linux 内存映射 文件拷贝

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

void copy_file(const char *src, const char *dest) {
    int src_fd = open(src, O_RDONLY);
    if (src_fd == -1) {
        perror("open src");
        exit(EXIT_FAILURE);
    }

    struct stat st;
    if (fstat(src_fd, &st) == -1) {
        perror("fstat");
        close(src_fd);
        exit(EXIT_FAILURE);
    }

    void *src_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, src_fd, 0);
    if (src_map == MAP_FAILED) {
        perror("mmap");
        close(src_fd);
        exit(EXIT_FAILURE);
    }

    int dest_fd = open(dest, O_RDWR | O_CREAT | O_TRUNC, st.st_mode);
    if (dest_fd == -1) {
        perror("open dest");
        munmap(src_map, st.st_size);
        close(src_fd);
        exit(EXIT_FAILURE);
    }

    if (ftruncate(dest_fd, st.st_size) == -1) {
        perror("ftruncate");
        munmap(src_map, st.st_size);
        close(src_fd);
        close(dest_fd);
        exit(EXIT_FAILURE);
    }

    void *dest_map = mmap(NULL, st.st_size, PROT_WRITE, MAP_SHARED, dest_fd, 0);
    if (dest_map == MAP_FAILED) {
        perror("mmap dest");
        munmap(src_map, st.st_size);
        close(src_fd);
        close(dest_fd);
        exit(EXIT_FAILURE);
    }

    memcpy(dest_map, src_map, st.st_size);

    munmap(src_map, st.st_size);
    munmap(dest_map, st.st_size);
    close(src_fd);
    close(dest_fd);
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <source> <destination>
", argv[0]);
        return EXIT_FAILURE;
    }
    copy_file(argv[1], argv[2]);
    return EXIT_SUCCESS;
}