new library: luafilesystem (lfs)

https://github.com/keplerproject/luafilesystem

The new commander.tlv app demonstrates it working.

7 files changed, 1425 insertions, 1 deletions

diff --git a/README.md b/README.md
index e4c02bf..0fe1718 100644
--- a/README.md
+++ b/README.md
@@ -158,6 +158,8 @@ behave unexpectedly under Teliva.
 ## What's included?
 
 * [Lua 5.1](https://www.lua.org/manual/5.1)
+* The [Lua File System](https://keplerproject.github.io/luafilesystem) library
+  for portably accessing directories (module `lfs`).
 * The [ncurses](https://tldp.org/HOWTO/NCURSES-Programming-HOWTO) library for
   building text-mode user interfaces. ([Alternative documentation](https://tldp.org/LDP/lpg-0.4.pdf))
 * The [Kilo](https://github.com/antirez/kilo) text editor, modified to use
diff --git a/commander.tlv b/commander.tlv
new file mode 100644
index 0000000..8617fd7
--- /dev/null
+++ b/commander.tlv
@@ -0,0 +1,199 @@
+# .tlv file generated by https://github.com/akkartik/teliva
+# You may edit it if you are careful; however, you may see cryptic errors if you
+# violate Teliva's assumptions.
+#
+# .tlv files are representations of Teliva programs. Teliva programs consist of
+# sequences of definitions. Each definition is a table of key/value pairs. Keys
+# and values are both strings.
+#
+# Lines in .tlv files always follow exactly one of the following forms:
+# - comment lines at the top of the file starting with '#' at column 0
+# - beginnings of definitions starting with '- ' at column 0, followed by a
+#   key/value pair
+# - key/value pairs consisting of '  ' at column 0, containing either a
+#   spaceless value on the same line, or a multi-line value
+# - multiline values indented by more than 2 spaces, starting with a '>'
+#
+# If these constraints are violated, Teliva may unceremoniously crash. Please
+# report bugs at http://akkartik.name/contact
+- __teliva_timestamp: original
+  str_helpers:
+    >-- some string helpers from http://lua-users.org/wiki/StringIndexing
+    >
+    >-- index characters using []
+    >getmetatable('').__index = function(str,i)
+    >  if type(i) == 'number' then
+    >    return string.sub(str,i,i)
+    >  else
+    >    return string[i]
+    >  end
+    >end
+    >
+    >-- ranges using (), selected bytes using {}
+    >getmetatable('').__call = function(str,i,j)
+    >  if type(i)~='table' then
+    >    return string.sub(str,i,j)
+    >  else
+    >    local t={}
+    >    for k,v in ipairs(i) do
+    >      t[k]=string.sub(str,v,v)
+    >    end
+    >    return table.concat(t)
+    >  end
+    >end
+    >
+    >-- iterate over an ordered sequence
+    >function q(x)
+    >  if type(x) == 'string' then
+    >    return x:gmatch('.')
+    >  else
+    >    return ipairs(x)
+    >  end
+    >end
+    >
+    >-- insert within string
+    >function string.insert(str1, str2, pos)
+    >  return str1:sub(1,pos)..str2..str1:sub(pos+1)
+    >end
+    >
+    >function string.remove(s, pos)
+    >  return s:sub(1,pos-1)..s:sub(pos+1)
+    >end
+    >
+    >-- TODO: backport utf-8 support from Lua 5.3
+- __teliva_timestamp: original
+  debugy:
+    >debugy = 5
+- __teliva_timestamp: original
+  dbg:
+    >-- helper for debug by print; overlay debug information towards the right
+    >-- reset debugy every time you refresh screen
+    >function dbg(window, s)
+    >  local oldy = 0
+    >  local oldx = 0
+    >  oldy, oldx = window:getyx()
+    >  window:mvaddstr(debugy, 60, s)
+    >  debugy = debugy+1
+    >  window:mvaddstr(oldy, oldx, '')
+    >end
+- __teliva_timestamp: original
+  check_eq:
+    >function check_eq(x, expected, msg)
+    >  if x == expected then
+    >    curses.addch('.')
+    >  else
+    >    print('F - '..msg)
+    >    print('  expected '..tostring(expected)..' but got '..x)
+    >    teliva_num_test_failures = teliva_num_test_failures + 1
+    >    -- overlay first test failure on editors
+    >    if teliva_first_failure == nil then
+    >      teliva_first_failure = msg
+    >    end
+    >  end
+    >end
+- __teliva_timestamp: original
+  map:
+    >-- only for arrays
+    >function map(l, f)
+    >  result = {}
+    >  for _, x in ipairs(l) do
+    >    table.insert(result, f(x))
+    >  end
+    >  return result
+    >end
+- __teliva_timestamp: original
+  reduce:
+    >-- only for arrays
+    >function reduce(l, f, init)
+    >  result = init
+    >  for _, x in ipairs(l) do
+    >    result = f(result, x)
+    >  end
+    >  return result
+    >end
+- __teliva_timestamp: original
+  filter:
+    >-- only for arrays
+    >function filter(l, f)
+    >  result = {}
+    >  for _, x in ipairs(l) do
+    >    if f(x) then
+    >      table.insert(result, x)
+    >    end
+    >  end
+    >  return result
+    >end
+- __teliva_timestamp: original
+  find_index:
+    >function find_index(arr, x)
+    >  for n, y in ipairs(arr) do
+    >    if x == y then
+    >      return n
+    >    end
+    >  end
+    >end
+- __teliva_timestamp: original
+  trim:
+    >function trim(s)
+    >  return s:gsub('^%s*', ''):gsub('%s*$', '')
+    >end
+- __teliva_timestamp: original
+  split:
+    >function split(s, d)
+    >  result = {}
+    >  for match in (s..d):gmatch("(.-)"..d) do
+    >    table.insert(result, match);
+    >  end
+    >  return result
+    >end
+- __teliva_timestamp: original
+  window:
+    >window = curses.stdscr()
+- __teliva_timestamp: original
+  render:
+    >function render(window)
+    >  window:clear()
+    >  for f in lfs.dir('.') do
+    >    if f ~= '.' and f ~= '..' then
+    >      local attr = lfs.attributes(f)
+    >      print(f, attr.permissions, attr.size, attr.access, attr.modification)
+    >    end
+    >  end
+    >  curses.refresh()
+    >end
+- __teliva_timestamp: original
+  menu:
+    >-- To show app-specific hotkeys in the menu bar, add hotkey/command
+    >-- arrays of strings to the menu array.
+    >menu = {}
+- __teliva_timestamp: original
+  update:
+    >function update(window)
+    >  local key = curses.getch()
+    >  -- process key here
+    >end
+- __teliva_timestamp: original
+  init_colors:
+    >function init_colors()
+    >  for i=0,7 do
+    >    curses.init_pair(i, i, -1)
+    >  end
+    >  curses.init_pair(8, 7, 0)
+    >  curses.init_pair(9, 7, 1)
+    >  curses.init_pair(10, 7, 2)
+    >  curses.init_pair(11, 7, 3)
+    >  curses.init_pair(12, 7, 4)
+    >  curses.init_pair(13, 7, 5)
+    >  curses.init_pair(14, 7, 6)
+    >  curses.init_pair(15, -1, 15)
+    >end
+- main:
+    >function main()
+    >  init_colors()
+    >
+    >  while true do
+    >    render(window)
+    >    update(window)
+    >  end
+    >end
+  __teliva_timestamp: original
diff --git a/src/Makefile b/src/Makefile
index 0d359ab..3d2a91e 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -26,7 +26,7 @@ LUA_A=	liblua.a
 CORE_O=	lapi.o lcode.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o lmem.o \
 	lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o ltm.o  \
 	lundump.o lvm.o lzio.o \
-	kilo.o tlv.o teliva.o
+	lfs.o kilo.o tlv.o teliva.o
 LIB_O=	lauxlib.o lbaselib.o ldblib.o liolib.o lmathlib.o loslib.o \
 	ltablib.o lstrlib.o loadlib.o linit.o
 
@@ -189,6 +189,7 @@ lzio.o: lzio.c lua.h luaconf.h llimits.h lmem.h lstate.h lobject.h ltm.h \
   lzio.h
 print.o: print.c ldebug.h lstate.h lua.h luaconf.h lobject.h llimits.h \
   ltm.h lzio.h lmem.h lopcodes.h lundump.h
+lfs.o: lfs.c lfs.h lua.h lauxlib.h lualib.h
 kilo.o: kilo.c lua.h teliva.h
 teliva.o: teliva.c lua.h lauxlib.h lualib.h teliva.h tlv.h
 
diff --git a/src/lfs.c b/src/lfs.c
new file mode 100644
index 0000000..29c4f55
--- /dev/null
+++ b/src/lfs.c
@@ -0,0 +1,1183 @@
+/*
+** LuaFileSystem
+** Copyright Kepler Project 2003 - 2020
+** (http://keplerproject.github.io/luafilesystem)
+**
+** File system manipulation library.
+** This library offers these functions:
+**   lfs.attributes (filepath [, attributename | attributetable])
+**   lfs.chdir (path)
+**   lfs.currentdir ()
+**   lfs.dir (path)
+**   lfs.link (old, new[, symlink])
+**   lfs.lock (fh, mode)
+**   lfs.lock_dir (path)
+**   lfs.mkdir (path)
+**   lfs.rmdir (path)
+**   lfs.setmode (filepath, mode)
+**   lfs.symlinkattributes (filepath [, attributename])
+**   lfs.touch (filepath [, atime [, mtime]])
+**   lfs.unlock (fh)
+*/
+
+#ifndef LFS_DO_NOT_USE_LARGE_FILE
+#ifndef _WIN32
+#ifndef _AIX
+#define _FILE_OFFSET_BITS 64    /* Linux, Solaris and HP-UX */
+#else
+#define _LARGE_FILES 1          /* AIX */
+#endif
+#endif
+#endif
+
+#ifdef _WIN32
+#define _WIN32_WINNT 0x600
+#endif
+
+#ifndef LFS_DO_NOT_USE_LARGE_FILE
+#define _LARGEFILE64_SOURCE
+#endif
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sys/stat.h>
+
+#ifdef _WIN32
+
+#include <direct.h>
+#include <windows.h>
+#include <io.h>
+#include <sys/locking.h>
+
+#ifdef __BORLANDC__
+#include <utime.h>
+#else
+#include <sys/utime.h>
+#endif
+
+#include <fcntl.h>
+
+/* MAX_PATH seems to be 260. Seems kind of small. Is there a better one? */
+#define LFS_MAXPATHLEN MAX_PATH
+
+#else
+
+#include <unistd.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <utime.h>
+#include <sys/param.h>          /* for MAXPATHLEN */
+
+#ifdef MAXPATHLEN
+#define LFS_MAXPATHLEN MAXPATHLEN
+#else
+#include <limits.h>             /* for _POSIX_PATH_MAX */
+#define LFS_MAXPATHLEN _POSIX_PATH_MAX
+#endif
+
+#endif
+
+#include "lua.h"
+#include "lauxlib.h"
+#include "lualib.h"
+
+#include "lfs.h"
+
+#define LFS_VERSION "1.8.0"
+#define LFS_LIBNAME "lfs"
+
+#if LUA_VERSION_NUM >= 503      /* Lua 5.3+ */
+
+#ifndef luaL_optlong
+#define luaL_optlong luaL_optinteger
+#endif
+
+#endif
+
+#if LUA_VERSION_NUM >= 502
+#define new_lib(L, l) (luaL_newlib(L, l))
+#else
+#define new_lib(L, l) (lua_newtable(L), luaL_register(L, NULL, l))
+#endif
+
+/* Define 'strerror' for systems that do not implement it */
+#ifdef NO_STRERROR
+#define strerror(_)     "System unable to describe the error"
+#endif
+
+#define DIR_METATABLE "directory metatable"
+typedef struct dir_data {
+  int closed;
+#ifdef _WIN32
+  intptr_t hFile;
+  char pattern[MAX_PATH + 1];
+#else
+  DIR *dir;
+#endif
+} dir_data;
+
+#define LOCK_METATABLE "lock metatable"
+
+#ifdef _WIN32
+
+#ifdef __BORLANDC__
+#define lfs_setmode(file, m)   (setmode(_fileno(file), m))
+#define STAT_STRUCT struct stati64
+#else
+#define lfs_setmode(file, m)   (_setmode(_fileno(file), m))
+#define STAT_STRUCT struct _stati64
+#endif
+
+#ifndef _S_IFLNK
+#define _S_IFLNK 0x400
+#endif
+
+#ifndef S_ISDIR
+#define S_ISDIR(mode)  (mode&_S_IFDIR)
+#endif
+#ifndef S_ISREG
+#define S_ISREG(mode)  (mode&_S_IFREG)
+#endif
+#ifndef S_ISLNK
+#define S_ISLNK(mode)  (mode&_S_IFLNK)
+#endif
+#ifndef S_ISSOCK
+#define S_ISSOCK(mode)  (0)
+#endif
+#ifndef S_ISFIFO
+#define S_ISFIFO(mode)  (0)
+#endif
+#ifndef S_ISCHR
+#define S_ISCHR(mode)  (mode&_S_IFCHR)
+#endif
+#ifndef S_ISBLK
+#define S_ISBLK(mode)  (0)
+#endif
+
+#define STAT_FUNC _stati64
+#define LSTAT_FUNC lfs_win32_lstat
+
+#else
+
+#define _O_TEXT               0
+#define _O_BINARY             0
+#define lfs_setmode(file, m)   ((void)file, (void)m, 0)
+#define STAT_STRUCT struct stat
+#define STAT_FUNC stat
+extern int lstat(const char * pathname, struct stat * statbuf);
+#define LSTAT_FUNC lstat
+
+#endif
+
+#ifdef _WIN32
+#define lfs_mkdir _mkdir
+#else
+#define lfs_mkdir(path) (mkdir((path), \
+    S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IWGRP | S_IXGRP | S_IROTH | S_IXOTH))
+#endif
+
+#ifdef _WIN32
+
+int lfs_win32_pusherror(lua_State * L)
+{
+  int en = GetLastError();
+  lua_pushnil(L);
+  if (en == ERROR_FILE_EXISTS || en == ERROR_SHARING_VIOLATION)
+    lua_pushstring(L, "File exists");
+  else
+    lua_pushstring(L, strerror(en));
+  return 2;
+}
+
+#define TICKS_PER_SECOND 10000000
+#define EPOCH_DIFFERENCE 11644473600LL
+time_t windowsToUnixTime(FILETIME ft)
+{
+  ULARGE_INTEGER uli;
+  uli.LowPart = ft.dwLowDateTime;
+  uli.HighPart = ft.dwHighDateTime;
+  return (time_t) (uli.QuadPart / TICKS_PER_SECOND - EPOCH_DIFFERENCE);
+}
+
+int lfs_win32_lstat(const char *path, STAT_STRUCT * buffer)
+{
+  WIN32_FILE_ATTRIBUTE_DATA win32buffer;
+  if (GetFileAttributesEx(path, GetFileExInfoStandard, &win32buffer)) {
+    if (!(win32buffer.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)) {
+      return STAT_FUNC(path, buffer);
+    }
+    buffer->st_mode = _S_IFLNK;
+    buffer->st_dev = 0;
+    buffer->st_ino = 0;
+    buffer->st_nlink = 0;
+    buffer->st_uid = 0;
+    buffer->st_gid = 0;
+    buffer->st_rdev = 0;
+    buffer->st_atime = windowsToUnixTime(win32buffer.ftLastAccessTime);
+    buffer->st_mtime = windowsToUnixTime(win32buffer.ftLastWriteTime);
+    buffer->st_ctime = windowsToUnixTime(win32buffer.ftCreationTime);
+    buffer->st_size = 0;
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+#endif
+
+/*
+** Utility functions
+*/
+static int pusherror(lua_State * L, const char *info)
+{
+  lua_pushnil(L);
+  if (info == NULL)
+    lua_pushstring(L, strerror(errno));
+  else
+    lua_pushfstring(L, "%s: %s", info, strerror(errno));
+  lua_pushinteger(L, errno);
+  return 3;
+}
+
+static int pushresult(lua_State * L, int res, const char *info)
+{
+  if (res == -1) {
+    return pusherror(L, info);
+  } else {
+    lua_pushboolean(L, 1);
+    return 1;
+  }
+}
+
+
+/*
+** This function changes the working (current) directory
+*/
+static int change_dir(lua_State * L)
+{
+  const char *path = luaL_checkstring(L, 1);
+  if (chdir(path)) {
+    lua_pushnil(L);
+    lua_pushfstring(L, "Unable to change working directory to '%s'\n%s\n",
+                    path, chdir_error);
+    return 2;
+  } else {
+    lua_pushboolean(L, 1);
+    return 1;
+  }
+}
+
+/*
+** This function returns the current directory
+** If unable to get the current directory, it returns nil
+**  and a string describing the error
+*/
+static int get_dir(lua_State * L)
+{
+#ifdef NO_GETCWD
+  lua_pushnil(L);
+  lua_pushstring(L, "Function 'getcwd' not provided by system");
+  return 2;
+#else
+  char *path = NULL;
+  /* Passing (NULL, 0) is not guaranteed to work.
+     Use a temp buffer and size instead. */
+  size_t size = LFS_MAXPATHLEN; /* initial buffer size */
+  int result;
+  while (1) {
+    char *path2 = realloc(path, size);
+    if (!path2) {               /* failed to allocate */
+      result = pusherror(L, "get_dir realloc() failed");
+      break;
+    }
+    path = path2;
+    if (getcwd(path, size) != NULL) {
+      /* success, push the path to the Lua stack */
+      lua_pushstring(L, path);
+      result = 1;
+      break;
+    }
+    if (errno != ERANGE) {      /* unexpected error */
+      result = pusherror(L, "get_dir getcwd() failed");
+      break;
+    }
+    /* ERANGE = insufficient buffer capacity, double size and retry */
+    size *= 2;
+  }
+  free(path);
+  return result;
+#endif
+}
+
+/*
+** Check if the given element on the stack is a file and returns it.
+*/
+static FILE *check_file(lua_State * L, int idx, const char *funcname)
+{
+#if LUA_VERSION_NUM == 501
+  FILE **fh = (FILE **) luaL_checkudata(L, idx, "FILE*");
+  if (*fh == NULL) {
+    luaL_error(L, "%s: closed file", funcname);
+    return 0;
+  } else
+    return *fh;
+#elif LUA_VERSION_NUM >= 502 && LUA_VERSION_NUM <= 504
+  luaL_Stream *fh = (luaL_Stream *) luaL_checkudata(L, idx, "FILE*");
+  if (fh->closef == 0 || fh->f == NULL) {
+    luaL_error(L, "%s: closed file", funcname);
+    return 0;
+  } else
+    return fh->f;
+#else
+#error unsupported Lua version
+#endif
+}
+
+
+/*
+**
+*/
+static int _file_lock(lua_State * L, FILE * fh, const char *mode,
+                      const long start, long len, const char *funcname)
+{
+  int code;
+#ifdef _WIN32
+  /* lkmode valid values are:
+     LK_LOCK    Locks the specified bytes. If the bytes cannot be locked,
+     the program immediately tries again after 1 second.
+     If, after 10 attempts, the bytes cannot be locked,
+     the constant returns an error.
+     LK_NBLCK   Locks the specified bytes. If the bytes cannot be locked,
+     the constant returns an error.
+     LK_NBRLCK  Same as _LK_NBLCK.
+     LK_RLCK    Same as _LK_LOCK.
+     LK_UNLCK   Unlocks the specified bytes, which must have been
+     previously locked.
+
+     Regions should be locked only briefly and should be unlocked
+     before closing a file or exiting the program.
+
+     http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt__locking.asp
+   */
+  int lkmode;
+  switch (*mode) {
+  case 'r':
+    lkmode = LK_NBLCK;
+    break;
+  case 'w':
+    lkmode = LK_NBLCK;
+    break;
+  case 'u':
+    lkmode = LK_UNLCK;
+    break;
+  default:
+    return luaL_error(L, "%s: invalid mode", funcname);
+  }
+  if (!len) {
+    fseek(fh, 0L, SEEK_END);
+    len = ftell(fh);
+  }
+  fseek(fh, start, SEEK_SET);
+#ifdef __BORLANDC__
+  code = locking(fileno(fh), lkmode, len);
+#else
+  code = _locking(fileno(fh), lkmode, len);
+#endif
+#else
+  struct flock f;
+  switch (*mode) {
+  case 'w':
+    f.l_type = F_WRLCK;
+    break;
+  case 'r':
+    f.l_type = F_RDLCK;
+    break;
+  case 'u':
+    f.l_type = F_UNLCK;
+    break;
+  default:
+    return luaL_error(L, "%s: invalid mode", funcname);
+  }
+  f.l_whence = SEEK_SET;
+  f.l_start = (off_t) start;
+  f.l_len = (off_t) len;
+  code = fcntl(fileno(fh), F_SETLK, &f);
+#endif
+  return (code != -1);
+}
+
+#ifdef _WIN32
+typedef struct lfs_Lock {
+  HANDLE fd;
+} lfs_Lock;
+static int lfs_lock_dir(lua_State * L)
+{
+  size_t pathl;
+  HANDLE fd;
+  lfs_Lock *lock;
+  char *ln;
+  const char *lockfile = "/lockfile.lfs";
+  const char *path = luaL_checklstring(L, 1, &pathl);
+  ln = (char *) malloc(pathl + strlen(lockfile) + 1);
+  if (!ln) {
+    lua_pushnil(L);
+    lua_pushstring(L, strerror(errno));
+    return 2;
+  }
+  strcpy(ln, path);
+  strcat(ln, lockfile);
+  fd = CreateFile(ln, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
+                  FILE_ATTRIBUTE_NORMAL | FILE_FLAG_DELETE_ON_CLOSE, NULL);
+  free(ln);
+  if (fd == INVALID_HANDLE_VALUE) {
+    return lfs_win32_pusherror(L);
+  }
+  lock = (lfs_Lock *) lua_newuserdata(L, sizeof(lfs_Lock));
+  lock->fd = fd;
+  luaL_getmetatable(L, LOCK_METATABLE);
+  lua_setmetatable(L, -2);
+  return 1;
+}
+
+static int lfs_unlock_dir(lua_State * L)
+{
+  lfs_Lock *lock = (lfs_Lock *) luaL_checkudata(L, 1, LOCK_METATABLE);
+  if (lock->fd != INVALID_HANDLE_VALUE) {
+    CloseHandle(lock->fd);
+    lock->fd = INVALID_HANDLE_VALUE;
+  }
+  return 0;
+}
+#else
+typedef struct lfs_Lock {
+  char *ln;
+} lfs_Lock;
+static int lfs_lock_dir(lua_State * L)
+{
+  lfs_Lock *lock;
+  size_t pathl;
+  char *ln;
+  const char *lockfile = "/lockfile.lfs";
+  const char *path = luaL_checklstring(L, 1, &pathl);
+  lock = (lfs_Lock *) lua_newuserdata(L, sizeof(lfs_Lock));
+  ln = (char *) malloc(pathl + strlen(lockfile) + 1);
+  if (!ln) {
+    lua_pushnil(L);
+    lua_pushstring(L, strerror(errno));
+    return 2;
+  }
+  strcpy(ln, path);
+  strcat(ln, lockfile);
+  if (symlink("lock", ln) == -1) {
+    free(ln);
+    lua_pushnil(L);
+    lua_pushstring(L, strerror(errno));
+    return 2;
+  }
+  lock->ln = ln;
+  luaL_getmetatable(L, LOCK_METATABLE);
+  lua_setmetatable(L, -2);
+  return 1;
+}
+
+static int lfs_unlock_dir(lua_State * L)
+{
+  lfs_Lock *lock = (lfs_Lock *) luaL_checkudata(L, 1, LOCK_METATABLE);
+  if (lock->ln) {
+    unlink(lock->ln);
+    free(lock->ln);
+    lock->ln = NULL;
+  }
+  return 0;
+}
+#endif
+
+static int lfs_g_setmode(lua_State * L, FILE * f, int arg)
+{
+  static const int mode[] = { _O_BINARY, _O_TEXT };
+  static const char *const modenames[] = { "binary", "text", NULL };
+  int op = luaL_checkoption(L, arg, NULL, modenames);
+  int res = lfs_setmode(f, mode[op]);
+  if (res != -1) {
+    int i;
+    lua_pushboolean(L, 1);
+    for (i = 0; modenames[i] != NULL; i++) {
+      if (mode[i] == res) {
+        lua_pushstring(L, modenames[i]);
+        return 2;
+      }
+    }
+    lua_pushnil(L);
+    return 2;
+  } else {
+    return pusherror(L, NULL);
+  }
+}
+
+static int lfs_f_setmode(lua_State * L)
+{
+  return lfs_g_setmode(L, check_file(L, 1, "setmode"), 2);
+}
+
+/*
+** Locks a file.
+** @param #1 File handle.
+** @param #2 String with lock mode ('w'rite, 'r'ead).
+** @param #3 Number with start position (optional).
+** @param #4 Number with length (optional).
+*/
+static int file_lock(lua_State * L)
+{
+  FILE *fh = check_file(L, 1, "lock");
+  const char *mode = luaL_checkstring(L, 2);
+  const long start = (long) luaL_optinteger(L, 3, 0);
+  long len = (long) luaL_optinteger(L, 4, 0);
+  if (_file_lock(L, fh, mode, start, len, "lock")) {
+    lua_pushboolean(L, 1);
+    return 1;
+  } else {
+    lua_pushnil(L);
+    lua_pushfstring(L, "%s", strerror(errno));
+    return 2;
+  }
+}
+
+
+/*
+** Unlocks a file.
+** @param #1 File handle.
+** @param #2 Number with start position (optional).
+** @param #3 Number with length (optional).
+*/
+static int file_unlock(lua_State * L)
+{
+  FILE *fh = check_file(L, 1, "unlock");
+  const long start = (long) luaL_optinteger(L, 2, 0);
+  long len = (long) luaL_optinteger(L, 3, 0);
+  if (_file_lock(L, fh, "u", start, len, "unlock")) {
+    lua_pushboolean(L, 1);
+    return 1;
+  } else {
+    lua_pushnil(L);
+    lua_pushfstring(L, "%s", strerror(errno));
+    return 2;
+  }
+}
+
+
+/*
+** Creates a link.
+** @param #1 Object to link to.
+** @param #2 Name of link.
+** @param #3 True if link is symbolic (optional).
+*/
+static int make_link(lua_State * L)
+{
+  const char *oldpath = luaL_checkstring(L, 1);
+  const char *newpath = luaL_checkstring(L, 2);
+#ifndef _WIN32
+  return pushresult(L,
+                    (lua_toboolean(L, 3) ? symlink : link) (oldpath,
+                                                            newpath),
+                    NULL);
+#else
+  int symbolic = lua_toboolean(L, 3);
+  STAT_STRUCT oldpathinfo;
+  int is_dir = 0;
+  if (STAT_FUNC(oldpath, &oldpathinfo) == 0) {
+    is_dir = S_ISDIR(oldpathinfo.st_mode) != 0;
+  }
+  if (!symbolic && is_dir) {
+    lua_pushnil(L);
+    lua_pushstring(L,
+                   "hard links to directories are not supported on Windows");
+    return 2;
+  }
+
+  int result = symbolic ? CreateSymbolicLink(newpath, oldpath, is_dir)
+      : CreateHardLink(newpath, oldpath, NULL);
+
+  if (result) {
+    return pushresult(L, result, NULL);
+  } else {
+    lua_pushnil(L);
+    lua_pushstring(L, symbolic ? "make_link CreateSymbolicLink() failed"
+                   : "make_link CreateHardLink() failed");
+    return 2;
+  }
+#endif
+}
+
+
+/*
+** Creates a directory.
+** @param #1 Directory path.
+*/
+static int make_dir(lua_State * L)
+{
+  const char *path = luaL_checkstring(L, 1);
+  return pushresult(L, lfs_mkdir(path), NULL);
+}
+
+
+/*
+** Removes a directory.
+** @param #1 Directory path.
+*/
+static int remove_dir(lua_State * L)
+{
+  const char *path = luaL_checkstring(L, 1);
+  return pushresult(L, rmdir(path), NULL);
+}
+
+
+/*
+** Directory iterator
+*/
+static int dir_iter(lua_State * L)
+{
+#ifdef _WIN32
+  struct _finddata_t c_file;
+#else
+  struct dirent *entry;
+#endif
+  dir_data *d = (dir_data *) luaL_checkudata(L, 1, DIR_METATABLE);
+  luaL_argcheck(L, d->closed == 0, 1, "closed directory");
+#ifdef _WIN32
+  if (d->hFile == 0L) {         /* first entry */
+    if ((d->hFile = _findfirst(d->pattern, &c_file)) == -1L) {
+      lua_pushnil(L);
+      lua_pushstring(L, strerror(errno));
+      d->closed = 1;
+      return 2;
+    } else {
+      lua_pushstring(L, c_file.name);
+      return 1;
+    }
+  } else {                      /* next entry */
+    if (_findnext(d->hFile, &c_file) == -1L) {
+      /* no more entries => close directory */
+      _findclose(d->hFile);
+      d->closed = 1;
+      return 0;
+    } else {
+      lua_pushstring(L, c_file.name);
+      return 1;
+    }
+  }
+#else
+  if ((entry = readdir(d->dir)) != NULL) {
+    lua_pushstring(L, entry->d_name);
+    return 1;
+  } else {
+    /* no more entries => close directory */
+    closedir(d->dir);
+    d->closed = 1;
+    return 0;
+  }
+#endif
+}
+
+
+/*
+** Closes directory iterators
+*/
+static int dir_close(lua_State * L)
+{
+  dir_data *d = (dir_data *) lua_touserdata(L, 1);
+#ifdef _WIN32
+  if (!d->closed && d->hFile) {
+    _findclose(d->hFile);
+  }
+#else
+  if (!d->closed && d->dir) {
+    closedir(d->dir);
+  }
+#endif
+  d->closed = 1;
+  return 0;
+}
+
+
+/*
+** Factory of directory iterators
+*/
+static int dir_iter_factory(lua_State * L)
+{
+  const char *path = luaL_checkstring(L, 1);
+  dir_data *d;
+  lua_pushcfunction(L, dir_iter);
+  d = (dir_data *) lua_newuserdata(L, sizeof(dir_data));
+  luaL_getmetatable(L, DIR_METATABLE);
+  lua_setmetatable(L, -2);
+  d->closed = 0;
+#ifdef _WIN32
+  d->hFile = 0L;
+  if (strlen(path) > MAX_PATH - 2)
+    luaL_error(L, "path too long: %s", path);
+  else
+    sprintf(d->pattern, "%s/*", path);
+#else
+  d->dir = opendir(path);
+  if (d->dir == NULL)
+    luaL_error(L, "cannot open %s: %s", path, strerror(errno));
+#endif
+#if LUA_VERSION_NUM >= 504
+  lua_pushnil(L);
+  lua_pushvalue(L, -2);
+  return 4;
+#else
+  return 2;
+#endif
+}
+
+
+/*
+** Creates directory metatable.
+*/
+static int dir_create_meta(lua_State * L)
+{
+  luaL_newmetatable(L, DIR_METATABLE);
+
+  /* Method table */
+  lua_newtable(L);
+  lua_pushcfunction(L, dir_iter);
+  lua_setfield(L, -2, "next");
+  lua_pushcfunction(L, dir_close);
+  lua_setfield(L, -2, "close");
+
+  /* Metamethods */
+  lua_setfield(L, -2, "__index");
+  lua_pushcfunction(L, dir_close);
+  lua_setfield(L, -2, "__gc");
+
+#if LUA_VERSION_NUM >= 504
+  lua_pushcfunction(L, dir_close);
+  lua_setfield(L, -2, "__close");
+#endif
+  return 1;
+}
+
+
+/*
+** Creates lock metatable.
+*/
+static int lock_create_meta(lua_State * L)
+{
+  luaL_newmetatable(L, LOCK_METATABLE);
+
+  /* Method table */
+  lua_newtable(L);
+  lua_pushcfunction(L, lfs_unlock_dir);
+  lua_setfield(L, -2, "free");
+
+  /* Metamethods */
+  lua_setfield(L, -2, "__index");
+  lua_pushcfunction(L, lfs_unlock_dir);
+  lua_setfield(L, -2, "__gc");
+  return 1;
+}
+
+
+/*
+** Convert the inode protection mode to a string.
+*/
+#ifdef _WIN32
+static const char *mode2string(unsigned short mode)
+{
+#else
+static const char *mode2string(mode_t mode)
+{
+#endif
+  if (S_ISREG(mode))
+    return "file";
+  else if (S_ISDIR(mode))
+    return "directory";
+  else if (S_ISLNK(mode))
+    return "link";
+  else if (S_ISSOCK(mode))
+    return "socket";
+  else if (S_ISFIFO(mode))
+    return "named pipe";
+  else if (S_ISCHR(mode))
+    return "char device";
+  else if (S_ISBLK(mode))
+    return "block device";
+  else
+    return "other";
+}
+
+
+/*
+** Set access time and modification values for a file.
+** @param #1 File path.
+** @param #2 Access time in seconds, current time is used if missing.
+** @param #3 Modification time in seconds, access time is used if missing.
+*/
+static int file_utime(lua_State * L)
+{
+  const char *file = luaL_checkstring(L, 1);
+  struct utimbuf utb, *buf;
+
+  if (lua_gettop(L) == 1)       /* set to current date/time */
+    buf = NULL;
+  else {
+    utb.actime = (time_t) luaL_optnumber(L, 2, 0);
+    utb.modtime = (time_t) luaL_optinteger(L, 3, utb.actime);
+    buf = &utb;
+  }
+
+  return pushresult(L, utime(file, buf), NULL);
+}
+
+
+/* inode protection mode */
+static void push_st_mode(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushstring(L, mode2string(info->st_mode));
+}
+
+/* device inode resides on */
+static void push_st_dev(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_dev);
+}
+
+/* inode's number */
+static void push_st_ino(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_ino);
+}
+
+/* number of hard links to the file */
+static void push_st_nlink(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_nlink);
+}
+
+/* user-id of owner */
+static void push_st_uid(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_uid);
+}
+
+/* group-id of owner */
+static void push_st_gid(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_gid);
+}
+
+/* device type, for special file inode */
+static void push_st_rdev(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_rdev);
+}
+
+/* time of last access */
+static void push_st_atime(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_atime);
+}
+
+/* time of last data modification */
+static void push_st_mtime(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_mtime);
+}
+
+/* time of last file status change */
+static void push_st_ctime(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_ctime);
+}
+
+/* file size, in bytes */
+static void push_st_size(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_size);
+}
+
+#ifndef _WIN32
+/* blocks allocated for file */
+static void push_st_blocks(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_blocks);
+}
+
+/* optimal file system I/O blocksize */
+static void push_st_blksize(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushinteger(L, (lua_Integer) info->st_blksize);
+}
+#endif
+
+ /*
+  ** Convert the inode protection mode to a permission list.
+  */
+
+#ifdef _WIN32
+static const char *perm2string(unsigned short mode)
+{
+  static char perms[10] = "---------";
+  int i;
+  for (i = 0; i < 9; i++)
+    perms[i] = '-';
+  if (mode & _S_IREAD) {
+    perms[0] = 'r';
+    perms[3] = 'r';
+    perms[6] = 'r';
+  }
+  if (mode & _S_IWRITE) {
+    perms[1] = 'w';
+    perms[4] = 'w';
+    perms[7] = 'w';
+  }
+  if (mode & _S_IEXEC) {
+    perms[2] = 'x';
+    perms[5] = 'x';
+    perms[8] = 'x';
+  }
+  return perms;
+}
+#else
+static const char *perm2string(mode_t mode)
+{
+  static char perms[10] = "---------";
+  int i;
+  for (i = 0; i < 9; i++)
+    perms[i] = '-';
+  if (mode & S_IRUSR)
+    perms[0] = 'r';
+  if (mode & S_IWUSR)
+    perms[1] = 'w';
+  if (mode & S_IXUSR)
+    perms[2] = 'x';
+  if (mode & S_IRGRP)
+    perms[3] = 'r';
+  if (mode & S_IWGRP)
+    perms[4] = 'w';
+  if (mode & S_IXGRP)
+    perms[5] = 'x';
+  if (mode & S_IROTH)
+    perms[6] = 'r';
+  if (mode & S_IWOTH)
+    perms[7] = 'w';
+  if (mode & S_IXOTH)
+    perms[8] = 'x';
+  return perms;
+}
+#endif
+
+/* permssions string */
+static void push_st_perm(lua_State * L, STAT_STRUCT * info)
+{
+  lua_pushstring(L, perm2string(info->st_mode));
+}
+
+typedef void (*_push_function)(lua_State * L, STAT_STRUCT * info);
+
+struct _stat_members {
+  const char *name;
+  _push_function push;
+};
+
+struct _stat_members members[] = {
+  { "mode", push_st_mode },
+  { "dev", push_st_dev },
+  { "ino", push_st_ino },
+  { "nlink", push_st_nlink },
+  { "uid", push_st_uid },
+  { "gid", push_st_gid },
+  { "rdev", push_st_rdev },
+  { "access", push_st_atime },
+  { "modification", push_st_mtime },
+  { "change", push_st_ctime },
+  { "size", push_st_size },
+  { "permissions", push_st_perm },
+#ifndef _WIN32
+  { "blocks", push_st_blocks },
+  { "blksize", push_st_blksize },
+#endif
+  { NULL, NULL }
+};
+
+/*
+** Get file or symbolic link information
+*/
+static int _file_info_(lua_State * L,
+                       int (*st)(const char *, STAT_STRUCT *))
+{
+  STAT_STRUCT info;
+  const char *file = luaL_checkstring(L, 1);
+  int i;
+
+  if (st(file, &info)) {
+    lua_pushnil(L);
+    lua_pushfstring(L, "cannot obtain information from file '%s': %s",
+                    file, strerror(errno));
+    lua_pushinteger(L, errno);
+    return 3;
+  }
+  if (lua_isstring(L, 2)) {
+    const char *member = lua_tostring(L, 2);
+    for (i = 0; members[i].name; i++) {
+      if (strcmp(members[i].name, member) == 0) {
+        /* push member value and return */
+        members[i].push(L, &info);
+        return 1;
+      }
+    }
+    /* member not found */
+    return luaL_error(L, "invalid attribute name '%s'", member);
+  }
+  /* creates a table if none is given, removes extra arguments */
+  lua_settop(L, 2);
+  if (!lua_istable(L, 2)) {
+    lua_newtable(L);
+  }
+  /* stores all members in table on top of the stack */
+  for (i = 0; members[i].name; i++) {
+    lua_pushstring(L, members[i].name);
+    members[i].push(L, &info);
+    lua_rawset(L, -3);
+  }
+  return 1;
+}
+
+
+/*
+** Get file information using stat.
+*/
+static int file_info(lua_State * L)
+{
+  return _file_info_(L, STAT_FUNC);
+}
+
+
+/*
+** Push the symlink target to the top of the stack.
+** Assumes the file name is at position 1 of the stack.
+** Returns 1 if successful (with the target on top of the stack),
+** 0 on failure (with stack unchanged, and errno set).
+*/
+static int push_link_target(lua_State * L)
+{
+  const char *file = luaL_checkstring(L, 1);
+#ifdef _WIN32
+  HANDLE h = CreateFile(file, GENERIC_READ,
+                        FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
+                        OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+  if (h == INVALID_HANDLE_VALUE) {
+    return lfs_win32_pusherror(L);
+  }
+#endif
+  char *target = NULL;
+  int tsize, size = 256;        /* size = initial buffer capacity */
+  int ok = 0;
+  while (!ok) {
+    char *target2 = realloc(target, size);
+    if (!target2) {             /* failed to allocate */
+      break;
+    }
+    target = target2;
+#ifdef _WIN32
+    tsize = GetFinalPathNameByHandle(h, target, size, FILE_NAME_OPENED);
+#else
+    tsize = readlink(file, target, size);
+#endif
+    if (tsize < 0) {            /* a readlink() error occurred */
+      break;
+    }
+    if (tsize < size) {
+#ifdef _WIN32
+      if (tsize > 4 && strncmp(target, "\\\\?\\", 4) == 0) {
+        memmove_s(target, tsize - 3, target + 4, tsize - 3);
+        tsize -= 4;
+      }
+#endif
+      ok = 1;
+      break;
+    }
+    /* possibly truncated readlink() result, double size and retry */
+    size *= 2;
+  }
+  if (ok) {
+    target[tsize] = '\0';
+    lua_pushlstring(L, target, tsize);
+  }
+#ifdef _WIN32
+  CloseHandle(h);
+#endif
+  free(target);
+  return ok;
+}
+
+/*
+** Get symbolic link information using lstat.
+*/
+static int link_info(lua_State * L)
+{
+  int ret;
+  if (lua_isstring(L, 2) && (strcmp(lua_tostring(L, 2), "target") == 0)) {
+    int ok = push_link_target(L);
+    return ok ? 1 : pusherror(L, "could not obtain link target");
+  }
+  ret = _file_info_(L, LSTAT_FUNC);
+  if (ret == 1 && lua_type(L, -1) == LUA_TTABLE) {
+    int ok = push_link_target(L);
+    if (ok) {
+      lua_setfield(L, -2, "target");
+    }
+  }
+  return ret;
+}
+
+
+/*
+** Assumes the table is on top of the stack.
+*/
+static void set_info(lua_State * L)
+{
+  lua_pushliteral(L, "Copyright (C) 2003-2017 Kepler Project");
+  lua_setfield(L, -2, "_COPYRIGHT");
+  lua_pushliteral(L,
+                  "LuaFileSystem is a Lua library developed to complement "
+                  "the set of functions related to file systems offered by "
+                  "the standard Lua distribution");
+  lua_setfield(L, -2, "_DESCRIPTION");
+  lua_pushliteral(L, "LuaFileSystem " LFS_VERSION);
+  lua_setfield(L, -2, "_VERSION");
+}
+
+
+static const struct luaL_Reg fslib[] = {
+  { "attributes", file_info },
+  { "chdir", change_dir },
+  { "currentdir", get_dir },
+  { "dir", dir_iter_factory },
+  { "link", make_link },
+  { "lock", file_lock },
+  { "mkdir", make_dir },
+  { "rmdir", remove_dir },
+  { "symlinkattributes", link_info },
+  { "setmode", lfs_f_setmode },
+  { "touch", file_utime },
+  { "unlock", file_unlock },
+  { "lock_dir", lfs_lock_dir },
+  { NULL, NULL },
+};
+
+LFS_EXPORT int luaopen_lfs(lua_State * L)
+{
+  dir_create_meta(L);
+  lock_create_meta(L);
+  new_lib(L, fslib);
+  lua_pushvalue(L, -1);
+  lua_setglobal(L, LFS_LIBNAME);
+  set_info(L);
+  return 1;
+}
diff --git a/src/lfs.h b/src/lfs.h
new file mode 100644
index 0000000..13b60a9
--- /dev/null
+++ b/src/lfs.h
@@ -0,0 +1,35 @@
+/*
+** LuaFileSystem
+** Copyright Kepler Project 2003 - 2020
+** (http://keplerproject.github.io/luafilesystem)
+*/
+
+/* Define 'chdir' for systems that do not implement it */
+#ifdef NO_CHDIR
+#define chdir(p)	(-1)
+#define chdir_error	"Function 'chdir' not provided by system"
+#else
+#define chdir_error	strerror(errno)
+#endif
+
+#ifdef _WIN32
+#define chdir(p) (_chdir(p))
+#define getcwd(d, s) (_getcwd(d, s))
+#define rmdir(p) (_rmdir(p))
+#define LFS_EXPORT __declspec (dllexport)
+#ifndef fileno
+#define fileno(f) (_fileno(f))
+#endif
+#else
+#define LFS_EXPORT
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+  LFS_EXPORT int luaopen_lfs(lua_State * L);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/src/linit.c b/src/linit.c
index f2fd331..b22d822 100644
--- a/src/linit.c
+++ b/src/linit.c
@@ -22,6 +22,7 @@ static const luaL_Reg lualibs[] = {
   {LUA_OSLIBNAME, luaopen_os},
   {LUA_STRLIBNAME, luaopen_string},
   {LUA_MATHLIBNAME, luaopen_math},
+  {LUA_LFSLIBNAME, luaopen_lfs},
   {LUA_CURSESLIBNAME, luaopen_curses},
   {LUA_SOCKETCORELIBNAME, luaopen_socket_core},
   {LUA_MIMECORELIBNAME, luaopen_mime_core},
diff --git a/src/lualib.h b/src/lualib.h
index 13a7b96..779f195 100644
--- a/src/lualib.h
+++ b/src/lualib.h
@@ -33,6 +33,9 @@ LUALIB_API int (luaopen_string) (lua_State *L);
 #define LUA_MATHLIBNAME	"math"
 LUALIB_API int (luaopen_math) (lua_State *L);
 
+#define LUA_LFSLIBNAME	"lfs"
+LUALIB_API int (luaopen_lfs) (lua_State *L);
+
 #define LUA_CURSESLIBNAME	"curses"
 LUALIB_API int (luaopen_curses) (lua_State *L);