【linux】——一个小程序

利用工作之余为小伙伴写了份作业，关于进程间通信的。题目如下：

父进程从键盘上接受1000个数据，对其求和sum1，子进程对这1000个数平方和sum2，结果传给父进程，父进程将sum1+sum2后，打印结果。

要求：用大小为10的共享区传递1000个数据；子进程用消息机制将sum2传给父进程。

主要利用共享内存实现进程间通信，使用管道实现进程间竞争关系，FreeBSD下测试通过。代码如下：时间有限，有可能有些不足，希望高手给予指点。

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/shm.h>
 #include <signal.h>

 const int key = 0x12345678;
 static int pfd1[], pfd2[];

 #define SHM_LEN    (10*1024)
 #define VAL_NUM    5

 int init_shm() {
     int shmid = -;

     shmid = shmget((key_t)key, SHM_LEN,  | IPC_CREAT);
     if (shmid < ) {
         printf("shmget failed!\n");
         exit(-);
     }

     return shmid;
 }

 void cancel_shm(int shmid) {
     if (shmctl(shmid, IPC_RMID, ) == -) {
         printf("shmctl failed!\n");
         exit(-);
     }
     printf("cancel_shm successfully!\n");
 }

 void *shm_get(int shmid) {
     void *mem = NULL;

     mem = shmat(shmid, , );
     if (mem == (void *)-) {
         printf("shmat failed!\n");
         exit(-);
     }

     return mem;
 }

 int get_val(int *val, int num) {
     int i;
     for (i = ; i < num; i++) {
         printf("please input a num:");
         scanf("%d", val + i);
     }
 }
 void show_val (int *val, int num) {
     int i;
     for (i = ; i < num; i++) {
         printf("%d\t", *(val + i));
     }
     printf("\n");
 }

 int add_val (int *val, int num) {
     int result = ;
     int i;

     for (i = ; i < num; i++) {
         result += *(val + i);
     }

     return result;
 }

 int square_val (int *val, int num) {
     int result = ;
     int i, tmp;

     for (i = ; i < num; i++) {
         tmp = *(val + i);
         result += (tmp * tmp);
     }

     return result;
 }

 void TELL_WAIT (void) {
     if (pipe(pfd1) <  || pipe(pfd2) < ) {
         printf("pipe error!\n");
         exit(-);
     }
 }

 void TELL_PARENT (pid_t pid) {
     if (write(pfd2[], "c", ) != ) {
         printf("write error!\n");
         exit(-);
     }
 }

 void WAIT_PARENT (void) {
     char c;

     if (read(pfd1[], &c, ) != ) {
         printf("read error!\n");
         exit(-);
     }
 }

 void TELL_CHILD (pid_t pid) {
     if (write(pfd1[], "p", ) != ) {
         printf("write error!\n");
         exit(-);
     }
 }

 void WAIT_CHILD (void) {
     char c;

     if (read(pfd2[], &c, ) != ) {
         printf("read error!\n");
         exit(-);
     }
 }

 int main(int argc, char *argv[]) {
     void *mem = NULL;
     int shmid = -;
     pid_t pid = -;
     int val[VAL_NUM];
     int result = ;

     shmid = init_shm();

     TELL_WAIT();
     if ((pid = fork()) < ) {        //error
         printf("fork error!\n");
         exit(-);
     } else if (pid == ) {            //child
         int result = ;

         WAIT_PARENT();

         mem = shm_get(shmid);        //get share memery

         memcpy(val, mem, sizeof(int) * VAL_NUM);
         result = square_val(val, VAL_NUM);    

         *(int *)((void *)mem + SHM_LEN - ) = result;

         TELL_PARENT(pid);

         exit();
     } else {                        //parent
         int child_result = ;

         mem = shm_get(shmid);        //get share memery
         get_val(val, VAL_NUM);        //get user input
         memcpy(mem, val, sizeof(int) * VAL_NUM);    //copy user input to share memery

         TELL_CHILD(pid);

         result = add_val(val, VAL_NUM);

         WAIT_CHILD();
         child_result = *(int *)((void *)mem + SHM_LEN - );
         printf("result:%d, child_result:%d, all:%d\n", result, child_result, result + child_result);
     }

     cancel_shm(shmid);

     return ;
 }