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写端代码
#include <stdio.h> #include <signal.h> #include <stdlib.h> #include <errno.h> #include <sys/ipc.h> #include <sys/types.h> #include <sys/shm.h> #include <string.h> #include <unistd.h> #define N 1024 typedef struct { pid_t pid; char text[N]; }SHMBUF; void handler(int signo) {printf("signo=%d\n", signo);} int main() { int shmid; SHMBUF *shmadd; key_t key; pid_t peerpid; if ((key = ftok(".", 'a')) == -1) { perror("ftok"); exit(-1); } signal(SIGUSR1, handler); if ((shmid = shmget(key, sizeof(SHMBUF), 0666 | IPC_CREAT | IPC_EXCL)) == -1) { if (errno == EEXIST) { shmid = shmget(key, sizeof(SHMBUF), 0666); if ((shmadd = (SHMBUF *)shmat(shmid, NULL, 0)) == (SHMBUF *)-1) { perror("shmat"); exit(-1); } peerpid = shmadd->pid; shmadd->pid = getpid(); kill(peerpid, SIGUSR1); } else { perror("shmget"); exit(-1); } } else //first process { if ((shmadd = (SHMBUF *)shmat(shmid, NULL, 0)) == (SHMBUF *)-1) { perror("shmat"); exit(-1); } shmadd->pid = getpid(); //sprintf(shmadd, "%d", getpid()); pause(); peerpid = shmadd->pid; } printf(">"); while (1) { fgets(shmadd->text, N, stdin); shmadd->text[strlen(shmadd->text)-1] = '\0'; kill(peerpid, SIGUSR1); if (strncmp(shmadd->text, "quit", 4) == 0) { sleep(1); if (shmdt(shmadd) == -1) { perror("shmdt"); } if (shmctl(shmid, IPC_RMID, NULL) == -1) { perror("RM"); exit(-1); } exit(0); } pause(); printf(">"); } return 0; }
读取端代码
#include <stdio.h> #include <signal.h> #include <stdlib.h> #include <errno.h> #include <sys/ipc.h> #include <sys/types.h> #include <sys/shm.h> #include <string.h> #include <unistd.h> #define N 1024 typedef struct { pid_t pid; char text[N]; }SHMBUF; void handler(int signo) {printf("signo=%d\n", signo);} int main() { int shmid; SHMBUF *shmadd; key_t key; pid_t peerpid; if ((key = ftok(".", 'a')) == -1) { perror("ftok"); exit(-1); } signal(SIGUSR1, handler); if ((shmid = shmget(key, sizeof(SHMBUF), 0666 | IPC_CREAT | IPC_EXCL)) == -1) { if (errno == EEXIST) { shmid = shmget(key, sizeof(SHMBUF), 0666); if ((shmadd = (SHMBUF *)shmat(shmid, NULL, 0)) == (SHMBUF *)-1) { perror("shmat"); exit(-1); } peerpid = shmadd->pid; shmadd->pid = getpid(); kill(peerpid, SIGUSR1); } else { perror("shmget"); exit(-1); } } else //first process { if ((shmadd = (SHMBUF *)shmat(shmid, NULL, 0)) == (SHMBUF *)-1) { perror("shmat"); exit(-1); } shmadd->pid = getpid(); pause(); peerpid = shmadd->pid; } while (1) { pause(); printf("read %s\n", shmadd->text); if (strncmp(shmadd->text, "quit", 4) == 0) { if (shmdt(shmadd) == -1) { perror("shmdt"); } exit(0); } // sleep(1); usleep(100000); kill(peerpid, SIGUSR1); } exit(0); }
编译
gcc reader.c -o reader gcc writer.c -o writer
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