nis: Fix stringop-truncation warning with -O3 in nis_local_host.
Checks
| Context |
Check |
Description |
| dj/TryBot-apply_patch |
success
|
Patch applied to master at the time it was sent
|
| dj/TryBot-32bit |
success
|
Build for i686
|
Commit Message
When building with -O3 on s390x/x86_64, I get this stringop-truncation warning
which leads to a build fail:
In function ‘nis_local_host’,
inlined from ‘nis_local_host’ at nis_local_names.c:147:1:
nis_local_names.c:171:11: error: ‘strncpy’ output may be truncated copying between 0 and 1023 bytes from a string of length 1024 [-Werror=stringop-truncation]
171 | strncpy (cp, nis_local_directory (), NIS_MAXNAMELEN - len -1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We can just ignore this warning as the hostname + '.' + directory-name + '\0' always fits
in __nishostname with length of (NIS_MAXNAMELEN + 1) as there is the runtime check above.
Furthermore as we already know the length of the directory-name, we can also just use
memcpy to copy the directory-name inclusive the NUL-termination.
Note: This werror was introduced with commit
32c7acd46401530fdbd4e98508c9baaa705f8b53
"Replace rawmemchr (s, '\0') with strchr"
---
nis/nis_local_names.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
@@ -161,15 +161,19 @@ nis_local_host (void)
if (cp[-1] == '.')
return __nishostname;
- if (len + strlen (nis_local_directory ()) + 1 > NIS_MAXNAMELEN)
+ nis_name local_directory = nis_local_directory ();
+ size_t local_directory_len = strlen (local_directory);
+ if (len + 1 + local_directory_len > NIS_MAXNAMELEN)
{
__nishostname[0] = '\0';
return __nishostname;
}
+ /* We have enough space in __nishostname with length of
+ (NIS_MAXNAMELEN + 1) for
+ hostname + '.' + directory-name + '\0'. */
*cp++ = '.';
- strncpy (cp, nis_local_directory (), NIS_MAXNAMELEN - len -1);
- __nishostname[NIS_MAXNAMELEN] = '\0';
+ memcpy (cp, local_directory, local_directory_len + 1);
}
}