Handle %c in json_printf()

PUBLISHED_FROM=98e913b0043585af159a55e1fef4d192d88dbd4e

frozen.c

@@ -630,7 +630,7 @@ int json_vprintf(struct json_out *out, const char *fmt, va_list xap) {
          * TODO(dfrank): reimplement %s and %.*s in order to avoid that.
          */
 
-        const char *end_of_format_specifier = "sdfFgGlhuI.*-0123456789";
+        const char *end_of_format_specifier = "sdfFgGlhuIc.*-0123456789";
         size_t n = strspn(fmt + 1, end_of_format_specifier);
         char *pbuf = buf;
         size_t need_len;

unit_test.c

@@ -323,6 +323,13 @@ static const char *test_json_printf(void) {
     ASSERT(strcmp(buf, "\"002001200220616263\"") == 0);
   }
 
+  {
+    struct json_out out = JSON_OUT_BUF(buf, sizeof(buf));
+    memset(buf, 0, sizeof(buf));
+    ASSERT(json_printf(&out, "%c", 0x53) > 0);
+    ASSERT(strcmp(buf, "S") == 0);
+  }
+
   return NULL;
 }