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| #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/shm.h> #include <sys/time.h> #include <unistd.h> #include <ctime> #include <iostream> #include "./shmdata.h"
int main() { int running = 1; void *shm = NULL; struct shared_use_st *shared = NULL; int shmid;
shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666 | IPC_CREAT); if (shmid == -1) { fprintf(stderr, "shmget failed\n"); exit(EXIT_FAILURE); }
shm = shmat(shmid, (void *)0, 0); if (shm == (void *)-1) { fprintf(stderr, "shmat err\n"); exit(EXIT_FAILURE); }
shared = (struct shared_use_st *)shm; while (running) { struct timeval tv; gettimeofday(&tv, NULL); std::string time_ = std::to_string(1000 * tv.tv_sec + tv.tv_usec / 1000); strcpy(shared->timestamp, time_.c_str()); std::cout << "You wrote: " << shared->timestamp << std::endl; usleep(1000);
shared->written = 1; } if (shmdt(shm) == -1) { exit(EXIT_FAILURE); } exit(EXIT_SUCCESS); }
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/shm.h> #include <unistd.h> #include <iostream> #include "./shmdata.h"
int main() { int running = 1; void *shm = NULL; struct shared_use_st *shared; int shmid;
shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666 | IPC_CREAT); if (shmid == -1) { fprintf(stderr, "shmget err\n"); exit(EXIT_FAILURE); }
shm = shmat(shmid, 0, 0); if (shm == (void *)-1) { fprintf(stderr, "shmat err\n"); exit(EXIT_FAILURE); } shared = (struct shared_use_st *)shm; shared->written = 0; while (running) { if (shared->written != 0) { std::cout << "You receivr: " << shared->timestamp << std::endl; shared->written = 0; } usleep(5000); }
if (shmdt(shm) == -1) { fprintf(stderr, "shmdt err\n"); exit(EXIT_FAILURE); }
if (shmctl(shmid, IPC_RMID, 0) == -1) { fprintf(stderr, "shmctl(IPC_RM)\n"); exit(EXIT_FAILURE); } exit(EXIT_SUCCESS); }
#include <string>
#ifndef __SHMDATA_H_HEADER #define __SHMDATA_H_HEADER
#define TEXT_SZ 2048 struct shared_use_st { int written; char timestamp[1]; }; #endif
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