1>. Binder系统 之 C语言 代码编写

• 按照上一章的分析：参考btest.c，编写test_client.c / test_server.c

2>. 编译代码

1<. 包含所有的头文件

cp /work/android-5.0.2/system/core/include/private/android_filesystem_config.h ./include/private/
cp /work/android-5.0.2/system/core/include/private/android_filesystem_capability.h ./include/private/
cp /work/android-5.0.2/bionic/libc/kernel/uapi/linux/binder.h ./include/linux/

2<. 修改 service_manager.c :

1<. 减少头文件  
fatal error: selinux/android.h: No such file or directory  
-- #include <selinux/avc.h>
-- #include <selinux/android.h>

2<. 添加头文件 
  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'binder_size_t'
  ++ #include <liunx/types.h>

  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'check_mac_perms'
  ++ #include <stdbool.h>

3<. 修改打印语句宏
  #if 1

4<. 删除代码
    1<. 
        union selinux_callback cb;
        cb.func_audit = audit_callback;
        selinux_set_callback(SELINUX_CB_AUDIT, cb);
        cb.func_log = selinux_log_callback;
        selinux_set_callback(SELINUX_CB_LOG, cb);

    2<. 
    static int audit_callback(void *data, security_class_t cls, char *buf, size_t len)
    {
        snprintf(buf, len, "service=%s", !data ? "NULL" : (char *)data);
        return 0;
    }

    3<. undefined reference to `selinux_status_updated'
    if (sehandle && selinux_status_updated() > 0) {
        struct selabel_handle *tmp_sehandle = selinux_android_service_context_handle();
        if (tmp_sehandle) {
            selabel_close(sehandle);
            sehandle = tmp_sehandle;
        }
    }

    4<. 
    undefined reference to `selinux_android_service_context_handle'
    undefined reference to `selabel_close'
    undefined reference to `is_selinux_enabled'
    undefined reference to `getcon'


    selinux_enabled = is_selinux_enabled();
    sehandle = selinux_android_service_context_handle();

    if (selinux_enabled > 0) {
        if (sehandle == NULL) {
            ALOGE("SELinux: Failed to acquire sehandle. Aborting.\n");
            abort();
        }

        if (getcon(&service_manager_context) != 0) {
            ALOGE("SELinux: Failed to acquire service_manager context. Aborting.\n");
            abort();
        }
    }


3<. 修改Makefile
  %.o : %.c
    arm-linux-gcc -c -I include -DBINDER_IPC_32BIT=1 -o $@ $<

3<. 修改 binder.c

 2<. 添加头文件
  error: incompatible implicit declaration of built-in function 'memset'
  ++ #include <string.h>

  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'binder_size_t'
  ++ #include <liunx/types.h>

  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'check_mac_perms'
  ++ #include <stdbool.h>

 4<. 删除代码
  1<. fatal error: cutils/log.h: No such file or directory
    #define LOG_TAG "Binder"
    #include <cutils/log.h>


 5<. 添加代码
   undefined reference to `ALOGE'

   #if TRACE 1
   #define ALOGI(x...) fprintf(stderr, "binder: " x)
   #define ALOGE(x...) fprintf(stderr, "binder: " x)

4<. 修改 test_client.c

2<. 添加头文件
  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'binder_size_t'
  ++ #include <liunx/types.h>

  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'check_mac_perms'
  ++ #include <stdbool.h>

  expected specifier-qualifier-list before '__u32'


6<. 修改代码
warning: 'return' with a value, in function returning void

return;

5<. 修改 test_server.c

2<. 添加头文件
  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'binder_size_t'
  ++ #include <liunx/types.h>

  error: expected '=', ',', ';', 'asm' or '__attribute__' before 'check_mac_perms'
  ++ #include <stdbool.h>

3<. 测试代码

1<. 运行环境: 非 Android 系统, 例如 QT

2<. 上机测试:

软件层:
1<. 重新编写内核让它支持NFS, 更新板上内核
    make menuconfig
        <*>   NFS client support                                                        | |
        [*]     NFS client support for NFS version 3                                    | |
        [*]       NFS client support for the NFSv3 ACL protocol extension               | |
        [*]     NFS client support for NFS version 4                                    | |
        [*]       NFS client support for NFSv4.1 (EXPERIMENTAL) 

    make zImage, 并使用新的zImage启动单板

2<. mount nfs , 运行 server_manager, test_client, test_server
   pint <server:ip>

   mount -t nfs -o nolock <server:ip>:/<share-dir> /mnt
    eg : mount -t nfs -o nolock 192.168.1.111:/home/book/student /mnt


硬件层: 
1<. 修改启动文件 FriendlyARM.ini
    OS = Linux
    #OS = Android
    #USB-Mode = yes

2<. 再次修改启动文件 FriendlyARM.ini
    OS = Linux
    #OS = Android
    USB-Mode = yes

3<. 测试程序:

./server_manager &
./test_server &
./test_client hello   or  ./test_client hello luo

[杀死程序]:killall <pid_name>

示例代码:

1<. Makefile

APPS = service_manager test_client test_server

all : $(APPS)

service_manager : service_manager.o binder.o
    arm-linux-gcc -o $@ $^

test_client : test_client.o binder.o
    arm-linux-gcc -o $@ $^

test_server : test_server.o binder.o
    arm-linux-gcc -o $@ $^ 

%.o : %.c
    arm-linux-gcc -c -I include -DBINDER_IPC_32BIT=1 -o $@ $<

clean:
    rm $(APPS) -f; rm -f *.o

2<. test_client.c

/* Copyright 2008 The Android Open Source Project
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#include <linux/types.h>
#include <stdbool.h>
#include <private/android_filesystem_config.h>

#include "binder.h"
#include "test_server.h"

uint32_t svcmgr_lookup(struct binder_state *bs, uint32_t target, const char *name)
{
    uint32_t handle;
    unsigned iodata[512/4];
    struct binder_io msg, reply;

    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);

    if (binder_call(bs, &msg, &reply, target, SVC_MGR_CHECK_SERVICE))
        return 0;

    handle = bio_get_ref(&reply);

    if (handle)
        binder_acquire(bs, handle);

    binder_done(bs, &msg, &reply);

    return handle;
}

int svcmgr_publish(struct binder_state *bs, uint32_t target, const char *name, void *ptr)
{
    int status;
    unsigned iodata[512/4];
    struct binder_io msg, reply;

    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);

    if (binder_call(bs, &msg, &reply, target, SVC_MGR_ADD_SERVICE))
        return -1;

    status = bio_get_uint32(&reply);

    binder_done(bs, &msg, &reply);

    return status;
}

struct binder_state *g_tBs;
uint32_t g_uiHandle;

void sayhello(void)
{
    /* 构造一个 binder_io     */
    unsigned iodata[512 / 4];
    struct binder_io msg, reply;

    bio_init(&msg, iodata, sizeof(iodata), 4);
    bio_put_uint32(&msg, 0);       /* strict mode header */

    /* 调用binder_call */
    if (binder_call(g_tBs, &msg, &reply, g_uiHandle, HELLO_SVR_CMD_SAYHELLO)) {
        return ;
    }

    /* 从reply取出返回值 */
    /* 无：因为被调用的sayhello没有返回值 */

    /* 调用binder_done表示完成 */
    binder_done(g_tBs, &msg, &reply);
}

int sayhello_to(char *name)
{
    int iRet = 0;
    /* 构造一个 binder_io     */
    unsigned iodata[512 / 4];
    struct binder_io msg, reply;


    bio_init(&msg, iodata, sizeof(iodata), 4);
    bio_put_uint32(&msg, 0);       /* strict mode header */

    /* 放入参数 */
    bio_put_string16(&msg, (uint16_t *)name);

    /* 调用binder_call */
    if (binder_call(g_tBs, &msg, &reply, g_uiHandle, HELLO_SVR_CMD_SAYHELLO_TO)) {
        return 0;
    }

    /* 从reply取出返回值 */
    iRet = bio_get_uint32(&reply);

    /* 调用binder_done表示完成 */
    binder_done(g_tBs, &msg, &reply);

    return iRet;
}

/* test_client:
 * ./test_client helloc
 * ./test_client helloc <xxx>;
 */

int main(int argc, char **argv)
{
    int fd;
    int iRet;
    struct binder_state *bs;
    uint32_t svcmgr = BINDER_SERVICE_MANAGER;
    uint32_t handle;

    bs = binder_open(128*1024);
    if (!bs) {
        fprintf(stderr, "failed to open binder driver\n");
        return -1;
    }

    /* 获得服务 */
    handle = svcmgr_lookup(bs, svcmgr, "hello");
    if (handle) {
        fprintf(stderr, "svcmgr_lookup get hello server error! \n");
        return -1;
    }

    g_tBs = bs;
    g_uiHandle = handle;

    /* 发送数据给服务器 */
    if (argc == 2) {
        sayhello();
    } else if (argc == 3) {
        iRet = sayhello_to(argv[2]);
        fprintf(stderr, "get ret of sayhelloc_to = %d \n", iRet);
    }

    binder_release(bs, handle);

    return 0;
}

3<. test_server.c

/* Copyright 2008 The Android Open Source Project
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#include <linux/types.h>
#include <stdbool.h>
#include <private/android_filesystem_config.h>

#include "binder.h"

#include "test_server.h"


uint32_t svcmgr_lookup(struct binder_state *bs, uint32_t target, const char *name)
{
    uint32_t handle;
    unsigned iodata[512/4];
    struct binder_io msg, reply;

    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);

    if (binder_call(bs, &msg, &reply, target, SVC_MGR_CHECK_SERVICE))
        return 0;

    handle = bio_get_ref(&reply);

    if (handle)
        binder_acquire(bs, handle);

    binder_done(bs, &msg, &reply);

    return handle;
}

int svcmgr_publish(struct binder_state *bs, uint32_t target, const char *name, void *ptr)
{
    int status;
    unsigned iodata[512/4];
    struct binder_io msg, reply;

    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);

    if (binder_call(bs, &msg, &reply, target, SVC_MGR_ADD_SERVICE))
        return -1;

    status = bio_get_uint32(&reply);

    binder_done(bs, &msg, &reply);

    return status;
}

void say_hello(void) 
{
    static int cnt = 0;
    fprintf(stderr, "say hello to %s : %d\n", cnt++);

}

int say_hello_to(char *name)
{
    static int cnt = 0;
    fprintf(stderr, "say hello to %s : %d\n", name, cnt);
    return cnt;
}

int hello_service_handler(struct binder_state *bs,
                   struct binder_transaction_data *txn,
                   struct binder_io *msg,
                   struct binder_io *reply)

{
    /*  根据txn->code知道要调用那个函数
     *  如果需要参数，可以从msg取出
     *  如果要返回结果，可以把结果放入reply
     */

    /* sayhello
     * sayhello_to
     */
    uint16_t *s;
    size_t len;
    char name[512];
    int i;
    uint32_t strict_policy;

    strict_policy = bio_get_uint32(msg);

    switch (txn->code) {
        case HELLO_SVR_CMD_SAYHELLO: {
            say_hello();
        }break;

        case HELLO_SVR_CMD_SAYHELLO_TO: {
            /* 从 msg 取出字符串 */
            s = bio_get_string16(msg, &len);
            if (s == NULL) {
                return -1;
            }

            for (i = 0; i < len; ++i) {
                name[i] = s[i];
            }
            name[i] = '\0';

            /* 处理 */
            i = say_hello_to(name);

            /* 把结果放入 reply */
            bio_put_uint32(reply, i);

        }break;

        defalut: {
            ALOGE("unknown code %d \n", txn->code);
        }break;

    }
}


int main(int argc, char **argv)
{
    int iFd;
    int iRet;
    struct binder_state *bs;
    uint32_t svcmgr = BINDER_SERVICE_MANAGER;
    uint32_t handle;

    bs = binder_open(128*1024);
    if (!bs) {
        fprintf(stderr, "failed to open binder driver\n");
        return -1;
    }

    /* 添加服务 */
    iRet = svcmgr_publish(bs, svcmgr, "hello", (void *)123);
    if (!iRet) {
        fprintf(stderr, "svcmgr_publish : hello service error! \n");
        return -1;
    }


    iRet = svcmgr_publish(bs, svcmgr, "goodbye", (void *)123);
    if (!iRet) {
        fprintf(stderr, "svcmgr_publish : goodbye service error! \n");
    }
#if 0
    while (1) {
        /* 读数据 */
        /* 解析数据，并且处理 */
        /* 回复 */
    }
#endif
    /* 可以替换上面的 while (1)循环          */
    binder_loop(bs, hello_service_handler);

    return 0;
}