337
 338 /*
 339 ** registry.CLIBS[path] = plib        -- for queries
 340 ** registry.CLIBS[#CLIBS + 1] = plib  -- also keep a list of all libraries
 341 */
 342 static void addtoclib(lua_State *L, const char *path, void *plib) {
 343     lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 344     lua_pushlightuserdata(L, plib);
 345     lua_pushvalue(L, -1);
 346     lua_setfield(L, -3, path);  /* CLIBS[path] = plib */
 347     lua_rawseti(L, -2, luaL_len(L, -2) + 1);  /* CLIBS[#CLIBS + 1] = plib */
 348     lua_pop(L, 1);  /* pop CLIBS table */
 349 }
 350
 351
 352 /*
 353 ** __gc tag method for CLIBS table: calls 'lsys_unloadlib' for all lib
 354 ** handles in list CLIBS
 355 */
 356 static int gctm(lua_State *L) {
 357     lua_Integer n = luaL_len(L, 1);
 358     for (; n >= 1; n--) {  /* for each handle, in reverse order */
 359         lua_rawgeti(L, 1, n);  /* get handle CLIBS[n] */
 360         lsys_unloadlib(lua_touserdata(L, -1));
 361         lua_pop(L, 1);  /* pop handle */
 362     }
 363     return 0;
 364 }
 365
 366
 367
 368 /* error codes for 'lookforfunc' */
 369 #define ERRLIB          1
 370 #define ERRFUNC         2
 371
 372 /*
 373 ** Look for a C function named 'sym' in a dynamically loaded library
 374 ** 'path'.
 375 ** First, check whether the library is already loaded; if not, try
 376 ** to load it.
 377 ** Then, if 'sym' is '*', return true (as library has been loaded).
 378 ** Otherwise, look for symbol 'sym' in the library and push a
 379 ** C function with that symbol.
 380 ** Return 0 and 'true' or a function in the stack; in case of
 381 ** errors, return an error code and an error message in the stack.
 382 */
 383 static int lookforfunc(lua_State *L, const char *path, const char *sym) {
 384     void *reg = checkclib(L, path);  /* check loaded C libraries */
 385     if (reg == NULL) {  /* must load library? */
 386         reg = lsys_load(L, path, *sym == '*');  /* global symbols if 'sym'=='*' */
 387         if (reg == NULL) return ERRLIB;  /* unable to load library */
 388         addtoclib(L, path, reg);
 389     }
 390     if (*sym == '*') {  /* loading only library (no function)? */
 391         lua_pushboolean(L, 1);  /* return 'true' */
 392         return 0;  /* no errors */
 393     } else {
 394         lua_CFunction f = lsys_sym(L, reg, sym);
 395         if (f == NULL)
 396             return ERRFUNC;  /* unable to find function */
 397         lua_pushcfunction(L, f);  /* else create new function */
 398         return 0;  /* no errors */
 399     }
 400 }
 401
 402
 403 static int ll_loadlib(lua_State *L) {
 404     const char *path = luaL_checkstring(L, 1);
 405     const char *init = luaL_checkstring(L, 2);
 406     int stat = lookforfunc(L, path, init);
 407     if (l_likely(stat == 0))  /* no errors? */
 408         return 1;  /* return the loaded function */
 409     else {  /* error; error message is on stack top */
 410         luaL_pushfail(L);
 411         lua_insert(L, -2);
 412         lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");
 413         return 3;  /* return fail, error message, and where */
 414     }
 415 }
 416
 417
 418
 419 /*
 420 ** {======================================================
 421 ** 'require' function
 422 ** =======================================================
 423 */
 424
 425
 426 static int readable(const char *filename) {
 427     FILE *f = fopen(filename, "r");  /* try to open file */
 428     if (f == NULL) return 0;  /* open failed */
 429     fclose(f);
 430     return 1;
 431 }
 432
 433
 434 /*
 435 ** Get the next name in '*path' = 'name1;name2;name3;...', changing
 436 ** the ending ';' to '\0' to create a zero-terminated string. Return
 437 ** NULL when list ends.
 438 */
 439 static const char *getnextfilename(char **path, char *end) {
 440     char *sep;
 441     char *name = *path;
 442     if (name == end)
 443         return NULL;  /* no more names */
 444     else if (*name == '\0') {  /* from previous iteration? */
 445         *name = *LUA_PATH_SEP;  /* restore separator */
 446         name++;  /* skip it */
 447     }
 448     sep = strchr(name, *LUA_PATH_SEP);  /* find next separator */
 449     if (sep == NULL)  /* separator not found? */
 450         sep = end;  /* name goes until the end */
 451     *sep = '\0';  /* finish file name */
 452     *path = sep;  /* will start next search from here */
 453     return name;
 454 }
 455
 456
 457 /*
 458 ** Given a path such as ";blabla.so;blublu.so", pushes the string
 459 **
 460 ** no file 'blabla.so'
 461 **      no file 'blublu.so'
 462 */
 463 static void pusherrornotfound(lua_State *L, const char *path) {
 464     luaL_Buffer b;
 465     luaL_buffinit(L, &b);
 466     luaL_addstring(&b, "no file '");
 467     luaL_addgsub(&b, path, LUA_PATH_SEP, "'\n\tno file '");
 468     luaL_addstring(&b, "'");
 469     luaL_pushresult(&b);
 470 }
 471
 472
 473 static const char *searchpath(lua_State *L, const char *name,
 474                               const char *path,
 475                               const char *sep,
 476                               const char *dirsep) {
 477     luaL_Buffer buff;
 478     char *pathname;  /* path with name inserted */
 479     char *endpathname;  /* its end */
 480     const char *filename;
 481     /* separator is non-empty and appears in 'name'? */
 482     if (*sep != '\0' && strchr(name, *sep) != NULL)
 483         name = luaL_gsub(L, name, sep, dirsep);  /* replace it by 'dirsep' */
 484     luaL_buffinit(L, &buff);
 485     /* add path to the buffer, replacing marks ('?') with the file name */
 486     luaL_addgsub(&buff, path, LUA_PATH_MARK, name);
 487     luaL_addchar(&buff, '\0');
 488     pathname = luaL_buffaddr(&buff);  /* writable list of file names */
 489     endpathname = pathname + luaL_bufflen(&buff) - 1;
 490     while ((filename = getnextfilename(&pathname, endpathname)) != NULL) {
 491         if (readable(filename))  /* does file exist and is readable? */
 492             return lua_pushstring(L, filename);  /* save and return name */
 493     }
 494     luaL_pushresult(&buff);  /* push path to create error message */
 495     pusherrornotfound(L, lua_tostring(L, -1));  /* create error message */
 496     return NULL;  /* not found */
 497 }
 498
 499
 500 static int ll_searchpath(lua_State *L) {
 501     const char *f = searchpath(L, luaL_checkstring(L, 1),
 502                                luaL_checkstring(L, 2),
 503                                luaL_optstring(L, 3, "."),
 504                                luaL_optstring(L, 4, LUA_DIRSEP));
 505     if (f != NULL) return 1;
 506     else {  /* error message is on top of the stack */
 507         luaL_pushfail(L);
 508         lua_insert(L, -2);
 509         return 2;  /* return fail + error message */
 510     }
 511 }
 512
 513
 514 static const char *findfile(lua_State *L, const char *name,
 515                             const char *pname,
 516                             const char *dirsep) {
 517     const char *path;
 518     lua_getfield(L, lua_upvalueindex(1), pname);
 519     path = lua_tostring(L, -1);
 520     if (l_unlikely(path == NULL))
 521         luaL_error(L, "'package.%s' must be a string", pname);
 522     return searchpath(L, name, path, ".", dirsep);
 523 }
 524
 525
 526 static int checkload(lua_State *L, int stat, const char *filename) {
 527     if (l_likely(stat)) {  /* module loaded successfully? */
 528         lua_pushstring(L, filename);  /* will be 2nd argument to module */
 529         return 2;  /* return open function and file name */
 530     } else
 531         return luaL_error(L, "error loading module '%s' from file '%s':\n\t%s",
 532                           lua_tostring(L, 1), filename, lua_tostring(L, -1));
 533 }
 534
 535
 536 static int searcher_Lua(lua_State *L) {
 537     const char *filename;
 538     const char *name = luaL_checkstring(L, 1);
 539     filename = findfile(L, name, "path", LUA_LSUBSEP);
 540     if (filename == NULL) return 1;  /* module not found in this path */
 541     return checkload(L, (luaL_loadfile(L, filename) == LUA_OK), filename);
 542 }
 543
 544
 545 /*
 546 ** Try to find a load function for module 'modname' at file 'filename'.
 547 ** First, change '.' to '_' in 'modname'; then, if 'modname' has
 548 ** the form X-Y (that is, it has an "ignore mark"), build a function
 549 ** name "luaopen_X" and look for it. (For compatibility, if that
 550 ** fails, it also tries "luaopen_Y".) If there is no ignore mark,
 551 ** look for a function named "luaopen_modname".
 552 */
 553 static int loadfunc(lua_State *L, const char *filename, const char *modname) {
 554     const char *openfunc;
 555     const char *mark;
 556     modname = luaL_gsub(L, modname, ".", LUA_OFSEP);
 557     mark = strchr(modname, *LUA_IGMARK);
 558     if (mark) {
 559         int stat;
 560         openfunc = lua_pushlstring(L, modname, mark - modname);
 561         openfunc = lua_pushfstring(L, LUA_POF"%s", openfunc);
 562         stat = lookforfunc(L, filename, openfunc);
 563         if (stat != ERRFUNC) return stat;
 564         modname = mark + 1;  /* else go ahead and try old-style name */
 565     }
 566     openfunc = lua_pushfstring(L, LUA_POF"%s", modname);
 567     return lookforfunc(L, filename, openfunc);
 568 }
 569
 570
 571 static int searcher_C(lua_State *L) {
 572     const char *name = luaL_checkstring(L, 1);
 573     const char *filename = findfile(L, name, "cpath", LUA_CSUBSEP);
 574     if (filename == NULL) return 1;  /* module not found in this path */
 575     return checkload(L, (loadfunc(L, filename, name) == 0), filename);
 576 }
 577
 578
 579 static int searcher_Croot(lua_State *L) {
 580     const char *filename;
 581     const char *name = luaL_checkstring(L, 1);
 582     const char *p = strchr(name, '.');
 583     int stat;
 584     if (p == NULL) return 0;  /* is root */
 585     lua_pushlstring(L, name, p - name);
 586     filename = findfile(L, lua_tostring(L, -1), "cpath", LUA_CSUBSEP);
 587     if (filename == NULL) return 1;  /* root not found */
 588     if ((stat = loadfunc(L, filename, name)) != 0) {
 589         if (stat != ERRFUNC)
 590             return checkload(L, 0, filename);  /* real error */
 591         else {  /* open function not found */
 592             lua_pushfstring(L, "no module '%s' in file '%s'", name, filename);
 593             return 1;
 594         }
 595     }
 596     lua_pushstring(L, filename);  /* will be 2nd argument to module */
 597     return 2;
 598 }
 599
 600
 601 static int searcher_preload(lua_State *L) {
 602     const char *name = luaL_checkstring(L, 1);
 603     lua_getfield(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 604     if (lua_getfield(L, -1, name) == LUA_TNIL) {  /* not found? */
 605         lua_pushfstring(L, "no field package.preload['%s']", name);
 606         return 1;
 607     } else {
 608         lua_pushliteral(L, ":preload:");
 609         return 2;
 610     }
 611 }
 612
 613
 614 static void findloader(lua_State *L, const char *name) {
 615     int i;
 616     luaL_Buffer msg;  /* to build error message */
 617     /* push 'package.searchers' to index 3 in the stack */
 618     if (l_unlikely(lua_getfield(L, lua_upvalueindex(1), "searchers")
 619                    != LUA_TTABLE))
 620         luaL_error(L, "'package.searchers' must be a table");
 621     luaL_buffinit(L, &msg);
 622     /*  iterate over available searchers to find a loader */
 623     for (i = 1; ; i++) {
 624         luaL_addstring(&msg, "\n\t");  /* error-message prefix */
 625         if (l_unlikely(lua_rawgeti(L, 3, i) == LUA_TNIL)) {  /* no more searchers? */
 626             lua_pop(L, 1);  /* remove nil */
 627             luaL_buffsub(&msg, 2);  /* remove prefix */
 628             luaL_pushresult(&msg);  /* create error message */
 629             luaL_error(L, "module '%s' not found:%s", name, lua_tostring(L, -1));
 630         }
 631         lua_pushstring(L, name);
 632         lua_call(L, 1, 2);  /* call it */
 633         if (lua_isfunction(L, -2))  /* did it find a loader? */
 634             return;  /* module loader found */
 635         else if (lua_isstring(L, -2)) {  /* searcher returned error message? */
 636             lua_pop(L, 1);  /* remove extra return */
 637             luaL_addvalue(&msg);  /* concatenate error message */
 638         } else { /* no error message */
 639             lua_pop(L, 2);  /* remove both returns */
 640             luaL_buffsub(&msg, 2);  /* remove prefix */
 641         }
 642     }
 643 }
 644
 645
 646 static int ll_require(lua_State *L) {
 647     const char *name = luaL_checkstring(L, 1);
 648     lua_settop(L, 1);  /* LOADED table will be at index 2 */
 649     lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 650     lua_getfield(L, 2, name);  /* LOADED[name] */
 651     if (lua_toboolean(L, -1))  /* is it there? */
 652         return 1;  /* package is already loaded */
 653     /* else must load package */
 654     lua_pop(L, 1);  /* remove 'getfield' result */
 655     findloader(L, name);
 656     lua_rotate(L, -2, 1);  /* function <-> loader data */
 657     lua_pushvalue(L, 1);  /* name is 1st argument to module loader */
 658     lua_pushvalue(L, -3);  /* loader data is 2nd argument */
 659     /* stack: ...; loader data; loader function; mod. name; loader data */
 660     lua_call(L, 2, 1);  /* run loader to load module */
 661     /* stack: ...; loader data; result from loader */
 662     if (!lua_isnil(L, -1))  /* non-nil return? */
 663         lua_setfield(L, 2, name);  /* LOADED[name] = returned value */
 664     else
 665         lua_pop(L, 1);  /* pop nil */
 666     if (lua_getfield(L, 2, name) == LUA_TNIL) {   /* module set no value? */
 667         lua_pushboolean(L, 1);  /* use true as result */
 668         lua_copy(L, -1, -2);  /* replace loader result */
 669         lua_setfield(L, 2, name);  /* LOADED[name] = true */
 670     }
 671     lua_rotate(L, -2, 1);  /* loader data <-> module result  */
 672     return 2;  /* return module result and loader data */
 673 }
 674
 675 /* }====================================================== */
 676
 677
 678
 679
 680 static const luaL_Reg pk_funcs[] = {
 681     {"loadlib", ll_loadlib},
 682     {"searchpath", ll_searchpath},
 683     /* placeholders */
 684     {"preload", NULL},
 685     {"cpath", NULL},
 686     {"path", NULL},
 687     {"searchers", NULL},
 688     {"loaded", NULL},
 689     {NULL, NULL}
 690 };
 691
 692
 693 static const luaL_Reg ll_funcs[] = {
 694     {"require", ll_require},
 695     {NULL, NULL}
 696 };
 697
 698
 699 static void createsearcherstable(lua_State *L) {
 700     static const lua_CFunction searchers[] = {
 701         searcher_preload,
 702         searcher_Lua,
 703         searcher_C,
 704         searcher_Croot,
 705         NULL
 706     };
 707     int i;
 708     /* create 'searchers' table */
 709     lua_createtable(L, sizeof(searchers) / sizeof(searchers[0]) - 1, 0);
 710     /* fill it with predefined searchers */
 711     for (i = 0; searchers[i] != NULL; i++) {
 712         lua_pushvalue(L, -2);  /* set 'package' as upvalue for all searchers */
 713         lua_pushcclosure(L, searchers[i], 1);
 714         lua_rawseti(L, -2, i + 1);
 715     }
 716     lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
 717 }
 718
 719
 720 /*
 721 ** create table CLIBS to keep track of loaded C libraries,
 722 ** setting a finalizer to close all libraries when closing state.
 723 */
 724 static void createclibstable(lua_State *L) {
 725     luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);  /* create CLIBS table */
 726     lua_createtable(L, 0, 1);  /* create metatable for CLIBS */
 727     lua_pushcfunction(L, gctm);
 728     lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */
 729     lua_setmetatable(L, -2);
 730 }
 731
 732
 733 LUAMOD_API int luaopen_package(lua_State *L) {
 734     createclibstable(L);
 735     luaL_newlib(L, pk_funcs);  /* create 'package' table */
 736     createsearcherstable(L);
 737     /* set paths */
 738     setpath(L, "path", LUA_PATH_VAR, LUA_PATH_DEFAULT);
 739     setpath(L, "cpath", LUA_CPATH_VAR, LUA_CPATH_DEFAULT);
 740     /* store config information */
 741     lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATH_SEP "\n" LUA_PATH_MARK "\n"
 742                     LUA_EXEC_DIR "\n" LUA_IGMARK "\n");
 743     lua_setfield(L, -2, "config");
 744     /* set field 'loaded' */
 745     luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 746     lua_setfield(L, -2, "loaded");
 747     /* set field 'preload' */
 748     luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 749     lua_setfield(L, -2, "preload");
 750     lua_pushglobaltable(L);
 751     lua_pushvalue(L, -2);  /* set 'package' as upvalue for next lib */
 752     luaL_setfuncs(L, ll_funcs, 1);  /* open lib into global table */
 753     lua_pop(L, 1);  /* pop global table */
 754     return 1;  /* return 'package' table */
 755 }
 756