On Freitag, 29. April 2022 16:35:07 CEST Greg Kurz wrote: > On Fri, 29 Apr 2022 15:50:35 +0200 > > Christian Schoenebeck <qemu_...@crudebyte.com> wrote: > > On Freitag, 29. April 2022 14:56:50 CEST Greg Kurz wrote: > > > On Fri, 29 Apr 2022 12:25:11 +0200 > > > > > > Christian Schoenebeck <qemu_...@crudebyte.com> wrote: > > > > mknod() on macOS does not support creating sockets, so divert to > > > > call sequence socket(), bind() and fchmodat() respectively if S_IFSOCK > > > > was passed with mode argument. > > > > > > > > Link: https://lore.kernel.org/qemu-devel/17933734.zYzKuhC07K@silver/ > > > > Signed-off-by: Christian Schoenebeck <qemu_...@crudebyte.com> > > > > --- > > > > > > > > hw/9pfs/9p-util-darwin.c | 42 > > > > +++++++++++++++++++++++++++++++++++++++- > > > > 1 file changed, 41 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c > > > > index e24d09763a..619c403ba7 100644 > > > > --- a/hw/9pfs/9p-util-darwin.c > > > > +++ b/hw/9pfs/9p-util-darwin.c > > > > @@ -74,6 +74,42 @@ int fsetxattrat_nofollow(int dirfd, const char > > > > *filename, const char *name,> > > > > > > > > */ > > > > > > > > #if defined CONFIG_PTHREAD_FCHDIR_NP > > > > > > > > +static int create_socket_file_at_cwd(const char *filename, mode_t > > > > mode) { > > > > + int fd, err; > > > > + struct sockaddr_un addr = { > > > > + .sun_family = AF_UNIX > > > > + }; > > > > + > > > > + err = snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", > > > > filename); + if (err < 0 || err >= sizeof(addr.sun_path)) { > > > > > > According to POSIX [1]: > > > > > > The snprintf() function shall fail if: > > > > > > [EOVERFLOW] > > > [CX] [Option Start] The value of n is greater than {INT_MAX}. [Option > > > End] > > > > > > [1] > > > https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.htm > > > l > > > > > > Since we're passing sizeof(addr.sun_path), I'm pretty sure snprintf() > > > cannot fail. No big deal. > > > > The question is whom you would want to trust on this? POSIX? ISO-C? Clang? > > BSD? Apple? And for how long into future? I mean in general yes, I would > > not > To improve overall portability across all possible hosts, I'd stick to > POSIX semantics but here this is macOS only code so you can assume > this is Apple's snprintf(). > > > expect it to fail with -1 here either, but there are various different API > > docs on snprintf() out there, and most of them don't even bother to > > enumarate which encoding errors may happen. And I'm pretty sure if I'd > > drop the negative err check here, then Akihiko would slap me for > > unforeseeable additional error cases on snprintf() that may be added in > > future. > > /o\ ;-) > > > Apple's documentation on snprintf() BTW just says: > > "These functions return a negative value if an error occurs." > > How valuable this is !!! ;-) > > > So Apple does not even restrict the return value to -1 on errrors, you > > would also need to expect other negative values. > > > > So on doubt, I leave this negative result check for now. ;-) > > Fair enough.
Hey, don't shoot the servant! I'm just trying to find compromises that aim to suit as many people as possible, as always. :) Best regards, Christian Schoenebeck
