我正在尝试编写一个小型应用程序,它在Mach上的“进程”之间发送消息(不是Mac OS,即使后者来自前者),这是我目前的代码:
#define _GNU_SOURCE
#include <mach.h>
#include <stdio.h>
#include <error.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <mach/port.h>
#include <mach/port.h>
#define MACH_MSG_PORT_DESCRIPTOR 0
#define PORT_NULL 1
static task_t child_task = MACH_PORT_NULL;
typedef unsigned int mach_msg_descriptor_type_t;
typedef unsigned int mach_msg_trailer_type_t;
typedef unsigned int mach_msg_trailer_size_t;
mach_port_t bootstrap_port = PORT_NULL;
typedef struct
{
mach_port_t name;
mach_msg_size_t pad1;
unsigned int pad2 : 16;
mach_msg_type_name_t disposition : 8;
mach_msg_descriptor_type_t type : 8;
} mach_msg_port_descriptor_t;
typedef struct
{
mach_msg_size_t msgh_descriptor_count;
} mach_msg_body_t;
typedef struct
{
mach_msg_trailer_type_t msgh_trailer_type;
mach_msg_trailer_size_t msgh_trailer_size;
} mach_msg_trailer_t;
#define CHECK_MACH_ERROR(err, msg) \
if (err != KERN_SUCCESS) { \
mach_error (msg, err); \
return -1; \
} \
static int
setup_recv_port (mach_port_t *recv_port)
{
kern_return_t err;
mach_port_t port = MACH_PORT_NULL;
err = mach_port_allocate (mach_task_self (),
MACH_PORT_RIGHT_RECEIVE, &port);
CHECK_MACH_ERROR (err, "mach_port_allocate failed:");
err = mach_port_insert_right (mach_task_self (),
port,
port,
MACH_MSG_TYPE_MAKE_SEND);
CHECK_MACH_ERROR (err, "mach_port_insert_right failed:");
*recv_port = port;
return 0;
}
static int
send_port (mach_port_t remote_port, mach_port_t port)
{
printf("Send Port\n");
kern_return_t err;
struct {
mach_msg_header_t header;
mach_msg_body_t body;
mach_msg_port_descriptor_t task_port;
} msg;
msg.header.msgh_remote_port = remote_port;
msg.header.msgh_local_port = MACH_PORT_NULL;
msg.header.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_COPY_SEND, 0) |
MACH_MSGH_BITS_COMPLEX;
msg.header.msgh_size = sizeof msg;
msg.body.msgh_descriptor_count = 1;
msg.task_port.name = port;
msg.task_port.disposition = MACH_MSG_TYPE_COPY_SEND;
msg.task_port.type = MACH_MSG_PORT_DESCRIPTOR;
err = mach_msg_send (&msg.header);
CHECK_MACH_ERROR (err, "mach_msg_send failed:");
return 0;
}
static int
recv_port (mach_port_t recv_port, mach_port_t *port)
{
kern_return_t err;
struct {
mach_msg_header_t header;
mach_msg_body_t body;
mach_msg_port_descriptor_t task_port;
mach_msg_trailer_t trailer;
} msg;
err = mach_msg (&msg.header, MACH_RCV_MSG,
0, sizeof msg, recv_port,
MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
CHECK_MACH_ERROR (err, "mach_msg failed:");
*port = msg.task_port.name;
return 0;
}
pid_t
sampling_fork ()
{
kern_return_t err;
mach_port_t parent_recv_port = MACH_PORT_NULL;
mach_port_t child_recv_port = MACH_PORT_NULL;
if (setup_recv_port (&parent_recv_port) != 0)
return -1;
err = task_set_bootstrap_port (mach_task_self (), parent_recv_port);
CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
pid_t pid;
switch (pid = fork ()) {
case -1:
err = mach_port_deallocate (mach_task_self(), parent_recv_port);
CHECK_MACH_ERROR (err, "mach_port_deallocate failed:");
return pid;
case 0: /* child */
err = task_get_bootstrap_port (mach_task_self (), &parent_recv_port);
CHECK_MACH_ERROR (err, "task_get_bootstrap_port failed:");
if (setup_recv_port (&child_recv_port) != 0)
return -1;
if (send_port (parent_recv_port, mach_task_self ()) != 0)
return -1;
if (send_port (parent_recv_port, child_recv_port) != 0)
return -1;
if (recv_port (child_recv_port, &bootstrap_port) != 0)
return -1;
err = task_set_bootstrap_port (mach_task_self (), bootstrap_port);
CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
break;
default: /* parent */
err = task_set_bootstrap_port (mach_task_self (), bootstrap_port);
CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
if (recv_port (parent_recv_port, &child_task) != 0)
return -1;
if (recv_port (parent_recv_port, &child_recv_port) != 0)
return -1;
if (send_port (child_recv_port, bootstrap_port) != 0)
return -1;
err = mach_port_deallocate (mach_task_self(), parent_recv_port);
CHECK_MACH_ERROR (err, "mach_port_deallocate failed:");
break;
}
return pid;
}
int main(void){
sampling_fork();
return 0;
}
运行代码时出现此错误:
mach_msg_send failed: (ipc/send) invalid destination port
有什么想法吗?