similar to: [RFC nbdkit PATCH 0/4] Progress towards .list_exports

Since v1: - patch 1: check size limits - patch 2: better handling of default export name canonicalization - patch 3: support filters as well as plugins - patch 4: new - patch 5: rewrite sh parser, fix testsuite to actually work and cover more cases (now that libnbd.git is fixed) Eric Blake (4): server: Add exports list functions server: Prepare to use export list from plugin log: Add

More patches on the way for improving .list_exports signature and adding .export_description, but this is the promised code showing why nbdkit_string_intern is useful. Patch 4 is somewhat RFC: we could either add new API to take the boilerplate from: foo_config(const char *key, const char *value) { if (strcmp (key, "file") == 0) { CLEANUP_FREE char *tmp = nbdkit_realpath (value);

This is a revision of my .default_export work, plus new work on .export_descriptions and a new exportname filter. I think it is now ready to check in. Things I'd still like in 1.22: - the file plugin should implement .list_exports (patch already posted, but it needs rebasing on this series) - the ext2 filter should override .list_exports when in exportname mode - the nbd plugin should be

It's been several weeks since I posted v2 (I got distracted by improving libnbd to better test things, which in turn surfaced some major memory leak problems in nbdsh that are now fixed). Many of the patches are minor rebases from v2, with the biggest changes being fallout from: - patch 2: rename nbdkit_add_default_export to nbdkit_use_default_export - overall: this missed 1.22, so update

If you're following nbdkit development upstream you'll have seen that we are still making changes to the .list_exports and related APIs. The current .list_exports API upstream is not how it will look finally. The latest set of proposals was here: https://www.redhat.com/archives/libguestfs/2020-August/thread.html#00330 At the same time I'd like to do an nbdkit 1.22 (stable) release.

Here's changes to the file plugin (which I'm happy with) and a new exportname filter (which is still at RFC stage; I need to finish implementing strict mode in .open, and add tests). I also discovered that we really want .list_exports and .open to know when they are used on plaintext vs. tls clients for --tls=on, and we may want to split out a new .default_export callback rather than

Updated proposal, taking into account the default export. Instead of adding a second call, I made a couple of changes to list_exports: (1) If the plugin has a concept of a default export, it should add it as the first element in the exports list. (2) There is a new default_only flag which tells the plugin that the client is trying to request the name of the default export, so the

I'm about to add an 'exportname' filter, and in the process, I noticed a few shortcomings in our API. Time to fix those before the 1.22 release locks our API in stone. First, .list_exports needs to know if it is pre- or post-TLS, as that may affect which names are exported. Next, overloading .list_exports to do both NBD_OPT_LIST and mapping "" to a canonical name is

On Wed, Aug 26, 2020 at 09:16:46PM -0500, Eric Blake wrote: > Rather than defaulting .list_exports to blindly returning "", it is > nicer to have it reflect the result of .default_export. Meanwhile, > language bindings will have a C callback for both .list_exports and > .default_export, even if the underlying script does not, which means > any logic in plugins.c for

This picks up python and ocaml. Some of our languages are lacking a number of bindings (for example, lua and perl lack .extents, so I didn't have anything to copy from), and I felt less comfortable with golang and rust. But for python and ocaml, I was able to test a working implementation. Eric Blake (2): python: Implement .list_exports and friends ocaml: Implement .list_exports and

On 7/31/20 5:22 PM, Eric Blake wrote: > From: "Richard W.M. Jones" <rjones@redhat.com> > > See also: > https://www.redhat.com/archives/libguestfs/2020-July/msg00090.html > Message-Id: <20200722124201.1823468-2-rjones@redhat.com> > > For now, this implementation is only for plugins; adding filter > support will come later (and probably requires

This creates filesystems on demand. A client simply connects with a desired export name and a new export is created. The export is persistent (until deleted by the server admin), and clients may disconnect and reconnect. In some respects this is similar to the nbdkit-tmpdisk-plugin, or nbdkit-file-plugin with the dir= option. --- plugins/ondemand/nbdkit-ondemand-plugin.pod | 190 ++++++

Patch 3 still needs tests added, but it is at least working from my simple command line tests. Eric Blake (3): server: Implement nbdkit_is_tls for use during .open server: Expose final thread_model to filter's .get_ready tlsdummy: New filter docs/nbdkit-filter.pod | 21 +- docs/nbdkit-plugin.pod | 34 ++- docs/nbdkit-tls.pod

I'm about to add an 'exportname' filter, and in the process, I noticed a few shortcomings in our API. Time to fix those before the 1.22 release locks our API in stone. Overloading .list_exports in order to determine a canonical export name at .open time is awkward; the two uses (answering NBD_OPT_LIST for a full list, vs. remapping a client's "" into a canonical name

Another series on top of my exportname filter, marking off another todo bullet point. With this, you can now use the NBD plugin as a transparent passthrough of all export names served by the remote server in both directions (list advertisement server to client, and export name from client to server). Eric Blake (3): nbd: Implement .default_export, .export_description nbd: Add

Of course at the moment nbdkit parses the NBD export name option but doesn't really do anything with it (except logging it). I wonder if we should make this available to plugins, in case they wish to serve different content to different clients based on the export name. Note I'm not suggesting that we use this feature in any existing plugins. If we wanted to do this there seem like two

On 9/1/20 8:25 AM, Eric Blake wrote: > Fairly straightforward. I'd love for type export to be a bit more > flexible to make description optional, but could not figure out how to > decode that from the C side of things, so for now this just requires > the caller to supply a description for all exports during > .list_exports. > Maybe I did figure it out after all, although

Rather than defaulting .list_exports to blindly returning "", it is nicer to have it reflect the result of .default_export. Meanwhile, language bindings will have a C callback for both .list_exports and .default_export, even if the underlying script does not, which means any logic in plugins.c for calling .default_export when .list_export is missing would have to be duplicated in each

On Thu, Aug 06, 2020 at 09:23:48PM -0500, Eric Blake wrote: > Add a new filter to make it easier to add exports to a plugin that > does advertise them, to avoid advertising where a plugin's list might does *not* advertise them(?) > be an information leak, and to alter which export name is used in > place of "". > > I would love to be able to have a strict mode

Hi Eric, Nir. $SUBJECT - it's complicated! Imagine a scenario where we have extended the file plugin so you can point it at a directory and it will use the client-supplied export name to select a file to serve. Also we have extended the tar filter so that you can map tar file components into export names. You may be able to see where this is going ... Now we point the file plugin at a