From: Greg Kurz <groug@kaod.org>
To: Christian Schoenebeck <qemu_oss@crudebyte.com>
Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org,
Keno Fischer <keno@juliacomputing.com>,
Michael Roitzsch <reactorcontrol@icloud.com>,
Will Cohen <wwcohen@gmail.com>,
Akihiko Odaki <akihiko.odaki@gmail.com>
Subject: Re: [PATCH 4/5] 9pfs: fix wrong errno being sent to Linux client on macOS host
Date: Thu, 21 Apr 2022 12:48:35 +0200 [thread overview]
Message-ID: <20220421124835.3e664669@bahia> (raw)
In-Reply-To: <c32aafaa3f29424fc13ae86b369c9baf1ceb0ec6.1650370027.git.qemu_oss@crudebyte.com>
On Tue, 19 Apr 2022 13:41:59 +0200
Christian Schoenebeck <qemu_oss@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_oss@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);
next prev parent reply other threads:[~2022-04-21 10:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-19 12:07 [PATCH 0/5] 9pfs: macOS host fixes Christian Schoenebeck
2022-04-19 11:40 ` [PATCH 1/5] 9pfs: fix qemu_mknodat(S_IFREG) on macOS Christian Schoenebeck
2022-04-19 13:44 ` Will Cohen
2022-04-20 2:03 ` Akihiko Odaki
2022-04-20 8:40 ` Greg Kurz
2022-04-20 9:38 ` Christian Schoenebeck
2022-04-19 11:41 ` [PATCH 2/5] 9pfs: fix qemu_mknodat(S_IFSOCK) " Christian Schoenebeck
2022-04-19 13:46 ` Will Cohen
2022-04-20 9:09 ` Greg Kurz
2022-04-20 10:28 ` Christian Schoenebeck
2022-04-20 12:08 ` Greg Kurz
2022-04-20 12:10 ` Greg Kurz
2022-04-20 12:41 ` Christian Schoenebeck
2022-04-19 11:41 ` [PATCH 3/5] 9pfs: fix wrong encoding of rdev field in Rgetattr " Christian Schoenebeck
2022-04-21 7:30 ` Greg Kurz
2022-04-21 10:25 ` Christian Schoenebeck
2022-04-21 10:31 ` Greg Kurz
2022-04-19 11:41 ` [PATCH 4/5] 9pfs: fix wrong errno being sent to Linux client on macOS host Christian Schoenebeck
2022-04-21 10:48 ` Greg Kurz [this message]
2022-04-21 11:13 ` Christian Schoenebeck
2022-04-21 11:46 ` Greg Kurz
2022-04-21 12:20 ` Christian Schoenebeck
2022-04-19 11:43 ` [PATCH 5/5] 9pfs: fix removing non-existent POSIX ACL xattr " Christian Schoenebeck
2022-04-21 8:26 ` Greg Kurz
2022-04-21 10:55 ` Christian Schoenebeck
2022-04-21 12:26 ` Greg Kurz
2022-04-21 13:03 ` Christian Schoenebeck
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