Hi Folks, I'm having some trouble instantiating a C struct from a 3rd party
API.
I'm not sure if this is more a C question or a Go question, details in the
code below, any help would be much appreciated!
M
// This non-compiling example demonstrates an issue I'm having integrating
a 3rd party C api with my Go code
// The comment preceding 'import "C"' constitutes C code which is
interpreted as a header when compiling.
// 'api_struct' represents the 3rd party struct I'm attempting to
instantiate and populate in my Go Code
// we cannot make changes to this struct
// other c functions in the comment are helper functions I've written to
instantiate certain C types
// The go code defines an array of strings and an array of ints. For each
of these arrays a helper
// function is called to create a C array of the C equivalent type before
populating that array.
// Once C arrays have been populated they are assigned to fields in the a
new api_struct.
// This method works fine for the string array, but compile fails when we
get to the int array
// This is because makeIntArray returns *_Ctype_int but api_struct.rLimits
expects [12]_Ctype_int. Here's the error...
// cannot use cInts (type *_Ctype_int) as type [12]_Ctype_int in field value
// I'd like to modify makeIntArray to return a [12]_Ctype_int but I can't
seem to find the right syntax to achieve this
package main
/*
#define ARRLEN 12
#include <stdlib.h>
struct api_struct {
char **askedHosts;
int rLimits[ARRLEN];
};
static char**makeCharArray(int size) {
return calloc(sizeof(char*), size);
}
static void setArrayString(char **a, char *s, int n) {
a[n] = s;
}
static void freeCharArray(char **a, int size) {
int i;
for (i = 0; i < size; i++)
free(a[i]);
free(a);
}
static int*makeIntArray() {
int* p = malloc(sizeof(p) * ARRLEN);
return p;
}
static void setArrayInt(int *a, int s, int n) {
a[n] = s;
}
static void freeIntArray(int *a, int size) {
free(a);
}
*/
import "C"
import "fmt"
func main() {
goHosts := []string{"host1", "host2", "host3"}
cHosts := C.makeCharArray(C.int(len(goHosts)))
for i, s := range goHosts {
C.setArrayString(cHosts, C.CString(s), C.int(i))
}
goLimits := []int{1,2,3,4,5,6,7,8,9,10,11,12}
cInts := C.makeIntArray()
for i, s := range goLimits {
C.setArrayInt(cInts, C.int(s), C.int(i))
}
s := C.struct_api_struct{
askedHosts: cHosts,
rLimits: cInts,
}
fmt.Printf("%+v\n", s)
}
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