Hi, > On 9 Aug 2017, at 17:56, Jonathan Wakely <jwak...@redhat.com> wrote: > > This fixes a couple of problems in __gnu_cxx::stdio_filebuf, > specifically in the __basic_file::sys_open(FILE*, openmode) function > it uses when constructed from an existing FILE stream. > > Firstly, r86756 changed __basic_file::sys_open(FILE*, openmode) to put > the call to sync() before the assignment that sets _M_cfile. This > means the fflush(_M_cfile) call has a null argument, and flushes all > open streams. I don't think that was intentional, and we only want to > flush the FILE we're constructing the streambuf with. (I think this is > a regression from 3.4.3, which just flushed the one stream). > > Secondly, we zero errno so that we can tell if fflush sets it. We need > to restore the original value to meet the promise we make at > https://gcc.gnu.org/onlinedocs/libstdc++/manual/errno.html > > Paolo, does the this->sync() to fflush(__file) change look right?
Yes, I went through the audit trail of libstdc++/81751 and the change looks good. Certainly we didn't intentionally want the behavior of fflush(0)! Thanks! Paolo
