If 'len' is zero the expected output is an empty string even if
'ascii' is requested.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 lib/test_hexdump.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
index ed6f0b0a1bb3..07a8cc7e9088 100644
--- a/lib/test_hexdump.c
+++ b/lib/test_hexdump.c
@@ -29,6 +29,11 @@ static size_t __init test_hexdump_prepare_test(size_t len, size_t rowsize,
 	char *p;
 	size_t byteswap, i, j;
 
+	if (!len) {
+		test[0] = 0;
+		return 0;
+	}
+
 	if (rowsize != 16 && rowsize != 32)
 		rowsize = 16;
 
@@ -58,8 +63,7 @@ static size_t __init test_hexdump_prepare_test(size_t len, size_t rowsize,
 			*p++ = ' ';
 		}
 	}
-	if (i)
-		p--;
+	p--;
 
 	/* ASCII part */
 	if (ascii) {
-- 
2.39.5

On Sat, Mar 08, 2025 at 09:34:49AM +0000, David Laight wrote:
> If 'len' is zero the expected output is an empty string even if
> 'ascii' is requested.

It's related to the previous one...
So, seems to me the series need a bit more (re-)thinking...

-- 
With Best Regards,
Andy Shevchenko

On Mon, 10 Mar 2025 11:03:07 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> On Sat, Mar 08, 2025 at 09:34:49AM +0000, David Laight wrote:
> > If 'len' is zero the expected output is an empty string even if
> > 'ascii' is requested.  
> 
> It's related to the previous one...
> So, seems to me the series need a bit more (re-)thinking...
> 

Nope, all its own bug.
This is a request to hexdump zero bytes into a valid buffer size.
hex_dump_to_buffer() gets it right unless the output buffer length
is also zero.

Found when I started doing a full range of tests.

	David