From bc82b4d78acd281f68f2f6fcd79395bbee32ee19 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 12 Dec 2007 12:36:12 -0200
Subject: [PATCH] new function 'package.searchpath'

---
 loadlib.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/loadlib.c b/loadlib.c
index 16d5c4f4..c06c56f4 100644
--- a/loadlib.c
+++ b/loadlib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: loadlib.c,v 1.57 2007/03/26 15:57:35 roberto Exp roberto $
+** $Id: loadlib.c,v 1.58 2007/06/21 13:52:27 roberto Exp roberto $
 ** Dynamic library loader for Lua
 ** See Copyright Notice in lua.h
 **
@@ -346,18 +346,12 @@ static const char *pushnexttemplate (lua_State *L, const char *path) {
 }
 
 
-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);
+static const char *searchpath (lua_State *L, const char *name,
+                                             const char *path) {
   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);
+    const char *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 */
@@ -369,6 +363,29 @@ static const char *findfile (lua_State *L, const char *name,
 }
 
 
+static int ll_searchpath (lua_State *L) {
+  const char *f = searchpath(L, luaL_checkstring(L, 1), luaL_checkstring(L, 2));
+  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 *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);
+  return searchpath(L, name, path);
+}
+
+
 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));
@@ -604,6 +621,7 @@ static void setpath (lua_State *L, const char *fieldname, const char *envname,
 
 static const luaL_Reg pk_funcs[] = {
   {"loadlib", ll_loadlib},
+  {"searchpath", ll_searchpath},
   {"seeall", ll_seeall},
   {NULL, NULL}
 };