Format string refactor

src/basic/stb_sprintf.h

@@ -574,11 +574,6 @@ STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback,
          char num[STBSP__NUMSZ];
          char lead[8];
          char tail[8];
-         struct stb__string {
-            char *data;
-            int64_t len;
-         } S;
-
          char *s;
          char const *h;
          stbsp__uint32 l, n, cs;
@@ -588,6 +583,11 @@ STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback,
 #endif
          stbsp__int32 dp;
          char const *sn;
+         struct stb__string {
+            char *data;
+            int64_t len;
+         };
+         struct stb__string S;
 
       case 'S':
          // get the string
@@ -596,7 +596,8 @@ STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback,
             S.data = (char *)"null";
             S.len = 4;
          }
-         l = (unsigned int)S.len;
+         s = S.data;
+         l = stbsp__strlen_limited(S.data, ((int)S.len >= 0) ? (int)S.len : ~0u);
          lead[0] = 0;
          tail[0] = 0;
          pr = 0;