Richard W.M. Jones
2020-Apr-23 16:55 UTC
[Libguestfs] [PATCH nbdkit] golang: Compile against the local nbdkit build, not installed.
When compiling when an older nbdkit is installed, the build would fail because certain symbols such as .get_ready were not defined: ../../src/libguestfs.org/nbdkit/nbdkit.go:541:8: plugin.get_ready undefined (type _Ctype_struct_nbdkit_plugin has no field or method get_ready) This happens because we were using the installed <nbdkit-plugin.h> rather than the local copy. We don't want to modify the *.go files themselves as they might be copied into other projects. Instead we can set PKG_CONFIG to point to a fake pkg-config binary which will return the correct CFLAGS. Fixes: commit 1ff44288ae1cf95428283e252edd9474c3fe3b55 Thanks: Dan Berrangé, Eric Blake --- .gitignore | 1 + configure.ac | 2 ++ plugins/golang/Makefile.am | 4 +++ plugins/golang/golang-pkgconf.sh.in | 40 +++++++++++++++++++++++++++++ 4 files changed, 47 insertions(+) diff --git a/.gitignore b/.gitignore index 4f6fcf1b..bda3b05a 100644 --- a/.gitignore +++ b/.gitignore @@ -74,6 +74,7 @@ plugins/*/*.3 /plugins/eval/methods.c /plugins/golang/examples/*/nbdkit-*-plugin.h /plugins/golang/examples/*/nbdkit-*-plugin.so +/plugins/golang/golang-pkgconf.sh /plugins/golang/test/nbdkit-gotest-plugin.h /plugins/golang/test/nbdkit-gotest-plugin.so /plugins/ocaml/nbdkit-ocamlexample-plugin.so diff --git a/configure.ac b/configure.ac index b71d9d8c..405890f5 100644 --- a/configure.ac +++ b/configure.ac @@ -1007,6 +1007,8 @@ AC_CONFIG_FILES([podwrapper.pl], [chmod +x,-w podwrapper.pl]) AC_CONFIG_FILES([common/protocol/generate-protostrings.sh], [chmod +x,-w common/protocol/generate-protostrings.sh]) +AC_CONFIG_FILES([plugins/golang/golang-pkgconf.sh], + [chmod +x,-w plugins/golang/golang-pkgconf.sh]) AC_CONFIG_FILES([Makefile bash/Makefile common/bitmap/Makefile diff --git a/plugins/golang/Makefile.am b/plugins/golang/Makefile.am index f189184c..60539229 100644 --- a/plugins/golang/Makefile.am +++ b/plugins/golang/Makefile.am @@ -66,18 +66,21 @@ noinst_DATA = \ examples/dump-plugin/nbdkit-godump-plugin.so: \ $(plugin_sources) examples/dump-plugin/dumpplugin.go cd examples/dump-plugin && \ + PKG_CONFIG=$(abs_builddir)/golang-pkgconf.sh \ GOPATH="$(abs_builddir)" \ $(GOLANG) build -o nbdkit-godump-plugin.so -buildmode=c-shared examples/minimal/nbdkit-gominimal-plugin.so: \ $(plugin_sources) examples/minimal/minimal.go cd examples/minimal && \ + PKG_CONFIG=$(abs_builddir)/golang-pkgconf.sh \ GOPATH="$(abs_builddir)" \ $(GOLANG) build -o nbdkit-gominimal-plugin.so -buildmode=c-shared examples/ramdisk/nbdkit-goramdisk-plugin.so: \ $(plugin_sources) examples/ramdisk/ramdisk.go cd examples/ramdisk && \ + PKG_CONFIG=$(abs_builddir)/golang-pkgconf.sh \ GOPATH="$(abs_builddir)" \ $(GOLANG) build -o nbdkit-goramdisk-plugin.so -buildmode=c-shared @@ -87,6 +90,7 @@ check_DATA = test/nbdkit-gotest-plugin.so test/nbdkit-gotest-plugin.so: $(plugin_sources) test/test.go cd test && \ + PKG_CONFIG=$(abs_builddir)/golang-pkgconf.sh \ GOPATH="$(abs_builddir)" \ $(GOLANG) build -o nbdkit-gotest-plugin.so -buildmode=c-shared diff --git a/plugins/golang/golang-pkgconf.sh.in b/plugins/golang/golang-pkgconf.sh.in new file mode 100644 index 00000000..11af3718 --- /dev/null +++ b/plugins/golang/golang-pkgconf.sh.in @@ -0,0 +1,40 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright (C) 2020 Red Hat Inc. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +# This fake pkg-config program is used to trick cgo so that +# "#cgo pkg-config nbdkit" lines are processed relative to the local +# directory and not the installed nbdkit. + +case "$1" in + --cflags*) echo "-I@abs_top_builddir@/include" ;; + *) ;; +esac -- 2.18.2
Daniel P. Berrangé
2020-Apr-23 16:58 UTC
Re: [Libguestfs] [PATCH nbdkit] golang: Compile against the local nbdkit build, not installed.
On Thu, Apr 23, 2020 at 05:55:14PM +0100, Richard W.M. Jones wrote:> When compiling when an older nbdkit is installed, the build would fail > because certain symbols such as .get_ready were not defined: > > ../../src/libguestfs.org/nbdkit/nbdkit.go:541:8: plugin.get_ready undefined (type _Ctype_struct_nbdkit_plugin has no field or method get_ready) > > This happens because we were using the installed <nbdkit-plugin.h> > rather than the local copy. > > We don't want to modify the *.go files themselves as they might be > copied into other projects. Instead we can set PKG_CONFIG to point to > a fake pkg-config binary which will return the correct CFLAGS. > > Fixes: commit 1ff44288ae1cf95428283e252edd9474c3fe3b55 > Thanks: Dan Berrangé, Eric Blake> +# This fake pkg-config program is used to trick cgo so that > +# "#cgo pkg-config nbdkit" lines are processed relative to the local > +# directory and not the installed nbdkit. > + > +case "$1" in > + --cflags*) echo "-I@abs_top_builddir@/include" ;; > + *) ;; > +esacDon't you need something like this too: --libs) echo "-L@abs_top_builddir@/lib -lnbdkit" The installed nbdkit.pc would do this I presume. Or are you happy relying on the allow undefined symbols LDFLAGS Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
Richard W.M. Jones
2020-Apr-23 17:04 UTC
Re: [Libguestfs] [PATCH nbdkit] golang: Compile against the local nbdkit build, not installed.
On Thu, Apr 23, 2020 at 05:58:25PM +0100, Daniel P. Berrangé wrote:> On Thu, Apr 23, 2020 at 05:55:14PM +0100, Richard W.M. Jones wrote: > > When compiling when an older nbdkit is installed, the build would fail > > because certain symbols such as .get_ready were not defined: > > > > ../../src/libguestfs.org/nbdkit/nbdkit.go:541:8: plugin.get_ready undefined (type _Ctype_struct_nbdkit_plugin has no field or method get_ready) > > > > This happens because we were using the installed <nbdkit-plugin.h> > > rather than the local copy. > > > > We don't want to modify the *.go files themselves as they might be > > copied into other projects. Instead we can set PKG_CONFIG to point to > > a fake pkg-config binary which will return the correct CFLAGS. > > > > Fixes: commit 1ff44288ae1cf95428283e252edd9474c3fe3b55 > > Thanks: Dan Berrangé, Eric Blake > > > +# This fake pkg-config program is used to trick cgo so that > > +# "#cgo pkg-config nbdkit" lines are processed relative to the local > > +# directory and not the installed nbdkit. > > + > > +case "$1" in > > + --cflags*) echo "-I@abs_top_builddir@/include" ;; > > + *) ;; > > +esac > > Don't you need something like this too: > > --libs) echo "-L@abs_top_builddir@/lib -lnbdkit"We don't actually have "libnbdkit". It was proposed a while back but we didn't get sufficient review feedback, and the code was very complex and unmaintainable so it never made it upstream. cgo currently issues the following two commands: $PKG_CONFIG --cflags -- nbdkit nbdkit nbdkit $PKG_CONFIG --libs -- nbdkit nbdkit nbdkit and yes I also don't know why it prints the package name 3 times.> The installed nbdkit.pc would do this I presume. Or are you happy relying > on the allow undefined symbols LDFLAGSA "local" nbdkit.pc might indeed be better because we'd be using pkg-config itself to parse the command line. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top
Eric Blake
2020-Apr-23 17:24 UTC
Re: [Libguestfs] [PATCH nbdkit] golang: Compile against the local nbdkit build, not installed.
On 4/23/20 11:58 AM, Daniel P. Berrangé wrote:> On Thu, Apr 23, 2020 at 05:55:14PM +0100, Richard W.M. Jones wrote: >> When compiling when an older nbdkit is installed, the build would fail >> because certain symbols such as .get_ready were not defined: >> >> ../../src/libguestfs.org/nbdkit/nbdkit.go:541:8: plugin.get_ready undefined (type _Ctype_struct_nbdkit_plugin has no field or method get_ready) >> >> This happens because we were using the installed <nbdkit-plugin.h> >> rather than the local copy. >> >> We don't want to modify the *.go files themselves as they might be >> copied into other projects. Instead we can set PKG_CONFIG to point to >> a fake pkg-config binary which will return the correct CFLAGS. >> >> Fixes: commit 1ff44288ae1cf95428283e252edd9474c3fe3b55 >> Thanks: Dan Berrangé, Eric Blake > >> +# This fake pkg-config program is used to trick cgo so that >> +# "#cgo pkg-config nbdkit" lines are processed relative to the local >> +# directory and not the installed nbdkit. >> + >> +case "$1" in >> + --cflags*) echo "-I@abs_top_builddir@/include" ;; >> + *) ;; >> +esac > > Don't you need something like this too: > > --libs) echo "-L@abs_top_builddir@/lib -lnbdkit"Also, if you're installing this in PATH prior to the real pkg-config, shouldn't you start by checking whether 'nbdkit' is one of the arguments? If so, fall through to the 'case "$1"' code, if not, short-circuit into 'exec /path/to/pkg-config "$@"', so that whatever _other_ pkg-config queries cgo makes will be answered as usual? -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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