[igt-dev] [PATCH i-g-t] lib/igt_edid: Properly pad display descriptor strings

[Petri Latvala]

Display descriptor strings should be terminated with LF (when less
than 13 bytes) and padded with space. Currently the termination is
there but we're missing the padding.

As a drive-by, this fixes the below compile warning by making sure
strncpy has enough room.

[206/1103] Compiling C object lib/libigt-igt_edid_c.a.p/igt_edid.c.o
In file included from /usr/include/string.h:495,
                 from ../lib/igt_edid.c:29:
In function ‘strncpy’,
    inlined from ‘detailed_timing_set_string’ at ../lib/igt_edid.c:186:2:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ specified bound 13 equals destination size [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Petri Latvala <petri.latvala at intel.com>
---
 lib/igt_edid.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/igt_edid.c b/lib/igt_edid.c
index 6fe984d9..908959f4 100644
--- a/lib/igt_edid.c
+++ b/lib/igt_edid.c
@@ -183,7 +183,8 @@ void detailed_timing_set_string(struct detailed_timing *dt,
 
 	np->type = type;
 
-	strncpy(ds->str, str, sizeof(ds->str));
+	memset(ds->str, ' ', sizeof(ds->str));
+	strncpy(ds->str, str, sizeof(ds->str) - 1);
 	len = strlen(str);
 	if (len < sizeof(ds->str))
 		ds->str[len] = '\n';
-- 
2.29.2