Linux程序设计：进程通信

#define TEXT_SZ 2048

struct shared_use_st

{

????int written_by_you;

????char some_text[TEXT_SZ];

};

typedef struct shared_use_st shared_use_st;

?

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/shm.h>

#include "shm_com.h"

?

int main()

{

????int running = 1;

????voID *shm_ptr = NulL;

????struct shared_use_st *shared_stuff;

????int shmID;

?

????srand((unsigned int)getpID());

?

????shmID = shmget((key_t)1234,sizeof(shared_use_st),0666 | IPC_CREAT);

????printf("shmID = %x\n",shmID);

????if (shmID == -1)

????{

????????fprintf(stderr,"shmget fail\n");

????????exit(EXIT_FAILURE);

????}

????shm_ptr = shmat(shmID,NulL,0);

????//该值应该是shm在当前进程空间中的虚拟地址，而不是shm真实的物理地址

????//所以shm1和shm2的返回值不一样

?

????if (shm_ptr == (voID *)-1)

????{

????????fprintf(stderr,"shmat Failed\n");

????????exit(EXIT_FAILURE);

????}

?

????printf("Memory attached at %p\n",shm_ptr);

?

????shared_stuff = (struct shared_use_st *)shm_ptr;

????shared_stuff->written_by_you = 0;

????while (running)

????{

????????if (shared_stuff->written_by_you)

????????{

????????????printf("You wrote %s\n",shared_stuff->some_text);

????????????sleep(5);

????????????shared_stuff->written_by_you = 0;

????????????if (strncmp(shared_stuff->some_text,"end",3) == 0)

????????????{

????????????????running = 0;

????????????}

????????}

????}

?

????if(shmdt(shm_ptr) == -1)

????{

????????fprintf(stderr,"shmdt Failed\n");

????????exit(EXIT_FAILURE);

????}

?

????if(shmctl(shmID,IPC_RMID,NulL) == -1)

????{

????????fprintf(stderr,"shmctl(IPC_RMID) Failed\n");

????????exit(EXIT_FAILURE);

????}

????exit(EXIT_SUCCESS);

}

?

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/shm.h>

#include "shm_com.h"

?

int main()

{

????int running = 1;

????voID *shm_ptr = NulL;

????struct shared_use_st *share_stuff;

????char buff[TEXT_SZ];

????int shmID;

?

????shmID = shmget((key_t)1234,sizeof(struct shared_use_st),0666|IPC_CREAT);

????printf("shmID = %x\n",shmID);

????if(shmID == -1)

????{

????????fprintf(stderr,"shmget Failed\n");

????????exit(EXIT_FAILURE);

????}

?

????shm_ptr = shmat(shmID,0);

????if(shm_ptr == (voID *)-1)

????{

????????fprintf(stderr,"shmat Failed\n");

????????exit(EXIT_FAILURE);

????}

????printf("Memory attached at %p\n",shm_ptr);

?

????share_stuff = (struct shared_use_st*)shm_ptr;

?

????while(running)

????{

????????if(share_stuff->written_by_you == 1)

????????{

????????????sleep(1);

????????????printf("waiting for clIEnt\n");

????????}

????????printf("Enter texts:");

????????fgets(buff,TEXT_SZ,stdin);

????????strncpy(share_stuff->some_text,buff,TEXT_SZ);

????????share_stuff->written_by_you = 1;

???????? ?

????????if(strncmp(share_stuff->some_text,3) == 0)

????????{

????????????running = 0;

????????}

????}

?

????if(shmdt(shm_ptr) == -1)

????{

????????fprintf(stderr,"shmdt Failed\n");

????????exit(EXIT_FAILURE);

????}

????exit(EXIT_SUCCESS);

?

}

?

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

?

#include <sys/msg.h>

struct msg_t

{

????long int msg_type;

????char content[BUFSIZ];

};

?

int main()

{

????int running = 1;

????int msgid;

????long int msg_to_receive = 0; //决定队列消息优先级，0表示获取队列第一个可用消息

????struct msg_t msg;

?

????msgid = msgget((key_t)1234,0666 | IPC_CREAT);

????printf("msgid = %d\n",msgid);

????if (msgid == -1)

????{

????????fprintf(stderr,"msgget Failed\n");

????????exit(EXIT_FAILURE);

????}

?

????while (running)

????{

????????if (msgrcv(msgid,(voID *)&msg,BUFSIZ,msg_to_receive,0) == -1)

????????{

????????????fprintf(stderr,"msgrcv failde\n");

????????????exit(EXIT_FAILURE);

????????}

????????printf("You wrote %s",msg.content);

????????if(strncmp(msg.content,3) == 0)

????????????running = 0;

????}

????if (msgctl(msgid,0) == -1)

????{

????????fprintf(stderr,"msgcntl Failed\n");

????????exit(EXIT_FAILURE);

????}

????exit(EXIT_SUCCESS);

?

}

?

?

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <sys/msg.h>

#define MAX_TEXT 512

struct msg_t

{

????long int msg_type;

????char content[BUFSIZ];

};

?

int main()

{

????int running = 1;

????struct msg_t msg;

????int msgid;

????char buffer[BUFSIZ];

?

????msgid = msgget((key_t)1234,msgid);

?

????if (msgid == -1)

????{

????????fprintf(stderr,"msgget Failed\n");

????????exit(EXIT_FAILURE);

????}

?

????while (running)

????{

????????printf("Enter texts:");

????????fgets(buffer,stdin);

????????msg.msg_type = 1;

????????strcpy(msg.content,buffer);

?

????????if(msgsnd(msgid,"msgsnd Failed\n");

????????????exit(EXIT_FAILURE);

????????}

????????if(strncmp(msg.content,3) == 0)

????????{

????????????running = 0;

????????}

????}

?

????exit(EXIT_SUCCESS);

}

?

#if defined(__GNU_liBRARY__) && !defined(_SEM_SEMUN_UNdefineD)

????/* union semun is defined by including <sys/sem.h> */

#else

????/* according to X/OPEN we have to define it ourselves */

????union semun {

????????int val; /* value for SETVAL */

????????struct semID_ds *buf; /* buffer for IPC_STAT,IPC_SET */

????????unsigned short int *array; /* array for GETALL,SETALL */

????????struct seminfo *__buf; /* buffer for IPC_INFO */

????};

#endif

?

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <sys/sem.h>

#include "semun.h"

?

static int sem_ID;

static int set_semvalue()

{

????union semun sem_union;

????sem_union.val = 1;

????if (semctl(sem_ID,0,SETVAL,sem_union) == -1)

????????return 0;

????return 1;

}

static voID del_semvalue()

{

????union semun sem_union;

????if (semctl(sem_ID,sem_union) == -1)

????????fprintf(stderr,"Fail to delete semaphore\n");

}

static int sema_p()

{

????struct sembuf sem_b;

????sem_b.sem_num = 0;//信号量编号，除非是一组信号量，否则0

????sem_b.sem_op = -1;//-1 *** 作

????sem_b.sem_flg = SEM_UNDO;//与 *** 作系统对信号量的 *** 作相关，一般是UNDO

????if (semop(sem_ID,&sem_b,1) == -1)

????{

????????fprintf(stderr,"sema_p Failed\n");

????????return 0;

????}

????return 1;

}

static int sema_v()

{

????struct sembuf sem_b;

????sem_b.sem_num = 0;

????sem_b.sem_op = 1;

????sem_b.sem_flg = SEM_UNDO;

????if (semop(sem_ID,"sema_v Failed\n");

????????return 0;

????}

????return 1;

}

?

int main(int argc,char *argv[])

{

????int i;

????int pause_time;

????char op_char = ‘O‘;

????srand((unsigned int)getpID());

????sem_ID = semget((key_t)1234,1,0666 | IPC_CREAT);

????if (argc > 1)

????{

????????if(set_semvalue() == 0)

????????{

????????????fprintf(stderr,"init fail\n");

????????????exit(EXIT_FAILURE);

????????}

????????op_char = ‘X‘;

????????sleep(2);

????}

?

????for (i = 0; i < 10; i++)

????{

????????if (sema_p() == 0)

????????????exit(EXIT_FAILURE);

????????printf("%c",op_char);

????????fflush(stdout);

?

????????pause_time = rand() % 3;

????????sleep(pause_time);

????????printf("%c",op_char);

????????fflush(stdout);

?

????????if (!sema_v())

????????????exit(EXIT_FAILURE);

????????pause_time = rand() % 2;

????????sleep(pause_time);

????}

????printf("\n%d - finished\n",getpID());

????if (argc > 1)

????{

????????sleep(10);

????????del_semvalue();

????}

????exit(EXIT_SUCCESS);

}