| Message ID | 20181228173356.15359-3-philmd@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix strncpy() warnings for GCC8 new -Wstringop-truncation | expand |
diff --git a/block/sheepdog.c b/block/sheepdog.c index 0125df9d49..5cd9618432 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -1224,7 +1224,7 @@ static int find_vdi_name(BDRVSheepdogState *s, const char *filename, SheepdogVdiReq hdr; SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr; unsigned int wlen, rlen = 0; - char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN]; + char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN] QEMU_NONSTRING; fd = connect_to_sdog(s, errp); if (fd < 0) {
GCC 8 added a -Wstringop-truncation warning: The -Wstringop-truncation warning added in GCC 8.0 via r254630 for bug 81117 is specifically intended to highlight likely unintended uses of the strncpy function that truncate the terminating NUL character from the source string. This new warning leads to compilation failures: CC block/sheepdog.o qemu/block/sheepdog.c: In function 'find_vdi_name': qemu/block/sheepdog.c:1239:5: error: 'strncpy' specified bound 256 equals destination size [-Werror=stringop-truncation] strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ make: *** [qemu/rules.mak:69: block/sheepdog.o] Error 1 As described previous to the strncpy() calls, the use of strncpy() is correct here: /* This pair of strncpy calls ensures that the buffer is zero-filled, * which is desirable since we'll soon be sending those bytes, and * don't want the send_req to read uninitialized data. */ strncpy(buf, filename, SD_MAX_VDI_LEN); strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN); Use the QEMU_NONSTRING attribute, since this array is intended to store character arrays that do not necessarily contain a terminating NUL. Suggested-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> --- block/sheepdog.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)