From 79cb336d74697ca38d6d2f2068781086cfaa9076 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 19 Apr 2007 17:22:32 -0300
Subject: does not allow standard files to be closed

---
 liolib.c | 51 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 36 insertions(+), 15 deletions(-)

(limited to 'liolib.c')

diff --git a/liolib.c b/liolib.c
index 4ddaab23..6ad58f31 100644
--- a/liolib.c
+++ b/liolib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: liolib.c,v 2.74 2006/06/22 16:12:59 roberto Exp roberto $
+** $Id: liolib.c,v 2.75 2006/09/18 14:03:18 roberto Exp roberto $
 ** Standard I/O (and system) library
 ** See Copyright Notice in lua.h
 */
@@ -93,8 +93,17 @@ static FILE **newfile (lua_State *L) {
 
 
 /*
-** this function has a separated environment, which defines the
-** correct __close for 'popen' files
+** function to (not) close the standard files stdin, stdout, and stderr
+*/
+static int io_noclose (lua_State *L) {
+  lua_pushnil(L);
+  lua_pushliteral(L, "cannot close standard file");
+  return 2;
+}
+
+
+/*
+** function to close 'popen' files
 */
 static int io_pclose (lua_State *L) {
   FILE **p = topfile(L);
@@ -104,6 +113,9 @@ static int io_pclose (lua_State *L) {
 }
 
 
+/*
+** function to close regular files
+*/
 static int io_fclose (lua_State *L) {
   FILE **p = topfile(L);
   int ok = (fclose(*p) == 0);
@@ -129,8 +141,8 @@ static int io_close (lua_State *L) {
 
 static int io_gc (lua_State *L) {
   FILE *f = *topfile(L);
-  /* ignore closed files and standard files */
-  if (f != NULL && f != stdin && f != stdout && f != stderr)
+  /* ignore closed files */
+  if (f != NULL)
     aux_close(L);
   return 0;
 }
@@ -155,6 +167,10 @@ static int io_open (lua_State *L) {
 }
 
 
+/*
+** this function has a separated environment, which defines the
+** correct __close for 'popen' files
+*/
 static int io_popen (lua_State *L) {
   const char *filename = luaL_checkstring(L, 1);
   const char *mode = luaL_optstring(L, 2, "r");
@@ -502,31 +518,36 @@ static void createstdfile (lua_State *L, FILE *f, int k, const char *fname) {
     lua_pushvalue(L, -1);
     lua_rawseti(L, LUA_ENVIRONINDEX, k);
   }
-  lua_setfield(L, -2, fname);
+  lua_pushvalue(L, -2);  /* copy environment */
+  lua_setfenv(L, -2);  /* set it */
+  lua_setfield(L, -3, fname);
+}
+
+
+static void newfenv (lua_State *L, lua_CFunction cls) {
+  lua_createtable(L, 0, 1);
+  lua_pushcfunction(L, cls);
+  lua_setfield(L, -2, "__close");
 }
 
 
 LUALIB_API int luaopen_io (lua_State *L) {
   createmeta(L);
   /* create (private) environment (with fields IO_INPUT, IO_OUTPUT, __close) */
-  lua_createtable(L, 2, 1);
+  newfenv(L, io_fclose);
   lua_replace(L, LUA_ENVIRONINDEX);
   /* open library */
   luaL_register(L, LUA_IOLIBNAME, iolib);
   /* create (and set) default files */
+  newfenv(L, io_noclose);  /* close function for default files */
   createstdfile(L, stdin, IO_INPUT, "stdin");
   createstdfile(L, stdout, IO_OUTPUT, "stdout");
   createstdfile(L, stderr, 0, "stderr");
-  /* create environment for 'popen' */
+  lua_pop(L, 1);  /* pop environment for default files */
   lua_getfield(L, -1, "popen");
-  lua_createtable(L, 0, 1);
-  lua_pushcfunction(L, io_pclose);
-  lua_setfield(L, -2, "__close");
-  lua_setfenv(L, -2);
+  newfenv(L, io_pclose);  /* create environment for 'popen' */
+  lua_setfenv(L, -2);  /* set fenv for 'popen' */
   lua_pop(L, 1);  /* pop 'popen' */
-  /* set default close function */
-  lua_pushcfunction(L, io_fclose);
-  lua_setfield(L, LUA_ENVIRONINDEX, "__close");
   return 1;
 }
 
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