c - 如何以最大分辨率获取文件时间戳？

Question

man 2 stat 显示 struct 中返回的值 st_atime、st_mtime 和 st_ctime stat 属于 time_t 类型，具有秒分辨率。如何以更高的分辨率获得相同的值，可能是 struct timespec 或 struct timeval，或者只是缺少的亚秒部分？

我需要这个用于 Linux 上的 C++，但我也用 C 标记，因为我认为两种语言的答案可能是相同的。

Answer 1

根据 man 2 stat 的注释部分:

   Since kernel 2.5.48, the stat structure supports nanosecond resolution  for  the  three  file  timestamp  fields.   Glibc
   exposes the nanosecond component of each field using names of the form st_atim.tv_nsec if the _BSD_SOURCE or _SVID_SOURCE
   feature test macro is defined.  These fields are specified in POSIX.1-2008, and, starting with version 2.12,  glibc  also
   exposes  these  field  names if _POSIX_C_SOURCE is defined with the value 200809L or greater, or _XOPEN_SOURCE is defined
   with the value 700 or greater.  If none of the aforementioned macros are defined, then the nanosecond values are  exposed
   with names of the form st_atimensec.  On file systems that do not support subsecond timestamps, the nanosecond fields are
   returned with the value 0.