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Member "memcached-1.6.15/vendor/lua/src/loadlib.c" (1 Oct 2021, 23030 Bytes) of package /linux/www/memcached-1.6.15.tar.gz:


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    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, searcher_Lua, searcher_C, searcher_Croot, NULL};
  713   int i;
  714   /* create 'searchers' table */
  715   lua_createtable(L, sizeof(searchers)/sizeof(searchers[0]) - 1, 0);
  716   /* fill it with predefined searchers */
  717   for (i=0; searchers[i] != NULL; i++) {
  718     lua_pushvalue(L, -2);  /* set 'package' as upvalue for all searchers */
  719     lua_pushcclosure(L, searchers[i], 1);
  720     lua_rawseti(L, -2, i+1);
  721   }
  722   lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
  723 }
  724 
  725 
  726 /*
  727 ** create table CLIBS to keep track of loaded C libraries,
  728 ** setting a finalizer to close all libraries when closing state.
  729 */
  730 static void createclibstable (lua_State *L) {
  731   luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);  /* create CLIBS table */
  732   lua_createtable(L, 0, 1);  /* create metatable for CLIBS */
  733   lua_pushcfunction(L, gctm);
  734   lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */
  735   lua_setmetatable(L, -2);
  736 }
  737 
  738 
  739 LUAMOD_API int luaopen_package (lua_State *L) {
  740   createclibstable(L);
  741   luaL_newlib(L, pk_funcs);  /* create 'package' table */
  742   createsearcherstable(L);
  743   /* set paths */
  744   setpath(L, "path", LUA_PATH_VAR, LUA_PATH_DEFAULT);
  745   setpath(L, "cpath", LUA_CPATH_VAR, LUA_CPATH_DEFAULT);
  746   /* store config information */
  747   lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATH_SEP "\n" LUA_PATH_MARK "\n"
  748                      LUA_EXEC_DIR "\n" LUA_IGMARK "\n");
  749   lua_setfield(L, -2, "config");
  750   /* set field 'loaded' */
  751   luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
  752   lua_setfield(L, -2, "loaded");
  753   /* set field 'preload' */
  754   luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
  755   lua_setfield(L, -2, "preload");
  756   lua_pushglobaltable(L);
  757   lua_pushvalue(L, -2);  /* set 'package' as upvalue for next lib */
  758   luaL_setfuncs(L, ll_funcs, 1);  /* open lib into global table */
  759   lua_pop(L, 1);  /* pop global table */
  760   return 1;  /* return 'package' table */
  761 }
  762