no need of lookahead in Zio

lzio.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lzio.c,v 1.31 2005/06/03 20:15:29 roberto Exp roberto $
+** $Id: lzio.c,v 1.32 2011/02/17 17:34:16 roberto Exp roberto $
 ** a generic input stream interface
 ** See Copyright Notice in lua.h
 */
@@ -22,40 +22,23 @@ int luaZ_fill (ZIO *z) {
   size_t size;
   lua_State *L = z->L;
   const char *buff;
-  if (z->eoz) return EOZ;
   lua_unlock(L);
   buff = z->reader(L, z->data, &size);
   lua_lock(L);
-  if (buff == NULL || size == 0) {
-    z->eoz = 1;  /* avoid calling reader function next time */
+  if (buff == NULL || size == 0)
     return EOZ;
-  }
-  z->n = size - 1;
+  z->n = size - 1;  /* discount char being returned */
   z->p = buff;
   return char2int(*(z->p++));
 }
 
 
-int luaZ_lookahead (ZIO *z) {
-  if (z->n == 0) {
-    if (luaZ_fill(z) == EOZ)
-      return EOZ;
-    else {
-      z->n++;  /* luaZ_fill removed first byte; put back it */
-      z->p--;
-    }
-  }
-  return char2int(*z->p);
-}
-
-
 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
   z->L = L;
   z->reader = reader;
   z->data = data;
   z->n = 0;
   z->p = NULL;
-  z->eoz = 0;
 }
 
 
@@ -63,8 +46,14 @@ void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
 size_t luaZ_read (ZIO *z, void *b, size_t n) {
   while (n) {
     size_t m;
-    if (luaZ_lookahead(z) == EOZ)
-      return n;  /* return number of missing bytes */
+    if (z->n == 0) {  /* no bytes in buffer? */
+      if (luaZ_fill(z) == EOZ)  /* try to read more */
+        return n;  /* no more input; return number of missing bytes */
+      else {
+        z->n++;  /* luaZ_fill consumed first byte; put it back */
+        z->p--;
+      }
+    }
     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
     memcpy(b, z->p, m);
     z->n -= m;