sandbox: Move CONFIG_SYS_VSNPRINTF to Kconfig

Move this over to Kconfig and tidy up.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/Kconfig

@@ -7,6 +7,9 @@ config SYS_ARCH
 config USE_PRIVATE_LIBGCC
 	default y
 
+config SYS_VSNPRINTF
+	default y
+
 choice
 	prompt "Target select"
 

configs/sandbox_defconfig

@@ -18,3 +18,4 @@ CONFIG_USB_STORAGE=y
 CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
 CONFIG_SANDBOX_GPIO=y
+CONFIG_SYS_VSNPRINTF=y

include/configs/sandbox.h

@@ -48,8 +48,6 @@
 #define CONFIG_CMD_FS_GENERIC
 #define CONFIG_CMD_MD5SUM
 
-#define CONFIG_SYS_VSNPRINTF
-
 #define CONFIG_CMD_GPIO
 
 #define CONFIG_CMD_GPT

include/configs/x86-common.h

@@ -16,7 +16,6 @@
  * (easy to change)
  */
 #define CONFIG_SHOW_BOOT_PROGRESS
-#define CONFIG_SYS_VSNPRINTF
 #define CONFIG_ZBOOT_32
 #define CONFIG_PHYSMEM
 #define CONFIG_DISPLAY_BOARDINFO_LATE

lib/Kconfig

@@ -27,6 +27,15 @@ config SYS_HZ
 	  get_timer() must operate in milliseconds and this option must be
 	  set to 1000.
 
+config SYS_VSNPRINTF
+	bool "Enable safe version of sprintf()"
+	help
+	  Since sprintf() can overflow its buffer, it is common to use
+	  snprintf() instead, which knows the buffer size and can avoid
+	  overflow. However, this does increase code size slightly (for
+	  Thumb-2, about 420 bytes). Enable this option for safety when
+	  using sprintf() with data you do not control.
+
 source lib/rsa/Kconfig
 
 menu "Hashing Support"