feat: 适配 Lua 5.2.4 (lua_5.2.4 分支)

- lib/lua 替换为 Lua 5.2.4 官方源码; CMakeLists 补 lbitlib.c(5.2 linit 注册 bit32)、删 lutf8lib.c(5.2 无此文件)
- I/O 重定向机制改造: 5.2 无 lua_getextraspace → iopath 指针存入
  Registry 固定索引(IOPATH_REG_IDX=1), 回调经 get_iopath() 取回,
  free_lua 时释放 —— 该方案同样适用于更低版本
- typed interop 版本自适应: capture_result() 的 lua_isinteger 分支用
  #if LUA_VERSION_NUM >= 503 包裹, 5.2 及以下所有数字统一 CJT_NUM
- 测试跨版本适配: PackagePathConfig 接受 require 的两种返回语义;
  typed 数值断言 EXPECT_INT_OR_NUM 宏兼容有无 integer 子类型;
  大整数保真断言仅对 5.3+ 生效(5.2 经 double 必然丢精度)
- 验证: GTest 44/44 通过

lib/lua/liolib.c

@@ -1,153 +1,120 @@
 /*
-** $Id: liolib.c $
+** $Id: liolib.c,v 2.112.1.1 2013/04/12 18:48:47 roberto Exp $
 ** Standard I/O (and system) library
 ** See Copyright Notice in lua.h
 */
 
-#define liolib_c
-#define LUA_LIB
 
-#include "lprefix.h"
+/*
+** This definition must come before the inclusion of 'stdio.h'; it
+** should not affect non-POSIX systems
+*/
+#if !defined(_FILE_OFFSET_BITS)
+#define	_LARGEFILE_SOURCE	1
+#define _FILE_OFFSET_BITS	64
+#endif
 
 
-#include <ctype.h>
 #include <errno.h>
-#include <locale.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#define liolib_c
+#define LUA_LIB
+
 #include "lua.h"
 
 #include "lauxlib.h"
 #include "lualib.h"
 
 
-
+#if !defined(lua_checkmode)
 
 /*
+** Check whether 'mode' matches '[rwa]%+?b?'.
 ** Change this macro to accept other modes for 'fopen' besides
 ** the standard ones.
 */
-#if !defined(l_checkmode)
-
-/* accepted extensions to 'mode' in 'fopen' */
-#if !defined(L_MODEEXT)
-#define L_MODEEXT	"b"
-#endif
-
-/* Check whether 'mode' matches '[rwa]%+?[L_MODEEXT]*' */
-static int l_checkmode (const char *mode) {
-  return (*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&
-         (*mode != '+' || ((void)(++mode), 1)) &&  /* skip if char is '+' */
-         (strspn(mode, L_MODEEXT) == strlen(mode)));  /* check extensions */
-}
+#define lua_checkmode(mode) \
+	(*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&	\
+	(*mode != '+' || ++mode) &&  /* skip if char is '+' */	\
+	(*mode != 'b' || ++mode) &&  /* skip if char is 'b' */	\
+	(*mode == '\0'))
 
 #endif
 
 /*
 ** {======================================================
-** l_popen spawns a new process connected to the current
+** lua_popen spawns a new process connected to the current
 ** one through the file streams.
 ** =======================================================
 */
 
-#if !defined(l_popen)		/* { */
+#if !defined(lua_popen)	/* { */
 
-#if defined(LUA_USE_POSIX)	/* { */
+#if defined(LUA_USE_POPEN)	/* { */
 
-#define l_popen(L,c,m)		(fflush(NULL), popen(c,m))
-#define l_pclose(L,file)	(pclose(file))
+#define lua_popen(L,c,m)	((void)L, fflush(NULL), popen(c,m))
+#define lua_pclose(L,file)	((void)L, pclose(file))
 
-#elif defined(LUA_USE_WINDOWS)	/* }{ */
+#elif defined(LUA_WIN)		/* }{ */
 
-#define l_popen(L,c,m)		(_popen(c,m))
-#define l_pclose(L,file)	(_pclose(file))
+#define lua_popen(L,c,m)		((void)L, _popen(c,m))
+#define lua_pclose(L,file)		((void)L, _pclose(file))
 
-#if !defined(l_checkmodep)
-/* Windows accepts "[rw][bt]?" as valid modes */
-#define l_checkmodep(m)	((m[0] == 'r' || m[0] == 'w') && \
-  (m[1] == '\0' || ((m[1] == 'b' || m[1] == 't') && m[2] == '\0')))
-#endif
 
 #else				/* }{ */
 
-/* ISO C definitions */
-#define l_popen(L,c,m)  \
-	  ((void)c, (void)m, \
-	  luaL_error(L, "'popen' not supported"), \
-	  (FILE*)0)
-#define l_pclose(L,file)		((void)L, (void)file, -1)
+#define lua_popen(L,c,m)		((void)((void)c, m),  \
+		luaL_error(L, LUA_QL("popen") " not supported"), (FILE*)0)
+#define lua_pclose(L,file)		((void)((void)L, file), -1)
+
 
 #endif				/* } */
 
-#endif				/* } */
-
-
-#if !defined(l_checkmodep)
-/* By default, Lua accepts only "r" or "w" as valid modes */
-#define l_checkmodep(m)        ((m[0] == 'r' || m[0] == 'w') && m[1] == '\0')
-#endif
+#endif			/* } */
 
 /* }====================================================== */
 
 
-#if !defined(l_getc)		/* { */
-
-#if defined(LUA_USE_POSIX)
-#define l_getc(f)		getc_unlocked(f)
-#define l_lockfile(f)		flockfile(f)
-#define l_unlockfile(f)		funlockfile(f)
-#else
-#define l_getc(f)		getc(f)
-#define l_lockfile(f)		((void)0)
-#define l_unlockfile(f)		((void)0)
-#endif
-
-#endif				/* } */
-
-
 /*
 ** {======================================================
-** l_fseek: configuration for longer offsets
+** lua_fseek: configuration for longer offsets
 ** =======================================================
 */
 
-#if !defined(l_fseek)		/* { */
+#if !defined(lua_fseek)	&& !defined(LUA_ANSI)	/* { */
 
 #if defined(LUA_USE_POSIX)	/* { */
 
-#include <sys/types.h>
-
 #define l_fseek(f,o,w)		fseeko(f,o,w)
 #define l_ftell(f)		ftello(f)
 #define l_seeknum		off_t
 
-#elif defined(LUA_USE_WINDOWS) && !defined(_CRTIMP_TYPEINFO) \
+#elif defined(LUA_WIN) && !defined(_CRTIMP_TYPEINFO) \
    && defined(_MSC_VER) && (_MSC_VER >= 1400)	/* }{ */
-
 /* Windows (but not DDK) and Visual C++ 2005 or higher */
+
 #define l_fseek(f,o,w)		_fseeki64(f,o,w)
 #define l_ftell(f)		_ftelli64(f)
 #define l_seeknum		__int64
 
-#else				/* }{ */
+#endif	/* } */
 
-/* ISO C definitions */
+#endif			/* } */
+
+
+#if !defined(l_fseek)		/* default definitions */
 #define l_fseek(f,o,w)		fseek(f,o,w)
 #define l_ftell(f)		ftell(f)
 #define l_seeknum		long
-
-#endif				/* } */
-
-#endif				/* } */
+#endif
 
 /* }====================================================== */
 
 
-
 #define IO_PREFIX	"_IO_"
-#define IOPREF_LEN	(sizeof(IO_PREFIX)/sizeof(char) - 1)
 #define IO_INPUT	(IO_PREFIX "input")
 #define IO_OUTPUT	(IO_PREFIX "output")
 
@@ -165,7 +132,7 @@ static int io_type (lua_State *L) {
   luaL_checkany(L, 1);
   p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE);
   if (p == NULL)
-    luaL_pushfail(L);  /* not a file */
+    lua_pushnil(L);  /* not a file */
   else if (isclosed(p))
     lua_pushliteral(L, "closed file");
   else
@@ -186,7 +153,7 @@ static int f_tostring (lua_State *L) {
 
 static FILE *tofile (lua_State *L) {
   LStream *p = tolstream(L);
-  if (l_unlikely(isclosed(p)))
+  if (isclosed(p))
     luaL_error(L, "attempt to use a closed file");
   lua_assert(p->f);
   return p->f;
@@ -194,41 +161,31 @@ static FILE *tofile (lua_State *L) {
 
 
 /*
-** When creating file handles, always creates a 'closed' file handle
+** When creating file handles, always creates a `closed' file handle
 ** before opening the actual file; so, if there is a memory error, the
-** handle is in a consistent state.
+** file is not left opened.
 */
 static LStream *newprefile (lua_State *L) {
-  LStream *p = (LStream *)lua_newuserdatauv(L, sizeof(LStream), 0);
+  LStream *p = (LStream *)lua_newuserdata(L, sizeof(LStream));
   p->closef = NULL;  /* mark file handle as 'closed' */
   luaL_setmetatable(L, LUA_FILEHANDLE);
   return p;
 }
 
 
-/*
-** Calls the 'close' function from a file handle. The 'volatile' avoids
-** a bug in some versions of the Clang compiler (e.g., clang 3.0 for
-** 32 bits).
-*/
 static int aux_close (lua_State *L) {
   LStream *p = tolstream(L);
-  volatile lua_CFunction cf = p->closef;
+  lua_CFunction cf = p->closef;
   p->closef = NULL;  /* mark stream as closed */
   return (*cf)(L);  /* close it */
 }
 
 
-static int f_close (lua_State *L) {
-  tofile(L);  /* make sure argument is an open stream */
-  return aux_close(L);
-}
-
-
 static int io_close (lua_State *L) {
   if (lua_isnone(L, 1))  /* no argument? */
-    lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use default output */
-  return f_close(L);
+    lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use standard output */
+  tofile(L);  /* make sure argument is an open stream */
+  return aux_close(L);
 }
 
 
@@ -245,8 +202,8 @@ static int f_gc (lua_State *L) {
 */
 static int io_fclose (lua_State *L) {
   LStream *p = tolstream(L);
-  errno = 0;
-  return luaL_fileresult(L, (fclose(p->f) == 0), NULL);
+  int res = fclose(p->f);
+  return luaL_fileresult(L, (res == 0), NULL);
 }
 
 
@@ -261,8 +218,8 @@ static LStream *newfile (lua_State *L) {
 static void opencheck (lua_State *L, const char *fname, const char *mode) {
   LStream *p = newfile(L);
   p->f = fopen(fname, mode);
-  if (l_unlikely(p->f == NULL))
-    luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno));
+  if (p->f == NULL)
+    luaL_error(L, "cannot open file " LUA_QS " (%s)", fname, strerror(errno));
 }
 
 
@@ -271,8 +228,7 @@ static int io_open (lua_State *L) {
   const char *mode = luaL_optstring(L, 2, "r");
   LStream *p = newfile(L);
   const char *md = mode;  /* to traverse/check mode */
-  luaL_argcheck(L, l_checkmode(md), 2, "invalid mode");
-  errno = 0;
+  luaL_argcheck(L, lua_checkmode(md), 2, "invalid mode");
   p->f = fopen(filename, mode);
   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
 }
@@ -283,8 +239,7 @@ static int io_open (lua_State *L) {
 */
 static int io_pclose (lua_State *L) {
   LStream *p = tolstream(L);
-  errno = 0;
-  return luaL_execresult(L, l_pclose(L, p->f));
+  return luaL_execresult(L, lua_pclose(L, p->f));
 }
 
 
@@ -292,9 +247,7 @@ static int io_popen (lua_State *L) {
   const char *filename = luaL_checkstring(L, 1);
   const char *mode = luaL_optstring(L, 2, "r");
   LStream *p = newprefile(L);
-  luaL_argcheck(L, l_checkmodep(mode), 2, "invalid mode");
-  errno = 0;
-  p->f = l_popen(L, filename, mode);
+  p->f = lua_popen(L, filename, mode);
   p->closef = &io_pclose;
   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
 }
@@ -302,7 +255,6 @@ static int io_popen (lua_State *L) {
 
 static int io_tmpfile (lua_State *L) {
   LStream *p = newfile(L);
-  errno = 0;
   p->f = tmpfile();
   return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1;
 }
@@ -312,8 +264,8 @@ static FILE *getiofile (lua_State *L, const char *findex) {
   LStream *p;
   lua_getfield(L, LUA_REGISTRYINDEX, findex);
   p = (LStream *)lua_touserdata(L, -1);
-  if (l_unlikely(isclosed(p)))
-    luaL_error(L, "default %s file is closed", findex + IOPREF_LEN);
+  if (isclosed(p))
+    luaL_error(L, "standard %s file is closed", findex + strlen(IO_PREFIX));
   return p->f;
 }
 
@@ -348,28 +300,15 @@ static int io_output (lua_State *L) {
 static int io_readline (lua_State *L);
 
 
-/*
-** maximum number of arguments to 'f:lines'/'io.lines' (it + 3 must fit
-** in the limit for upvalues of a closure)
-*/
-#define MAXARGLINE	250
-
-/*
-** Auxiliary function to create the iteration function for 'lines'.
-** The iteration function is a closure over 'io_readline', with
-** the following upvalues:
-** 1) The file being read (first value in the stack)
-** 2) the number of arguments to read
-** 3) a boolean, true iff file has to be closed when finished ('toclose')
-** *) a variable number of format arguments (rest of the stack)
-*/
 static void aux_lines (lua_State *L, int toclose) {
+  int i;
   int n = lua_gettop(L) - 1;  /* number of arguments to read */
-  luaL_argcheck(L, n <= MAXARGLINE, MAXARGLINE + 2, "too many arguments");
-  lua_pushvalue(L, 1);  /* file */
+  /* ensure that arguments will fit here and into 'io_readline' stack */
+  luaL_argcheck(L, n <= LUA_MINSTACK - 3, LUA_MINSTACK - 3, "too many options");
+  lua_pushvalue(L, 1);  /* file handle */
   lua_pushinteger(L, n);  /* number of arguments to read */
   lua_pushboolean(L, toclose);  /* close/not close file when finished */
-  lua_rotate(L, 2, 3);  /* move the three values to their positions */
+  for (i = 1; i <= n; i++) lua_pushvalue(L, i + 1);  /* copy arguments */
   lua_pushcclosure(L, io_readline, 3 + n);
 }
 
@@ -381,11 +320,6 @@ static int f_lines (lua_State *L) {
 }
 
 
-/*
-** Return an iteration function for 'io.lines'. If file has to be
-** closed, also returns the file itself as a second result (to be
-** closed as the state at the exit of a generic for).
-*/
 static int io_lines (lua_State *L) {
   int toclose;
   if (lua_isnone(L, 1)) lua_pushnil(L);  /* at least one argument */
@@ -401,15 +335,8 @@ static int io_lines (lua_State *L) {
     lua_replace(L, 1);  /* put file at index 1 */
     toclose = 1;  /* close it after iteration */
   }
-  aux_lines(L, toclose);  /* push iteration function */
-  if (toclose) {
-    lua_pushnil(L);  /* state */
-    lua_pushnil(L);  /* control */
-    lua_pushvalue(L, 1);  /* file is the to-be-closed variable (4th result) */
-    return 4;
-  }
-  else
-    return 1;
+  aux_lines(L, toclose);
+  return 1;
 }
 
 
@@ -420,91 +347,13 @@ static int io_lines (lua_State *L) {
 */
 
 
-/* maximum length of a numeral */
-#if !defined (L_MAXLENNUM)
-#define L_MAXLENNUM     200
-#endif
-
-
-/* auxiliary structure used by 'read_number' */
-typedef struct {
-  FILE *f;  /* file being read */
-  int c;  /* current character (look ahead) */
-  int n;  /* number of elements in buffer 'buff' */
-  char buff[L_MAXLENNUM + 1];  /* +1 for ending '\0' */
-} RN;
-
-
-/*
-** Add current char to buffer (if not out of space) and read next one
-*/
-static int nextc (RN *rn) {
-  if (l_unlikely(rn->n >= L_MAXLENNUM)) {  /* buffer overflow? */
-    rn->buff[0] = '\0';  /* invalidate result */
-    return 0;  /* fail */
-  }
-  else {
-    rn->buff[rn->n++] = rn->c;  /* save current char */
-    rn->c = l_getc(rn->f);  /* read next one */
+static int read_number (lua_State *L, FILE *f) {
+  lua_Number d;
+  if (fscanf(f, LUA_NUMBER_SCAN, &d) == 1) {
+    lua_pushnumber(L, d);
     return 1;
   }
-}
-
-
-/*
-** Accept current char if it is in 'set' (of size 2)
-*/
-static int test2 (RN *rn, const char *set) {
-  if (rn->c == set[0] || rn->c == set[1])
-    return nextc(rn);
-  else return 0;
-}
-
-
-/*
-** Read a sequence of (hex)digits
-*/
-static int readdigits (RN *rn, int hex) {
-  int count = 0;
-  while ((hex ? isxdigit(rn->c) : isdigit(rn->c)) && nextc(rn))
-    count++;
-  return count;
-}
-
-
-/*
-** Read a number: first reads a valid prefix of a numeral into a buffer.
-** Then it calls 'lua_stringtonumber' to check whether the format is
-** correct and to convert it to a Lua number.
-*/
-static int read_number (lua_State *L, FILE *f) {
-  RN rn;
-  int count = 0;
-  int hex = 0;
-  char decp[2];
-  rn.f = f; rn.n = 0;
-  decp[0] = lua_getlocaledecpoint();  /* get decimal point from locale */
-  decp[1] = '.';  /* always accept a dot */
-  l_lockfile(rn.f);
-  do { rn.c = l_getc(rn.f); } while (isspace(rn.c));  /* skip spaces */
-  test2(&rn, "-+");  /* optional sign */
-  if (test2(&rn, "00")) {
-    if (test2(&rn, "xX")) hex = 1;  /* numeral is hexadecimal */
-    else count = 1;  /* count initial '0' as a valid digit */
-  }
-  count += readdigits(&rn, hex);  /* integral part */
-  if (test2(&rn, decp))  /* decimal point? */
-    count += readdigits(&rn, hex);  /* fractional part */
-  if (count > 0 && test2(&rn, (hex ? "pP" : "eE"))) {  /* exponent mark? */
-    test2(&rn, "-+");  /* exponent sign */
-    readdigits(&rn, 0);  /* exponent digits */
-  }
-  ungetc(rn.c, rn.f);  /* unread look-ahead char */
-  l_unlockfile(rn.f);
-  rn.buff[rn.n] = '\0';  /* finish string */
-  if (l_likely(lua_stringtonumber(L, rn.buff)))
-    return 1;  /* ok, it is a valid number */
-  else {  /* invalid format */
+  else {
    lua_pushnil(L);  /* "result" to be removed */
    return 0;  /* read fails */
   }
@@ -513,42 +362,48 @@ static int read_number (lua_State *L, FILE *f) {
 
 static int test_eof (lua_State *L, FILE *f) {
   int c = getc(f);
-  ungetc(c, f);  /* no-op when c == EOF */
-  lua_pushliteral(L, "");
+  ungetc(c, f);
+  lua_pushlstring(L, NULL, 0);
   return (c != EOF);
 }
 
 
 static int read_line (lua_State *L, FILE *f, int chop) {
   luaL_Buffer b;
-  int c;
   luaL_buffinit(L, &b);
-  do {  /* may need to read several chunks to get whole line */
-    char *buff = luaL_prepbuffer(&b);  /* preallocate buffer space */
-    int i = 0;
-    l_lockfile(f);  /* no memory errors can happen inside the lock */
-    while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n')
-      buff[i++] = c;  /* read up to end of line or buffer limit */
-    l_unlockfile(f);
-    luaL_addsize(&b, i);
-  } while (c != EOF && c != '\n');  /* repeat until end of line */
-  if (!chop && c == '\n')  /* want a newline and have one? */
-    luaL_addchar(&b, c);  /* add ending newline to result */
-  luaL_pushresult(&b);  /* close buffer */
-  /* return ok if read something (either a newline or something else) */
-  return (c == '\n' || lua_rawlen(L, -1) > 0);
+  for (;;) {
+    size_t l;
+    char *p = luaL_prepbuffer(&b);
+    if (fgets(p, LUAL_BUFFERSIZE, f) == NULL) {  /* eof? */
+      luaL_pushresult(&b);  /* close buffer */
+      return (lua_rawlen(L, -1) > 0);  /* check whether read something */
+    }
+    l = strlen(p);
+    if (l == 0 || p[l-1] != '\n')
+      luaL_addsize(&b, l);
+    else {
+      luaL_addsize(&b, l - chop);  /* chop 'eol' if needed */
+      luaL_pushresult(&b);  /* close buffer */
+      return 1;  /* read at least an `eol' */
+    }
+  }
 }
 
 
+#define MAX_SIZE_T	(~(size_t)0)
+
 static void read_all (lua_State *L, FILE *f) {
-  size_t nr;
+  size_t rlen = LUAL_BUFFERSIZE;  /* how much to read in each cycle */
   luaL_Buffer b;
   luaL_buffinit(L, &b);
-  do {  /* read file in chunks of LUAL_BUFFERSIZE bytes */
-    char *p = luaL_prepbuffer(&b);
-    nr = fread(p, sizeof(char), LUAL_BUFFERSIZE, f);
+  for (;;) {
+    char *p = luaL_prepbuffsize(&b, rlen);
+    size_t nr = fread(p, sizeof(char), rlen, f);
     luaL_addsize(&b, nr);
-  } while (nr == LUAL_BUFFERSIZE);
+    if (nr < rlen) break;  /* eof? */
+    else if (rlen <= (MAX_SIZE_T / 4))  /* avoid buffers too large */
+      rlen *= 2;  /* double buffer size at each iteration */
+  }
   luaL_pushresult(&b);  /* close buffer */
 }
 
@@ -568,26 +423,25 @@ static int read_chars (lua_State *L, FILE *f, size_t n) {
 
 static int g_read (lua_State *L, FILE *f, int first) {
   int nargs = lua_gettop(L) - 1;
-  int n, success;
+  int success;
+  int n;
   clearerr(f);
-  errno = 0;
   if (nargs == 0) {  /* no arguments? */
     success = read_line(L, f, 1);
-    n = first + 1;  /* to return 1 result */
+    n = first+1;  /* to return 1 result */
   }
-  else {
-    /* ensure stack space for all results and for auxlib's buffer */
+  else {  /* ensure stack space for all results and for auxlib's buffer */
     luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
     success = 1;
     for (n = first; nargs-- && success; n++) {
       if (lua_type(L, n) == LUA_TNUMBER) {
-        size_t l = (size_t)luaL_checkinteger(L, n);
+        size_t l = (size_t)lua_tointeger(L, n);
         success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
       }
       else {
-        const char *p = luaL_checkstring(L, n);
-        if (*p == '*') p++;  /* skip optional '*' (for compatibility) */
-        switch (*p) {
+        const char *p = lua_tostring(L, n);
+        luaL_argcheck(L, p && p[0] == '*', n, "invalid option");
+        switch (p[1]) {
           case 'n':  /* number */
             success = read_number(L, f);
             break;
@@ -611,7 +465,7 @@ static int g_read (lua_State *L, FILE *f, int first) {
     return luaL_fileresult(L, 0, NULL);
   if (!success) {
     lua_pop(L, 1);  /* remove last result */
-    luaL_pushfail(L);  /* push nil instead */
+    lua_pushnil(L);  /* push nil instead */
   }
   return n - first;
 }
@@ -627,9 +481,6 @@ static int f_read (lua_State *L) {
 }
 
 
-/*
-** Iteration function for 'lines'.
-*/
 static int io_readline (lua_State *L) {
   LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1));
   int i;
@@ -637,21 +488,20 @@ static int io_readline (lua_State *L) {
   if (isclosed(p))  /* file is already closed? */
     return luaL_error(L, "file is already closed");
   lua_settop(L , 1);
-  luaL_checkstack(L, n, "too many arguments");
   for (i = 1; i <= n; i++)  /* push arguments to 'g_read' */
     lua_pushvalue(L, lua_upvalueindex(3 + i));
   n = g_read(L, p->f, 2);  /* 'n' is number of results */
   lua_assert(n > 0);  /* should return at least a nil */
-  if (lua_toboolean(L, -n))  /* read at least one value? */
+  if (!lua_isnil(L, -n))  /* read at least one value? */
     return n;  /* return them */
-  else {  /* first result is false: EOF or error */
+  else {  /* first result is nil: EOF or error */
     if (n > 1) {  /* is there error information? */
       /* 2nd result is error message */
       return luaL_error(L, "%s", lua_tostring(L, -n + 1));
     }
     if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
-      lua_settop(L, 0);  /* clear stack */
-      lua_pushvalue(L, lua_upvalueindex(1));  /* push file at index 1 */
+      lua_settop(L, 0);
+      lua_pushvalue(L, lua_upvalueindex(1));
       aux_close(L);  /* close it */
     }
     return 0;
@@ -664,16 +514,11 @@ static int io_readline (lua_State *L) {
 static int g_write (lua_State *L, FILE *f, int arg) {
   int nargs = lua_gettop(L) - arg;
   int status = 1;
-  errno = 0;
   for (; nargs--; arg++) {
     if (lua_type(L, arg) == LUA_TNUMBER) {
       /* optimization: could be done exactly as for strings */
-      int len = lua_isinteger(L, arg)
-                ? fprintf(f, LUA_INTEGER_FMT,
-                             (LUAI_UACINT)lua_tointeger(L, arg))
-                : fprintf(f, LUA_NUMBER_FMT,
-                             (LUAI_UACNUMBER)lua_tonumber(L, arg));
-      status = status && (len > 0);
+      status = status &&
+          fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)) > 0;
     }
     else {
       size_t l;
@@ -681,10 +526,8 @@ static int g_write (lua_State *L, FILE *f, int arg) {
       status = status && (fwrite(s, sizeof(char), l, f) == l);
     }
   }
-  if (l_likely(status))
-    return 1;  /* file handle already on stack top */
-  else
-    return luaL_fileresult(L, status, NULL);
+  if (status) return 1;  /* file handle already on stack top */
+  else return luaL_fileresult(L, status, NULL);
 }
 
 
@@ -705,16 +548,15 @@ static int f_seek (lua_State *L) {
   static const char *const modenames[] = {"set", "cur", "end", NULL};
   FILE *f = tofile(L);
   int op = luaL_checkoption(L, 2, "cur", modenames);
-  lua_Integer p3 = luaL_optinteger(L, 3, 0);
+  lua_Number p3 = luaL_optnumber(L, 3, 0);
   l_seeknum offset = (l_seeknum)p3;
-  luaL_argcheck(L, (lua_Integer)offset == p3, 3,
+  luaL_argcheck(L, (lua_Number)offset == p3, 3,
                   "not an integer in proper range");
-  errno = 0;
   op = l_fseek(f, offset, mode[op]);
-  if (l_unlikely(op))
+  if (op)
     return luaL_fileresult(L, 0, NULL);  /* error */
   else {
-    lua_pushinteger(L, (lua_Integer)l_ftell(f));
+    lua_pushnumber(L, (lua_Number)l_ftell(f));
     return 1;
   }
 }
@@ -726,25 +568,19 @@ static int f_setvbuf (lua_State *L) {
   FILE *f = tofile(L);
   int op = luaL_checkoption(L, 2, NULL, modenames);
   lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
-  int res;
-  errno = 0;
-  res = setvbuf(f, NULL, mode[op], (size_t)sz);
+  int res = setvbuf(f, NULL, mode[op], sz);
   return luaL_fileresult(L, res == 0, NULL);
 }
 
 
 
 static int io_flush (lua_State *L) {
-  FILE *f = getiofile(L, IO_OUTPUT);
-  errno = 0;
-  return luaL_fileresult(L, fflush(f) == 0, NULL);
+  return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
 }
 
 
 static int f_flush (lua_State *L) {
-  FILE *f = tofile(L);
-  errno = 0;
-  return luaL_fileresult(L, fflush(f) == 0, NULL);
+  return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL);
 }
 
 
@@ -770,37 +606,26 @@ static const luaL_Reg iolib[] = {
 /*
 ** methods for file handles
 */
-static const luaL_Reg meth[] = {
-  {"read", f_read},
-  {"write", f_write},
-  {"lines", f_lines},
+static const luaL_Reg flib[] = {
+  {"close", io_close},
   {"flush", f_flush},
+  {"lines", f_lines},
+  {"read", f_read},
   {"seek", f_seek},
-  {"close", f_close},
   {"setvbuf", f_setvbuf},
-  {NULL, NULL}
-};
-
-
-/*
-** metamethods for file handles
-*/
-static const luaL_Reg metameth[] = {
-  {"__index", NULL},  /* placeholder */
+  {"write", f_write},
   {"__gc", f_gc},
-  {"__close", f_gc},
   {"__tostring", f_tostring},
   {NULL, NULL}
 };
 
 
 static void createmeta (lua_State *L) {
-  luaL_newmetatable(L, LUA_FILEHANDLE);  /* metatable for file handles */
-  luaL_setfuncs(L, metameth, 0);  /* add metamethods to new metatable */
-  luaL_newlibtable(L, meth);  /* create method table */
-  luaL_setfuncs(L, meth, 0);  /* add file methods to method table */
-  lua_setfield(L, -2, "__index");  /* metatable.__index = method table */
-  lua_pop(L, 1);  /* pop metatable */
+  luaL_newmetatable(L, LUA_FILEHANDLE);  /* create metatable for file handles */
+  lua_pushvalue(L, -1);  /* push metatable */
+  lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
+  luaL_setfuncs(L, flib, 0);  /* add file methods to new metatable */
+  lua_pop(L, 1);  /* pop new metatable */
 }
 
 
@@ -810,7 +635,7 @@ static void createmeta (lua_State *L) {
 static int io_noclose (lua_State *L) {
   LStream *p = tolstream(L);
   p->closef = &io_noclose;  /* keep file opened */
-  luaL_pushfail(L);
+  lua_pushnil(L);
   lua_pushliteral(L, "cannot close standard file");
   return 2;
 }