/*
** $Id: loadlib.c,v 1.52.1.3 2008/08/06 13:29:28 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 Darwin (Mac OS X), an
** implementation for Windows, and a stub for other systems.
*/

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

#define loadlib_c
#define LUA_LIB

#include "lua.h"

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

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

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

#define LIBPREFIX "LOADLIB: "

#define POF LUA_POF
#define LIB_FAIL "open"

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

static void ll_unloadlib(void *lib);
static void *ll_load(lua_State *L, const char *path);
static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym);
static void setprogdir(lua_State *L);

/*
** {=========================================================================
** This determines the location of the executable for relative module loading
** Modified by the LuaDist project for UNIX platforms
** ==========================================================================
*/
#if defined(_WIN32)
    #include <windows.h>
    #define _PATH_MAX MAX_PATH
#else
    #define _PATH_MAX PATH_MAX
#endif

#if defined(__CYGWIN__)
    #include <sys/cygwin.h>
#endif

#if defined(__linux__) || defined(__sun)
    #include <unistd.h> /* readlink */
#endif

#if defined(__APPLE__)
    #include <sys/param.h>
    #include <mach-o/dyld.h>
#endif

#if defined(__FreeBSD__)
    #include <sys/types.h>
    #include <sys/sysctl.h>
#endif

static void setprogdir(lua_State *L)
{
    char progdir[_PATH_MAX + 1];
    char *lb;
    int nsize = sizeof(progdir) / sizeof(char);
    int n = 0;
#if defined(__CYGWIN__)
    char win_buff[_PATH_MAX + 1];
    GetModuleFileNameA(NULL, win_buff, nsize);
    cygwin_conv_path(CCP_WIN_A_TO_POSIX, win_buff, progdir, nsize);
    n = strlen(progdir);
#elif defined(_WIN32)
    n = GetModuleFileNameA(NULL, progdir, nsize);
#elif defined(__linux__)
    n = readlink("/proc/self/exe", progdir, nsize);
    if (n > 0)
        progdir[n] = 0;
#elif defined(__sun)
    pid_t pid = getpid();
    char linkname[256];
    sprintf(linkname, "/proc/%d/path/a.out", pid);
    n = readlink(linkname, progdir, nsize);
    if (n > 0)
        progdir[n] = 0;
#elif defined(__FreeBSD__)
    int mib[4];
    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PATHNAME;
    mib[3] = -1;
    size_t cb = nsize;
    sysctl(mib, 4, progdir, &cb, NULL, 0);
    n = cb;
#elif defined(__BSD__)
    n = readlink("/proc/curproc/file", progdir, nsize);
    if (n > 0)
        progdir[n] = 0;
#elif defined(__APPLE__)
    uint32_t nsize_apple = nsize;
    if (_NSGetExecutablePath(progdir, &nsize_apple) == 0)
        n = strlen(progdir);
#else
    // FALLBACK
    // Use 'lsof' ... should work on most UNIX systems (incl. OSX)
    // lsof will list open files, this captures the 1st file listed (usually the executable)
    int pid;
    FILE *fd;
    char cmd[80];
    pid = getpid();

    sprintf(
        cmd,
        "lsof -p %d | awk '{if ($5==\"REG\") { print $9 ; exit}}' 2> /dev/null",
        pid);
    fd = popen(cmd, "r");
    n = fread(progdir, 1, nsize, fd);
    pclose(fd);

    // remove newline
    if (n > 1)
        progdir[--n] = '\0';
#endif
    if (n == 0 || n == nsize ||
        (lb = strrchr(progdir, (int)LUA_DIRSEP[0])) == NULL)
        luaL_error(L, "unable to get process executable path");
    else {
        *lb = '\0';

        // Replace the relative path placeholder
        luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, progdir);
        lua_remove(L, -2);
    }
}

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

#if defined(LUA_DL_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>
    #include <sys/stat.h>

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

static void *ll_load(lua_State *L, const char *path)
{
    void *lib = dlopen(path, RTLD_NOW);
    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.
** =======================================================================
*/

    #include <windows.h>

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), NULL))
        lua_pushstring(L, buffer);
    else
        lua_pushfstring(L, "system error %d\n", error);
}

static void ll_unloadlib(void *lib) { FreeLibrary((HINSTANCE)lib); }

static void *ll_load(lua_State *L, const char *path)
{
    HINSTANCE lib = LoadLibraryA(path);
    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((HINSTANCE)lib, sym);
    if (f == NULL)
        pusherror(L);
    return f;
}

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

#elif defined(LUA_DL_DYLD)
/*
** {======================================================================
** Native Mac OS X / Darwin Implementation
** =======================================================================
*/

    #include <mach-o/dyld.h>

    /* Mac appends a `_' before C function names */
    #undef POF
    #define POF "_" LUA_POF

static void pusherror(lua_State *L)
{
    const char *err_str;
    const char *err_file;
    NSLinkEditErrors err;
    int err_num;
    NSLinkEditError(&err, &err_num, &err_file, &err_str);
    lua_pushstring(L, err_str);
}

static const char *errorfromcode(NSObjectFileImageReturnCode ret)
{
    switch (ret) {
    case NSObjectFileImageInappropriateFile:
        return "file is not a bundle";
    case NSObjectFileImageArch:
        return "library is for wrong CPU type";
    case NSObjectFileImageFormat:
        return "bad format";
    case NSObjectFileImageAccess:
        return "cannot access file";
    case NSObjectFileImageFailure:
    default:
        return "unable to load library";
    }
}

static void ll_unloadlib(void *lib)
{
    NSUnLinkModule((NSModule)lib, NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES);
}

static void *ll_load(lua_State *L, const char *path)
{
    NSObjectFileImage img;
    NSObjectFileImageReturnCode ret;
    /* this would be a rare case, but prevents crashing if it happens */
    if (!_dyld_present()) {
        lua_pushliteral(L, "dyld not present");
        return NULL;
    }
    ret = NSCreateObjectFileImageFromFile(path, &img);
    if (ret == NSObjectFileImageSuccess) {
        NSModule mod = NSLinkModule(img, path,
                                    NSLINKMODULE_OPTION_PRIVATE |
                                        NSLINKMODULE_OPTION_RETURN_ON_ERROR);
        NSDestroyObjectFileImage(img);
        if (mod == NULL)
            pusherror(L);
        return mod;
    }
    lua_pushstring(L, errorfromcode(ret));
    return NULL;
}

static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    NSSymbol nss = NSLookupSymbolInModule((NSModule)lib, sym);
    if (nss == NULL) {
        lua_pushfstring(L, "symbol " LUA_QS " not found", sym);
        return NULL;
    }
    return (lua_CFunction)NSAddressOfSymbol(nss);
}

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

#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; /* to avoid warnings */ }

static void *ll_load(lua_State *L, const char *path)
{
    (void)path; /* to avoid warnings */
    lua_pushliteral(L, DLMSG);
    return NULL;
}

static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    (void)lib;
    (void)sym; /* to avoid warnings */
    lua_pushliteral(L, DLMSG);
    return NULL;
}

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

static void **ll_register(lua_State *L, const char *path)
{
    void **plib;
    lua_pushfstring(L, "%s%s", LIBPREFIX, path);
    lua_gettable(L, LUA_REGISTRYINDEX); /* check library in registry? */
    if (!lua_isnil(L, -1))              /* is there an entry? */
        plib = (void **)lua_touserdata(L, -1);
    else { /* no entry yet; create one */
        lua_pop(L, 1);
        plib = (void **)lua_newuserdata(L, sizeof(const void *));
        *plib = NULL;
        luaL_getmetatable(L, "_LOADLIB");
        lua_setmetatable(L, -2);
        lua_pushfstring(L, "%s%s", LIBPREFIX, path);
        lua_pushvalue(L, -2);
        lua_settable(L, LUA_REGISTRYINDEX);
    }
    return plib;
}

/*
** __gc tag method: calls library's `ll_unloadlib' function with the lib
** handle
*/
static int gctm(lua_State *L)
{
    void **lib = (void **)luaL_checkudata(L, 1, "_LOADLIB");
    if (*lib)
        ll_unloadlib(*lib);
    *lib = NULL; /* mark library as closed */
    return 0;
}

static int ll_loadfunc(lua_State *L, const char *path, const char *sym)
{
    void **reg = ll_register(L, path);
    if (*reg == NULL)
        *reg = ll_load(L, path);
    if (*reg == NULL)
        return ERRLIB; /* unable to load library */
    else {
        lua_CFunction f = ll_sym(L, *reg, sym);
        if (f == NULL)
            return ERRFUNC; /* unable to find function */
        lua_pushcfunction(L, f);
        return 0; /* return function */
    }
}

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_PATHSEP)
        path++; /* skip separators */
    if (*path == '\0')
        return NULL;                /* no more templates */
    l = strchr(path, *LUA_PATHSEP); /* find next separator */
    if (l == NULL)
        l = path + strlen(path);
    lua_pushlstring(L, path, l - path); /* template */
    return l;
}

static const char *findfile(lua_State *L, const char *name, const char *pname)
{
    const char *path;
    name = luaL_gsub(L, name, ".", LUA_DIRSEP);
    lua_getfield(L, LUA_ENVIRONINDEX, pname);
    path = lua_tostring(L, -1);
    if (path == NULL)
        luaL_error(L, LUA_QL("package.%s") " must be a string", pname);
    lua_pushliteral(L, ""); /* error accumulator */
    while ((path = pushnexttemplate(L, path)) != NULL) {
        const char *filename;
        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 */
        lua_concat(L, 2);  /* add entry to possible error message */
    }
    return NULL; /* not found */
}

static void loaderror(lua_State *L, const char *filename)
{
    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 loader_Lua(lua_State *L)
{
    const char *filename;
    const char *name = luaL_checkstring(L, 1);
    filename = findfile(L, name, "path");
    if (filename == NULL)
        return 1; /* library not found in this path */
    if (luaL_loadfile(L, filename) != 0)
        loaderror(L, filename);
    return 1; /* library loaded successfully */
}

static const char *mkfuncname(lua_State *L, const char *modname)
{
    const char *funcname;
    const char *mark = strchr(modname, *LUA_IGMARK);
    if (mark)
        modname = mark + 1;
    funcname = luaL_gsub(L, modname, ".", LUA_OFSEP);
    funcname = lua_pushfstring(L, POF "%s", funcname);
    lua_remove(L, -2); /* remove 'gsub' result */
    return funcname;
}

static int loader_C(lua_State *L)
{
    const char *funcname;
    const char *name = luaL_checkstring(L, 1);
    const char *filename = findfile(L, name, "cpath");
    if (filename == NULL)
        return 1; /* library not found in this path */
    funcname = mkfuncname(L, name);
    if (ll_loadfunc(L, filename, funcname) != 0)
        loaderror(L, filename);
    return 1; /* library loaded successfully */
}

static int loader_Croot(lua_State *L)
{
    const char *funcname;
    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");
    if (filename == NULL)
        return 1; /* root not found */
    funcname = mkfuncname(L, name);
    if ((stat = ll_loadfunc(L, filename, funcname)) != 0) {
        if (stat != ERRFUNC)
            loaderror(L, filename); /* real error */
        lua_pushfstring(L, "\n\tno module " LUA_QS " in file " LUA_QS, name,
                        filename);
        return 1; /* function not found */
    }
    return 1;
}

static int loader_preload(lua_State *L)
{
    const char *name = luaL_checkstring(L, 1);
    lua_getfield(L, LUA_ENVIRONINDEX, "preload");
    if (!lua_istable(L, -1))
        luaL_error(L, LUA_QL("package.preload") " must be a table");
    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 const int sentinel_ = 0;
#define sentinel ((void *)&sentinel_)

static int ll_require(lua_State *L)
{
    const char *name = luaL_checkstring(L, 1);
    int i;
    lua_settop(L, 1); /* _LOADED table will be at index 2 */
    lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
    lua_getfield(L, 2, name);
    if (lua_toboolean(L, -1)) {                /* is it there? */
        if (lua_touserdata(L, -1) == sentinel) /* check loops */
            luaL_error(L, "loop or previous error loading module " LUA_QS,
                       name);
        return 1; /* package is already loaded */
    }
    /* else must load it; iterate over available loaders */
    lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
    if (!lua_istable(L, -1))
        luaL_error(L, LUA_QL("package.loaders") " must be a table");
    lua_pushliteral(L, ""); /* error message accumulator */
    for (i = 1;; i++) {
        lua_rawgeti(L, -2, i); /* get a loader */
        if (lua_isnil(L, -1))
            luaL_error(L, "module " LUA_QS " not found:%s", name,
                       lua_tostring(L, -2));
        lua_pushstring(L, name);
        lua_call(L, 1, 1);            /* call it */
        if (lua_isfunction(L, -1))    /* did it find module? */
            break;                    /* module loaded successfully */
        else if (lua_isstring(L, -1)) /* loader returned error message? */
            lua_concat(L, 2);         /* accumulate it */
        else
            lua_pop(L, 1);
    }
    lua_pushlightuserdata(L, sentinel);
    lua_setfield(L, 2, name);     /* _LOADED[name] = sentinel */
    lua_pushstring(L, name);      /* pass name as argument to module */
    lua_call(L, 1, 1);            /* run loaded 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_touserdata(L, -1) == sentinel) { /* 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
** =======================================================
*/

static void setfenv(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);
    lua_setfenv(L, -2);
    lua_pop(L, 1);
}

static void dooptions(lua_State *L, int n)
{
    int i;
    for (i = 2; i <= n; i++) {
        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 loaded = lua_gettop(L) + 1; /* index of _LOADED table */
    lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
    lua_getfield(L, loaded, modname); /* get _LOADED[modname] */
    if (!lua_istable(L, -1)) {        /* not found? */
        lua_pop(L, 1);                /* remove previous result */
        /* try global variable (and create one if it does not exist) */
        if (luaL_findtable(L, LUA_GLOBALSINDEX, modname, 1) != NULL)
            return luaL_error(L, "name conflict for module " LUA_QS, modname);
        lua_pushvalue(L, -1);
        lua_setfield(L, loaded, modname); /* _LOADED[modname] = new 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);
    setfenv(L);
    dooptions(L, loaded - 1);
    return 0;
}

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_pushvalue(L, LUA_GLOBALSINDEX);
    lua_setfield(L, -2, "__index"); /* mt.__index = _G */
    return 0;
}

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

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

static void setpath(lua_State *L, const char *fieldname, const char *envname,
                    const char *def)
{
    const char *path = getenv(envname);
    if (path == NULL)           /* 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_PATHSEP LUA_PATHSEP,
                         LUA_PATHSEP AUXMARK LUA_PATHSEP);
        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}, {"seeall", ll_seeall}, {NULL, NULL}};

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

static const lua_CFunction loaders[] = {loader_preload, loader_Lua, loader_C,
                                        loader_Croot, NULL};

LUALIB_API int luaopen_package(lua_State *L)
{
    int i;
    /* create new type _LOADLIB */
    luaL_newmetatable(L, "_LOADLIB");
    lua_pushcfunction(L, gctm);
    lua_setfield(L, -2, "__gc");
    /* create `package' table */
    luaL_register(L, LUA_LOADLIBNAME, pk_funcs);
#if defined(LUA_COMPAT_LOADLIB)
    lua_getfield(L, -1, "loadlib");
    lua_setfield(L, LUA_GLOBALSINDEX, "loadlib");
#endif
    lua_pushvalue(L, -1);
    lua_replace(L, LUA_ENVIRONINDEX);
    /* create `loaders' table */
    lua_createtable(L, sizeof(loaders) / sizeof(loaders[0]) - 1, 0);
    /* fill it with pre-defined loaders */
    for (i = 0; loaders[i] != NULL; i++) {
        lua_pushcfunction(L, loaders[i]);
        lua_rawseti(L, -2, i + 1);
    }
    lua_setfield(L, -2, "loaders"); /* put it in field `loaders' */
    setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT);    /* set field `path' */
    setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT); /* set field `cpath' */
    /* store config information */
    lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATHSEP "\n" LUA_PATH_MARK
                                  "\n" LUA_EXECDIR "\n" LUA_IGMARK);
    lua_setfield(L, -2, "config");
    /* set field `loaded' */
    luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 2);
    lua_setfield(L, -2, "loaded");
    /* set field `preload' */
    lua_newtable(L);
    lua_setfield(L, -2, "preload");
    lua_pushvalue(L, LUA_GLOBALSINDEX);
    luaL_register(L, NULL, ll_funcs); /* open lib into global table */
    lua_pop(L, 1);
    return 1; /* return 'package' table */
}
