/*
** $Id: loadlib.c,v 1.111 2012/05/30 12:33:44 roberto Exp $
** 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.
*/


/*
** if needed, includes windows header before everything else
*/
#if defined(_WIN32)
#include <windows.h>
#endif


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


#define loadlib_c
#define LUA_LIB

#include "lua.h"

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


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

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

#define LUA_PATHSUFFIX "_" LUA_VERSION_MAJOR "_" LUA_VERSION_MINOR

#define LUA_PATHVERSION LUA_PATH LUA_PATHSUFFIX
#define LUA_CPATHVERSION LUA_CPATH LUA_PATHSUFFIX

/*
** LUA_PATH_SEP is the character that separates templates in a path.
** LUA_PATH_MARK is the string that marks the substitution points in a
** template.
** LUA_EXEC_DIR in a Windows path is replaced by the executable's
** directory.
** LUA_IGMARK is a mark to ignore all before it when building the
** luaopen_ function name.
*/
#if !defined (LUA_PATH_SEP)
#define LUA_PATH_SEP ";"
#endif
#if !defined (LUA_PATH_MARK)
#define LUA_PATH_MARK "?"
#endif
#if !defined (LUA_EXEC_DIR)
#define LUA_EXEC_DIR "!"
#endif
#if !defined (LUA_IGMARK)
#define LUA_IGMARK "-"
#endif


/*
** 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 "_"


/* table (in the registry) that keeps handles for all loaded C libraries */
#define CLIBS "_CLIBS"

#define LIB_FAIL "open"


/* error codes for ll_loadfunc */
#define ERRLIB  1
#define ERRFUNC 2

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


/*
** system-dependent functions
*/
static void ll_unloadlib(void *lib);
static void *ll_load(lua_State *L, const char *path, int seeglb);
static lua_CFunction ll_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>

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


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


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

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



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

#undef setprogdir

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


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);
    if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
        luaL_error(L, "unable to get ModuleFileName");
    else {
        *lb = '\0';
        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 ll_unloadlib(void *lib) {
    FreeLibrary((HMODULE)lib);
}


static void *ll_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 ll_sym(lua_State *L, void *lib, const char *sym) {
    lua_CFunction f = (lua_CFunction)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 ll_unloadlib(void *lib) {
    (void)(lib);  /* not used */
}


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


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

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


static void *ll_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;
}


static void ll_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 'll_unloadlib' for all lib
** handles in list CLIBS
*/
static int gctm(lua_State *L) {
    int n = luaL_len(L, 1);
    for (; n >= 1; n--) {  /* for each handle, in reverse order */
        lua_rawgeti(L, 1, n);  /* get handle CLIBS[n] */
        ll_unloadlib(lua_touserdata(L, -1));
        lua_pop(L, 1);  /* pop handle */
    }
    return 0;
}


static int ll_loadfunc(lua_State *L, const char *path, const char *sym) {
    void *reg = ll_checkclib(L, path);  /* check loaded C libraries */
    if (reg == NULL) {  /* must load library? */
        reg = ll_load(L, path, *sym == '*');
        if (reg == NULL) return ERRLIB;  /* unable to load library */
        ll_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 = ll_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 = ll_loadfunc(L, path, init);
    if (stat == 0)  /* no errors? */
        return 1;  /* return the loaded function */
    else {  /* error; error message is on stack top */
        lua_pushnil(L);
        lua_insert(L, -2);
        lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");
        return 3;  /* return nil, 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;
}


static const char *pushnexttemplate(lua_State *L, const char *path) {
    const char *l;
    while (*path == *LUA_PATH_SEP) path++;  /* skip separators */
    if (*path == '\0') return NULL;  /* no more templates */
    l = strchr(path, *LUA_PATH_SEP);  /* find next separator */
    if (l == NULL) l = path + strlen(path);
    lua_pushlstring(L, path, l - path);  /* template */
    return l;
}


static const char *searchpath(lua_State *L, const char *name,
                              const char *path,
                              const char *sep,
                              const char *dirsep) {
    luaL_Buffer msg;  /* to build error message */
    luaL_buffinit(L, &msg);
    if (*sep != '\0')  /* non-empty separator? */
        name = luaL_gsub(L, name, sep, dirsep);  /* replace it by 'dirsep' */
    while ((path = pushnexttemplate(L, path)) != NULL) {
        const char *filename = luaL_gsub(L, lua_tostring(L, -1),
                                         LUA_PATH_MARK, name);
        lua_remove(L, -2);  /* remove path template */
        if (readable(filename))  /* does file exist and is readable? */
            return filename;  /* return that file name */
        lua_pushfstring(L, "\n\tno file " LUA_QS, filename);
        lua_remove(L, -2);  /* remove file name */
        luaL_addvalue(&msg);  /* concatenate error msg. entry */
    }
    luaL_pushresult(&msg);  /* 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 */
        lua_pushnil(L);
        lua_insert(L, -2);
        return 2;  /* return nil + 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 (path == NULL)
        luaL_error(L, LUA_QL("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 (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 " LUA_QS
                          " from file " LUA_QS ":\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);
}


static int loadfunc(lua_State *L, const char *filename, const char *modname) {
    const char *funcname;
    const char *mark;
    modname = luaL_gsub(L, modname, ".", LUA_OFSEP);
    mark = strchr(modname, *LUA_IGMARK);
    if (mark) {
        int stat;
        funcname = lua_pushlstring(L, modname, mark - modname);
        funcname = lua_pushfstring(L, LUA_POF"%s", funcname);
        stat = ll_loadfunc(L, filename, funcname);
        if (stat != ERRFUNC) return stat;
        modname = mark + 1;  /* else go ahead and try old-style name */
    }
    funcname = lua_pushfstring(L, LUA_POF"%s", modname);
    return ll_loadfunc(L, filename, funcname);
}


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, "\n\tno module " LUA_QS " in file " LUA_QS,
                            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, "_PRELOAD");
    lua_getfield(L, -1, name);
    if (lua_isnil(L, -1))  /* not found? */
        lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
    return 1;
}


static void findloader(lua_State *L, const char *name) {
    int i;
    luaL_Buffer msg;  /* to build error message */
    luaL_buffinit(L, &msg);
    lua_getfield(L, lua_upvalueindex(1), "searchers");  /* will be at index 3 */
    if (!lua_istable(L, 3))
        luaL_error(L, LUA_QL("package.searchers") " must be a table");
    /*  iterate over available searchers to find a loader */
    for (i = 1; ; i++) {
        lua_rawgeti(L, 3, i);  /* get a searcher */
        if (lua_isnil(L, -1)) {  /* no more searchers? */
            lua_pop(L, 1);  /* remove nil */
            luaL_pushresult(&msg);  /* create error message */
            luaL_error(L, "module " LUA_QS " 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
            lua_pop(L, 2);  /* remove both returns */
    }
}


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, "_LOADED");
    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_pushstring(L, name);  /* pass name as argument to module loader */
    lua_insert(L, -2);  /* name is 1st argument (before search data) */
    lua_call(L, 2, 1);  /* run loader to load module */
    if (!lua_isnil(L, -1))  /* non-nil return? */
        lua_setfield(L, 2, name);  /* _LOADED[name] = returned value */
    lua_getfield(L, 2, name);
    if (lua_isnil(L, -1)) {   /* module did not set a value? */
        lua_pushboolean(L, 1);  /* use true as result */
        lua_pushvalue(L, -1);  /* extra copy to be returned */
        lua_setfield(L, 2, name);  /* _LOADED[name] = true */
    }
    return 1;
}

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



/*
** {======================================================
** 'module' function
** =======================================================
*/
#if defined(LUA_COMPAT_MODULE)

/*
** changes the environment variable of calling function
*/
static void set_env(lua_State *L) {
    lua_Debug ar;
    if (lua_getstack(L, 1, &ar) == 0 ||
            lua_getinfo(L, "f", &ar) == 0 ||  /* get calling function */
            lua_iscfunction(L, -1))
        luaL_error(L, LUA_QL("module") " not called from a Lua function");
    lua_pushvalue(L, -2);  /* copy new environment table to top */
    lua_setupvalue(L, -2, 1);
    lua_pop(L, 1);  /* remove function */
}


static void dooptions(lua_State *L, int n) {
    int i;
    for (i = 2; i <= n; i++) {
        if (lua_isfunction(L, i)) {  /* avoid 'calling' extra info. */
            lua_pushvalue(L, i);  /* get option (a function) */
            lua_pushvalue(L, -2);  /* module */
            lua_call(L, 1, 0);
        }
    }
}


static void modinit(lua_State *L, const char *modname) {
    const char *dot;
    lua_pushvalue(L, -1);
    lua_setfield(L, -2, "_M");  /* module._M = module */
    lua_pushstring(L, modname);
    lua_setfield(L, -2, "_NAME");
    dot = strrchr(modname, '.');  /* look for last dot in module name */
    if (dot == NULL) dot = modname;
    else dot++;
    /* set _PACKAGE as package name (full module name minus last part) */
    lua_pushlstring(L, modname, dot - modname);
    lua_setfield(L, -2, "_PACKAGE");
}


static int ll_module(lua_State *L) {
    const char *modname = luaL_checkstring(L, 1);
    int lastarg = lua_gettop(L);  /* last parameter */
    luaL_pushmodule(L, modname, 1);  /* get/create module table */
    /* check whether table already has a _NAME field */
    lua_getfield(L, -1, "_NAME");
    if (!lua_isnil(L, -1))  /* is table an initialized module? */
        lua_pop(L, 1);
    else {  /* no; initialize it */
        lua_pop(L, 1);
        modinit(L, modname);
    }
    lua_pushvalue(L, -1);
    set_env(L);
    dooptions(L, lastarg);
    return 1;
}


static int ll_seeall(lua_State *L) {
    luaL_checktype(L, 1, LUA_TTABLE);
    if (!lua_getmetatable(L, 1)) {
        lua_createtable(L, 0, 1); /* create new metatable */
        lua_pushvalue(L, -1);
        lua_setmetatable(L, 1);
    }
    lua_pushglobaltable(L);
    lua_setfield(L, -2, "__index");  /* mt.__index = _G */
    return 0;
}

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



/* auxiliary mark (for internal use) */
#define AUXMARK "\1"


/*
** 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;
}


static void setpath(lua_State *L, const char *fieldname, const char *envname1,
                    const char *envname2, const char *def) {
    const char *path = getenv(envname1);
    if (path == NULL)  /* no environment variable? */
        path = getenv(envname2);  /* try alternative name */
    if (path == NULL || noenv(L))  /* no environment variable? */
        lua_pushstring(L, def);  /* use default */
    else {
        /* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */
        path = luaL_gsub(L, path, LUA_PATH_SEP LUA_PATH_SEP,
                         LUA_PATH_SEP AUXMARK LUA_PATH_SEP);
        luaL_gsub(L, path, AUXMARK, def);
        lua_remove(L, -2);
    }
    setprogdir(L);
    lua_setfield(L, -2, fieldname);
}


static const luaL_Reg pk_funcs[] = {
    {"loadlib", ll_loadlib},
    {"searchpath", ll_searchpath},
#if defined(LUA_COMPAT_MODULE)
    {"seeall", ll_seeall},
#endif
    {NULL, NULL}
};


static const luaL_Reg ll_funcs[] = {
#if defined(LUA_COMPAT_MODULE)
    {"module", ll_module},
#endif
    {"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 pre-defined 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);
    }
}


LUAMOD_API int luaopen_package(lua_State *L) {
    /* create table CLIBS to keep track of loaded C libraries */
    luaL_getsubtable(L, LUA_REGISTRYINDEX, CLIBS);
    lua_createtable(L, 0, 1);  /* metatable for CLIBS */
    lua_pushcfunction(L, gctm);
    lua_setfield(L, -2, "__gc");  /* set finalizer for CLIBS table */
    lua_setmetatable(L, -2);
    /* create `package' table */
    luaL_newlib(L, pk_funcs);
    createsearcherstable(L);
#if defined(LUA_COMPAT_LOADERS)
    lua_pushvalue(L, -1);  /* make a copy of 'searchers' table */
    lua_setfield(L, -3, "loaders");  /* put it in field `loaders' */
#endif
    lua_setfield(L, -2, "searchers");  /* put it in field 'searchers' */
    /* set field 'path' */
    setpath(L, "path", LUA_PATHVERSION, LUA_PATH, LUA_PATH_DEFAULT);
    /* set field 'cpath' */
    setpath(L, "cpath", LUA_CPATHVERSION, LUA_CPATH, 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, "_LOADED");
    lua_setfield(L, -2, "loaded");
    /* set field `preload' */
    luaL_getsubtable(L, LUA_REGISTRYINDEX, "_PRELOAD");
    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 */
}

