On Mon, Mar 05, 2018 at 12:19:24PM +0000, Daniel P. Berrangé wrote: > Fedora rawhide has just upgraded to the latest glibc git master snapshot, > of what will become the 2.28 release, and this has exposed bugs in gnulib's > fseeko.c implementation (and probably more macros) besides. > > The issue starts are line 50: > > http://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/fseeko.c#n50 > > #if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ > > Historically the _IO_ftrylockfile symbol has been defined unconditionally > in glibc, by /usr/include/libio.h, which is pulled in unconditionally from > /usr/include/stdio.h > > The libio.h header was deprecated in 2.27 release and is removed in git > master for future 2.28. Thus the _IO_ftrylockfile symbol has gone away. > > https://sourceware.org/ml/libc-announce/2018/msg00000.html > > "The nonstandard header files <libio.h> and <_G_config.h> are deprecated > and will be removed in a future release. Software that is still using > either header should be updated to use standard <stdio.h> interfaces > instead. > > libio.h was originally the header for a set of supported GNU extensions, > but they have not been maintained as such in many years, they are now > standing in the way of improvements to stdio, and we don't think there are > any remaining external users. _G_config.h was never intended for public > use, but predates the bits convention." > > > We then fail the __GNU_LIBRARY__ test too, because modern glibc defines > that to a value of '6', not '1'. > > For added fun __GNU_LIBRARY__ is considered deprecated too, with > recommendation to use other symbols like __GLIBC__ and __GLIBC_MINOR__ > > > /* This macro indicates that the installed library is the GNU C Library. > For historic reasons the value now is 6 and this will stay from now > on. The use of this variable is deprecated. Use __GLIBC__ and > __GLIBC_MINOR__ now (see below) when you want to test for a specific > GNU C library version and use the values in <gnu/lib-names.h> to get > the sonames of the shared libraries. * > #define __GNU_LIBRARY__ 6 > > I hit failure on fseeko.c, but many other files in gnulib test on > _IO_ftrylockfile so I presume they are all broken. > > I'm curious why we're trying to replace fseeko impl at all, since I > would expect the modern glibc impl to be suitable to use as-is. Changing the test for '__GNU_LIBRARY__ == 1' to just "__GNU_LIBRARY__" does appear to work at first, but fflush.c then fails fflush.c: In function 'clear_ungetc_buffer_preserving_position': fflush.c:42:20: error: '_IO_IN_BACKUP' undeclared (first use in this function) if (fp->_flags & _IO_IN_BACKUP) ^~~~~~~~~~~~~ This constant was also in libio.h and so no longer defined. Re-defining it in gnulib feels dangerous because glibc is free to change its value at any time now this is no longer a public API symbol. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
