linux mmap范例

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

int main() {
    int fd; // 文件描述符
    struct stat sb; // 文件状态信息
    char *addr; // 映射后的内存地址

    // 打开文件
    fd = open("example.txt", O_RDONLY);
    if (fd == -1) {
        perror("Error opening file for reading");
        exit(EXIT_FAILURE);
    }

    // 获取文件状态信息
    if (fstat(fd, &sb) == -1) {
        perror("Error getting the file size");
        exit(EXIT_FAILURE);
    }

    // 映射文件到内存
    addr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (addr == MAP_FAILED) {
        perror("Error mapping file to memory");
        exit(EXIT_FAILURE);
    }

    // 关闭文件描述符，因为我们已经有了内存映射
    close(fd);

    // 读取并打印文件内容
    printf("%s
", addr);

    // 解除内存映射
    if (munmap(addr, sb.st_size) == -1) {
        perror("Error unmapping file from memory");
        exit(EXIT_FAILURE);
    }

    return 0;
}