func GetPriv(ctx uintptr, privatedata interface{}) int {
/* Retrieve the private data stored by the milter
Retrieving the data will release the memory allocated for it
Don't try to retrieve it again unless you call SetPriv first
*/
// Call libmilter smfi_getpriv to get a pointer to our data
CArray := (*byte)(C.smfi_getpriv(int2ctx(ctx)))
// Make sure data has been set with a previous call to SetPriv
if CArray == nil {
return -1
}
// Read uint32 size bytes from the start of the pointer
var length uint32
lengthsize := unsafe.Sizeof(length)
lengthbytes := make([]byte, lengthsize)
lenStart := uintptr(unsafe.Pointer(CArray))
seqStart := lenStart + uintptr(lengthsize)
for i := uintptr(0); i < uintptr(lengthsize); i++ {
CArray = (*byte)(unsafe.Pointer(lenStart + i))
lengthbytes[i] = *CArray
}
// Binary decode the length bytes
buf := bytes.NewBuffer(lengthbytes)
err := binary.Read(buf, binary.BigEndian, &length)
if err != nil {
return -1
}
// Read byte sequence of data
databytes := make([]byte, length)
for i := uintptr(0); i < uintptr(length); i++ {
CArray = (*byte)(unsafe.Pointer(seqStart + i))
databytes[i] = *CArray
}
// Free the data malloc'ed by C
C.free(unsafe.Pointer(lenStart))
C.smfi_setpriv(int2ctx(ctx), nil)
// Unserialize the data bytes back into a data structure
err = GobDecode(databytes, privatedata)
if err != nil {
return -1
}
return 0
}
// See also: http://bit.ly/1HVWA9I
func SetPriv(ctx uintptr, privatedata interface{}) int {
// privatedata seems to work for any data type
// Structs must have exported fields
// Serialize Go privatedata into a byte slice
bytedata, _ := GobEncode(privatedata)
// length and size
// length is a uint32 (usually 4 bytes)
// the length will be stored in front of the byte sequence
length := uint32(len(bytedata))
lengthsize := C.size_t(unsafe.Sizeof(length))
buf := new(bytes.Buffer)
err := binary.Write(buf, binary.BigEndian, length)
if err != nil {
return -1
}
lengthbytes := buf.Bytes()
// Allocate memory for the length and byte sequence
CArray := (*C.uchar)(C.malloc(lengthsize + C.size_t(length)))
var lenStart, seqStart uintptr
lenStart = uintptr(unsafe.Pointer(CArray))
seqStart = lenStart + uintptr(lengthsize)
CArray = (*C.uchar)(unsafe.Pointer(lenStart))
for i := uintptr(0); i < uintptr(lengthsize); i++ {
CArray = (*C.uchar)(unsafe.Pointer(lenStart + i))
*CArray = C.uchar(lengthbytes[i])
}
// Now copy the data bytes to the position after the length
for i := uintptr(0); i < uintptr(length); i++ {
CArray = (*C.uchar)(unsafe.Pointer(seqStart + i))
*CArray = C.uchar(bytedata[i])
}
// Call libmilter smfi_setpriv
type CtxPtr *C.struct_smfi_str
return int(C.smfi_setpriv(int2ctx(ctx), unsafe.Pointer(lenStart)))
}