I have issue when using cgo with c struct array.
My program as follow:
I have struct in c and contain a pointer to a c struct array.
In C, I provide a initialize function (take two parameter: the pointer to
the variable, the length of the array inside the variable) to malloc the
memory of the variable.
Then In go, I assign the value to this variable and assign value to the
array in variable. And in go , I call another C function to using this
variable.
After the C function handle it. Go pick up the variable again and return
to other Go function.
When I coded like this, I go a array like. type *C.struct does not support
indexing.
My code like follow.
C:
test.h
typedef struct
{
int profileCnt;
_profile *profile; //pointer to profile array
}_profiles;
// variable using in Go
typedef struct
{
int profileId;
_name userName;
char *dateOfBirth;
int stateFipsId;
}_profile;
typedef struct
{
char first[32];
char last[32];
} _name;
void initializeProfiles(_profiles *profiles, int profileCount, bool create);
int doSomething _In_C( _profiles *profiles, int log);
test.c
void initializeProfiles(_profiles *profiles, int profileCount, bool create)
{
profiles->profileCnt = profileCount; // initialize profiles struct &
profile[] Array
if (profileCount > 0)
{
if (create == true)
profiles->profile = malloc(profileCount * sizeof *profiles->profile + 1); //
allocate
memory for profiles[numProfiles]
for (int i = 0; i < profiles->profileCnt; i++)
initializeProfile(&profiles->profile[i], create);
if (create == false)
{
free(profiles->profile);
profiles->profileCnt = 0;
}
}
else
profiles->profile = NULL;
}
int doSomething _In_C( _profiles *profiles, int log)
{
/* ===========================================
*/ ==== did something to that variable============================
if (errStatus.code == _SUCCESS)
return(_SUCCESS);
else
return(FAILURE);
}
My GO code
package main
//#cgo CFLAGS: -std=c99 -ggdb3 -O0 -Wall
//#cgo CFLAGS: -I../../include/common
//#cgo LDFLAGS: -L string.h
//#cgo LDFLAGS: -lstdc++ -lpthread -lm -lc -lssl -lcrypto
//#include <stdio.h>
//#include <stdlib.h>
//#include "test.h"
import "C"
//import "unsafe"
func Test() {
log := 1 // sets logging level
numProfiles := 3
var profiles C._profiles
C.initializeProfiles(&profiles, C.int(numProfiles), C.bool(true))
profiles.profile[0].profileId = C.int(2)
profiles.profile[0].stateFipsId = "MD"
profiles.profile[0].userName.first = "test"
profiles.profile[0].userName.last = "test"
C.dosomething_In_C( &profiles,C.int(3))
C.initializeProfiles(&profiles, C.int(numProfiles), C.bool(false))
fmt.Println(int("get c variable and return")
}
When I compile in like this
profiles.profile[0].profileId = C.int(2)
I got error message : invalid operation: profiles.profile[0] (type
*C.struct___6 does not support indexing)
So, I try another solution. Transfer the c struct array form c to go. like
this
profile.profikes = (*[1 <<
30]C._profile)(unsafe.Pointer(&profiles.profile))[:numProfiles:numProfiles]
But get error like cannot use
(*[1073741824]C.struct___6)(unsafe.Pointer(&profiles.profile))[:numProfiles:numProfiles]
(type []C.struct___6) as type *C.struct___6 in assignment
and I afraid It create another piece of memory, when I call in
dosomething_In_C function, it can not get the data.
Is anyone know how to fix this?
Thank you
--
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.
For more options, visit https://groups.google.com/d/optout.
