Fix issues in nickm's review of format_helper_exit_status for bug #1903

- Responsibility of clearing hex_errno is no longer with caller
- More conservative bounds checking
- Length requirement of hex_errno documented
- Output format documented

1 files changed, 2 insertions, 3 deletions

diff --git a/src/test/test_util.c b/src/test/test_util.c
index 68a0ca2984..208c5c4f59 100644
--- a/src/test/test_util.c
+++ b/src/test/test_util.c
@@ -1212,14 +1212,13 @@ test_util_load_win_lib(void *ptr)
 static void
 clear_hex_errno(char *hex_errno)
 {
-  memset(hex_errno, ' ', HEX_ERRNO_SIZE - 2);
-  hex_errno[HEX_ERRNO_SIZE - 1] = '\n';
-  hex_errno[HEX_ERRNO_SIZE] = '\0';
+  memset(hex_errno, '\0', HEX_ERRNO_SIZE + 1);
 }
 
 static void
 test_util_exit_status(void *ptr)
 {
+  /* Leave an extra byte for a \0 so we can do string comparison */
   char hex_errno[HEX_ERRNO_SIZE + 1];
 
   (void)ptr;