标签：解析 信号 mod 标识符 cat 方法 选择 清除 使用
#include <sys/shm.h> int shmget(key_t key, size_t size, int shmflg); void *shmat(int shm_id, const void *shm_addr, int shmflg); int shmdt(const void *shm_addr); int shmctl(int shm_id, int cmd, struct shmid_ds *buf);
int shmget(key_t key, size_t size, int shmflg);
void *shmat(int shm_id, const void *shm_addr, int shmflg);
int shmdt(const void *shm_addr);
int shmctl(int shm_id, int cmd, struct shmid_ds *buf);
shmid_ds结构至少包含以下成员:
struct shmid_ds { uid_t shm_perm.uid; uid_t shm_perm.gid; mode_t shm_perm.mode; }
shm_com.h
#define TEXT_SZ 2048 struct shared_use_st { int written_by_you; char some_text[TEXT_SZ]; };
#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/shm.h> #include "shm_com.h" int main() { int running = 1; void *shared_memory = (void *)0; struct shared_use_st *shared_stuff; int shmid; srand((unsigned int)getpid()); shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666 | IPC_CREAT); if (shmid == -1) { fprintf(stderr, "shmget failed\n"); exit(EXIT_FAILURE); }
现在，让程序可以访问这个共享内存:
shared_memory = shmat(shmid, (void *)0, 0); if (shared_memory == (void *)-1) { fprintf(stderr, "shmat failed\n"); exit(EXIT_FAILURE); } printf("Memory attached at %X\n", (int)shared_memory);
shared_stuff = (struct shared_use_st *)shared_memory; shared_stuff->written_by_you = 0; while(running) { if (shared_stuff->written_by_you) { printf("You wrote: %s", shared_stuff->some_text); sleep( rand() % 4 ); /* make the other process wait for us ! */ shared_stuff->written_by_you = 0; if (strncmp(shared_stuff->some_text, “end”, 3) == 0) { running = 0; } } }
最后，共享内存被分离，然后被删除:
if (shmdt(shared_memory) == -1) { fprintf(stderr, "shmdt failed\n"); exit(EXIT_FAILURE); } if (shmctl(shmid, IPC_RMID, 0) == -1) { fprintf(stderr, "shmctl(IPC_RMID) failed\n"); exit(EXIT_FAILURE); } exit(EXIT_SUCCESS); }
#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/shm.h> #include "shm_com.h" int main() { int running = 1; void *shared_memory = (void *)0; struct shared_use_st *shared_stuff; char buffer[BUFSIZ]; 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); } shared_memory = shmat(shmid, (void *)0, 0); if (shared_memory == (void *)-1) { fprintf(stderr, "shmat failed\n"); exit(EXIT_FAILURE); } printf("Memory attached at %X\n", (int)shared_memory); shared_stuff = (struct shared_use_st *)shared_memory; while(running) { while(shared_stuff->written_by_you == 1) { sleep(1); printf("waiting for client...\n"); } printf("Enter some text: "); fgets(buffer, BUFSIZ, stdin); strncpy(shared_stuff->some_text, buffer, TEXT_SZ); shared_stuff->written_by_you = 1; if (strncmp(buffer, "end", 3) == 0) { running = 0; } } if (shmdt(shared_memory) == -1) { fprintf(stderr, "shmdt failed\n"); exit(EXIT_FAILURE); } exit(EXIT_SUCCESS); }
$ ./shm1 & [1] 294 Memory attached at 40017000 $ ./shm2 Memory attached at 40017000 Enter some text: hello You wrote: hello waiting for client... waiting for client... Enter some text: You wrote: waiting for client... waiting for client... waiting for client... Enter some text: end You wrote: end $
标签：解析 信号 mod 标识符 cat 方法 选择 清除 使用
原文地址：http://www.cnblogs.com/mingfeng002/p/7008063.html
