Re: [PATCH] support: Report NULL blobs explicitly in TEST_COMPARE

[Florian Weimer <fweimer at redhat dot com>]

* Florian Weimer:

> Provide an explicit diagnostic if the length is positive, and
> do not just crash with a null pointer dereference.  Null pointers
> are only valid if the length is zero, so this can only happen with
> a faulty test.
>
> 2019-05-03  Florian Weimer  <fweimer@redhat.com>
>
> 	* support/support_test_compare_blob.c (report_blob): Report
> 	incorrect NULL blobs.
>
> diff --git a/support/support_test_compare_blob.c b/support/support_test_compare_blob.c
> index 5bcb03418c..00491b0df1 100644
> --- a/support/support_test_compare_blob.c
> +++ b/support/support_test_compare_blob.c
> @@ -33,7 +33,9 @@ static void
>  report_blob (const char *what, const unsigned char *blob,
>               unsigned long int length, const char *expr)
>  {
> -  if (length > 0)
> +  if (blob == NULL)
> +    printf ("  %s (evaluated from %s): NULL\n", what, expr);
> +  else if (length > 0)
>      {
>        printf ("  %s (evaluated from %s):\n", what, expr);
>        char *quoted = support_quote_blob (blob, length);

Hmph, this patch is better because it does not change test failure
output with for NULL with zero length:

diff --git a/support/support_test_compare_blob.c b/support/support_test_compare_blob.c
index 5bcb03418c..37f012257d 100644
--- a/support/support_test_compare_blob.c
+++ b/support/support_test_compare_blob.c
@@ -33,7 +33,9 @@ static void
 report_blob (const char *what, const unsigned char *blob,
              unsigned long int length, const char *expr)
 {
-  if (length > 0)
+  if (blob == NULL && length > 0)
+    printf ("  %s (evaluated from %s): NULL\n", what, expr);
+  else if (length > 0)
     {
       printf ("  %s (evaluated from %s):\n", what, expr);
       char *quoted = support_quote_blob (blob, length);