On Tue, 19 Apr 2022 13:41:59 +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 Tlerror replies (if 9p2000.L is used that is), which > fixes a bunch of misbehaviours when running a Linux client on macOS > host. > This even fixes an actual protocol violation : lerror -- return error code size[4] Rlerror tag[2] ecode[4] lerror replaces the reply message used in a successful call. ecode is a numerical Linux errno. ^^^^^^^^^^^^^^^^^^^^^ Taken from https://github.com/chaos/diod/wiki/protocol#lerror----return-error-code > 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> > --- > hw/9pfs/9p.c | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index d953035e1c..becc41cbfd 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -57,6 +57,31 @@ enum { > > P9ARRAY_DEFINE_TYPE(V9fsPath, v9fs_path_free); > > +/* Translates errno from host -> Linux if needed */ > +static int errno_to_dotl(int err) { > +#if defined(CONFIG_LINUX) > + /* nothing to translate (Linux -> Linux) */ > +#elif defined(CONFIG_DARWIN) > + /* translation mandatory for macOS hosts */ > + 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 */ > + } I'm assuming you have audited all errnos, right ? Just to be sure that this won't bite anymore. > +#else > +#error Missing errno translation to Linux for this host system > +#endif > + return err; > +} > + As with the other patch, I'd rather move this magic to 9p-util.h . > static ssize_t pdu_marshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...) > { > ssize_t ret; > @@ -1054,6 +1079,8 @@ 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);
