问题
In C, we can use setvbuf(...) to set a buffer, its size, and a buffering mode. I am surprised to find that no one has asked how to read these values, given an open FILE* (e.g. stdout, or user-provided). I.e., how could one implement a "getvbuf(...)" routine (or even a subset of it)?
void getvbuf(FILE* stream, char** pbuf,int* bufmode,size_t* bufsize);
回答1:
I don't think its available as part of the standard. However Solaris has introduced some non standard mechanism to query few of these properties which are also available in GNU C compiler.
Check this for more details: https://www.gnu.org/software/libc/manual/html_node/Controlling-Buffering.html
I was curious to know the use case where you want to do a getvbuf(..) kind of stuff.
来源：https://stackoverflow.com/questions/41197000/get-buffering-parameters-from-an-open-file