ipc.zip_ipc 进程通信

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/shm.h> #define BUFFER_SIZE 2048 int main() { pid_t pid; int shmid; char *shm_addr; char flag[]="Parent"; char buff[BUFFER_SIZE]; if ((shmid=shmget(IPC_PRIVATE,BUFFER_SIZE,0666))<0) { perror("shmget"); exit(1); } else printf("Create shared memory: %d.\n",shmid); printf("Created shared memory status:\n"); system("ipcs -m"); if((pid=fork())<0) { perror("fork"); exit(1); }else if (pid==0) { if ((shm_addr=shmat(shmid,0,0))==(void*)-1) { perror("Child:shmat"); exit(1); }else printf("Child: Attach shared-memory: %p.\n",shm_addr); printf("Child Attach shared memory status:\n"); system("ipcs -m"); while (strncmp(shm_addr,flag,strlen(flag))) { printf("Child: Waiting for data...\n"); sleep(10); } strcpy(buff,shm_addr+strlen(flag)); printf("Child: Shared-memory: %s\n",buff); if (shmdt(shm_addr)<0) { perror("Child:shmdt"); exit(1); }else printf("Child: Deattach shared-memory.\n"); printf("Child Deattach shared memory status:\n"); system("ipcs -m"); }else{ sleep(1); if ((shm_addr=shmat(shmid,0,0))==(void*)-1) { perror("Parent:shmat"); exit(1); }else printf("Parent: Attach shared-memory: %p.\n",shm_addr); printf("Parent Attach shared memory status:\n"); system("ipcs -m"); sleep(1); printf("\nInput string:\n"); fgets(buff,BUFFER_SIZE-strlen(flag),stdin); strncpy(shm_addr+strlen(flag),buff,strlen(buff)); strncpy(shm_addr,flag,strlen(flag)); if (shmdt(shm_addr)<0) { perror("Parent:shmdt"); exit(1); }else printf("Parent: Deattach shared-memory.\n"); printf("Parent Deattach shared memory status:\n"); system("ipcs -m"); waitpid(pid,NULL,0); if (shmctl(shmid,IPC_RMID,NULL)==-1) { perror("shmct:IPC_RMID"); exit(1); }else printf("Delete shared-memory.\n"); printf("Child Delete shared memory status:\n"); system("ipcs -m"); printf("Finished!\n"); } exit(0); }