On 12/22/2010 03:19 PM, Jim Meyering wrote: > Bruno Haible wrote: > >> Ping? No one wants to solve this? It's a critical issue for libposix. >> >> Eric Blake wrote: >>> error() is not POSIX. Maybe the thing to do is figure out what in >>> libposix is dragging in error(), and work on breaking that dependency. >>> That way, a package using libposix then makes their own decision of >>> whether to supplement things with error() and program_name. >> >> I replied: >>> Very good point. The dependency comes from >>> >>> openat --> openat-die --> error >>> fdopendir >>> >>> Can you work on breaking this dependency? I mean, for example, >>> instead of directly calling openat_save_fail() and >>> openat_restore_fail(), go through a variable that contains two >>> function pointers, and have openat() and fdopendir() return an error code >>> if these function pointers are NULL. Like we do with >>> argp_program_version_hook >>> error_print_progname >>> obstack_alloc_failed_handler >>> See also >>> c_stack_action >>> install_sigpipe_die_handler > > Hi Bruno, > > Perhaps I don't understand the proposal, but here is my reaction: > > IMHO, those functions must never return in the unusual case for which > they now call error and then exit. The failures are too fundamental[0], > and we cannot require that all callers handle any new error code or > interpret existing error codes differently, can we?
Perhaps the thing to do would be: The openat module has a function pointer openat_failed_handler, defaulting to NULL. If we get into the situation where we changed directories but can't return, then call any non-NULL handler, and resort to calling abort() if the handler returns or if it was NULL. The openat-die module then populates the openat_failed_handler with a function that uses error() rather than abort. That way, posix modules use just openat and don't drag in error(), but coreutils imports openat-die to get the nicer behavior than an abort() (that is, no change from current behavior). -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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