Open the object for read-write access. O_CREAT Create the shared memory object if it does not exist. The user and group ownership of the object are taken from the corresponding effective IDs of the calling process, and the object's permission bits are set according to the low-order 9 bit...
O_CREAT|O_RDWR,0666);if(shm_fd==-1){perror("shm_open");return1;}// 设置共享内存对象的大小ftruncate(shm_fd,4096);// 映射共享内存对象到进程地址空间void*ptr=mmap(0,4096,PROT_READ|PROT_WRITE,MAP_
ptr=mmap(NULL,100,PROT_READ|PROT_WRITE,MAP_SHARED,shm_id,0);/*第三步:连接共享内存区*/strcpy(ptr,"\0"); sem_wait(sem);/*第四步:申请信号量*/printf("server : %s\n",ptr);/*输入共享内存区内容*/strcpy(ptr,"\0");/*清空共享内存区*/sem_unlink(argv[1]);/*第五步:删除信号量*/...
// 映射内存到进程的地址空间 char* map = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,0); if(map == MAP_FAILED) { perror("Error mmapping the file"); exit(EXIT_FAILURE); } // 打印映射的内存内容,即文件内容 for(off_t i =0; i < length; i++) { printf("%c",...
O_RDWR Open the object for read-write access. O_CREAT Create the shared memory object if it does not exist. The user and group ownership of the object are taken from the corresponding effective IDs of the calling process, and the object's permission bits are set according to the low-...
int main(){ int fd;fd = shm_open("region", O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);if (fd<0) { printf("error open region\n");return 0;} ftruncate(fd, 10);ptr = mmap(NULL, 10, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);if (ptr == MAP_FAILED) { printf("error ...
read.c #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/mman.h> #include <string.h> #include <errno.h> #include <unistd.h> /* int shm_open(const char *name, int oflag, mode_t mode); ...
共享内存优点： 1.在进程之间不通过内核传递数据，即不通过系统调用拷贝数据，达到快速，高效的数据...
(2),read(2), orwrite(2) on a shared memory object, or on the descriptor returned byshm_open(), is undefined. However, the FreeBSD kernel implementation explicitly includes support forread(2) andwrite(2). FreeBSD also supports zero-copy transmission of data from shared memory objects with...
但是如果我使用POSIX，然后使用空值的mmap (mmap( NULL，LARGE_SIZE，PROT_READ|PROT_WRITE，MAP_SHARED...