From 513559cc4760392b6fa33754c516683ef49dba22 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 16 Mar 2020 14:13:13 -0300
Subject: Fixed bug in 'string.format("%p")'

The string "(null)" used for non-collectable values must be printed as a
string, not as a pointer. (Bug introduced in commit e0cbaa50fa7).
---
 lstrlib.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'lstrlib.c')

diff --git a/lstrlib.c b/lstrlib.c
index 28df2d45..2ba8bde4 100644
--- a/lstrlib.c
+++ b/lstrlib.c
@@ -1271,8 +1271,10 @@ static int str_format (lua_State *L) {
         }
         case 'p': {
           const void *p = lua_topointer(L, arg);
-          if (p == NULL)
-            p = "(null)";  /* NULL not a valid parameter in ISO C 'printf' */
+          if (p == NULL) {  /* avoid calling 'printf' with argument NULL */
+            p = "(null)";  /* result */
+            form[strlen(form) - 1] = 's';  /* format it as a string */
+          }
           nb = l_sprintf(buff, maxitem, form, p);
           break;
         }
-- 
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