On 08.05.2015 14:45, Max Reitz wrote:
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 <pbonz...@redhat.com>
---
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?
Oops, I missed v2. Sorry.
Max
