Le mer. 19 déc. 2018 00:09, Michael S. Tsirkin <[email protected]> a écrit :
> On Tue, Dec 18, 2018 at 06:51:19PM +0100, Philippe Mathieu-Daudé wrote: > > 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 <[email protected]> > > Signed-off-by: Philippe Mathieu-Daudé <[email protected]> > > --- > > block/sheepdog.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/block/sheepdog.c b/block/sheepdog.c > > index 0125df9d49..d4ad6b119d 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]; > > + QEMU_NONSTRING char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN]; > > In case you decide to respin anyway - this would be > a bit nicer as: > char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN] QEMU_NONSTRING > I'll have to, so OK. (it looked to me more explicit prepended). > > > > > fd = connect_to_sdog(s, errp); > > if (fd < 0) { > > -- > > 2.17.2 >
