上一小节介绍了Binder系统的框架，为了加深理解，这小节别写一个示例程序，最要有以下程序c文件 1.test_server.c： 提供“hello”服务， 提供函数：void sayhello（void），int sayhello_to（char *name）。
下面我们开始编写test_server.c。
test_server.c/* Copyright 2008 The Android Open Source Project
*/
#include
#include
#include
#include
#include
#include
#include
#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;
}
struct binder_state *g_bs;
uint32_t g_hello_handle;
uint32_t g_goodbye_handle;
void sayhello(void)
{
unsigned iodata[512/4];
struct binder_io msg, reply;
/* 构造binder_io */
bio_init(&msg, iodata, sizeof(iodata), 4);
bio_put_uint32(&msg, 0); // strict mode header
bio_put_string16_x(&msg, "IHelloService");
/* 放入参数 */
/* 调用binder_call */
if (binder_call(g_bs, &msg, &reply, g_hello_handle, HELLO_SVR_CMD_SAYHELLO))
return ;
/* 从reply中解析出返回值 */
binder_done(g_bs, &msg, &reply);
}
int sayhello_to(char *name)
{
unsigned iodata[512/4];
struct binder_io msg, reply;
int ret;
int exception;
/* 构造binder_io */
bio_init(&msg, iodata, sizeof(iodata), 4);
bio_put_uint32(&msg, 0); // strict mode header
bio_put_string16_x(&msg, "IHelloService");
/* 放入参数 */
bio_put_string16_x(&msg, name);
/* 调用binder_call */
if (binder_call(g_bs, &msg, &reply, g_hello_handle, HELLO_SVR_CMD_SAYHELLO_TO))
return 0;
/* 从reply中解析出返回值 */
exception = bio_get_uint32(&reply);
if (exception)
ret = -1;
else
ret = bio_get_uint32(&reply);
binder_done(g_bs, &msg, &reply);
return ret;
}
void saygoodbye(void)
{
unsigned iodata[512/4];
struct binder_io msg, reply;
/* 构造binder_io */
bio_init(&msg, iodata, sizeof(iodata), 4);
bio_put_uint32(&msg, 0); // strict mode header
bio_put_string16_x(&msg, "IGoodbyeService");
/* 放入参数 */
/* 调用binder_call */
if (binder_call(g_bs, &msg, &reply, g_goodbye_handle, GOODBYE_SVR_CMD_SAYGOODBYE))
return ;
/* 从reply中解析出返回值 */
binder_done(g_bs, &msg, &reply);
}
int saygoodbye_to(char *name)
{
unsigned iodata[512/4];
struct binder_io msg, reply;
int ret;
int exception;
/* 构造binder_io */
bio_init(&msg, iodata, sizeof(iodata), 4);
bio_put_uint32(&msg, 0); // strict mode header
bio_put_string16_x(&msg, "IGoodbyeService");
/* 放入参数 */
bio_put_string16_x(&msg, name);
/* 调用binder_call */
if (binder_call(g_bs, &msg, &reply, g_goodbye_handle, GOODBYE_SVR_CMD_SAYGOODBYE_TO))
return 0;
/* 从reply中解析出返回值 */
exception = bio_get_uint32(&reply);
if (exception)
ret = -1;
else
ret = bio_get_uint32(&reply);
binder_done(g_bs, &msg, &reply);
return ret;
}
/* ./test_client hello
* ./test_client hello
*/
int main(int argc, char **argv)
{
int fd;
struct binder_state *bs;
uint32_t svcmgr = BINDER_SERVICE_MANAGER;
uint32_t handle;
int ret;
if (argc code判断调用sayhello()或者sayhello_to(name)*/
switch(txn->code)
case sayhello();
case sayhello_to(name);
int goodbye_service_handler(struct binder_state *bs,struct binder_transaction_data *txn,struct binder_io *msg,struct binder_io *reply)
/*同上*/
switch(txn->code)
case saygoodbye();
case saygoodbye_to(name);
test_server_handler()
/*定义一个函数指针*/
int (*handler)(struct binder_state *bs,struct binder_transaction_data *txn,struct binder_io *msg,struct binder_io *reply);
/*根据传入的txn->target.ptr函数指针分辨调用goodbye_service_handler或者hello_service_handler*/
handler = (int (*)(struct binder_state *bs,struct binder_transaction_data *txn,struct binder_io *msg,struct binder_io *reply))txn->target.ptr;
main()
bs = binder_open(128*1024);//打开binder驱动
svcmgr_publish(bs, svcmgr, "hello", hello_service_handler);/*注册一个"hello"服务，把hello_service_handler函数指针当做参数，为方便后面的调用*/
ret = svcmgr_publish(bs, svcmgr, "goodbye", goodbye_service_handler);//注册一个"goodbye"服务
binder_loop(bs, test_server_handler);//循环等待，如果有"goodbye或者"hello"服务申请，则test_server_handler函数被调用
/* Copyright 2008 The Android Open Source Project
*/
#include
#include
#include
#include
#include
#include
#include
#include "binder.h"
#include "test_server.h"
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 sayhello(void)
{
static int cnt = 0;
fprintf(stderr, "say hello : %d\n", ++cnt);
}
int sayhello_to(char *name)
{
static int cnt = 0;
fprintf(stderr, "say hello to %s : %d\n", name, ++cnt);
return cnt;
}
void saygoodbye(void)
{
static int cnt = 0;
fprintf(stderr, "say goodbye : %d\n", ++cnt);
}
int saygoodbye_to(char *name)
{
static int cnt = 0;
fprintf(stderr, "say goodbye 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知道要调用哪一个函数
* 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;
char name[512];
size_t len;
uint32_t handle;
uint32_t strict_policy;
int i;
// Equivalent to Parcel::enforceInterface(), reading the RPC
// header with the strict mode policy mask and the interface name.
// Note that we ignore the strict_policy and don't propagate it
// further (since we do no outbound RPCs anyway).
strict_policy = bio_get_uint32(msg);
switch(txn->code) {
case HELLO_SVR_CMD_SAYHELLO:
sayhello();
bio_put_uint32(reply, 0); /* no exception */
return 0;
case HELLO_SVR_CMD_SAYHELLO_TO:
/* 从msg里取出字符串 */
s = bio_get_string16(msg, &len); //"IHelloService"
s = bio_get_string16(msg, &len); // name
if (s == NULL) {
return -1;
}
for (i = 0; i code);
return -1;
}
return 0;
}
int goodbye_service_handler(struct binder_state *bs,
struct binder_transaction_data *txn,
struct binder_io *msg,
struct binder_io *reply)
{
/* 根据txn->code知道要调用哪一个函数
* 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;
char name[512];
size_t len;
uint32_t handle;
uint32_t strict_policy;
int i;
// Equivalent to Parcel::enforceInterface(), reading the RPC
// header with the strict mode policy mask and the interface name.
// Note that we ignore the strict_policy and don't propagate it
// further (since we do no outbound RPCs anyway).
strict_policy = bio_get_uint32(msg);
switch(txn->code) {
case GOODBYE_SVR_CMD_SAYGOODBYE:
saygoodbye();
bio_put_uint32(reply, 0); /* no exception */
return 0;
case GOODBYE_SVR_CMD_SAYGOODBYE_TO:
/* 从msg里取出字符串 */
s = bio_get_string16(msg, &len); //"IGoodbyeService"
s = bio_get_string16(msg, &len); // name
if (s == NULL) {
return -1;
}
for (i = 0; i code);
return -1;
}
return 0;
}
int test_server_handler(struct binder_state *bs,
struct binder_transaction_data *txn,
struct binder_io *msg,
struct binder_io *reply)
{
int (*handler)(struct binder_state *bs,
struct binder_transaction_data *txn,
struct binder_io *msg,
struct binder_io *reply);
handler = (int (*)(struct binder_state *bs,
struct binder_transaction_data *txn,
struct binder_io *msg,
struct binder_io *reply))txn->target.ptr;
return handler(bs, txn, msg, reply);
}
int main(int argc, char **argv)
{
int fd;
struct binder_state *bs;
uint32_t svcmgr = BINDER_SERVICE_MANAGER;
uint32_t handle;
int ret;
bs = binder_open(128*1024);
if (!bs) {
fprintf(stderr, "failed to open binder driver\n");
return -1;
}
/* add service */
ret = svcmgr_publish(bs, svcmgr, "hello", hello_service_handler);
if (ret) {
fprintf(stderr, "failed to publish hello service\n");
return -1;
}
ret = svcmgr_publish(bs, svcmgr, "goodbye", goodbye_service_handler);
if (ret) {
fprintf(stderr, "failed to publish goodbye service\n");
}
#if 0
while (1)
{
/* read data */
/* parse data, and process */
/* reply */
}
#endif
//binder_set_maxthreads(bs, 10);
binder_loop(bs, test_server_handler);
return 0;
}
简单调用逻辑如下
sayhello(void)或者sayhello_to(char *name)或者saygoodbye(void)saygoodbye_to(char *name)
//调用binder_call建构造binder_io msg，然后确定target与code
int binder_call(struct binder_state *bs,struct binder_io *msg, struct binder_io *reply,uint32_t target, uint32_t code)
main()
bs = binder_open(128*1024); //同样打开derbin驱动
g_goodbye_handle = svcmgr_lookup(bs, svcmgr, "goodbye");//获取"goodbye"服务
g_hello_handle = svcmgr_lookup(bs, svcmgr, "hello");//获取"hello"服务
if (!strcmp(argv[1], "hello")) //如果为 "hello"服务
{
//根据argc判断调用sayhello()或者sayhello_to
}
if (!strcmp(argv[1], "goodbye")) //如果为"goodbye"服务
{
//根据argc判断调用saygoodbye()或者saygoodbye_to
}
编写完成之后makefile如下：
MakefleAPPS = service_manager test_client test_server
all : $(APPS)
service_manager : service_manager.o binder.o
aarch64-linux-gnu-gcc -static -o $@ $^
test_client : test_client.o binder.o
aarch64-linux-gnu-gcc -static -o $@ $^
test_server : test_server.o binder.o
aarch64-linux-gnu-gcc -static -o $@ $^
%.o : %.c
aarch64-linux-gnu-gcc -static -I include -c -o $@ $
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