linux c 读取超大文件

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

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
        return 1;
    }

    int fd = open(argv[1], O_RDONLY);
    if (fd == -1) {
        perror("Error opening file");
        return 1;
    }

    struct stat fileInfo;
    if (fstat(fd, &fileInfo) == -1) {
        perror("Error getting file size");
        close(fd);
        return 1;
    }

    void *fileData = mmap(NULL, fileInfo.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (fileData == MAP_FAILED) {
        perror("Error mmapping the file");
        close(fd);
        return 1;
    }

    // 现在可以像访问数组一样访问fileData指向的内存区域
    // 例如，打印文件的前100个字节
    for (int i = 0; i < 100 && i < fileInfo.st_size; i++) {
        putchar(((char *)fileData)[i]);
    }
    putchar('\n');

    if (munmap(fileData, fileInfo.st_size) == -1) {
        perror("Error un-mmapping the file");
    }
    close(fd);

    return 0;
}