Re: [PATCH 3/6] tests/9pfs: compare QIDs in fs_walk_none() test

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Mittwoch, 9. März 2022 15:49:04 CET Christian Schoenebeck wrote:
> 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>
> ---
>  tests/qtest/virtio-9p-test.c | 70 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/tests/qtest/virtio-9p-test.c b/tests/qtest/virtio-9p-test.c
> index 6c00da03f4..9098e21173 100644
> --- a/tests/qtest/virtio-9p-test.c
> +++ b/tests/qtest/virtio-9p-test.c
> @@ -146,6 +146,11 @@ static void v9fs_uint16_read(P9Req *req, uint16_t *val)
> le16_to_cpus(val);
>  }
> 
> +static void v9fs_int16_read(P9Req *req, int16_t *val)
> +{
> +    v9fs_uint16_read(req, (uint16_t *)val);
> +}
> +
>  static void v9fs_uint32_write(P9Req *req, uint32_t val)
>  {
>      uint32_t le_val = cpu_to_le32(val);
> @@ -166,12 +171,22 @@ static void v9fs_uint32_read(P9Req *req, uint32_t
> *val) le32_to_cpus(val);
>  }
> 
> +static void v9fs_int32_read(P9Req *req, int32_t *val)
> +{
> +    v9fs_uint32_read(req, (uint32_t *)val);
> +}
> +
>  static void v9fs_uint64_read(P9Req *req, uint64_t *val)
>  {
>      v9fs_memread(req, val, 8);
>      le64_to_cpus(val);
>  }
> 
> +static void v9fs_int64_read(P9Req *req, int64_t *val)
> +{
> +    v9fs_uint64_read(req, (uint64_t *)val);
> +}
> +
>  /* len[2] string[len] */
>  static uint16_t v9fs_string_size(const char *string)
>  {
> @@ -425,6 +440,40 @@ static void v9fs_rwalk(P9Req *req, uint16_t *nwqid,
> v9fs_qid **wqid) v9fs_req_free(req);
>  }
> 
> +/* size[4] Tstat tag[2] fid[4] */
> +static P9Req *v9fs_tstat(QVirtio9P *v9p, uint32_t fid, uint16_t tag)
> +{
> +    P9Req *req;
> +
> +    req = v9fs_req_init(v9p, 4, P9_TSTAT, tag);
> +    v9fs_uint32_write(req, fid);
> +    v9fs_req_send(req);
> +    return req;
> +}
> +
> +/* size[4] Rstat tag[2] stat[n] */
> +static void v9fs_rstat(P9Req *req, struct V9fsStat *st)
> +{
> +    v9fs_req_recv(req, P9_RSTAT);
> +
> +    v9fs_int16_read(req, &st->size);
> +    v9fs_int16_read(req, &st->type);
> +    v9fs_int32_read(req, &st->dev);
> +    v9fs_uint8_read(req, &st->qid.type);
> +    v9fs_uint32_read(req, &st->qid.version);
> +    v9fs_uint64_read(req, &st->qid.path);
> +    v9fs_int32_read(req, &st->mode);
> +    v9fs_int32_read(req, &st->mtime);
> +    v9fs_int32_read(req, &st->atime);
> +    v9fs_int64_read(req, &st->length);
> +    v9fs_string_read(req, &st->name.size, &st->name.data);
> +    v9fs_string_read(req, &st->uid.size, &st->uid.data);
> +    v9fs_string_read(req, &st->gid.size, &st->gid.data);
> +    v9fs_string_read(req, &st->muid.size, &st->muid.data);
> +
> +    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 +1058,8 @@ 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 V9fsStat st[2];
> +    int i;
> 
>      do_version(v9p);
>      req = v9fs_tattach(v9p, 0, getuid(), 0);
> @@ -1021,6 +1072,25 @@ 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_tstat(v9p, 0, 0);
> +    v9fs_req_wait_for_reply(req, NULL);
> +    v9fs_rstat(req, &st[0]);

Probably stat-ing the root fid (0) should happen before sending Twalk, to 
better counter the 1st fid (0) having become potentially mutated?

> +
> +    req = v9fs_tstat(v9p, 1, 0);
> +    v9fs_req_wait_for_reply(req, NULL);
> +    v9fs_rstat(req, &st[1]);
> +
> +    /* don't compare QID version for checking for file ID equalness */
> +    g_assert(st[0].qid.type == st[1].qid.type);
> +    g_assert(st[0].qid.path == st[1].qid.path);

I could add a helper function is_same_qid() for this if desired.

> +
> +    for (i = 0; i < 2; ++i) {
> +        g_free(st[i].name.data);
> +        g_free(st[i].uid.data);
> +        g_free(st[i].gid.data);
> +        g_free(st[i].muid.data);
> +    }

I didn't find a more elegant way to do this cleanup.

>  }
> 
>  static void fs_walk_dotdot(void *obj, void *data, QGuestAllocator *t_alloc)