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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.  
  763.