linux c 文件映射

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

int main() {
    int fd = open("example.txt", O_RDWR);
    if (fd == -1) {
        perror("Error opening file for writing");
        return 1;
    }

    struct stat fileInfo = {0};
    fstat(fd, &fileInfo);
    int size = fileInfo.st_size;

    char *map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if (map == MAP_FAILED) {
        close(fd);
        perror("Error mmapping the file");
        return 1;
    }

    // 修改文件内容
    strcpy(map, "This is a test.");

    if (munmap(map, size) == -1) {
        perror("Error un-mmapping the file");
    }
    close(fd);
    return 0;
}

if (msync(map, size, MS_SYNC) == -1) {
    perror("Could not sync the file to disk");
}