第6课第4节_Binder系统_驱动情景分析_服务注册过程_分析

Service_manager.c 8074 2017/6/30

首先从应用程序分析（Android）

   binder_loop(bs, svcmgr_handler)

{

  readbuf[0] = BC_ENTER_LOOPER;

    res = ioctl(bs->fd, BINDER_WRITE_READ, &bwr); /导致驱动程序的ioctl调用-------》会创建一个binder_thread 
}

Binder.c (linux-3.0.86driversstagingandroid) 105029 2015/3/24

static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{

两个重要的结构体：

struct binder_proc *proc = filp->private_data;
struct binder_thread *thread;

一个重要的函数：

thread = binder_get_thread(proc);

switch (cmd) {
case BINDER_WRITE_READ: {
struct binder_write_read bwr;
if (size != sizeof(struct binder_write_read)) {
ret = -EINVAL;
goto err;
}
if (copy_from_user(&bwr, ubuf, sizeof(bwr))) {
ret = -EFAULT;
goto err;
}
binder_debug(BINDER_DEBUG_READ_WRITE,
"binder: %d:%d write %ld at %08lx, read %ld at %08lx
",
proc->pid, thread->pid, bwr.write_size, bwr.write_buffer,
bwr.read_size, bwr.read_buffer);

if (bwr.write_size > 0) {
ret = binder_thread_write(proc, thread, (void __user *)bwr.write_buffer, bwr.write_size, &bwr.write_consumed);
if (ret < 0) {
bwr.read_consumed = 0;
if (copy_to_user(ubuf, &bwr, sizeof(bwr)))
ret = -EFAULT;
goto err;
}
}


}

在Linux内核中 Binder.c (linux-3.0.86driversstagingandroid) 105029 2015/3/24

调用对应的

binder_ioctl

{

读操作

ret = binder_thread_read(proc, thread, (void __user *)bwr.read_buffer, bwr.read_size, &bwr.read_consumed, filp->f_flags & O_NONBLOCK);

}

binder_thread_read{

BR_NOOP 对于所有的读操作，数据头都是BR_NOOP

读出的数据 binder_write_read.redbuf-------------->BR_NOOP ， cmd | 数据， cmd | 数据

}

进入休眠，等待text_server(Android)

   bio_init(&msg, iodata, sizeof(iodata), 4);
    bio_put_uint32(&msg, 0);  // strict mode header
    bio_put_string16_x(&msg, SVC_MGR_NAME);
    bio_put_string16_x(&msg, name);
    bio_put_obj(&msg, ptr);

#define SVC_MGR_NAME "android.os.IServiceManager"

 binder_thread_read : BR_TRANSACTION
 service_manager (1362, 1362), binder_thread_read , print data :
0000: 00 . 00 . 00 . 00 . 1a . 00 . 00 . 00 . 61 a 00 . 6e n 00 . 64 d 00 . 72 r 00 .
 0016: 6f o 00 . 69 i 00 . 64 d 00 . 2e . 00 . 6f o 00 . 73 s 00 . 2e . 00 . 49 I 00 .
 0032: 53 S 00 . 65 e 00 . 72 r 00 . 76 v 00 . 69 i 00 . 63 c 00 . 65 e 00 . 4d M 00 .
 0048: 61 a 00 . 6e n 00 . 61 a 00 . 67 g 00 . 65 e 00 . 72 r 00 . 00 . 00 . 00 . 00 .
0064: 05 . 00 . 00 . 00 . 68 h 00 . 65 e 00 . 6c l 00 . 6c l 00 . 6f o 00 . 00 . 00 .
 0080: 85 . 2a * 68 h 73 s 7f . 01 . 00 . 00 . 01 . 00 . 00 . 00 . 00 . 00 . 00 . 00 .