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 <eblake@redhat.com>
Message-Id: <20200212023101.1162686-1-eblake@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Eric Blake 2020-02-11 20:31:01 -06:00
parent 73e064ccf0
commit 2485f22fe9
1 changed files with 4 additions and 2 deletions

View File

@ -1528,8 +1528,10 @@ 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);
}