mingw32 build on fedora fails with this warning: /scm/qemu/block/sheepdog.c: In function 'find_vdi_name': /scm/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); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors make: *** [/scm/qemu/rules.mak:69: block/sheepdog.o] Error 1 make: *** Waiting for unfinished jobs....
Reading the code one sees it's working as intended: static int find_vdi_name(BDRVSheepdogState *s, const char *filename, uint32_t snapid, const char *tag, uint32_t *vid, bool lock, Error **errp) { int ret, fd; SheepdogVdiReq hdr; SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr; unsigned int wlen, rlen = 0; char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN]; fd = connect_to_sdog(s, errp); if (fd < 0) { return fd; } /* 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); ..... } so this seems to be the case of GCC developers deciding that strncpy is simply a bad API and a correct use of it should be warned against. I propose either 1. simply adding #pragma GCC diagnostic ignored "-Wstringop-truncation" in osdep. 2. adding an inline wrapper with said pragma in there. 3. -Wno-stringop-truncation is the makefile Thoughts? -- MST