similar to: [nbdkit PATCH v2 0/6] bind .zero to Python

This cleans up the existing code base with regards to implicit use of errno from language bindings, then rebases the previous work in python on top of that. I'm still playing with the perl bindings, but got further after reading 'perldoc perlembed'. Eric Blake (4): plugins: Don't use bogus errno from non-C plugins plugins: Add new nbdkit_set_error() utility function python:

And fill out most of the missing bits of the API. Rich.

v1: https://www.redhat.com/archives/libguestfs/2019-November/msg00153.html v2: - Fix implementation of can_cache. - Add implementation of can_fua. - Add a very thorough test suite which tests every command + flag combination.

First out of our four language bindings to add FUA support (for reference, I added 'zero' support for python, perl, and ruby back in 1.1.13, then Rich had to add it for ocaml in 1.1.20). I tested this heavily under python 2, but for now only compile tested under python 3; I plan to do further testing there and make any tweaks if necessary. I wrote patch 5 early on, but then realized I

As mentioned in my reviews, I wonder if we should make our python callbacks look a bit more Pythonic by having kwargs added for each new flag that we want to expose. The idea was first floated here: https://www.redhat.com/archives/libguestfs/2018-April/msg00108.html Note that with my proposal, there is no need for a python script to expose a global API_VERSION variable; new flags are added

I noticed these while working on adding fua support into python, these are independent enough to push now (and I'll have to rebase my 'optional may_trim' patch on top of this). Eric Blake (2): python: Use Py_XDEFREF() python: Simplify calling into plugin plugins/python/python.c | 106 ++++++++---------------------------------------- 1 file changed, 18 insertions(+), 88

v3 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00209.html In v4: - Rebase on top of current master. Includes various fixes and updates required because of Nir's patches that went into master. - Fix api_version() -> API_VERSION in patch 2 noted previously on the mailing list. Rich.

v2 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00163.html I pushed patch 1 (with spelling fix), patch 4 and patch 5 since those were previously ACKed on the list. Differences in v3: - Add error checking to PyModule_AddIntConstant. - Use API_VERSION constant instead of function. - Add max API version supported to --dump-plugin output. - Print API_VERSION selected by

In preparation for adding other optional flag arguments to the python bindings, start by making the existing 'may_trim' flag to 'zero' be optional. That is, the plugin need not define the parameter if it does not make any semantic difference (ie. if the plugin ignores the hint and never trims); while if the parameter exists, we now pass it as a keyword argument rather than as a

Begin the language binding followups to my new .zero callback, since Rich was indeed correct that we want them. I'm more familiar with python and perl (at least to the point that I was able to modify the appropriate example files and prove to myself that the bindings worked), so I've started with those. I'm less familiar with ruby and ocaml, so I've left those for tomorrow (it

Similar to python and perl. But MUCH easier (especially considering that this is the first time I've every tried to run Ruby). I even had fun making set_error() polymorphic. Eric Blake (2): ruby: Expose nbdkit_set_error to ruby script ruby: Support zero callback plugins/ruby/example.rb | 11 ++++++++ plugins/ruby/nbdkit-ruby-plugin.pod | 54

Requires patch 1 and 2 of the python series: https://www.redhat.com/archives/libguestfs/2017-January/msg00126.html This is the perl implementation along the same lines. We still haven't decided if patch 1 of the python series should change OCaml to report errno as reliable or not, but perhaps we can commit that patch as-is now and then touch things up further when we actually get set_error

I ran into these while trying to prepare patches to add NBD_CMD_FLAG_FAST_ZERO, which will expose a new NBD_ENOTSUP wire value. Eric Blake (2): plugins: Don't lose original error when emulating FUA plugins: Permit ENOTSUP as synonym for EOPNOTSUPP docs/nbdkit-filter.pod | 11 ++++++----- docs/nbdkit-plugin.pod | 12 +++++++----- plugins/file/file.c | 16 +++++++++++-----

See patch 1 for rationale.

Add a python language binding for the .zero callback, used for implementing NBD_CMD_WRITE_ZEROES. The caller doesn't have to return anything, but should use nbdkit.set_error(errno.EOPNOTSUPP) to get an automatic fallback to pwrite. Enhance the example to show the use of the fallback mechanism, and to serve as a test of nbdkit.set_error(). Signed-off-by: Eric Blake <eblake@redhat.com>

This is working for me now, although possibly only on Python 3.9. Dan suggested PyEval_InitThreads but that was deprecated in Python 3.7. Rich.

Add a python language binding for the .zero callback, used for implementing NBD_CMD_WRITE_ZEROES. The caller doesn't have to return anything, but should use nbdkit.set_error(errno.EOPNOTSUPP) to get an automatic fallback to pwrite. Enhance the example to show the use of the fallback mechanism, and to serve as a test of nbdkit.set_error(). Signed-off-by: Eric Blake <eblake@redhat.com>

On 11/22/19 3:20 PM, Nir Soffer wrote: >>> +# There are several variants of the API. nbdkit will call this >>> +# function first to determine which one you want to use. This is the >>> +# latest version at the time this example was written. >>> +def api_version(): >>> + return 2 >> >> Matches the C counterpart of #define

POD errors are not nice, and 'pod2man --stderr' does not do what we want. Eric Blake (2): perl: Fix previous patches build: Kill build on POD error .gitignore | 2 ++ configure.ac | 10 +--------- docs/Makefile.am | 8 ++++++-- docs/nbdkit-plugin.pod | 2 +- plugins/curl/Makefile.am | 4 +++-

When I added .can_FOO caching in 1.16, I missed the case that the sh plugin itself was calling .can_flush twice in some situations (in order to default .can_fua). Then right after, I regressed it to call .can_zero twice (in order to default .can_fast_zero). I also missed that .thread_model could use better caching, because at the time, I did not add testsuite coverage. Fix that now. Eric Blake