* [PATCH] nbd-client: Support leading / in NBD URI
@ 2020-02-12 2:31 Eric Blake
2020-02-12 13:33 ` Ján Tomko
2020-02-12 13:41 ` Richard W.M. Jones
0 siblings, 2 replies; 4+ messages in thread
From: Eric Blake @ 2020-02-12 2:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, vsementsov, rjones, open list:Network Block Dev...,
Max Reitz
The NBD URI specification [1] states that only one leading slash at
the beginning of the URI path component is stripped, not all such
slashes. This becomes important to a patch I just proposed to nbdkit
[2], which would allow the exportname to select a file embedded within
an ext2 image: ext2fs demands an absolute pathname beginning with '/',
and because qemu was inadvertantly stripping it, my nbdkit patch had
to work around the behavior.
[1] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md
[2] https://www.redhat.com/archives/libguestfs/2020-February/msg00109.html
Note that the qemu bug only affects handling of URIs such as
nbd://host:port//abs/path (where '/abs/path' should be the export
name); it is still possible to use --image-opts and pass the desired
export name with a leading slash directly through JSON even without
this patch.
Signed-off-by: Eric Blake <eblake@redhat.com>
---
block/nbd.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index d085554f21ea..82f9b7ef50a5 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -1516,8 +1516,10 @@ static int nbd_parse_uri(const char *filename, QDict *options)
goto out;
}
- p = uri->path ? uri->path : "/";
- p += strspn(p, "/");
+ p = uri->path ? uri->path : "";
+ if (p[0] == '/') {
+ p++;
+ }
if (p[0]) {
qdict_put_str(options, "export", p);
}
--
2.24.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd-client: Support leading / in NBD URI
2020-02-12 2:31 [PATCH] nbd-client: Support leading / in NBD URI Eric Blake
@ 2020-02-12 13:33 ` Ján Tomko
2020-02-12 13:42 ` Maxim Levitsky
2020-02-12 13:41 ` Richard W.M. Jones
1 sibling, 1 reply; 4+ messages in thread
From: Ján Tomko @ 2020-02-12 13:33 UTC (permalink / raw)
To: Eric Blake
Cc: Kevin Wolf, vsementsov, open list:Network Block Dev...,
rjones, qemu-devel, Max Reitz
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On Tue, Feb 11, 2020 at 08:31:01PM -0600, Eric Blake wrote:
>The NBD URI specification [1] states that only one leading slash at
>the beginning of the URI path component is stripped, not all such
>slashes. This becomes important to a patch I just proposed to nbdkit
>[2], which would allow the exportname to select a file embedded within
>an ext2 image: ext2fs demands an absolute pathname beginning with '/',
>and because qemu was inadvertantly stripping it, my nbdkit patch had
>to work around the behavior.
>
>[1] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md
>[2] https://www.redhat.com/archives/libguestfs/2020-February/msg00109.html
>
>Note that the qemu bug only affects handling of URIs such as
>nbd://host:port//abs/path (where '/abs/path' should be the export
>name); it is still possible to use --image-opts and pass the desired
>export name with a leading slash directly through JSON even without
>this patch.
>
>Signed-off-by: Eric Blake <eblake@redhat.com>
>---
> block/nbd.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Jano
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd-client: Support leading / in NBD URI
2020-02-12 2:31 [PATCH] nbd-client: Support leading / in NBD URI Eric Blake
2020-02-12 13:33 ` Ján Tomko
@ 2020-02-12 13:41 ` Richard W.M. Jones
1 sibling, 0 replies; 4+ messages in thread
From: Richard W.M. Jones @ 2020-02-12 13:41 UTC (permalink / raw)
To: Eric Blake
Cc: Kevin Wolf, vsementsov, qemu-devel,
open list:Network Block Dev...,
Max Reitz
On Tue, Feb 11, 2020 at 08:31:01PM -0600, Eric Blake wrote:
> The NBD URI specification [1] states that only one leading slash at
> the beginning of the URI path component is stripped, not all such
> slashes. This becomes important to a patch I just proposed to nbdkit
> [2], which would allow the exportname to select a file embedded within
> an ext2 image: ext2fs demands an absolute pathname beginning with '/',
> and because qemu was inadvertantly stripping it, my nbdkit patch had
> to work around the behavior.
>
> [1] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md
> [2] https://www.redhat.com/archives/libguestfs/2020-February/msg00109.html
>
> Note that the qemu bug only affects handling of URIs such as
> nbd://host:port//abs/path (where '/abs/path' should be the export
> name); it is still possible to use --image-opts and pass the desired
> export name with a leading slash directly through JSON even without
> this patch.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
> block/nbd.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block/nbd.c b/block/nbd.c
> index d085554f21ea..82f9b7ef50a5 100644
> --- a/block/nbd.c
> +++ b/block/nbd.c
> @@ -1516,8 +1516,10 @@ static int nbd_parse_uri(const char *filename, QDict *options)
> goto out;
> }
>
> - p = uri->path ? uri->path : "/";
> - p += strspn(p, "/");
> + p = uri->path ? uri->path : "";
> + if (p[0] == '/') {
> + p++;
> + }
> if (p[0]) {
> qdict_put_str(options, "export", p);
> }
Looks reasonable, ACK.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd-client: Support leading / in NBD URI
2020-02-12 13:33 ` Ján Tomko
@ 2020-02-12 13:42 ` Maxim Levitsky
0 siblings, 0 replies; 4+ messages in thread
From: Maxim Levitsky @ 2020-02-12 13:42 UTC (permalink / raw)
To: Ján Tomko, Eric Blake
Cc: Kevin Wolf, vsementsov, qemu-devel,
open list:Network Block Dev...,
Max Reitz
On Wed, 2020-02-12 at 14:33 +0100, Ján Tomko wrote:
> On Tue, Feb 11, 2020 at 08:31:01PM -0600, Eric Blake wrote:
> > The NBD URI specification [1] states that only one leading slash at
> > the beginning of the URI path component is stripped, not all such
> > slashes. This becomes important to a patch I just proposed to nbdkit
> > [2], which would allow the exportname to select a file embedded within
> > an ext2 image: ext2fs demands an absolute pathname beginning with '/',
> > and because qemu was inadvertantly stripping it, my nbdkit patch had
> > to work around the behavior.
> >
> > [1] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md
> > [2] https://www.redhat.com/archives/libguestfs/2020-February/msg00109.html
> >
> > Note that the qemu bug only affects handling of URIs such as
> > nbd://host:port//abs/path (where '/abs/path' should be the export
> > name); it is still possible to use --image-opts and pass the desired
> > export name with a leading slash directly through JSON even without
> > this patch.
> >
> > Signed-off-by: Eric Blake <eblake@redhat.com>
> > ---
> > block/nbd.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
>
> Reviewed-by: Ján Tomko <jtomko@redhat.com>
>
> Jano
Note that I had a bug open for this.
https://bugzilla.redhat.com/show_bug.cgi?id=1728545
I expected this to be a feature to be honest,
and was afraid to break existing users that might rely on this.
Best regards,
Maxim Levitsky
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-02-12 13:52 UTC | newest]
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2020-02-12 2:31 [PATCH] nbd-client: Support leading / in NBD URI Eric Blake
2020-02-12 13:33 ` Ján Tomko
2020-02-12 13:42 ` Maxim Levitsky
2020-02-12 13:41 ` Richard W.M. Jones
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