如何以最大分辨率獲取文件時間戳？

man 2 stat顯示在struct stat中返回的值爲st_atime,st_mtime和st_ctime的類型爲time_t，其具有秒分辨率。如何獲得更高分辨率的相同數值，可能是struct timespec或struct timeval，或者只是缺少的亞秒部分？如何以最大分辨率獲取文件時間戳？

我需要這個在Linux上的C++，但我也用C標記，因爲我認爲這兩種語言的答案可能是相同的。

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2014-02-14 lvella

據man 2 stat說明部分：

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.

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2014-02-14 19:42:09 twalberg

有一點要記住，即使是在納秒級的分辨率是，你可能在你的硬件沒有get精確到納秒。例如，我認爲典型的英特爾硬件只能精確到1毫秒左右，所以即使你在幾納秒內得到一個值，你通常也不能相信低於1毫秒。 – jia103

如何以最大分辨率獲取文件時間戳？

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