【Linux系统编程】文件_02_文件描述符fd_04_fstat

fstat

1. 功能：获取文件的元数据
2. 原型：

int fstat(int fd, struct stat *statbuf);

3. 参数：
   1）fd
   2）struct stat* statbuf，传出参数，保存文件元数据信息
4. 返回值：
   成功：返回0
   失败：返回-1，并会设置errno
5. DO

#include <func.h>

int main(int argc, char* argv[]) {
    // ./test_fstat file
    if (argc != 2) {
        error(1, 0, "Usage: %s file", argv[0]);
    }

    int fd = open(argv[1], O_RDONLY);
    if (fd == -1) {
        error(1, errno, "open %s", argv[1]);
    }

    struct stat sb; // 存储文件元数据信息
    if (fstat(fd, &sb) == -1) {
        error(1, errno, "fstat %d", fd);
    }
    // struct stat* sb = (struct stat*)malloc(sizeof(struct stat));
    // if (fstat(fd, sb) == -1) {
    //     free(sb);
    //     error(1, errno, "fstat %d", fd);
    // }

    // 打印struct stat里的成员
    printf("st_ino = %ld\nst_mode = %lo\nst_nlink = %ld\nst_size = %ld\nst_blocks = %ld\n",
           (long)sb.st_ino,     // (long)sb->st_ino,
           (long)sb.st_mode,    // (long)sb->st_mode,
           (long)sb.st_nlink,   // (long)sb->st_nlink,
           (long)sb.st_size,    // (long)sb->st_size,
           (long)sb.st_blocks); // (long)sb->st_blocks,
    // free(sb);

    return 0;
}