nanocoat/lib/3rdparty/lua/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_IGMARK is a mark to ignore all before it when building the
  29 ** luaopen_ function name.
  30 */
  31 #if !defined (LUA_IGMARK)
  32 #define LUA_IGMARK              "-"
  33 #endif
  34
  35
  36 /*
  37 ** LUA_CSUBSEP is the character that replaces dots in submodule names
  38 ** when searching for a C loader.
  39 ** LUA_LSUBSEP is the character that replaces dots in submodule names
  40 ** when searching for a Lua loader.
  41 */
  42 #if !defined(LUA_CSUBSEP)
  43 #define LUA_CSUBSEP             LUA_DIRSEP
  44 #endif
  45
  46 #if !defined(LUA_LSUBSEP)
  47 #define LUA_LSUBSEP             LUA_DIRSEP
  48 #endif
  49
  50
  51 /* prefix for open functions in C libraries */
  52 #define LUA_POF         "luaopen_"
  53
  54 /* separator for open functions in C libraries */
  55 #define LUA_OFSEP       "_"
  56
  57
  58 /*
  59 ** key for table in the registry that keeps handles
  60 ** for all loaded C libraries
  61 */
  62 static const char *const CLIBS = "_CLIBS";
  63
  64 #define LIB_FAIL        "open"
  65
  66
  67 #define setprogdir(L)           ((void)0)
  68
  69
  70 /*
  71 ** Special type equivalent to '(void*)' for functions in gcc
  72 ** (to suppress warnings when converting function pointers)
  73 */
  74 typedef void (*voidf)(void);
  75
  76
  77 /*
  78 ** system-dependent functions
  79 */
  80
  81 /*
  82 ** unload library 'lib'
  83 */
  84 static void lsys_unloadlib (void *lib);
  85
  86 /*
  87 ** load C library in file 'path'. If 'seeglb', load with all names in
  88 ** the library global.
  89 ** Returns the library; in case of error, returns NULL plus an
  90 ** error string in the stack.
  91 */
  92 static void *lsys_load (lua_State *L, const char *path, int seeglb);
  93
  94 /*
  95 ** Try to find a function named 'sym' in library 'lib'.
  96 ** Returns the function; in case of error, returns NULL plus an
  97 ** error string in the stack.
  98 */
  99 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym);
 100
 101
 102
 103
 104 #if defined(LUA_USE_DLOPEN)     /* { */
 105 /*
 106 ** {========================================================================
 107 ** This is an implementation of loadlib based on the dlfcn interface.
 108 ** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
 109 ** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
 110 ** as an emulation layer on top of native functions.
 111 ** =========================================================================
 112 */
 113
 114 #include <dlfcn.h>
 115
 116 /*
 117 ** Macro to convert pointer-to-void* to pointer-to-function. This cast
 118 ** is undefined according to ISO C, but POSIX assumes that it works.
 119 ** (The '__extension__' in gnu compilers is only to avoid warnings.)
 120 */
 121 #if defined(__GNUC__)
 122 #define cast_func(p) (__extension__ (lua_CFunction)(p))
 123 #else
 124 #define cast_func(p) ((lua_CFunction)(p))
 125 #endif
 126
 127
 128 static void lsys_unloadlib (void *lib) {
 129   dlclose(lib);
 130 }
 131
 132
 133 static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 134   void *lib = dlopen(path, RTLD_NOW | (seeglb ? RTLD_GLOBAL : RTLD_LOCAL));
 135   if (l_unlikely(lib == NULL))
 136     lua_pushstring(L, dlerror());
 137   return lib;
 138 }
 139
 140
 141 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 142   lua_CFunction f = cast_func(dlsym(lib, sym));
 143   if (l_unlikely(f == NULL))
 144     lua_pushstring(L, dlerror());
 145   return f;
 146 }
 147
 148 /* }====================================================== */
 149
 150
 151
 152 #elif defined(LUA_DL_DLL)       /* }{ */
 153 /*
 154 ** {======================================================================
 155 ** This is an implementation of loadlib for Windows using native functions.
 156 ** =======================================================================
 157 */
 158
 159 #include <windows.h>
 160
 161
 162 /*
 163 ** optional flags for LoadLibraryEx
 164 */
 165 #if !defined(LUA_LLE_FLAGS)
 166 #define LUA_LLE_FLAGS   0
 167 #endif
 168
 169
 170 #undef setprogdir
 171
 172
 173 /*
 174 ** Replace in the path (on the top of the stack) any occurrence
 175 ** of LUA_EXEC_DIR with the executable's path.
 176 */
 177 static void setprogdir (lua_State *L) {
 178   char buff[MAX_PATH + 1];
 179   char *lb;
 180   DWORD nsize = sizeof(buff)/sizeof(char);
 181   DWORD n = GetModuleFileNameA(NULL, buff, nsize);  /* get exec. name */
 182   if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
 183     luaL_error(L, "unable to get ModuleFileName");
 184   else {
 185     *lb = '\0';  /* cut name on the last '\\' to get the path */
 186     luaL_gsub(L, lua_tostring(L, -1), LUA_EXEC_DIR, buff);
 187     lua_remove(L, -2);  /* remove original string */
 188   }
 189 }
 190
 191
 192
 193
 194 static void pusherror (lua_State *L) {
 195   int error = GetLastError();
 196   char buffer[128];
 197   if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
 198       NULL, error, 0, buffer, sizeof(buffer)/sizeof(char), NULL))
 199     lua_pushstring(L, buffer);
 200   else
 201     lua_pushfstring(L, "system error %d\n", error);
 202 }
 203
 204 static void lsys_unloadlib (void *lib) {
 205   FreeLibrary((HMODULE)lib);
 206 }
 207
 208
 209 static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 210   HMODULE lib = LoadLibraryExA(path, NULL, LUA_LLE_FLAGS);
 211   (void)(seeglb);  /* not used: symbols are 'global' by default */
 212   if (lib == NULL) pusherror(L);
 213   return lib;
 214 }
 215
 216
 217 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 218   lua_CFunction f = (lua_CFunction)(voidf)GetProcAddress((HMODULE)lib, sym);
 219   if (f == NULL) pusherror(L);
 220   return f;
 221 }
 222
 223 /* }====================================================== */
 224
 225
 226 #else                           /* }{ */
 227 /*
 228 ** {======================================================
 229 ** Fallback for other systems
 230 ** =======================================================
 231 */
 232
 233 #undef LIB_FAIL
 234 #define LIB_FAIL        "absent"
 235
 236
 237 #define DLMSG   "dynamic libraries not enabled; check your Lua installation"
 238
 239
 240 static void lsys_unloadlib (void *lib) {
 241   (void)(lib);  /* not used */
 242 }
 243
 244
 245 static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 246   (void)(path); (void)(seeglb);  /* not used */
 247   lua_pushliteral(L, DLMSG);
 248   return NULL;
 249 }
 250
 251
 252 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 253   (void)(lib); (void)(sym);  /* not used */
 254   lua_pushliteral(L, DLMSG);
 255   return NULL;
 256 }
 257
 258 /* }====================================================== */
 259 #endif                          /* } */
 260
 261
 262 /*
 263 ** {==================================================================
 264 ** Set Paths
 265 ** ===================================================================
 266 */
 267
 268 /*
 269 ** LUA_PATH_VAR and LUA_CPATH_VAR are the names of the environment
 270 ** variables that Lua check to set its paths.
 271 */
 272 #if !defined(LUA_PATH_VAR)
 273 #define LUA_PATH_VAR    "LUA_PATH"
 274 #endif
 275
 276 #if !defined(LUA_CPATH_VAR)
 277 #define LUA_CPATH_VAR   "LUA_CPATH"
 278 #endif
 279
 280
 281
 282 /*
 283 ** return registry.LUA_NOENV as a boolean
 284 */
 285 static int noenv (lua_State *L) {
 286   int b;
 287   lua_getfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
 288   b = lua_toboolean(L, -1);
 289   lua_pop(L, 1);  /* remove value */
 290   return b;
 291 }
 292
 293
 294 /*
 295 ** Set a path
 296 */
 297 static void setpath (lua_State *L, const char *fieldname,
 298                                    const char *envname,
 299                                    const char *dft) {
 300   const char *dftmark;
 301   const char *nver = lua_pushfstring(L, "%s%s", envname, LUA_VERSUFFIX);
 302   const char *path = getenv(nver);  /* try versioned name */
 303   if (path == NULL)  /* no versioned environment variable? */
 304     path = getenv(envname);  /* try unversioned name */
 305   if (path == NULL || noenv(L))  /* no environment variable? */
 306     lua_pushstring(L, dft);  /* use default */
 307   else if ((dftmark = strstr(path, LUA_PATH_SEP LUA_PATH_SEP)) == NULL)
 308     lua_pushstring(L, path);  /* nothing to change */
 309   else {  /* path contains a ";;": insert default path in its place */
 310     size_t len = strlen(path);
 311     luaL_Buffer b;
 312     luaL_buffinit(L, &b);
 313     if (path < dftmark) {  /* is there a prefix before ';;'? */
 314       luaL_addlstring(&b, path, dftmark - path);  /* add it */
 315       luaL_addchar(&b, *LUA_PATH_SEP);
 316     }
 317     luaL_addstring(&b, dft);  /* add default */
 318     if (dftmark < path + len - 2) {  /* is there a suffix after ';;'? */
 319       luaL_addchar(&b, *LUA_PATH_SEP);
 320       luaL_addlstring(&b, dftmark + 2, (path + len - 2) - dftmark);
 321     }
 322     luaL_pushresult(&b);
 323   }
 324   setprogdir(L);
 325   lua_setfield(L, -3, fieldname);  /* package[fieldname] = path value */
 326   lua_pop(L, 1);  /* pop versioned variable name ('nver') */
 327 }
 328
 329 /* }================================================================== */
 330
 331
 332 /*
 333 ** return registry.CLIBS[path]
 334 */
 335 static void *checkclib (lua_State *L, const char *path) {
 336   void *plib;
 337   lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 338   lua_getfield(L, -1, path);
 339   plib = lua_touserdata(L, -1);  /* plib = CLIBS[path] */
 340   lua_pop(L, 2);  /* pop CLIBS table and 'plib' */
 341   return plib;
 342 }
 343
 344
 345 /*
 346 ** registry.CLIBS[path] = plib        -- for queries
 347 ** registry.CLIBS[#CLIBS + 1] = plib  -- also keep a list of all libraries
 348 */
 349 static void addtoclib (lua_State *L, const char *path, void *plib) {
 350   lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 351   lua_pushlightuserdata(L, plib);
 352   lua_pushvalue(L, -1);
 353   lua_setfield(L, -3, path);  /* CLIBS[path] = plib */
 354   lua_rawseti(L, -2, luaL_len(L, -2) + 1);  /* CLIBS[#CLIBS + 1] = plib */
 355   lua_pop(L, 1);  /* pop CLIBS table */
 356 }
 357
 358
 359 /*
 360 ** __gc tag method for CLIBS table: calls 'lsys_unloadlib' for all lib
 361 ** handles in list CLIBS
 362 */
 363 static int gctm (lua_State *L) {
 364   lua_Integer n = luaL_len(L, 1);
 365   for (; n >= 1; n--) {  /* for each handle, in reverse order */
 366     lua_rawgeti(L, 1, n);  /* get handle CLIBS[n] */
 367     lsys_unloadlib(lua_touserdata(L, -1));
 368     lua_pop(L, 1);  /* pop handle */
 369   }
 370   return 0;
 371 }
 372
 373
 374
 375 /* error codes for 'lookforfunc' */
 376 #define ERRLIB          1
 377 #define ERRFUNC         2
 378
 379 /*
 380 ** Look for a C function named 'sym' in a dynamically loaded library
 381 ** 'path'.
 382 ** First, check whether the library is already loaded; if not, try
 383 ** to load it.
 384 ** Then, if 'sym' is '*', return true (as library has been loaded).
 385 ** Otherwise, look for symbol 'sym' in the library and push a
 386 ** C function with that symbol.
 387 ** Return 0 and 'true' or a function in the stack; in case of
 388 ** errors, return an error code and an error message in the stack.
 389 */
 390 static int lookforfunc (lua_State *L, const char *path, const char *sym) {
 391   void *reg = checkclib(L, path);  /* check loaded C libraries */
 392   if (reg == NULL) {  /* must load library? */
 393     reg = lsys_load(L, path, *sym == '*');  /* global symbols if 'sym'=='*' */
 394     if (reg == NULL) return ERRLIB;  /* unable to load library */
 395     addtoclib(L, path, reg);
 396   }
 397   if (*sym == '*') {  /* loading only library (no function)? */
 398     lua_pushboolean(L, 1);  /* return 'true' */
 399     return 0;  /* no errors */
 400   }
 401   else {
 402     lua_CFunction f = lsys_sym(L, reg, sym);
 403     if (f == NULL)
 404       return ERRFUNC;  /* unable to find function */
 405     lua_pushcfunction(L, f);  /* else create new function */
 406     return 0;  /* no errors */
 407   }
 408 }
 409
 410
 411 static int ll_loadlib (lua_State *L) {
 412   const char *path = luaL_checkstring(L, 1);
 413   const char *init = luaL_checkstring(L, 2);
 414   int stat = lookforfunc(L, path, init);
 415   if (l_likely(stat == 0))  /* no errors? */
 416     return 1;  /* return the loaded function */
 417   else {  /* error; error message is on stack top */
 418     luaL_pushfail(L);
 419     lua_insert(L, -2);
 420     lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");
 421     return 3;  /* return fail, error message, and where */
 422   }
 423 }
 424
 425
 426
 427 /*
 428 ** {======================================================
 429 ** 'require' function
 430 ** =======================================================
 431 */
 432
 433
 434 static int readable (const char *filename) {
 435   FILE *f = fopen(filename, "r");  /* try to open file */
 436   if (f == NULL) return 0;  /* open failed */
 437   fclose(f);
 438   return 1;
 439 }
 440
 441
 442 /*
 443 ** Get the next name in '*path' = 'name1;name2;name3;...', changing
 444 ** the ending ';' to '\0' to create a zero-terminated string. Return
 445 ** NULL when list ends.
 446 */
 447 static const char *getnextfilename (char **path, char *end) {
 448   char *sep;
 449   char *name = *path;
 450   if (name == end)
 451     return NULL;  /* no more names */
 452   else if (*name == '\0') {  /* from previous iteration? */
 453     *name = *LUA_PATH_SEP;  /* restore separator */
 454     name++;  /* skip it */
 455   }
 456   sep = strchr(name, *LUA_PATH_SEP);  /* find next separator */
 457   if (sep == NULL)  /* separator not found? */
 458     sep = end;  /* name goes until the end */
 459   *sep = '\0';  /* finish file name */
 460   *path = sep;  /* will start next search from here */
 461   return name;
 462 }
 463
 464
 465 /*
 466 ** Given a path such as ";blabla.so;blublu.so", pushes the string
 467 **
 468 ** no file 'blabla.so'
 469 **      no file 'blublu.so'
 470 */
 471 static void pusherrornotfound (lua_State *L, const char *path) {
 472   luaL_Buffer b;
 473   luaL_buffinit(L, &b);
 474   luaL_addstring(&b, "no file '");
 475   luaL_addgsub(&b, path, LUA_PATH_SEP, "'\n\tno file '");
 476   luaL_addstring(&b, "'");
 477   luaL_pushresult(&b);
 478 }
 479
 480
 481 static const char *searchpath (lua_State *L, const char *name,
 482                                              const char *path,
 483                                              const char *sep,
 484                                              const char *dirsep) {
 485   luaL_Buffer buff;
 486   char *pathname;  /* path with name inserted */
 487   char *endpathname;  /* its end */
 488   const char *filename;
 489   /* separator is non-empty and appears in 'name'? */
 490   if (*sep != '\0' && strchr(name, *sep) != NULL)
 491     name = luaL_gsub(L, name, sep, dirsep);  /* replace it by 'dirsep' */
 492   luaL_buffinit(L, &buff);
 493   /* add path to the buffer, replacing marks ('?') with the file name */
 494   luaL_addgsub(&buff, path, LUA_PATH_MARK, name);
 495   luaL_addchar(&buff, '\0');
 496   pathname = luaL_buffaddr(&buff);  /* writable list of file names */
 497   endpathname = pathname + luaL_bufflen(&buff) - 1;
 498   while ((filename = getnextfilename(&pathname, endpathname)) != NULL) {
 499     if (readable(filename))  /* does file exist and is readable? */
 500       return lua_pushstring(L, filename);  /* save and return name */
 501   }
 502   luaL_pushresult(&buff);  /* push path to create error message */
 503   pusherrornotfound(L, lua_tostring(L, -1));  /* create error message */
 504   return NULL;  /* not found */
 505 }
 506
 507
 508 static int ll_searchpath (lua_State *L) {
 509   const char *f = searchpath(L, luaL_checkstring(L, 1),
 510                                 luaL_checkstring(L, 2),
 511                                 luaL_optstring(L, 3, "."),
 512                                 luaL_optstring(L, 4, LUA_DIRSEP));
 513   if (f != NULL) return 1;
 514   else {  /* error message is on top of the stack */
 515     luaL_pushfail(L);
 516     lua_insert(L, -2);
 517     return 2;  /* return fail + error message */
 518   }
 519 }
 520
 521
 522 static const char *findfile (lua_State *L, const char *name,
 523                                            const char *pname,
 524                                            const char *dirsep) {
 525   const char *path;
 526   lua_getfield(L, lua_upvalueindex(1), pname);
 527   path = lua_tostring(L, -1);
 528   if (l_unlikely(path == NULL))
 529     luaL_error(L, "'package.%s' must be a string", pname);
 530   return searchpath(L, name, path, ".", dirsep);
 531 }
 532
 533
 534 static int checkload (lua_State *L, int stat, const char *filename) {
 535   if (l_likely(stat)) {  /* module loaded successfully? */
 536     lua_pushstring(L, filename);  /* will be 2nd argument to module */
 537     return 2;  /* return open function and file name */
 538   }
 539   else
 540     return luaL_error(L, "error loading module '%s' from file '%s':\n\t%s",
 541                           lua_tostring(L, 1), filename, lua_tostring(L, -1));
 542 }
 543
 544
 545 static int searcher_Lua (lua_State *L) {
 546   const char *filename;
 547   const char *name = luaL_checkstring(L, 1);
 548   filename = findfile(L, name, "path", LUA_LSUBSEP);
 549   if (filename == NULL) return 1;  /* module not found in this path */
 550   return checkload(L, (luaL_loadfile(L, filename) == LUA_OK), filename);
 551 }
 552
 553
 554 /*
 555 ** Try to find a load function for module 'modname' at file 'filename'.
 556 ** First, change '.' to '_' in 'modname'; then, if 'modname' has
 557 ** the form X-Y (that is, it has an "ignore mark"), build a function
 558 ** name "luaopen_X" and look for it. (For compatibility, if that
 559 ** fails, it also tries "luaopen_Y".) If there is no ignore mark,
 560 ** look for a function named "luaopen_modname".
 561 */
 562 static int loadfunc (lua_State *L, const char *filename, const char *modname) {
 563   const char *openfunc;
 564   const char *mark;
 565   modname = luaL_gsub(L, modname, ".", LUA_OFSEP);
 566   mark = strchr(modname, *LUA_IGMARK);
 567   if (mark) {
 568     int stat;
 569     openfunc = lua_pushlstring(L, modname, mark - modname);
 570     openfunc = lua_pushfstring(L, LUA_POF"%s", openfunc);
 571     stat = lookforfunc(L, filename, openfunc);
 572     if (stat != ERRFUNC) return stat;
 573     modname = mark + 1;  /* else go ahead and try old-style name */
 574   }
 575   openfunc = lua_pushfstring(L, LUA_POF"%s", modname);
 576   return lookforfunc(L, filename, openfunc);
 577 }
 578
 579
 580 static int searcher_C (lua_State *L) {
 581   const char *name = luaL_checkstring(L, 1);
 582   const char *filename = findfile(L, name, "cpath", LUA_CSUBSEP);
 583   if (filename == NULL) return 1;  /* module not found in this path */
 584   return checkload(L, (loadfunc(L, filename, name) == 0), filename);
 585 }
 586
 587
 588 static int searcher_Croot (lua_State *L) {
 589   const char *filename;
 590   const char *name = luaL_checkstring(L, 1);
 591   const char *p = strchr(name, '.');
 592   int stat;
 593   if (p == NULL) return 0;  /* is root */
 594   lua_pushlstring(L, name, p - name);
 595   filename = findfile(L, lua_tostring(L, -1), "cpath", LUA_CSUBSEP);
 596   if (filename == NULL) return 1;  /* root not found */
 597   if ((stat = loadfunc(L, filename, name)) != 0) {
 598     if (stat != ERRFUNC)
 599       return checkload(L, 0, filename);  /* real error */
 600     else {  /* open function not found */
 601       lua_pushfstring(L, "no module '%s' in file '%s'", name, filename);
 602       return 1;
 603     }
 604   }
 605   lua_pushstring(L, filename);  /* will be 2nd argument to module */
 606   return 2;
 607 }
 608
 609
 610 static int searcher_preload (lua_State *L) {
 611   const char *name = luaL_checkstring(L, 1);
 612   lua_getfield(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 613   if (lua_getfield(L, -1, name) == LUA_TNIL) {  /* not found? */
 614     lua_pushfstring(L, "no field package.preload['%s']", name);
 615     return 1;
 616   }
 617   else {
 618     lua_pushliteral(L, ":preload:");
 619     return 2;
 620   }
 621 }
 622
 623
 624 static void findloader (lua_State *L, const char *name) {
 625   int i;
 626   luaL_Buffer msg;  /* to build error message */
 627   /* push 'package.searchers' to index 3 in the stack */
 628   if (l_unlikely(lua_getfield(L, lua_upvalueindex(1), "searchers")
 629                  != LUA_TTABLE))
 630     luaL_error(L, "'package.searchers' must be a table");
 631   luaL_buffinit(L, &msg);
 632   /*  iterate over available searchers to find a loader */
 633   for (i = 1; ; i++) {
 634     luaL_addstring(&msg, "\n\t");  /* error-message prefix */
 635     if (l_unlikely(lua_rawgeti(L, 3, i) == LUA_TNIL)) {  /* no more searchers? */
 636       lua_pop(L, 1);  /* remove nil */
 637       luaL_buffsub(&msg, 2);  /* remove prefix */
 638       luaL_pushresult(&msg);  /* create error message */
 639       luaL_error(L, "module '%s' not found:%s", name, lua_tostring(L, -1));
 640     }
 641     lua_pushstring(L, name);
 642     lua_call(L, 1, 2);  /* call it */
 643     if (lua_isfunction(L, -2))  /* did it find a loader? */
 644       return;  /* module loader found */
 645     else if (lua_isstring(L, -2)) {  /* searcher returned error message? */
 646       lua_pop(L, 1);  /* remove extra return */
 647       luaL_addvalue(&msg);  /* concatenate error message */
 648     }
 649     else {  /* no error message */
 650       lua_pop(L, 2);  /* remove both returns */
 651       luaL_buffsub(&msg, 2);  /* remove prefix */
 652     }
 653   }
 654 }
 655
 656
 657 static int ll_require (lua_State *L) {
 658   const char *name = luaL_checkstring(L, 1);
 659   lua_settop(L, 1);  /* LOADED table will be at index 2 */
 660   lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 661   lua_getfield(L, 2, name);  /* LOADED[name] */
 662   if (lua_toboolean(L, -1))  /* is it there? */
 663     return 1;  /* package is already loaded */
 664   /* else must load package */
 665   lua_pop(L, 1);  /* remove 'getfield' result */
 666   findloader(L, name);
 667   lua_rotate(L, -2, 1);  /* function <-> loader data */
 668   lua_pushvalue(L, 1);  /* name is 1st argument to module loader */
 669   lua_pushvalue(L, -3);  /* loader data is 2nd argument */
 670   /* stack: ...; loader data; loader function; mod. name; loader data */
 671   lua_call(L, 2, 1);  /* run loader to load module */
 672   /* stack: ...; loader data; result from loader */
 673   if (!lua_isnil(L, -1))  /* non-nil return? */
 674     lua_setfield(L, 2, name);  /* LOADED[name] = returned value */
 675   else
 676     lua_pop(L, 1);  /* pop nil */
 677   if (lua_getfield(L, 2, name) == LUA_TNIL) {   /* module set no value? */
 678     lua_pushboolean(L, 1);  /* use true as result */
 679     lua_copy(L, -1, -2);  /* replace loader result */
 680     lua_setfield(L, 2, name);  /* LOADED[name] = true */
 681   }
 682   lua_rotate(L, -2, 1);  /* loader data <-> module result  */
 683   return 2;  /* return module result and loader data */
 684 }
 685
 686 /* }====================================================== */
 687
 688
 689
 690
 691 static const luaL_Reg pk_funcs[] = {
 692   {"loadlib", ll_loadlib},
 693   {"searchpath", ll_searchpath},
 694   /* placeholders */
 695   {"preload", NULL},
 696   {"cpath", NULL},
 697   {"path", NULL},
 698   {"searchers", NULL},
 699   {"loaded", NULL},
 700   {NULL, NULL}
 701 };
 702
 703
 704 static const luaL_Reg ll_funcs[] = {
 705   {"require", ll_require},
 706   {NULL, NULL}
 707 };
 708
 709
 710 static void createsearcherstable (lua_State *L) {
 711   static const lua_CFunction searchers[] = {
 712     searcher_preload,
 713     searcher_Lua,
 714     searcher_C,
 715     searcher_Croot,
 716     NULL
 717   };
 718   int i;
 719   /* create 'searchers' table */
 720   lua_createtable(L, sizeof(searchers)/sizeof(searchers[0]) - 1, 0);
 721   /* fill it with predefined searchers */
 722   for (i=0; searchers[i] != NULL; i++) {
 723     lua_pushvalue(L, -2);  /* set 'package' as upvalue for all searchers */
 724     lua_pushcclosure(L, searchers[i], 1);
 725     lua_rawseti(L, -2, i+1);
 726   }
 727   lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
 728 }
 729
 730
 731 /*
 732 ** create table CLIBS to keep track of loaded C libraries,
 733 ** setting a finalizer to close all libraries when closing state.
 734 */
 735 static void createclibstable (lua_State *L) {
 736   luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);  /* create CLIBS table */
 737   lua_createtable(L, 0, 1);  /* create metatable for CLIBS */
 738   lua_pushcfunction(L, gctm);
 739   lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */
 740   lua_setmetatable(L, -2);
 741 }
 742
 743
 744 LUAMOD_API int luaopen_package (lua_State *L) {
 745   createclibstable(L);
 746   luaL_newlib(L, pk_funcs);  /* create 'package' table */
 747   createsearcherstable(L);
 748   /* set paths */
 749   setpath(L, "path", LUA_PATH_VAR, LUA_PATH_DEFAULT);
 750   setpath(L, "cpath", LUA_CPATH_VAR, LUA_CPATH_DEFAULT);
 751   /* store config information */
 752   lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATH_SEP "\n" LUA_PATH_MARK "\n"
 753                      LUA_EXEC_DIR "\n" LUA_IGMARK "\n");
 754   lua_setfield(L, -2, "config");
 755   /* set field 'loaded' */
 756   luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 757   lua_setfield(L, -2, "loaded");
 758   /* set field 'preload' */
 759   luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 760   lua_setfield(L, -2, "preload");
 761   lua_pushglobaltable(L);
 762   lua_pushvalue(L, -2);  /* set 'package' as upvalue for next lib */
 763   luaL_setfuncs(L, ll_funcs, 1);  /* open lib into global table */
 764   lua_pop(L, 1);  /* pop global table */
 765   return 1;  /* return 'package' table */
 766 }
 767