Re: [go-nuts] Passing Struct from Go to C
Hi Andrey, I made the following changes as suggested by you: InitStruct := C.calloc(1, C.sizeof_struct_Foo) InitStruct.key_value_cb = C.callOnMeGo_cgo InitStruct.data = C.int(1) C.initialize_engine(pattern_db, module_path, (*C.Foo)(unsafe.Pointer(InitStruct))) Still Getting following error: Am i missing something? go build -v -x main.go cfuncs.go WORK=/tmp/go-build822337807 command-line-arguments mkdir -p $WORK/b001/ cd /home/nsaboo/Documents/goworkspace/src/poc pkg-config --cflags -- syslog-ng eventlog pkg-config --libs -- syslog-ng eventlog CGO_LDFLAGS='"-g" "-O2" "syslog-node.so" "-L/usr/local/lib/" "-lsyslog-ng" "-L/usr/local/lib/syslog-ng" "-ldbparser" "-L/usr/local/lib" "-Wl,--export-dynamic" "-lgmodule-2.0" "-pthread" "-lgthread-2.0" "-pthread" "-lglib-2.0" "-lsyslog-ng" "-lglib-2.0" "-levtlog"' /usr/local/go/pkg/tool/linux_amd64/cgo -objdir $WORK/b001/ -importpath command-line-arguments -- -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I $WORK/b001/ -g -O2 -I/usr/local/include/ ./main.go ./cfuncs.go cd $WORK gcc -fno-caret-diagnostics -c -x c - || true gcc -Qunused-arguments -c -x c - || true gcc -fdebug-prefix-map=a=b -c -x c - || true gcc -gno-record-gcc-switches -c -x c - || true cd $WORK/b001 TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x001.o -c _cgo_export.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x002.o -c main.cgo2.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x003.o -c cfuncs.cgo2.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_cgo_main.o -c _cgo_main.c cd /home/nsaboo/Documents/goworkspace/src/poc TERM='dumb' gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -o $WORK/b001/_cgo_.o $WORK/b001/_cgo_main.o $WORK/b001/_x001.o $WORK/b001/_x002.o $WORK/b001/_x003.o -g -O2 syslog-node.so -L/usr/local/lib/ -lsyslog-ng -L/usr/local/lib/syslog-ng -ldbparser -L/usr/local/lib -Wl,--export-dynamic -lgmodule-2.0 -pthread -lgthread-2.0 -pthread -lglib-2.0 -lsyslog-ng -lglib-2.0 -levtlog TERM='dumb' /usr/local/go/pkg/tool/linux_amd64/cgo -dynpackage main -dynimport $WORK/b001/_cgo_.o -dynout $WORK/b001/_cgo_import.go cat >$WORK/b001/importcfg << 'EOF' # internal # import config packagefile bufio=/usr/local/go/pkg/linux_amd64/bufio.a packagefile encoding/json=/usr/local/go/pkg/linux_amd64/encoding/json.a packagefile fmt=/usr/local/go/pkg/linux_amd64/fmt.a packagefile os=/usr/local/go/pkg/linux_amd64/os.a packagefile path=/usr/local/go/pkg/linux_amd64/path.a packagefile runtime=/usr/local/go/pkg/linux_amd64/runtime.a packagefile time=/usr/local/go/pkg/linux_amd64/time.a packagefile runtime/cgo=/usr/local/go/pkg/linux_amd64/runtime/cgo.a packagefile syscall=/usr/local/go/pkg/linux_amd64/syscall.a EOF /usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/b001/_pkg_.a -trimpath $WORK/b001 -p main -buildid 6VU9NC3t5EyTg_0nt_wU/6VU9NC3t5EyTg_0nt_wU -goversion go1.12.4 -D _/home/nsaboo/Documents/goworkspace/src/poc -importcfg $WORK/b001/importcfg -pack -c=2 $WORK/b001/_cgo_gotypes.go $WORK/b001/main.cgo1.go $WORK/b001/cfuncs.cgo1.go $WORK/b001/_cgo_import.go # command-line-arguments ./main.go:92:12: InitStruct.key_value_cb undefined (type unsafe.Pointer has no field or method key_value_cb) ./main.go:93:12: InitStruct.data undefined (type unsafe.Pointer has no field or method data) ./main.go:170:12: InitStruct.key_value_cb undefined (type unsafe.Pointer has no field or method key_value_cb) ./main.go:171:12: InitStruct.data undefined (type unsafe.Pointer has no field or method data) makefile:6: recipe for
Re: [go-nuts] Passing Struct from Go to C
the Go "Callback" struct may have completely different size and
alignment than the C.Foo one expected by C.initialize_engine.
therefore you want to construct the C version when calling
C.initialize_engine, and the Go version for everything else. Your call
may look something like this:
initStruct := C.calloc(1, sizeof(C.Foo))
initStruct.key_value_cb = C.callOnMeGo_cgo
initStrudct.data: C.int(1)
C.initialize_engine(pattern_db, module_path,
(*C.Foo)(unsafe.Pointer(initStruct)))
the Go Callback struct is not required unless you expect the callbacks
to change or be settable by library clients, in which case you'll need
to construct a more elaborate struct that implements locking and (at
least what I do) a map between callback names and interface{} pointing
to the callbacks sent by the library clients.
On Wed, Jul 10, 2019 at 8:14 AM Nitish Saboo wrote:
>
> Hi Andrey,
>
> I am new to Go and cgo therefore did not exactly understand your point.
> Can you explain me in the context of the code that I had posted.It will
> really help me to get hold of the things much better.
>
> Thanks,
> Nitish
>
> On Wed, Jul 10, 2019 at 5:19 PM andrey mirtchovski
> wrote:
>>
>> what i do is have a similar struct in Go, and the original C one. here
>> 'callbacks' is the go one, and
>> "type Engine C.struct_cl_engine" is the opaque C one:
>>
>> https://github.com/mirtchovski/clamav/blob/master/callback.go#L63
>>
>> On Wed, Jul 10, 2019 at 5:25 AM Nitish Saboo
>> wrote:
>> >
>> > Hi Andrey,
>> >
>> > I understand the issue here but how can I pass a callback function in a
>> > struct to C code.I need a struct because I want to pass and an extra
>> > parameter 'userdata' as well that I would require back as part of callback.
>> >
>> > Thanks,
>> > Nitish
>> >
>> > On Wed, Jul 10, 2019 at 4:39 PM andrey mirtchovski
>> > wrote:
>> >>
>> >> i don't think you can use a go function directly in the callback. you
>> >> need a correctly-typed C helper to do it. at least that used to be the
>> >> case. see examples:
>> >>
>> >> https://github.com/mirtchovski/clamav/blob/master/cfuncs.go
>> >> https://github.com/mirtchovski/clamav/blob/master/callback.go
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Re: [go-nuts] Passing Struct from Go to C
what i do is have a similar struct in Go, and the original C one. here 'callbacks' is the go one, and "type Engine C.struct_cl_engine" is the opaque C one: https://github.com/mirtchovski/clamav/blob/master/callback.go#L63 On Wed, Jul 10, 2019 at 5:25 AM Nitish Saboo wrote: > > Hi Andrey, > > I understand the issue here but how can I pass a callback function in a > struct to C code.I need a struct because I want to pass and an extra > parameter 'userdata' as well that I would require back as part of callback. > > Thanks, > Nitish > > On Wed, Jul 10, 2019 at 4:39 PM andrey mirtchovski > wrote: >> >> i don't think you can use a go function directly in the callback. you >> need a correctly-typed C helper to do it. at least that used to be the >> case. see examples: >> >> https://github.com/mirtchovski/clamav/blob/master/cfuncs.go >> https://github.com/mirtchovski/clamav/blob/master/callback.go -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAK4xykVRS61Z5d-60QKTtNm%2BGO2TNbWeteb6KGNQq0490f8BVw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
Re: [go-nuts] Passing Struct from Go to C
Hi Andrey, I understand the issue here but how can I pass a callback function in a struct to C code.I need a struct because I want to pass and an extra parameter 'userdata' as well that I would require back as part of callback. Thanks, Nitish On Wed, Jul 10, 2019 at 4:39 PM andrey mirtchovski wrote: > i don't think you can use a go function directly in the callback. you > need a correctly-typed C helper to do it. at least that used to be the > case. see examples: > > https://github.com/mirtchovski/clamav/blob/master/cfuncs.go > https://github.com/mirtchovski/clamav/blob/master/callback.go > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CALjMrq7Xsz7PB3T3SpZD%3Dg%3DtXahAPMjo7k77HGmDkDKf2_p_bQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
Re: [go-nuts] Passing Struct from Go to C
i don't think you can use a go function directly in the callback. you need a correctly-typed C helper to do it. at least that used to be the case. see examples: https://github.com/mirtchovski/clamav/blob/master/cfuncs.go https://github.com/mirtchovski/clamav/blob/master/callback.go -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAK4xykXyfti3P-49W-jbM9s_Jssb6m0w_FvN7JM6%3DR1s8mdGcg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
Re: [go-nuts] Passing Struct from Go to C
Hi Tamas,
I made it *C.Foo but still getting the error.
main.go
===
type Callback struct {
Func func(*C.char , *C.char , C.size_t, C.int)
UserData int32
}
Calling C code in the following manner
=
C.initialize_engine(pattern_db, module_path,
(*C.Foo)(unsafe.Pointer({
Func: C.callOnMeGo_cgo
UserData: C.int(1),
})))
//export ParsedData
func ParsedData(key *C.char, value *C.char, value_len C.size_t, work C.int)
{
fmt.Println("WORK:")
fmt.Print()
//performing some operation here
}
cfunc.go
=
package main
/*
#include
// The gateway function
void callOnMeGo_cgo(char *key, char *value, size_t value_len, int work)
{
//printf("C.callOnMeGo_cgo(): called");
void ParsedData(const char *key, const char *value, size_t value_len, int
work);
ParsedData(key, value, value_len, work);
}
*/
import "C"
syslog-node.h
===
#ifndef _TEST_H_
#define _TEST_H_
#include
typedef void (*key_value_cb)(const char* key, const char* value, size_t
value_len, int work);
typedef struct Foo{
key_value_cb cbnitish;
int data;
}Foo;
int initialize_engine(const char* filename, const char* module_path, Foo
*cb);
int reload_pattern_db(const char* filename, Foo *cb);
#endif
syslog-node.c
===
gboolean pdbtool_accumulate_fields(NVHandle handle, const gchar *name,
const gchar *value, gssize length, gpointer user_data)
{
user_data->cbnitish(name, value, length, user_data->data);// Callback
happening here
return FALSE;
}
Eventually user_data will get the instance of the struct.
Looks like there is some issue with my struct declaration in Go.Can some
please guide me as in what is the issue ?
Error:
go build -v -x main.go cfuncs.go
WORK=/tmp/go-build037176041
command-line-arguments
mkdir -p $WORK/b001/
cd /home/nsaboo/Documents/goworkspace/src/poc
pkg-config --cflags -- syslog-ng eventlog
pkg-config --libs -- syslog-ng eventlog
CGO_LDFLAGS='"-g" "-O2" "syslog-node.so" "-L/usr/local/lib/" "-lsyslog-ng"
"-L/usr/local/lib/syslog-ng" "-ldbparser" "-L/usr/local/lib"
"-Wl,--export-dynamic" "-lgmodule-2.0" "-pthread" "-lgthread-2.0"
"-pthread" "-lglib-2.0" "-lsyslog-ng" "-lglib-2.0" "-levtlog"'
/usr/local/go/pkg/tool/linux_amd64/cgo -objdir $WORK/b001/ -importpath
command-line-arguments -- -I/usr/local/include/syslog-ng
-I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I
$WORK/b001/ -g -O2 -I/usr/local/include/ ./main.go ./cfuncs.go
cd $WORK
gcc -fno-caret-diagnostics -c -x c - || true
gcc -Qunused-arguments -c -x c - || true
gcc -fdebug-prefix-map=a=b -c -x c - || true
gcc -gno-record-gcc-switches -c -x c - || true
cd $WORK/b001
TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64
-pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build
-gno-record-gcc-switches -I/usr/local/include/syslog-ng
-I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./
-g -O2 -I/usr/local/include/ -o ./_x001.o -c _cgo_export.c
TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64
-pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build
-gno-record-gcc-switches -I/usr/local/include/syslog-ng
-I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./
-g -O2 -I/usr/local/include/ -o ./_x002.o -c main.cgo2.c
TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64
-pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build
-gno-record-gcc-switches -I/usr/local/include/syslog-ng
-I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./
-g -O2 -I/usr/local/include/ -o ./_x003.o -c cfuncs.cgo2.c
TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64
-pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build
-gno-record-gcc-switches -I/usr/local/include/syslog-ng
-I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./
-g -O2 -I/usr/local/include/ -o ./_cgo_main.o -c _cgo_main.c
cd /home/nsaboo/Documents/goworkspace/src/poc
TERM='dumb' gcc -I . -fPIC -m64 -pthread -fmessage-length=0
-fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -o
$WORK/b001/_cgo_.o $WORK/b001/_cgo_main.o $WORK/b001/_x001.o
$WORK/b001/_x002.o $WORK/b001/_x003.o -g -O2 syslog-node.so
-L/usr/local/lib/ -lsyslog-ng -L/usr/local/lib/syslog-ng -ldbparser
-L/usr/local/lib -Wl,--export-dynamic -lgmodule-2.0 -pthread -lgthread-2.0
-pthread -lglib-2.0 -lsyslog-ng -lglib-2.0 -levtlog
TERM='dumb' /usr/local/go/pkg/tool/linux_amd64/cgo -dynpackage main
-dynimport $WORK/b001/_cgo_.o -dynout $WORK/b001/_cgo_import.go
cat >$WORK/b001/importcfg <<
Re: [go-nuts] Passing Struct from Go to C
*C.foo -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/32a3a3c6-78e2-492d-9542-8a1c29deb600%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [go-nuts] Passing Struct from Go to C
Hi, Looks like I was able to resolve the C error.I am getting the following Go error while running 'make' command: gcc -L/usr/local/lib -lsyslog-ng -o syslog-node.so -L/usr/local/lib/syslog-ng -ldbparser -c `pkg-config --libs --cflags glib-2.0` -I/usr/local/include/syslog-ng/ -I./syslog-ng-3.6.2/ -I/usr/local/include/eventlog/ syslog-node.c go build -v -x main.go cfuncs.go WORK=/tmp/go-build873967443 command-line-arguments mkdir -p $WORK/b001/ cd /home/nsaboo/Documents/goworkspace/src/poc pkg-config --cflags -- syslog-ng eventlog pkg-config --libs -- syslog-ng eventlog CGO_LDFLAGS='"-g" "-O2" "syslog-node.so" "-L/usr/local/lib/" "-lsyslog-ng" "-L/usr/local/lib/syslog-ng" "-ldbparser" "-L/usr/local/lib" "-Wl,--export-dynamic" "-lgmodule-2.0" "-pthread" "-lgthread-2.0" "-pthread" "-lglib-2.0" "-lsyslog-ng" "-lglib-2.0" "-levtlog"' /usr/local/go/pkg/tool/linux_amd64/cgo -objdir $WORK/b001/ -importpath command-line-arguments -- -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I $WORK/b001/ -g -O2 -I/usr/local/include/ ./main.go ./cfuncs.go cd $WORK gcc -fno-caret-diagnostics -c -x c - || true gcc -Qunused-arguments -c -x c - || true gcc -fdebug-prefix-map=a=b -c -x c - || true gcc -gno-record-gcc-switches -c -x c - || true cd $WORK/b001 TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x001.o -c _cgo_export.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x002.o -c main.cgo2.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_x003.o -c cfuncs.cgo2.c TERM='dumb' gcc -I /home/nsaboo/Documents/goworkspace/src/poc -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -I/usr/local/include/syslog-ng -I/usr/local/include/syslog-ng/ivykis -I/usr/local/include/eventlog -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ./ -g -O2 -I/usr/local/include/ -o ./_cgo_main.o -c _cgo_main.c cd /home/nsaboo/Documents/goworkspace/src/poc TERM='dumb' gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=$WORK/b001=/tmp/go-build -gno-record-gcc-switches -o $WORK/b001/_cgo_.o $WORK/b001/_cgo_main.o $WORK/b001/_x001.o $WORK/b001/_x002.o $WORK/b001/_x003.o -g -O2 syslog-node.so -L/usr/local/lib/ -lsyslog-ng -L/usr/local/lib/syslog-ng -ldbparser -L/usr/local/lib -Wl,--export-dynamic -lgmodule-2.0 -pthread -lgthread-2.0 -pthread -lglib-2.0 -lsyslog-ng -lglib-2.0 -levtlog TERM='dumb' /usr/local/go/pkg/tool/linux_amd64/cgo -dynpackage main -dynimport $WORK/b001/_cgo_.o -dynout $WORK/b001/_cgo_import.go cat >$WORK/b001/importcfg << 'EOF' # internal # import config packagefile bufio=/usr/local/go/pkg/linux_amd64/bufio.a packagefile encoding/json=/usr/local/go/pkg/linux_amd64/encoding/json.a packagefile fmt=/usr/local/go/pkg/linux_amd64/fmt.a packagefile os=/usr/local/go/pkg/linux_amd64/os.a packagefile path=/usr/local/go/pkg/linux_amd64/path.a packagefile runtime=/usr/local/go/pkg/linux_amd64/runtime.a packagefile time=/usr/local/go/pkg/linux_amd64/time.a packagefile runtime/cgo=/usr/local/go/pkg/linux_amd64/runtime/cgo.a packagefile syscall=/usr/local/go/pkg/linux_amd64/syscall.a EOF /usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/b001/_pkg_.a -trimpath $WORK/b001 -p main -buildid hIEYVdT7igzjOGrFONpW/hIEYVdT7igzjOGrFONpW -goversion go1.12.4 -D _/home/nsaboo/Documents/goworkspace/src/poc -importcfg $WORK/b001/importcfg -pack -c=2 $WORK/b001/_cgo_gotypes.go $WORK/b001/main.cgo1.go $WORK/b001/cfuncs.cgo1.go $WORK/b001/_cgo_import.go # command-line-arguments ./main.go:91:57: cannot convert unsafe.Pointer(*Callback literal) (type unsafe.Pointer) to type _Ctype_struct_Foo ./main.go:91:84: cannot use _Cgo_ptr(_Cfpvar_fp_callOnMeGo_cgo) (type unsafe.Pointer) as type func(*_Ctype_char, *_Ctype_char, _Ctype_ulong, _Ctype_int) in field value ./main.go:91:128: cannot use _Ctype_int(1) (type _Ctype_int) as type int32 in field value ./main.go:166:66: cannot convert
[go-nuts] Passing Struct from Go to C
Hi,
I am trying to pass a Struct from Go to C (this is cgo).I m passing a
callback function in that struct that will be called from C code to Go.
main.go
===
type Callback struct {
Func func(*C.char , *C.char , C.size_t, C.int)
UserData int32
}
Calling C code in the following manner
=
C.initialize_engine(pattern_db, module_path,
(C.Foo)(unsafe.Pointer({
Func: C.callOnMeGo_cgo,
UserData: C.int(1),
})))
//export ParsedData
func ParsedData(key *C.char, value *C.char, value_len C.size_t, work C.int)
{
fmt.Println("WORK:")
fmt.Print()
//performing some operation here
}
cfunc.go
=
package main
/*
#include
// The gateway function
void callOnMeGo_cgo(char *key, char *value, size_t value_len, int work)
{
//printf("C.callOnMeGo_cgo(): called");
void ParsedData(const char *key, const char *value, size_t value_len, int
work);
ParsedData(key, value, value_len, work);
}
*/
import "C"
syslog-node.h
===
#ifndef _TEST_H_
#define _TEST_H_
#include
typedef void (*key_value_cb)(const char* key, const char* value, size_t
value_len, int work);
typedef struct Foo{
key_value_cb cbnitish;
int data;
}Foo;
int initialize_engine(const char* filename, const char* module_path, Foo
*cb);
int reload_pattern_db(const char* filename, Foo *cb);
#endif
syslog-node.c
===
gboolean pdbtool_accumulate_fields(NVHandle handle, const gchar *name,
const gchar *value, gssize length, gpointer user_data)
{
user_data->cbnitish(name, value, length, user_data->data);// Callback
happening here
return FALSE;
}
Eventually user_data will get the instance of the struct.
Getting following error during make command:
==
nsaboo@ubuntu:~/Documents/goworkspace/src/poc$ make
gcc -L/usr/local/lib -lsyslog-ng -o syslog-node.so
-L/usr/local/lib/syslog-ng -ldbparser -c `pkg-config --libs --cflags
glib-2.0` -I/usr/local/include/syslog-ng/ -I./syslog-ng-3.6.2/
-I/usr/local/include/eventlog/ syslog-node.c
syslog-node.c: In function ‘pdbtool_accumulate_fields’:
syslog-node.c:33:12: warning: dereferencing ‘void *’ pointer
user_data->cbnitish(name, value, length, user_data->data);
^~
syslog-node.c:33:12: error: request for member ‘cbnitish’ in something not
a structure or union
syslog-node.c:33:53: warning: dereferencing ‘void *’ pointer
user_data->cbnitish(name, value, length, user_data->data);
^~
syslog-node.c:33:53: error: request for member ‘data’ in something not a
structure or union
makefile:12: recipe for target 'syslog-node.so' failed
make: *** [syslog-node.so] Error 1
Can someone please guide me here ?
Thanks,
Nitish
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