From b58094c881ba2dc27dee80a09399c61a9e4ff46b Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Wed, 29 Jun 2022 15:03:41 +0900
Subject: [PATCH] mruby-sprintf/sprintf.c: call mrb_str_resize() less often.

---
 mrbgems/mruby-sprintf/src/sprintf.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/mrbgems/mruby-sprintf/src/sprintf.c b/mrbgems/mruby-sprintf/src/sprintf.c
index a562bdac1..41c84eff1 100644
--- a/mrbgems/mruby-sprintf/src/sprintf.c
+++ b/mrbgems/mruby-sprintf/src/sprintf.c
@@ -153,12 +153,14 @@ fmt_float(char *buf, size_t buf_size, char fmt, int flags, mrb_int width, int pr
 }
 #endif
 
-#define CHECK(l) do {                           \
-  while ((l) >= bsiz - blen) {\
-    if (bsiz > MRB_INT_MAX/2) mrb_raise(mrb, E_ARGUMENT_ERROR, "too big specifier"); \
-    bsiz*=2;\
+#define CHECK(l) do { \
+  if (blen+(l) >= bsiz) {\
+    while (blen+(l) >= bsiz) {\
+      if (bsiz > MRB_INT_MAX/2) mrb_raise(mrb, E_ARGUMENT_ERROR, "too big specifier");\
+      bsiz*=2;\
+    }\
+    mrb_str_resize(mrb, result, bsiz);\
   }\
-  mrb_str_resize(mrb, result, bsiz);\
   buf = RSTRING_PTR(result);\
 } while (0)