文件的内存映射

#include<stdio.h>#include<stdlib.h>#include<sys/mman.h>#include<sys/stat.h>#include<sys/types.h>#include<fcntl.h>#define FILE_LENGTH 0x1000int main(){void* file_memory;int fd;fd = open("test", O_RDWR|O_CREAT);if(fd < 0)printf("open test.txt error!/n");lseek(fd, FILE_LENGTH, SEEK_SET);write(fd, " ", 1);lseek(fd, 0, SEEK_SET);file_memory = mmap(NULL, FILE_LENGTH, PROT_WRITE, MAP_SHARED, fd, 0);if(file_memory == MAP_FAILED)printf("mmap failed/n");close(fd);//printf("%s/n", file_memory);sprintf((char*)file_memory, "%d/n", 1234);munmap(file_memory, FILE_LENGTH);}