On Thu, 21 Apr 2022 17:07:49 +0200 Christian Schoenebeck <qemu_...@crudebyte.com> wrote:
> Linux and macOS only share some errno definitions with equal macro > name and value. In fact most mappings for errno are completely > different on the two systems. > > This patch converts some important errno values from macOS host to > corresponding Linux errno values before eventually sending such error > codes along with 'Rlerror' replies (if 9p2000.L is used that is). Not > having translated errnos before violated the 9p2000.L protocol spec, > which says: > > " > size[4] Rlerror tag[2] ecode[4] > > ... ecode is a numerical Linux errno. > " > > https://github.com/chaos/diod/wiki/protocol#lerror----return-error-code > > This patch fixes a bunch of misbehaviours when running a Linux client > on macOS host. For instance this patch fixes: > > mount -t 9p -o posixacl ... > > on Linux guest if security_mode=mapped was used for 9p server, which > refused to mount successfully, because macOS returned ENOATTR==93 > when client tried to retrieve POSIX ACL xattrs, because errno 93 > is defined as EPROTONOSUPPORT==93 on Linux, so Linux client believed > that xattrs were not supported by filesystem on host in general. > > Signed-off-by: Christian Schoenebeck <qemu_...@crudebyte.com> > Link: https://lore.kernel.org/qemu-devel/20220421124835.3e664669@bahia/ > --- Reviewed-by: Greg Kurz <gr...@kaod.org> > hw/9pfs/9p-util.h | 30 ++++++++++++++++++++++++++++++ > hw/9pfs/9p.c | 2 ++ > 2 files changed, 32 insertions(+) > > diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h > index 2cc9a5dbfb..c3526144c9 100644 > --- a/hw/9pfs/9p-util.h > +++ b/hw/9pfs/9p-util.h > @@ -58,6 +58,36 @@ static inline uint64_t host_dev_to_dotl_dev(dev_t dev) > #endif > } > > +/* Translates errno from host -> Linux if needed */ > +static inline int errno_to_dotl(int err) { > +#if defined(CONFIG_LINUX) > + /* nothing to translate (Linux -> Linux) */ > +#elif defined(CONFIG_DARWIN) > + /* > + * translation mandatory for macOS hosts > + * > + * FIXME: Only most important errnos translated here yet, this should be > + * extended to as many errnos being translated as possible in future. > + */ > + if (err == ENAMETOOLONG) { > + err = 36; /* ==ENAMETOOLONG on Linux */ > + } else if (err == ENOTEMPTY) { > + err = 39; /* ==ENOTEMPTY on Linux */ > + } else if (err == ELOOP) { > + err = 40; /* ==ELOOP on Linux */ > + } else if (err == ENOATTR) { > + err = 61; /* ==ENODATA on Linux */ > + } else if (err == ENOTSUP) { > + err = 95; /* ==EOPNOTSUPP on Linux */ > + } else if (err == EOPNOTSUPP) { > + err = 95; /* ==EOPNOTSUPP on Linux */ > + } > +#else > +#error Missing errno translation to Linux for this host system > +#endif > + return err; > +} > + > #ifdef CONFIG_DARWIN > #define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0) > #define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW) > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 4a296a0b94..0cd0c14c2a 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -1054,6 +1054,8 @@ static void coroutine_fn pdu_complete(V9fsPDU *pdu, > ssize_t len) > } > len += ret; > id = P9_RERROR; > + } else { > + err = errno_to_dotl(err); > } > > ret = pdu_marshal(pdu, len, "d", err);
