On Mittwoch, 27. April 2022 22:36:25 CEST Greg Kurz wrote: > On Wed, 27 Apr 2022 20:54:17 +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 | 45 +++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 44 insertions(+), 1 deletion(-) > > > > diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c > > index e24d09763a..7d00db47a9 100644 > > --- a/hw/9pfs/9p-util-darwin.c > > +++ b/hw/9pfs/9p-util-darwin.c > > @@ -74,6 +74,45 @@ 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 > > + }; > > + > > + /* > > + * sun_path is only 104 bytes, explicit filename length check > > required > > + */ > > + if (sizeof(addr.sun_path) - 1 < strlen(filename) + 2) { > > True but I was a bit puzzled by the math until I realized the '+ 2' was > for the prepended "./" ;-)
Correct ... > > + errno = ENAMETOOLONG; > > + return -1; > > + } > > + fd = socket(PF_UNIX, SOCK_DGRAM, 0); > > + if (fd == -1) { > > + return fd; > > + } > > + snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename); > > What about the more generic approach of checking snprintf()'s return > value ? If it is >= sizeof(addr.sun_path) then truncation occured. ... well, I can send a v5 if you prefer that solution, or you can send a follow-up patch later on. As you wish. > > + err = bind(fd, (struct sockaddr *) &addr, sizeof(addr)); > > + if (err == -1) { > > + goto out; > > + } > > + /* > > + * FIXME: Should rather be using descriptor-based fchmod() on the > > + * socket file descriptor above (preferably before bind() call), > > + * instead of path-based fchmodat(), to prevent concurrent transient > > + * state issues between creating the named FIFO file at bind() and > > + * delayed adjustment of permissions at fchmodat(). However currently > > + * macOS (12.x) does not support such operations on socket file > > + * descriptors yet. > > + * > > + * Filed report with Apple: FB9997731 > > + */ > > + err = fchmodat(AT_FDCWD, filename, mode, AT_SYMLINK_NOFOLLOW_ANY); > > +out: > > + close_preserve_errno(fd); > > You could close(fd) earlier now, but you might want to keep the code > as is in case FB9997731 gets proper attention. > > Anyway, this should do the job so: Sounds like Akihiko's previous suggestion. I would keep it that way: https://lore.kernel.org/qemu-devel/eafd4bbf-dbff-323a-179f-8f2990570...@gmail.com/ > Reviewed-by: Greg Kurz <gr...@kaod.org> Thanks! Best regards, Christian Schoenebeck > > + return err; > > +} > > + > > > > int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev) > > { > > > > int preserved_errno, err; > > > > @@ -93,7 +132,11 @@ int qemu_mknodat(int dirfd, const char *filename, > > mode_t mode, dev_t dev)> > > if (pthread_fchdir_np(dirfd) < 0) { > > > > return -1; > > > > } > > > > - err = mknod(filename, mode, dev); > > + if (S_ISSOCK(mode)) { > > + err = create_socket_file_at_cwd(filename, mode); > > + } else { > > + err = mknod(filename, mode, dev); > > + } > > > > preserved_errno = errno; > > /* Stop using the thread-local cwd */ > > pthread_fchdir_np(-1);