Eric Blake wrote: > According to Jim Meyering on 7/18/2009 2:42 AM: >> How about fixing gnulib's lib/error.c to do the right thing? >> Then if you teach m4/error.m4 to detect when glibc's error function >> is defective (currently always) it can use the improved replacement. > > It is not defective on Linux (that is, glibc's fflush behaves reliably > even after fclose(stdout), and glibc can exploit this fact in its error() > implementation). And according to doc/glibc-functions/error.texi, no > other platforms provide error(), so we already provide it everywhere else. > Since the gnulib error module already has changes not currently in glibc, > we can go ahead and change error() without worrying about glibc adopting > it (although with #if _LIBC guards to make upstream adoption easier). > > How about this patch? It was enough to fix the behavior of m4 on cygwin
I have a slight preference for omitting the #if !_LIBC guards, and thus adopting the improvement unconditionally whenever error.c is used. The added fcntl call has minimal cost (at least that's my recollection from back when I measured it), and in the unusual case of already-closed stdout, there will be no failing close syscall to distract readers of strace output logs. But either way is fine. Thanks for working on this. ... > +2009-07-18 Eric Blake <e...@byu.net> > + > + error: avoid undefined use of stdout > + * lib/error.c (error, error_at_line): Check that fd 1 is open > + before flushing stdout. Avoids a crash on cygwin when libsigsegv > + is handling faults and the close_stdout module wants to report the > + detection of closed stdout as an error.
