Hello everyone,

the implementation of fflush() in musl doesn't seem to conform to the opengroup standard:

https://pubs.opengroup.org/onlinepubs/009695399/functions/fflush.html

In addition to flushing unwritten data, which is expected, musl flushes the read buffer when calling fflush(). This leads to data loss in bidirectional communication uses. Other standard libraries don't do this.

As a reference compare musl to openbsd's libc:

https://git.musl-libc.org/cgit/musl/tree/src/stdio/fflush.c
https://github.com/openbsd/src/blob/master/lib/libc/stdio/fflush.c

I think this is unexpected behavior and should be changed.

Greetings,
  Michael