From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57475) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yqhf0-0007na-5Q for qemu-devel@nongnu.org; Fri, 08 May 2015 08:45:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yqhev-0000kK-25 for qemu-devel@nongnu.org; Fri, 08 May 2015 08:45:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41246) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yqheu-0000kE-Rh for qemu-devel@nongnu.org; Fri, 08 May 2015 08:45:41 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t48Cje8u013750 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Fri, 8 May 2015 08:45:40 -0400 Message-ID: <554CAFF1.9070308@redhat.com> Date: Fri, 08 May 2015 14:45:37 +0200 From: Max Reitz MIME-Version: 1.0 References: <1431012374-14113-1-git-send-email-pbonzini@redhat.com> <1431012374-14113-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1431012374-14113-2-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] qemu-nbd: only send a limited number of errno codes on the wire List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org Cc: kwolf@redhat.com On 07.05.2015 17:26, Paolo Bonzini wrote: > Right now, NBD includes potentially platform-specific error values in > the wire protocol. > > Luckily, most common error values are more or less universal: in > particular, of all errno values <= 34 (up to ERANGE), they are all > the same on supported platforms except for 11 (which is EAGAIN on > Windows and Linux, but EDEADLK on Darwin and the *BSDs). > > So, in order to guarantee some portability, only keep a dozen > possible error codes and squash everything else to EINVAL. > > Signed-off-by: Paolo Bonzini > --- > nbd.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 47 insertions(+) > > diff --git a/nbd.c b/nbd.c > index eea8c51..1ad5b66 100644 > --- a/nbd.c > +++ b/nbd.c > @@ -86,6 +86,37 @@ > #define NBD_OPT_ABORT (2) > #define NBD_OPT_LIST (3) > > +/* NBD errors are based on errno numbers, so there is a 1:1 mapping, > + * but only a limited set of errno values is specified in the protocol. > + * Everything else is squashed to EINVAL. > + */ > +static int system_errno_to_nbd_errno(int err) > +{ > + switch (err) { > + case EPERM: > + return 1; > + case EIO: > + return 5; > + case ENXIO: > + return 6; > + case E2BIG: > + return 7; > + case ENOMEM: > + return 12; > + case EACCES: > + return 13; > + case EFBIG: > + return 27; > + case ENOSPC: > + return 28; > + case EROFS: > + return 30; > + case EINVAL: > + default: > + return 22; > + } > +} > + > /* Definitions for opaque data types */ > > typedef struct NBDRequest NBDRequest; > @@ -856,6 +887,20 @@ ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply) > reply->error = be32_to_cpup((uint32_t*)(buf + 4)); > reply->handle = be64_to_cpup((uint64_t*)(buf + 8)); > > + /* NBD errors should be universally equal to the corresponding > + * errno values, check it here. > + */ > + QEMU_BUILD_BUG_ON(EPERM != 1); > + QEMU_BUILD_BUG_ON(EIO != 5); > + QEMU_BUILD_BUG_ON(ENXIO != 6); > + QEMU_BUILD_BUG_ON(E2BIG != 7); > + QEMU_BUILD_BUG_ON(ENOMEM != 12); > + QEMU_BUILD_BUG_ON(EACCES != 13); > + QEMU_BUILD_BUG_ON(EINVAL != 22); > + QEMU_BUILD_BUG_ON(EFBIG != 27); > + QEMU_BUILD_BUG_ON(ENOSPC != 28); > + QEMU_BUILD_BUG_ON(EROFS != 30); > + Why no nbd_errno_to_system_errno() function? Max > TRACE("Got reply: " > "{ magic = 0x%x, .error = %d, handle = %" PRIu64" }", > magic, reply->error, reply->handle); > @@ -872,6 +917,8 @@ static ssize_t nbd_send_reply(int csock, struct nbd_reply *reply) > uint8_t buf[NBD_REPLY_SIZE]; > ssize_t ret; > > + reply->error = system_errno_to_nbd_errno(reply->error); > + > /* Reply > [ 0 .. 3] magic (NBD_REPLY_MAGIC) > [ 4 .. 7] error (0 == no error)