loadlib.c

/*
** $Id: loadlib.c $
** Dynamic library loader for Lua
** See Copyright Notice in lua.h
**
** This module contains an implementation of loadlib for Unix systems
** that have dlfcn, an implementation for Windows, and a stub for other
** systems.
*/

#define loadlib_c
#define LUA_LIB

#include "lprefix.h"


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


/*
** LUA_CSUBSEP is the character that replaces dots in submodule names
** when searching for a C loader.
** LUA_LSUBSEP is the character that replaces dots in submodule names
** when searching for a Lua loader.
*/
#if !defined(LUA_CSUBSEP)
#define LUA_CSUBSEP		LUA_DIRSEP
#endif

#if !defined(LUA_LSUBSEP)
#define LUA_LSUBSEP		LUA_DIRSEP
#endif


/* prefix for open functions in C libraries */
#define LUA_POF		"luaopen_"

/* separator for open functions in C libraries */
#define LUA_OFSEP	"_"


/*
** key for table in the registry that keeps handles
** for all loaded C libraries
*/
static const char *const CLIBS = "_CLIBS";

#define LIB_FAIL	"open"


#define setprogdir(L) ((void)0)


/*
** Special type equivalent to '(void*)' for functions in gcc
** (to suppress warnings when converting function pointers)
*/
typedef void (*voidf)(void);


/*
** system-dependent functions
*/

/*
** unload library 'lib'
*/
static void lsys_unloadlib (void *lib);

/*
** load C library in file 'path'. If 'seeglb', load with all names in
** the library global.
** Returns the library; in case of error, returns NULL plus an
** error string in the stack.
*/
static void *lsys_load (lua_State *L, const char *path, int seeglb);

/*
** Try to find a function named 'sym' in library 'lib'.
** Returns the function; in case of error, returns NULL plus an
** error string in the stack.
*/
static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym);




#if defined(LUA_USE_DLOPEN)	/* { */
/*
** {========================================================================
** This is an implementation of loadlib based on the dlfcn interface.
** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
** NetBSD, AIX 4.2, HPUX 11, and probably most other Unix flavors, at least
** as an emulation layer on top of native functions.
** =========================================================================
*/

#include <dlfcn.h>

/*
** Macro to convert pointer-to-void* to pointer-to-function. This cast
** is undefined according to ISO C, but POSIX assumes that it works.
** (The '__extension__' in gnu compilers is only to avoid warnings.)
*/
#if defined(__GNUC__)
#define cast_func(p) (__extension__ (lua_CFunction)(p))
#else
#define cast_func(p) ((lua_CFunction)(p))
#endif


static void lsys_unloadlib (void *lib) {
 dlclose(lib);
}


static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 void *lib = dlopen(path, RTLD_NOW | (seeglb ? RTLD_GLOBAL : RTLD_LOCAL));
 if (l_unlikely(lib == NULL))
 lua_pushstring(L, dlerror());
 return lib;
}


static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 lua_CFunction f = cast_func(dlsym(lib, sym));
 if (l_unlikely(f == NULL))
 lua_pushstring(L, dlerror());
 return f;
}

/* }====================================================== */



#elif defined(LUA_DL_DLL)	/* }{ */
/*
** {======================================================================
** This is an implementation of loadlib for Windows using native functions.
** =======================================================================
*/

#include <windows.h>


/*
** optional flags for LoadLibraryEx
*/
#if !defined(LUA_LLE_FLAGS)
#define LUA_LLE_FLAGS	0
#endif


#undef setprogdir


/*
** Replace in the path (on the top of the stack) any occurrence
** of LUA_EXEC_DIR with the executable's path.
*/
static void setprogdir (lua_State *L) {
 char buff[MAX_PATH + 1];
 char *lb;
 DWORD nsize = sizeof(buff)/sizeof(char);
 DWORD n = GetModuleFileNameA(NULL, buff, nsize); /* get exec. name */
 if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
 luaL_error(L, "unable to get ModuleFileName");
 else {
 *lb = '\0'; /* cut name on the last '\\' to get the path */
 luaL_gsub(L, lua_tostring(L, -1), LUA_EXEC_DIR, buff);
 lua_remove(L, -2); /* remove original string */
 }
}




static void pusherror (lua_State *L) {
 int error = GetLastError();
 char buffer[128];
 if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
 NULL, error, 0, buffer, sizeof(buffer)/sizeof(char), NULL))
 lua_pushstring(L, buffer);
 else
 lua_pushfstring(L, "system error %d\n", error);
}

static void lsys_unloadlib (void *lib) {
 FreeLibrary((HMODULE)lib);
}


static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 HMODULE lib = LoadLibraryExA(path, NULL, LUA_LLE_FLAGS);
 (void)(seeglb); /* not used: symbols are 'global' by default */
 if (lib == NULL) pusherror(L);
 return lib;
}


static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 lua_CFunction f = (lua_CFunction)(voidf)GetProcAddress((HMODULE)lib, sym);
 if (f == NULL) pusherror(L);
 return f;
}

/* }====================================================== */


#else				/* }{ */
/*
** {======================================================
** Fallback for other systems
** =======================================================
*/

#undef LIB_FAIL
#define LIB_FAIL	"absent"


#define DLMSG	"dynamic libraries not enabled; check your Lua installation"


static void lsys_unloadlib (void *lib) {
 (void)(lib); /* not used */
}


static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 (void)(path); (void)(seeglb); /* not used */
 lua_pushliteral(L, DLMSG);
 return NULL;
}


static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
 (void)(lib); (void)(sym); /* not used */
 lua_pushliteral(L, DLMSG);
 return NULL;
}

/* }====================================================== */
#endif				/* } */


/*
** {==================================================================
** Set Paths
** ===================================================================
*/

/*
** LUA_PATH_VAR and LUA_CPATH_VAR are the names of the environment
** variables that Lua check to set its paths.
*/
#if !defined(LUA_PATH_VAR)
#define LUA_PATH_VAR "LUA_PATH"
#endif

#if !defined(LUA_CPATH_VAR)
#define LUA_CPATH_VAR "LUA_CPATH"
#endif



/*
** return registry.LUA_NOENV as a boolean
*/
static int noenv (lua_State *L) {
 int b;
 lua_getfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
 b = lua_toboolean(L, -1);
 lua_pop(L, 1); /* remove value */
 return b;
}


/*
** Set a path
*/
static void setpath (lua_State *L, const char *fieldname,
 const char *envname,
 const char *dft) {
 const char *dftmark;
 const char *nver = lua_pushfstring(L, "%s%s", envname, LUA_VERSUFFIX);
 const char *path = getenv(nver); /* try versioned name */
 if (path == NULL) /* no versioned environment variable? */
 path = getenv(envname); /* try unversioned name */
 if (path == NULL || noenv(L)) /* no environment variable? */
 lua_pushstring(L, dft); /* use default */
 else if ((dftmark = strstr(path, LUA_PATH_SEP LUA_PATH_SEP)) == NULL)
 lua_pushstring(L, path); /* nothing to change */
 else { /* path contains a ";;": insert default path in its place */
 size_t len = strlen(path);
 luaL_Buffer b;
 luaL_buffinit(L, &b);
 if (path < dftmark) { /* is there a prefix before ';;'? */
 luaL_addlstring(&b, path, dftmark - path); /* add it */
 luaL_addchar(&b, *LUA_PATH_SEP);
 }
 luaL_addstring(&b, dft); /* add default */
 if (dftmark < path + len - 2) { /* is there a suffix after ';;'? */
 luaL_addchar(&b, *LUA_PATH_SEP);
 luaL_addlstring(&b, dftmark + 2, (path + len - 2) - dftmark);
 }
 luaL_pushresult(&b);
 }
 setprogdir(L);
 lua_setfield(L, -3, fieldname); /* package[fieldname] = path value */
 lua_pop(L, 1); /* pop versioned variable name ('nver') */
}

/* }================================================================== */


/*
** return registry.CLIBS[path]
*/
static void *checkclib (lua_State *L, const char *path) {
 void *plib;
 lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 lua_getfield(L, -1, path);
 plib = lua_touserdata(L, -1); /* plib = CLIBS[path] */
 lua_pop(L, 2); /* pop CLIBS table and 'plib' */
 return plib;
}


/*
** registry.CLIBS[path] = plib -- for queries
** registry.CLIBS[#CLIBS + 1] = plib -- also keep a list of all libraries
*/
static void addtoclib (lua_State *L, const char *path, void *plib) {
 lua_getfield(L, LUA_REGISTRYINDEX, CLIBS);
 lua_pushlightuserdata(L, plib);
 lua_pushvalue(L, -1);
 lua_setfield(L, -3, path); /* CLIBS[path] = plib */
 lua_rawseti(L, -2, luaL_len(L, -2) + 1); /* CLIBS[#CLIBS + 1] = plib */
 lua_pop(L, 1); /* pop CLIBS table */
}


/*
** __gc tag method for CLIBS table: calls 'lsys_unloadlib' for all lib
** handles in list CLIBS
*/
static int gctm (lua_State *L) {
 lua_Integer n = luaL_len(L, 1);
 for (; n >= 1; n--) { /* for each handle, in reverse order */
 lua_rawgeti(L, 1, n); /* get handle CLIBS[n] */
 lsys_unloadlib(lua_touserdata(L, -1));
 lua_pop(L, 1); /* pop handle */
 }
 return 0;
}



/* error codes for 'lookforfunc' */
#define ERRLIB		1
#define ERRFUNC		2

/*
** Look for a C function named 'sym' in a dynamically loaded library
** 'path'.
** First, check whether the library is already loaded; if not, try
** to load it.
** Then, if 'sym' is '*', return true (as library has been loaded).
** Otherwise, look for symbol 'sym' in the library and push a
** C function with that symbol.
** Return 0 and 'true' or a function in the stack; in case of
** errors, return an error code and an error message in the stack.
*/
static int lookforfunc (lua_State *L, const char *path, const char *sym) {
 void *reg = checkclib(L, path); /* check loaded C libraries */
 if (reg == NULL) { /* must load library? */
 reg = lsys_load(L, path, *sym == '*'); /* global symbols if 'sym'=='*' */
 if (reg == NULL) return ERRLIB; /* unable to load library */
 addtoclib(L, path, reg);
 }
 if (*sym == '*') { /* loading only library (no function)? */
 lua_pushboolean(L, 1); /* return 'true' */
 return 0; /* no errors */
 }
 else {
 lua_CFunction f = lsys_sym(L, reg, sym);
 if (f == NULL)
 return ERRFUNC; /* unable to find function */
 lua_pushcfunction(L, f); /* else create new function */
 return 0; /* no errors */
 }
}


static int ll_loadlib (lua_State *L) {
 const char *path = luaL_checkstring(L, 1);
 const char *init = luaL_checkstring(L, 2);
 int stat = lookforfunc(L, path, init);
 if (l_likely(stat == 0)) /* no errors? */
 return 1; /* return the loaded function */
 else { /* error; error message is on stack top */
 luaL_pushfail(L);
 lua_insert(L, -2);
 lua_pushstring(L, (stat == ERRLIB) ? LIB_FAIL : "init");
 return 3; /* return fail, error message, and where */
 }
}



/*
** {======================================================
** 'require' function
** =======================================================
*/


static int readable (const char *filename) {
 FILE *f = fopen(filename, "r"); /* try to open file */
 if (f == NULL) return 0; /* open failed */
 fclose(f);
 return 1;
}


/*
** Get the next name in '*path' = 'name1;name2;name3;...', changing
** the ending ';' to '\0' to create a zero-terminated string. Return
** NULL when list ends.
*/
static const char *getnextfilename (char **path, char *end) {
 char *sep;
 char *name = *path;
 if (name == end)
 return NULL; /* no more names */
 else if (*name == '\0') { /* from previous iteration? */
 *name = *LUA_PATH_SEP; /* restore separator */
 name++; /* skip it */
 }
 sep = strchr(name, *LUA_PATH_SEP); /* find next separator */
 if (sep == NULL) /* separator not found? */
 sep = end; /* name goes until the end */
 *sep = '\0'; /* finish file name */
 *path = sep; /* will start next search from here */
 return name;
}


/*
** Given a path such as ";blabla.so;blublu.so", pushes the string
**
** no file 'blabla.so'
**	no file 'blublu.so'
*/
static void pusherrornotfound (lua_State *L, const char *path) {
 luaL_Buffer b;
 luaL_buffinit(L, &b);
 luaL_addstring(&b, "no file '");
 luaL_addgsub(&b, path, LUA_PATH_SEP, "'\n\tno file '");
 luaL_addstring(&b, "'");
 luaL_pushresult(&b);
}


static const char *searchpath (lua_State *L, const char *name,
 const char *path,
 const char *sep,
 const char *dirsep) {
 luaL_Buffer buff;
 char *pathname; /* path with name inserted */
 char *endpathname; /* its end */
 const char *filename;
 /* separator is non-empty and appears in 'name'? */
 if (*sep != '\0' && strchr(name, *sep) != NULL)
 name = luaL_gsub(L, name, sep, dirsep); /* replace it by 'dirsep' */
 luaL_buffinit(L, &buff);
 /* add path to the buffer, replacing marks ('?') with the file name */
 luaL_addgsub(&buff, path, LUA_PATH_MARK, name);
 luaL_addchar(&buff, '\0');
 pathname = luaL_buffaddr(&buff); /* writable list of file names */
 endpathname = pathname + luaL_bufflen(&buff) - 1;
 while ((filename = getnextfilename(&pathname, endpathname)) != NULL) {
 if (readable(filename)) /* does file exist and is readable? */
 return lua_pushstring(L, filename); /* save and return name */
 }
 luaL_pushresult(&buff); /* push path to create error message */
 pusherrornotfound(L, lua_tostring(L, -1)); /* create error message */
 return NULL; /* not found */
}


static int ll_searchpath (lua_State *L) {
 const char *f = searchpath(L, luaL_checkstring(L, 1),
 luaL_checkstring(L, 2),
 luaL_optstring(L, 3, "."),
 luaL_optstring(L, 4, LUA_DIRSEP));
 if (f != NULL) return 1;
 else { /* error message is on top of the stack */
 luaL_pushfail(L);
 lua_insert(L, -2);
 return 2; /* return fail + error message */
 }
}


static const char *findfile (lua_State *L, const char *name,
 const char *pname,
 const char *dirsep) {
 const char *path;
 lua_getfield(L, lua_upvalueindex(1), pname);
 path = lua_tostring(L, -1);
 if (l_unlikely(path == NULL))
 luaL_error(L, "'package.%s' must be a string", pname);
 return searchpath(L, name, path, ".", dirsep);
}


static int checkload (lua_State *L, int stat, const char *filename) {
 if (l_likely(stat)) { /* module loaded successfully? */
 lua_pushstring(L, filename); /* will be 2nd argument to module */
 return 2; /* return open function and file name */
 }
 else
 return luaL_error(L, "error loading module '%s' from file '%s':\n\t%s",
 lua_tostring(L, 1), filename, lua_tostring(L, -1));
}


static int searcher_Lua (lua_State *L) {
 const char *filename;
 const char *name = luaL_checkstring(L, 1);
 filename = findfile(L, name, "path", LUA_LSUBSEP);
 if (filename == NULL) return 1; /* module not found in this path */
 return checkload(L, (luaL_loadfile(L, filename) == LUA_OK), filename);
}


/*
** Try to find a load function for module 'modname' at file 'filename'.
** First, change '.' to '_' in 'modname'; then, if 'modname' has
** the form X-Y (that is, it has an "ignore mark"), build a function
** name "luaopen_X" and look for it. (For compatibility, if that
** fails, it also tries "luaopen_Y".) If there is no ignore mark,
** look for a function named "luaopen_modname".
*/
static int loadfunc (lua_State *L, const char *filename, const char *modname) {
 const char *openfunc;
 const char *mark;
 modname = luaL_gsub(L, modname, ".", LUA_OFSEP);
 mark = strchr(modname, *LUA_IGMARK);
 if (mark) {
 int stat;
 openfunc = lua_pushlstring(L, modname, mark - modname);
 openfunc = lua_pushfstring(L, LUA_POF"%s", openfunc);
 stat = lookforfunc(L, filename, openfunc);
 if (stat != ERRFUNC) return stat;
 modname = mark + 1; /* else go ahead and try old-style name */
 }
 openfunc = lua_pushfstring(L, LUA_POF"%s", modname);
 return lookforfunc(L, filename, openfunc);
}


static int searcher_C (lua_State *L) {
 const char *name = luaL_checkstring(L, 1);
 const char *filename = findfile(L, name, "cpath", LUA_CSUBSEP);
 if (filename == NULL) return 1; /* module not found in this path */
 return checkload(L, (loadfunc(L, filename, name) == 0), filename);
}


static int searcher_Croot (lua_State *L) {
 const char *filename;
 const char *name = luaL_checkstring(L, 1);
 const char *p = strchr(name, '.');
 int stat;
 if (p == NULL) return 0; /* is root */
 lua_pushlstring(L, name, p - name);
 filename = findfile(L, lua_tostring(L, -1), "cpath", LUA_CSUBSEP);
 if (filename == NULL) return 1; /* root not found */
 if ((stat = loadfunc(L, filename, name)) != 0) {
 if (stat != ERRFUNC)
 return checkload(L, 0, filename); /* real error */
 else { /* open function not found */
 lua_pushfstring(L, "no module '%s' in file '%s'", name, filename);
 return 1;
 }
 }
 lua_pushstring(L, filename); /* will be 2nd argument to module */
 return 2;
}


static int searcher_preload (lua_State *L) {
 const char *name = luaL_checkstring(L, 1);
 lua_getfield(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 if (lua_getfield(L, -1, name) == LUA_TNIL) { /* not found? */
 lua_pushfstring(L, "no field package.preload['%s']", name);
 return 1;
 }
 else {
 lua_pushliteral(L, ":preload:");
 return 2;
 }
}


static void findloader (lua_State *L, const char *name) {
 int i;
 luaL_Buffer msg; /* to build error message */
 /* push 'package.searchers' to index 3 in the stack */
 if (l_unlikely(lua_getfield(L, lua_upvalueindex(1), "searchers")
 != LUA_TTABLE))
 luaL_error(L, "'package.searchers' must be a table");
 luaL_buffinit(L, &msg);
 /* iterate over available searchers to find a loader */
 for (i = 1; ; i++) {
 luaL_addstring(&msg, "\n\t"); /* error-message prefix */
 if (l_unlikely(lua_rawgeti(L, 3, i) == LUA_TNIL)) { /* no more searchers? */
 lua_pop(L, 1); /* remove nil */
 luaL_buffsub(&msg, 2); /* remove prefix */
 luaL_pushresult(&msg); /* create error message */
 luaL_error(L, "module '%s' not found:%s", name, lua_tostring(L, -1));
 }
 lua_pushstring(L, name);
 lua_call(L, 1, 2); /* call it */
 if (lua_isfunction(L, -2)) /* did it find a loader? */
 return; /* module loader found */
 else if (lua_isstring(L, -2)) { /* searcher returned error message? */
 lua_pop(L, 1); /* remove extra return */
 luaL_addvalue(&msg); /* concatenate error message */
 }
 else { /* no error message */
 lua_pop(L, 2); /* remove both returns */
 luaL_buffsub(&msg, 2); /* remove prefix */
 }
 }
}


static int ll_require (lua_State *L) {
 const char *name = luaL_checkstring(L, 1);
 lua_settop(L, 1); /* LOADED table will be at index 2 */
 lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 lua_getfield(L, 2, name); /* LOADED[name] */
 if (lua_toboolean(L, -1)) /* is it there? */
 return 1; /* package is already loaded */
 /* else must load package */
 lua_pop(L, 1); /* remove 'getfield' result */
 findloader(L, name);
 lua_rotate(L, -2, 1); /* function <-> loader data */
 lua_pushvalue(L, 1); /* name is 1st argument to module loader */
 lua_pushvalue(L, -3); /* loader data is 2nd argument */
 /* stack: ...; loader data; loader function; mod. name; loader data */
 lua_call(L, 2, 1); /* run loader to load module */
 /* stack: ...; loader data; result from loader */
 if (!lua_isnil(L, -1)) /* non-nil return? */
 lua_setfield(L, 2, name); /* LOADED[name] = returned value */
 else
 lua_pop(L, 1); /* pop nil */
 if (lua_getfield(L, 2, name) == LUA_TNIL) { /* module set no value? */
 lua_pushboolean(L, 1); /* use true as result */
 lua_copy(L, -1, -2); /* replace loader result */
 lua_setfield(L, 2, name); /* LOADED[name] = true */
 }
 lua_rotate(L, -2, 1); /* loader data <-> module result */
 return 2; /* return module result and loader data */
}

/* }====================================================== */




static const luaL_Reg pk_funcs[] = {
 {"loadlib", ll_loadlib},
 {"searchpath", ll_searchpath},
 /* placeholders */
 {"preload", NULL},
 {"cpath", NULL},
 {"path", NULL},
 {"searchers", NULL},
 {"loaded", NULL},
 {NULL, NULL}
};


static const luaL_Reg ll_funcs[] = {
 {"require", ll_require},
 {NULL, NULL}
};


static void createsearcherstable (lua_State *L) {
 static const lua_CFunction searchers[] = {
 searcher_preload,
 searcher_Lua,
 searcher_C,
 searcher_Croot,
 NULL
 };
 int i;
 /* create 'searchers' table */
 lua_createtable(L, sizeof(searchers)/sizeof(searchers[0]) - 1, 0);
 /* fill it with predefined searchers */
 for (i=0; searchers[i] != NULL; i++) {
 lua_pushvalue(L, -2); /* set 'package' as upvalue for all searchers */
 lua_pushcclosure(L, searchers[i], 1);
 lua_rawseti(L, -2, i+1);
 }
 lua_setfield(L, -2, "searchers"); /* put it in field 'searchers' */
}


/*
** create table CLIBS to keep track of loaded C libraries,
** setting a finalizer to close all libraries when closing state.
*/
static void createclibstable (lua_State *L) {
 luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS); /* create CLIBS table */
 lua_createtable(L, 0, 1); /* create metatable for CLIBS */
 lua_pushcfunction(L, gctm);
 lua_setfield(L, -2, "__gc"); /* set finalizer for CLIBS table */
 lua_setmetatable(L, -2);
}


LUAMOD_API int luaopen_package (lua_State *L) {
 createclibstable(L);
 luaL_newlib(L, pk_funcs); /* create 'package' table */
 createsearcherstable(L);
 /* set paths */
 setpath(L, "path", LUA_PATH_VAR, LUA_PATH_DEFAULT);
 setpath(L, "cpath", LUA_CPATH_VAR, LUA_CPATH_DEFAULT);
 /* store config information */
 lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATH_SEP "\n" LUA_PATH_MARK "\n"
 LUA_EXEC_DIR "\n" LUA_IGMARK "\n");
 lua_setfield(L, -2, "config");
 /* set field 'loaded' */
 luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
 lua_setfield(L, -2, "loaded");
 /* set field 'preload' */
 luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
 lua_setfield(L, -2, "preload");
 lua_pushglobaltable(L);
 lua_pushvalue(L, -2); /* set 'package' as upvalue for next lib */
 luaL_setfuncs(L, ll_funcs, 1); /* open lib into global table */
 lua_pop(L, 1); /* pop global table */
 return 1; /* return 'package' table */
}