'io.read("n")' accepts both a dot and the locale point as its

radix character + 'MAXRN' -> 'L_MAXLENNUM' + small detail in
'test2'

liolib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: liolib.c,v 2.147 2015/07/15 14:40:28 roberto Exp roberto $
+** $Id: liolib.c,v 2.148 2015/11/23 11:36:11 roberto Exp roberto $
 ** Standard I/O (and system) library
 ** See Copyright Notice in lua.h
 */
@@ -375,14 +375,17 @@ static int io_lines (lua_State *L) {
 
 
 /* maximum length of a numeral */
-#define MAXRN		200
+#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[MAXRN + 1];  /* +1 for ending '\0' */
+  char buff[L_MAXLENNUM + 1];  /* +1 for ending '\0' */
 } RN;
 
 
@@ -390,7 +393,7 @@ typedef struct {
 ** Add current char to buffer (if not out of space) and read next one
 */
 static int nextc (RN *rn) {
-  if (rn->n >= MAXRN) {  /* buffer overflow? */
+  if (rn->n >= L_MAXLENNUM) {  /* buffer overflow? */
     rn->buff[0] = '\0';  /* invalidate result */
     return 0;  /* fail */
   }
@@ -403,10 +406,10 @@ static int nextc (RN *rn) {
 
 
 /*
-** Accept current char if it is in 'set' (of size 1 or 2)
+** 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] && rn->c != '\0'))
+  if (rn->c == set[0] || rn->c == set[1])
     return nextc(rn);
   else return 0;
 }
@@ -435,11 +438,11 @@ static int read_number (lua_State *L, FILE *f) {
   char decp[2];
   rn.f = f; rn.n = 0;
   decp[0] = lua_getlocaledecpoint();  /* get decimal point from locale */
-  decp[1] = '\0';
+  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 signal */
-  if (test2(&rn, "0")) {
+  if (test2(&rn, "00")) {
     if (test2(&rn, "xX")) hex = 1;  /* numeral is hexadecimal */
     else count = 1;  /* count initial '0' as a valid digit */
   }