[PULL 5/7] 9pfs: fix 'Twalk' to only send error if no component walked

[PULL 5/7] 9pfs: fix 'Twalk' to only send error if no component walked

[Christian Schoenebeck via]

Current implementation of 'Twalk' request handling always sends an 'Rerror'
response if any error occured. The 9p2000 protocol spec says though:

  "
  If the first element cannot be walked for any reason, Rerror is returned.
  Otherwise, the walk will return an Rwalk message containing nwqid qids
  corresponding, in order, to the files that are visited by the nwqid
  successful elementwise walks; nwqid is therefore either nwname or the index
  of the first elementwise walk that failed.
  "

  http://ericvh.github.io/9p-rfc/rfc9p2000.html#anchor33

For that reason we are no longer leaving from an error path in function
v9fs_walk(), unless really no path component could be walked successfully or
if the request has been interrupted.

Local variable 'nwalked' counts and reflects the number of path components
successfully processed by background I/O thread, whereas local variable
'name_idx' subsequently counts and reflects the number of path components
eventually accepted successfully by 9p server controller portion.

New local variable 'any_err' is an aggregate variable reflecting whether any
error occurred at all, while already existing variable 'err' only reflects
the last error.

Despite QIDs being delivered to client in a more relaxed way now, it is
important to note though that fid still must remain unaffected if any error
occurred.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <bc73e24258a75dc29458024c7936c8a036c3eac5.1647339025.git.qemu_oss@crudebyte.com>
---
 hw/9pfs/9p.c | 49 +++++++++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 16 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index f29611e9ed..aebadeaa03 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1768,7 +1768,7 @@ static void coroutine_fn v9fs_walk(void *opaque)
 {
     int name_idx, nwalked;
     g_autofree V9fsQID *qids = NULL;
-    int i, err = 0;
+    int i, err = 0, any_err = 0;
     V9fsPath dpath, path;
     P9ARRAY_REF(V9fsPath) pathes = NULL;
     uint16_t nwnames;
@@ -1834,19 +1834,20 @@ static void coroutine_fn v9fs_walk(void *opaque)
      * driver code altogether inside the following block.
      */
     v9fs_co_run_in_worker({
+        nwalked = 0;
         if (v9fs_request_cancelled(pdu)) {
-            err = -EINTR;
+            any_err |= err = -EINTR;
             break;
         }
         err = s->ops->lstat(&s->ctx, &dpath, &fidst);
         if (err < 0) {
-            err = -errno;
+            any_err |= err = -errno;
             break;
         }
         stbuf = fidst;
-        for (nwalked = 0; nwalked < nwnames; nwalked++) {
+        for (; nwalked < nwnames; nwalked++) {
             if (v9fs_request_cancelled(pdu)) {
-                err = -EINTR;
+                any_err |= err = -EINTR;
                 break;
             }
             if (!same_stat_id(&pdu->s->root_st, &stbuf) ||
@@ -1856,16 +1857,16 @@ static void coroutine_fn v9fs_walk(void *opaque)
                                            wnames[nwalked].data,
                                            &pathes[nwalked]);
                 if (err < 0) {
-                    err = -errno;
+                    any_err |= err = -errno;
                     break;
                 }
                 if (v9fs_request_cancelled(pdu)) {
-                    err = -EINTR;
+                    any_err |= err = -EINTR;
                     break;
                 }
                 err = s->ops->lstat(&s->ctx, &pathes[nwalked], &stbuf);
                 if (err < 0) {
-                    err = -errno;
+                    any_err |= err = -errno;
                     break;
                 }
                 stbufs[nwalked] = stbuf;
@@ -1875,13 +1876,19 @@ static void coroutine_fn v9fs_walk(void *opaque)
     });
     /*
      * Handle all the rest of this Twalk request on main thread ...
+     *
+     * NOTE: -EINTR is an exception where we deviate from the protocol spec
+     * and simply send a (R)Lerror response instead of bothering to assemble
+     * a (deducted) Rwalk response; because -EINTR is always the result of a
+     * Tflush request, so client would no longer wait for a response in this
+     * case anyway.
      */
-    if (err < 0) {
+    if ((err < 0 && !nwalked) || err == -EINTR) {
         goto out;
     }
 
-    err = stat_to_qid(pdu, &fidst, &qid);
-    if (err < 0) {
+    any_err |= err = stat_to_qid(pdu, &fidst, &qid);
+    if (err < 0 && !nwalked) {
         goto out;
     }
     stbuf = fidst;
@@ -1890,20 +1897,29 @@ static void coroutine_fn v9fs_walk(void *opaque)
     v9fs_path_copy(&dpath, &fidp->path);
     v9fs_path_copy(&path, &fidp->path);
 
-    for (name_idx = 0; name_idx < nwnames; name_idx++) {
+    for (name_idx = 0; name_idx < nwalked; name_idx++) {
         if (!same_stat_id(&pdu->s->root_st, &stbuf) ||
             strcmp("..", wnames[name_idx].data))
         {
             stbuf = stbufs[name_idx];
-            err = stat_to_qid(pdu, &stbuf, &qid);
+            any_err |= err = stat_to_qid(pdu, &stbuf, &qid);
             if (err < 0) {
-                goto out;
+                break;
             }
             v9fs_path_copy(&path, &pathes[name_idx]);
             v9fs_path_copy(&dpath, &path);
         }
         memcpy(&qids[name_idx], &qid, sizeof(qid));
     }
+    if (any_err < 0) {
+        if (!name_idx) {
+            /* don't send any QIDs, send Rlerror instead */
+            goto out;
+        } else {
+            /* send QIDs (not Rlerror), but fid MUST remain unaffected */
+            goto send_qids;
+        }
+    }
     if (fid == newfid) {
         if (fidp->fid_type != P9_FID_NONE) {
             err = -EINVAL;
@@ -1921,8 +1937,9 @@ static void coroutine_fn v9fs_walk(void *opaque)
         newfidp->uid = fidp->uid;
         v9fs_path_copy(&newfidp->path, &path);
     }
-    err = v9fs_walk_marshal(pdu, nwnames, qids);
-    trace_v9fs_walk_return(pdu->tag, pdu->id, nwnames, qids);
+send_qids:
+    err = v9fs_walk_marshal(pdu, name_idx, qids);
+    trace_v9fs_walk_return(pdu->tag, pdu->id, name_idx, qids);
 out:
     put_fid(pdu, fidp);
     if (newfidp) {
-- 
2.30.2

[PULL 7/7] tests/9pfs: check fid being unaffected in fs_walk_2nd_nonexistent

[Christian Schoenebeck]

Extend previously added test case by checking that fid was unaffected
by 'Twalk' request (i.e. when 2nd path component of request being
invalid). Do that by subsequently sending a 'Tgetattr' request with
the fid previously used for 'Twalk'; that 'Tgetattr' request should
return an 'Rlerror' response by 9p server with error code ENOENT as
that fid is basically invalid.

And as we are at it, also check that the QID returned by 'Twalk' is
not identical to the root node's QID.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <6f0813cafdbf683cdac8b1492dd4ef8699c5b1d9.1647339025.git.qemu_oss@crudebyte.com>
---
 tests/qtest/virtio-9p-test.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index c787ded4d2..25305a4cf7 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -721,14 +721,19 @@ static void fs_version(void *obj, void *data, QGuestAllocator *t_alloc)
     do_version(obj);
 }
 
-static void do_attach(QVirtio9P *v9p)
+static void do_attach_rqid(QVirtio9P *v9p, v9fs_qid *qid)
 {
     P9Req *req;
 
     do_version(v9p);
     req = v9fs_tattach(v9p, 0, getuid(), 0);
     v9fs_req_wait_for_reply(req, NULL);
-    v9fs_rattach(req, NULL);
+    v9fs_rattach(req, qid);
+}
+
+static void do_attach(QVirtio9P *v9p)
+{
+    do_attach_rqid(v9p, NULL);
 }
 
 static void fs_attach(void *obj, void *data, QGuestAllocator *t_alloc)
@@ -1101,19 +1106,32 @@ static void fs_walk_2nd_nonexistent(void *obj, void *data,
 {
     QVirtio9P *v9p = obj;
     alloc = t_alloc;
+    v9fs_qid root_qid;
     uint16_t nwqid;
+    uint32_t fid, err;
+    P9Req *req;
     g_autofree v9fs_qid *wqid = NULL;
     g_autofree char *path = g_strdup_printf(
         QTEST_V9FS_SYNTH_WALK_FILE "/non-existent", 0
     );
 
-    do_attach(v9p);
-    do_walk_rqids(v9p, path, &nwqid, &wqid);
+    do_attach_rqid(v9p, &root_qid);
+    fid = do_walk_rqids(v9p, path, &nwqid, &wqid);
     /*
      * The 9p2000 protocol spec says: "nwqid is therefore either nwname or the
      * index of the first elementwise walk that failed."
      */
     assert(nwqid == 1);
+
+    /* returned QID wqid[0] is file ID of 1st subdir */
+    g_assert(wqid && wqid[0] && !is_same_qid(root_qid, wqid[0]));
+
+    /* expect fid being unaffected by walk above */
+    req = v9fs_tgetattr(v9p, fid, P9_GETATTR_BASIC, 0);
+    v9fs_req_wait_for_reply(req, NULL);
+    v9fs_rlerror(req, &err);
+
+    g_assert_cmpint(err, ==, ENOENT);
 }
 
 static void fs_walk_none(void *obj, void *data, QGuestAllocator *t_alloc)
-- 
2.30.2

[PULL 0/7] 9p queue 2022-06-16

[Christian Schoenebeck]

The following changes since commit 9ac873a46963098441be920ef7a2eaf244a3352d:

  Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging (2022-06-15 09:47:24 -0700)

are available in the Git repository at:

  https://github.com/cschoenebeck/qemu.git tags/pull-9p-20220616

for you to fetch changes up to 0e43495d3b4a50fc5e22f7b71261fdd5b56fdfcb:

  tests/9pfs: check fid being unaffected in fs_walk_2nd_nonexistent (2022-06-16 12:44:52 +0200)

----------------------------------------------------------------
9pfs: fix 'Twalk' protocol violation

Actual fix is patch 5, whereas patch 4 being preparatory, all other
patches are test cases to guard this Twalk issue.

----------------------------------------------------------------
Christian Schoenebeck (7):
      tests/9pfs: walk to non-existent dir
      tests/9pfs: Twalk with nwname=0
      tests/9pfs: compare QIDs in fs_walk_none() test
      9pfs: refactor 'name_idx' -> 'nwalked' in v9fs_walk()
      9pfs: fix 'Twalk' to only send error if no component walked
      tests/9pfs: guard recent 'Twalk' behaviour fix
      tests/9pfs: check fid being unaffected in fs_walk_2nd_nonexistent

 hw/9pfs/9p.c                 |  63 +++++++++-----
 tests/qtest/virtio-9p-test.c | 201 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 237 insertions(+), 27 deletions(-)

[PULL 4/7] 9pfs: refactor 'name_idx' -> 'nwalked' in v9fs_walk()

[Christian Schoenebeck]

The local variable 'name_idx' is used in two loops in function v9fs_walk().
Let the first loop use its own variable 'nwalked' instead, which we will
use in subsequent patch as the number of (requested) path components
successfully walked by background I/O thread.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <d506308e7e343023c4db95d0e6053dd2627ed3c1.1647339025.git.qemu_oss@crudebyte.com>
---
 hw/9pfs/9p.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 0cd0c14c2a..f29611e9ed 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1766,7 +1766,7 @@ static bool same_stat_id(const struct stat *a, const struct stat *b)
 
 static void coroutine_fn v9fs_walk(void *opaque)
 {
-    int name_idx;
+    int name_idx, nwalked;
     g_autofree V9fsQID *qids = NULL;
     int i, err = 0;
     V9fsPath dpath, path;
@@ -1844,17 +1844,17 @@ static void coroutine_fn v9fs_walk(void *opaque)
             break;
         }
         stbuf = fidst;
-        for (name_idx = 0; name_idx < nwnames; name_idx++) {
+        for (nwalked = 0; nwalked < nwnames; nwalked++) {
             if (v9fs_request_cancelled(pdu)) {
                 err = -EINTR;
                 break;
             }
             if (!same_stat_id(&pdu->s->root_st, &stbuf) ||
-                strcmp("..", wnames[name_idx].data))
+                strcmp("..", wnames[nwalked].data))
             {
                 err = s->ops->name_to_path(&s->ctx, &dpath,
-                                           wnames[name_idx].data,
-                                           &pathes[name_idx]);
+                                           wnames[nwalked].data,
+                                           &pathes[nwalked]);
                 if (err < 0) {
                     err = -errno;
                     break;
@@ -1863,13 +1863,13 @@ static void coroutine_fn v9fs_walk(void *opaque)
                     err = -EINTR;
                     break;
                 }
-                err = s->ops->lstat(&s->ctx, &pathes[name_idx], &stbuf);
+                err = s->ops->lstat(&s->ctx, &pathes[nwalked], &stbuf);
                 if (err < 0) {
                     err = -errno;
                     break;
                 }
-                stbufs[name_idx] = stbuf;
-                v9fs_path_copy(&dpath, &pathes[name_idx]);
+                stbufs[nwalked] = stbuf;
+                v9fs_path_copy(&dpath, &pathes[nwalked]);
             }
         }
     });
-- 
2.30.2

[PULL 1/7] tests/9pfs: walk to non-existent dir

[Christian Schoenebeck]

Expect ENOENT Rlerror response when trying to walk to a
non-existent directory.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Based-on: <E1nTpyU-0000yR-9o@lizzy.crudebyte.com>
Message-Id: <1f5aa50ace3ba3861ea31e8888367518282065a6.1647339025.git.qemu_oss@crudebyte.com>
---
 tests/qtest/virtio-9p-test.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index e28c71bd8f..b3837546be 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -606,6 +606,25 @@ static uint32_t do_walk(QVirtio9P *v9p, const char *path)
     return fid;
 }
 
+/* utility function: walk to requested dir and expect passed error response */
+static void do_walk_expect_error(QVirtio9P *v9p, const char *path, uint32_t err)
+{
+    char **wnames;
+    P9Req *req;
+    uint32_t _err;
+    const uint32_t fid = genfid();
+
+    int nwnames = split(path, "/", &wnames);
+
+    req = v9fs_twalk(v9p, 0, fid, nwnames, wnames, 0);
+    v9fs_req_wait_for_reply(req, NULL);
+    v9fs_rlerror(req, &_err);
+
+    g_assert_cmpint(_err, ==, err);
+
+    split_free(&wnames);
+}
+
 static void fs_version(void *obj, void *data, QGuestAllocator *t_alloc)
 {
     alloc = t_alloc;
@@ -974,6 +993,15 @@ static void fs_walk_no_slash(void *obj, void *data, QGuestAllocator *t_alloc)
     g_free(wnames[0]);
 }
 
+static void fs_walk_nonexistent(void *obj, void *data, QGuestAllocator *t_alloc)
+{
+    QVirtio9P *v9p = obj;
+    alloc = t_alloc;
+
+    do_attach(v9p);
+    do_walk_expect_error(v9p, "non-existent", ENOENT);
+}
+
 static void fs_walk_dotdot(void *obj, void *data, QGuestAllocator *t_alloc)
 {
     QVirtio9P *v9p = obj;
@@ -1409,6 +1437,8 @@ static void register_virtio_9p_test(void)
                   &opts);
     qos_add_test("synth/walk/dotdot_from_root", "virtio-9p",
                  fs_walk_dotdot,  &opts);
+    qos_add_test("synth/walk/non_existent", "virtio-9p", fs_walk_nonexistent,
+                  &opts);
     qos_add_test("synth/lopen/basic", "virtio-9p", fs_lopen,  &opts);
     qos_add_test("synth/write/basic", "virtio-9p", fs_write,  &opts);
     qos_add_test("synth/flush/success", "virtio-9p", fs_flush_success,
-- 
2.30.2

[PULL 3/7] tests/9pfs: compare QIDs in fs_walk_none() test

[Christian Schoenebeck]

Extend previously added fs_walk_none() test by comparing the QID
of the root fid with the QID of the cloned fid. They should be
equal.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <5bbe9c6931b4600a9a23742f5ff2d38c1188237d.1647339025.git.qemu_oss@crudebyte.com>
---
 tests/qtest/virtio-9p-test.c | 87 ++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index 7942d5fef9..3c0f094929 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -371,8 +371,15 @@ static P9Req *v9fs_tattach(QVirtio9P *v9p, uint32_t fid, uint32_t n_uname,
     return req;
 }
 
+/* type[1] version[4] path[8] */
 typedef char v9fs_qid[13];
 
+static inline bool is_same_qid(v9fs_qid a, v9fs_qid b)
+{
+    /* don't compare QID version for checking for file ID equalness */
+    return a[0] == b[0] && memcmp(&a[5], &b[5], 8) == 0;
+}
+
 /* size[4] Rattach tag[2] qid[13] */
 static void v9fs_rattach(P9Req *req, v9fs_qid *qid)
 {
@@ -425,6 +432,79 @@ static void v9fs_rwalk(P9Req *req, uint16_t *nwqid, v9fs_qid **wqid)
     v9fs_req_free(req);
 }
 
+/* size[4] Tgetattr tag[2] fid[4] request_mask[8] */
+static P9Req *v9fs_tgetattr(QVirtio9P *v9p, uint32_t fid, uint64_t request_mask,
+                            uint16_t tag)
+{
+    P9Req *req;
+
+    req = v9fs_req_init(v9p, 4 + 8, P9_TGETATTR, tag);
+    v9fs_uint32_write(req, fid);
+    v9fs_uint64_write(req, request_mask);
+    v9fs_req_send(req);
+    return req;
+}
+
+typedef struct v9fs_attr {
+    uint64_t valid;
+    v9fs_qid qid;
+    uint32_t mode;
+    uint32_t uid;
+    uint32_t gid;
+    uint64_t nlink;
+    uint64_t rdev;
+    uint64_t size;
+    uint64_t blksize;
+    uint64_t blocks;
+    uint64_t atime_sec;
+    uint64_t atime_nsec;
+    uint64_t mtime_sec;
+    uint64_t mtime_nsec;
+    uint64_t ctime_sec;
+    uint64_t ctime_nsec;
+    uint64_t btime_sec;
+    uint64_t btime_nsec;
+    uint64_t gen;
+    uint64_t data_version;
+} v9fs_attr;
+
+#define P9_GETATTR_BASIC    0x000007ffULL /* Mask for fields up to BLOCKS */
+
+/*
+ * size[4] Rgetattr tag[2] valid[8] qid[13] mode[4] uid[4] gid[4] nlink[8]
+ *                  rdev[8] size[8] blksize[8] blocks[8]
+ *                  atime_sec[8] atime_nsec[8] mtime_sec[8] mtime_nsec[8]
+ *                  ctime_sec[8] ctime_nsec[8] btime_sec[8] btime_nsec[8]
+ *                  gen[8] data_version[8]
+ */
+static void v9fs_rgetattr(P9Req *req, v9fs_attr *attr)
+{
+    v9fs_req_recv(req, P9_RGETATTR);
+
+    v9fs_uint64_read(req, &attr->valid);
+    v9fs_memread(req, &attr->qid, 13);
+    v9fs_uint32_read(req, &attr->mode);
+    v9fs_uint32_read(req, &attr->uid);
+    v9fs_uint32_read(req, &attr->gid);
+    v9fs_uint64_read(req, &attr->nlink);
+    v9fs_uint64_read(req, &attr->rdev);
+    v9fs_uint64_read(req, &attr->size);
+    v9fs_uint64_read(req, &attr->blksize);
+    v9fs_uint64_read(req, &attr->blocks);
+    v9fs_uint64_read(req, &attr->atime_sec);
+    v9fs_uint64_read(req, &attr->atime_nsec);
+    v9fs_uint64_read(req, &attr->mtime_sec);
+    v9fs_uint64_read(req, &attr->mtime_nsec);
+    v9fs_uint64_read(req, &attr->ctime_sec);
+    v9fs_uint64_read(req, &attr->ctime_nsec);
+    v9fs_uint64_read(req, &attr->btime_sec);
+    v9fs_uint64_read(req, &attr->btime_nsec);
+    v9fs_uint64_read(req, &attr->gen);
+    v9fs_uint64_read(req, &attr->data_version);
+
+    v9fs_req_free(req);
+}
+
 /* size[4] Treaddir tag[2] fid[4] offset[8] count[4] */
 static P9Req *v9fs_treaddir(QVirtio9P *v9p, uint32_t fid, uint64_t offset,
                             uint32_t count, uint16_t tag)
@@ -1009,6 +1089,7 @@ static void fs_walk_none(void *obj, void *data, QGuestAllocator *t_alloc)
     v9fs_qid root_qid;
     g_autofree v9fs_qid *wqid = NULL;
     P9Req *req;
+    struct v9fs_attr attr;
 
     do_version(v9p);
     req = v9fs_tattach(v9p, 0, getuid(), 0);
@@ -1021,6 +1102,12 @@ static void fs_walk_none(void *obj, void *data, QGuestAllocator *t_alloc)
 
     /* special case: no QID is returned if nwname=0 was sent */
     g_assert(wqid == NULL);
+
+    req = v9fs_tgetattr(v9p, 1, P9_GETATTR_BASIC, 0);
+    v9fs_req_wait_for_reply(req, NULL);
+    v9fs_rgetattr(req, &attr);
+
+    g_assert(is_same_qid(root_qid, attr.qid));
 }
 
 static void fs_walk_dotdot(void *obj, void *data, QGuestAllocator *t_alloc)
-- 
2.30.2

[PULL 6/7] tests/9pfs: guard recent 'Twalk' behaviour fix

[Christian Schoenebeck]

Previous 9p patch fixed 'Twalk' request handling, which was previously not
behaving as specified by the 9p2000 protocol spec. This patch adds a new test
case which guards the new 'Twalk' behaviour in question.

More specifically: it sends a 'Twalk' request where the 1st path component
is valid, whereas the 2nd path component transmitted to server does not
exist. The expected behaviour is that 9p server would respond by sending
a 'Rwalk' response with exactly 1 QID (instead of 'Rlerror' response).

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <61bde2f44b87e24b70ec098dfb81765665b2dfcb.1647339025.git.qemu_oss@crudebyte.com>
---
 tests/qtest/virtio-9p-test.c | 42 +++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index 3c0f094929..c787ded4d2 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -669,8 +669,12 @@ static void do_version(QVirtio9P *v9p)
     g_assert_cmpmem(server_version, server_len, version, strlen(version));
 }
 
-/* utility function: walk to requested dir and return fid for that dir */
-static uint32_t do_walk(QVirtio9P *v9p, const char *path)
+/*
+ * utility function: walk to requested dir and return fid for that dir and
+ * the QIDs of server response
+ */
+static uint32_t do_walk_rqids(QVirtio9P *v9p, const char *path, uint16_t *nwqid,
+                              v9fs_qid **wqid)
 {
     char **wnames;
     P9Req *req;
@@ -680,12 +684,18 @@ static uint32_t do_walk(QVirtio9P *v9p, const char *path)
 
     req = v9fs_twalk(v9p, 0, fid, nwnames, wnames, 0);
     v9fs_req_wait_for_reply(req, NULL);
-    v9fs_rwalk(req, NULL, NULL);
+    v9fs_rwalk(req, nwqid, wqid);
 
     split_free(&wnames);
     return fid;
 }
 
+/* utility function: walk to requested dir and return fid for that dir */
+static uint32_t do_walk(QVirtio9P *v9p, const char *path)
+{
+    return do_walk_rqids(v9p, path, NULL, NULL);
+}
+
 /* utility function: walk to requested dir and expect passed error response */
 static void do_walk_expect_error(QVirtio9P *v9p, const char *path, uint32_t err)
 {
@@ -1079,9 +1089,33 @@ static void fs_walk_nonexistent(void *obj, void *data, QGuestAllocator *t_alloc)
     alloc = t_alloc;
 
     do_attach(v9p);
+    /*
+     * The 9p2000 protocol spec says: "If the first element cannot be walked
+     * for any reason, Rerror is returned."
+     */
     do_walk_expect_error(v9p, "non-existent", ENOENT);
 }
 
+static void fs_walk_2nd_nonexistent(void *obj, void *data,
+                                    QGuestAllocator *t_alloc)
+{
+    QVirtio9P *v9p = obj;
+    alloc = t_alloc;
+    uint16_t nwqid;
+    g_autofree v9fs_qid *wqid = NULL;
+    g_autofree char *path = g_strdup_printf(
+        QTEST_V9FS_SYNTH_WALK_FILE "/non-existent", 0
+    );
+
+    do_attach(v9p);
+    do_walk_rqids(v9p, path, &nwqid, &wqid);
+    /*
+     * The 9p2000 protocol spec says: "nwqid is therefore either nwname or the
+     * index of the first elementwise walk that failed."
+     */
+    assert(nwqid == 1);
+}
+
 static void fs_walk_none(void *obj, void *data, QGuestAllocator *t_alloc)
 {
     QVirtio9P *v9p = obj;
@@ -1548,6 +1582,8 @@ static void register_virtio_9p_test(void)
                  fs_walk_dotdot,  &opts);
     qos_add_test("synth/walk/non_existent", "virtio-9p", fs_walk_nonexistent,
                   &opts);
+    qos_add_test("synth/walk/2nd_non_existent", "virtio-9p",
+                 fs_walk_2nd_nonexistent, &opts);
     qos_add_test("synth/lopen/basic", "virtio-9p", fs_lopen,  &opts);
     qos_add_test("synth/write/basic", "virtio-9p", fs_write,  &opts);
     qos_add_test("synth/flush/success", "virtio-9p", fs_flush_success,
-- 
2.30.2

[PULL 2/7] tests/9pfs: Twalk with nwname=0

[Christian Schoenebeck]

Send Twalk request with nwname=0. In this case no QIDs should
be returned by 9p server; this is equivalent to walking to dot.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <b5ead2775000203607801f09bcefc04c493d8bfa.1647339025.git.qemu_oss@crudebyte.com>
---
 tests/qtest/virtio-9p-test.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
index b3837546be..7942d5fef9 100644
--- a/tests/qtest/virtio-9p-test.c
+++ b/tests/qtest/virtio-9p-test.c
@@ -1002,6 +1002,27 @@ static void fs_walk_nonexistent(void *obj, void *data, QGuestAllocator *t_alloc)
     do_walk_expect_error(v9p, "non-existent", ENOENT);
 }
 
+static void fs_walk_none(void *obj, void *data, QGuestAllocator *t_alloc)
+{
+    QVirtio9P *v9p = obj;
+    alloc = t_alloc;
+    v9fs_qid root_qid;
+    g_autofree v9fs_qid *wqid = NULL;
+    P9Req *req;
+
+    do_version(v9p);
+    req = v9fs_tattach(v9p, 0, getuid(), 0);
+    v9fs_req_wait_for_reply(req, NULL);
+    v9fs_rattach(req, &root_qid);
+
+    req = v9fs_twalk(v9p, 0, 1, 0, NULL, 0);
+    v9fs_req_wait_for_reply(req, NULL);
+    v9fs_rwalk(req, NULL, &wqid);
+
+    /* special case: no QID is returned if nwname=0 was sent */
+    g_assert(wqid == NULL);
+}
+
 static void fs_walk_dotdot(void *obj, void *data, QGuestAllocator *t_alloc)
 {
     QVirtio9P *v9p = obj;
@@ -1435,6 +1456,7 @@ static void register_virtio_9p_test(void)
     qos_add_test("synth/walk/basic", "virtio-9p", fs_walk,  &opts);
     qos_add_test("synth/walk/no_slash", "virtio-9p", fs_walk_no_slash,
                   &opts);
+    qos_add_test("synth/walk/none", "virtio-9p", fs_walk_none, &opts);
     qos_add_test("synth/walk/dotdot_from_root", "virtio-9p",
                  fs_walk_dotdot,  &opts);
     qos_add_test("synth/walk/non_existent", "virtio-9p", fs_walk_nonexistent,
-- 
2.30.2

Re: [PULL 0/7] 9p queue 2022-06-16

[Richard Henderson]

On 6/16/22 04:00, Christian Schoenebeck wrote:
> The following changes since commit 9ac873a46963098441be920ef7a2eaf244a3352d:
> 
>    Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging (2022-06-15 09:47:24 -0700)
> 
> are available in the Git repository at:
> 
>    https://github.com/cschoenebeck/qemu.git tags/pull-9p-20220616
> 
> for you to fetch changes up to 0e43495d3b4a50fc5e22f7b71261fdd5b56fdfcb:
> 
>    tests/9pfs: check fid being unaffected in fs_walk_2nd_nonexistent (2022-06-16 12:44:52 +0200)
> 
> ----------------------------------------------------------------
> 9pfs: fix 'Twalk' protocol violation
> 
> Actual fix is patch 5, whereas patch 4 being preparatory, all other
> patches are test cases to guard this Twalk issue.

Applied, thanks.  Please update https://wiki.qemu.org/ChangeLog/7.1 as appropriate.


r~


> 
> ----------------------------------------------------------------
> Christian Schoenebeck (7):
>        tests/9pfs: walk to non-existent dir
>        tests/9pfs: Twalk with nwname=0
>        tests/9pfs: compare QIDs in fs_walk_none() test
>        9pfs: refactor 'name_idx' -> 'nwalked' in v9fs_walk()
>        9pfs: fix 'Twalk' to only send error if no component walked
>        tests/9pfs: guard recent 'Twalk' behaviour fix
>        tests/9pfs: check fid being unaffected in fs_walk_2nd_nonexistent
> 
>   hw/9pfs/9p.c                 |  63 +++++++++-----
>   tests/qtest/virtio-9p-test.c | 201 ++++++++++++++++++++++++++++++++++++++++++-
>   2 files changed, 237 insertions(+), 27 deletions(-)
>