Re: [PATCH] nbd-client: Support leading / in NBD URI
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 > > --- > > block/nbd.c | 6 -- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > Reviewed-by: Ján Tomko > > 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
Re: [PATCH] nbd-client: Support leading / in NBD URI
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
> ---
> 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.
--
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Re: [PATCH] nbd-client: Support leading / in NBD URI
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 --- block/nbd.c | 6 -- 1 file changed, 4 insertions(+), 2 deletions(-) Reviewed-by: Ján Tomko Jano signature.asc Description: PGP signature
[PATCH] nbd-client: Support leading / in NBD URI
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
---
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
