[Libguestfs] [nbdkit PATCH] captive: Support $uri in --run

The existing --run '$nbd' outputs an older form that differs between libguestfs and qemu, and which is not always a valid URI. For historical compatibility, we probably can't change that; but we can instead add a new '$uri' that outputs a valid URI. Note that the libguestfs '$nbd' TCP form is already a valid URI, but that libguestfs still needs to be taught about the nbd+unix:// scheme, so for there, you are still better off using '$nbd'; but for qemu, using '$uri' already works since qemu v1.3.0 in 2012. Note that the NBD project has not actually yet posted a link for the preferred URI syntax; once Rich is happy with his work on that project, we can touch this up to link to that page. Reported-by: Martin Kletzander <mkletzan(a)redhat.com&gt; Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- docs/nbdkit-captive.pod | 8 +++++++- server/captive.c | 14 +++++++++++++- 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/docs/nbdkit-captive.pod b/docs/nbdkit-captive.pod index 6f69cca5..59df6690 100644 --- a/docs/nbdkit-captive.pod +++ b/docs/nbdkit-captive.pod @@ -42,9 +42,15 @@ The following shell variables are available in the I<--run> argument: =over 4 +=item C<$uri> + +A URI that refers to the nbdkit port or socket in the preferred form +documented by the NBD project. + =item C<$nbd> -A URL that refers to the nbdkit port or socket. +An older URL that refers to the nbdkit port or socket in a manner +specific to certain tools. Note there is some magic here, since qemu and guestfish URLs have a different format, so nbdkit tries to guess which you are running. If diff --git a/server/captive.c b/server/captive.c index 6971af2e..c5274f65 100644 --- a/server/captive.c +++ b/server/captive.c @@ -66,7 +66,19 @@ run_command (void) exit (EXIT_FAILURE); } - /* Construct $nbd "URL". Unfortunately guestfish and qemu take + /* Construct $uri. */ + fprintf (fp, "uri="); + if (port) { + fprintf (fp, "nbd://localhost:"); + shell_quote (port, fp); + } + else if (unixsocket) { + fprintf (fp, "nbd+unix://\\?socket="); + shell_quote (unixsocket, fp); + } + fprintf (fp, "\n"); + + /* Construct older $nbd "URL". Unfortunately guestfish and qemu take * different syntax, so try to guess which one we need. */ fprintf (fp, "nbd="); -- 2.20.1