11:55 a.m.
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
11:58 a.m.
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"
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 :|
12:04 p.m.
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 LDFLAGS
A "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
12:06 p.m.
On Thu, Apr 23, 2020 at 06:04:20PM +0100, Richard W.M. Jones wrote:
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.
Ah I see then.
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.
You have three .go files which have the pkg-config stanza in them.
It is just combining them all and not bothering to eliminate duplicates
as they're harmless
> The installed nbdkit.pc would do this I presume. Or are you happy relying
> on the allow undefined symbols LDFLAGS
A "local" nbdkit.pc might indeed be better because we'd be using
pkg-config itself to parse the command line.
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 :|
12:09 p.m.
On Thu, Apr 23, 2020 at 06:06:12PM +0100, Daniel P. Berrangé wrote:
On Thu, Apr 23, 2020 at 06:04:20PM +0100, Richard W.M. Jones wrote:
> 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.
Ah I see then.
> 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.
You have three .go files which have the pkg-config stanza in them.
It is just combining them all and not bothering to eliminate duplicates
as they're harmless
Ah yes, good point!
Rich.
>
> > The installed nbdkit.pc would do this I presume. Or are you happy relying
> > on the allow undefined symbols LDFLAGS
>
> A "local" nbdkit.pc might indeed be better because we'd be using
> pkg-config itself to parse the command line.
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 Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/
12:24 p.m.
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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5 comments
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Richard W.M. Jones