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lua/loadlib.c
Roberto Ierusalimschy ccf6d098f6 'searchpath' creates less temporary strings 
When creating error messages, package loaders may create dozens of
temporary strings (one or more for each tried template). This change
reduces the number of these strings, and avoid creating some of
them if the search is successful.
2018-07-09 13:29:08 -03:00

714 lines
21 KiB
C
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/*
** $Id: loadlib.c,v 1.133 2018/07/06 13:38:38 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.
*/
#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_IGMARK is a mark to ignore all before it when building the
** luaopen_ function name.
*/
#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 "_"
/*
** unique key for table in the registry that keeps handles
** for all loaded C libraries
*/
static const int CLIBS = 0;
#define LIB_FAIL "open"
#define setprogdir(L) ((void)0)
/*
** 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 (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 (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)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
#define AUXMARK "\1" /* auxiliary mark */
/*
** 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 *nver = lua_pushfstring(L, "%s%s", envname, LUA_VERSUFFIX);
const char *path = getenv(nver); /* use versioned name */
if (path == NULL) /* no environment variable? */
path = getenv(envname); /* try unversioned name */
if (path == NULL || noenv(L)) /* no environment variable? */
lua_pushstring(L, dft); /* 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, dft);
lua_remove(L, -2); /* remove result from 1st 'gsub' */
}
setprogdir(L);
lua_setfield(L, -3, fieldname); /* package[fieldname] = path value */
lua_pop(L, 1); /* pop versioned variable name */
}
/* }================================================================== */
/*
** return registry.CLIBS[path]
*/
static void *checkclib (lua_State *L, const char *path) {
void *plib;
lua_rawgetp(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_rawgetp(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 (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 *pushnextfilename (lua_State *L, const char *path) {
const char *l;
if (*path == *LUA_PATH_SEP)
path++; /* skip separator */
if (*path == '\0')
return NULL; /* no more names */
l = strchr(path, *LUA_PATH_SEP); /* find next separator */
if (l == NULL) /* no more separators? */
l = path + strlen(path); /* go until the end */
lua_pushlstring(L, path, l - path); /* file name */
return l; /* rest of the path */
}
/*
** 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) {
if (*path == *LUA_PATH_SEP)
path++; /* skip separator */
lua_pushstring(L, "\n\tno file '");
luaL_gsub(L, path, LUA_PATH_SEP, "'\n\tno file '");
lua_pushstring(L, "'");
lua_concat(L, 3);
}
static const char *searchpath (lua_State *L, const char *name,
const char *path,
const char *sep,
const char *dirsep) {
/* 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' */
/* replace marks ('?') in 'path' by the file name */
path = luaL_gsub(L, path, LUA_PATH_MARK, name);
while ((path = pushnextfilename(L, path)) != NULL) {
const char *filename = lua_tostring(L, -1);
if (readable(filename)) /* does file exist and is readable? */
return filename; /* return that file name */
lua_pop(L, 1); /* else remove file name */
}
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 */
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, "'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 '%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, "\n\tno 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, "\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 */
/* push 'package.searchers' to index 3 in the stack */
if (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++) {
if (lua_rawgeti(L, 3, i) == LUA_TNIL) { /* no more searchers? */
lua_pop(L, 1); /* remove nil */
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
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, 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_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 */
if (lua_getfield(L, 2, name) == LUA_TNIL) { /* module set no 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;
}
/* }====================================================== */
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) {
lua_newtable(L); /* 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);
lua_rawsetp(L, LUA_REGISTRYINDEX, &CLIBS); /* set CLIBS table in registry */
}
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 */
}
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