On Wed, 14 Jun 2017, Richard Biener wrote: > The following patch makes sure we build the 32bit multilib libgcov with > large file support on x86_64-linux. libgcov.h ends up using auto-host.h > via including tconfig.h which is only valid for the main multilib > (and on x86_64 doesn't need explicit large-file support defines). That > libgcc ends up using that is probably from times where it wasn't at > the toplevel, some files already include auto-target.h generated by > libgcc configure but most do so after including tsystem.h which is > of course too late. I suppose libgcc files shouldn't include tconfig.h > from gcc/, but that's a change going to far for this bug ;)
tconfig.h shouldn't include host-specific configure test results (as the relevant bits of config.in should be conditioned on USED_FOR_TARGET), though that doesn't mean everything is indeed properly conditioned (and ideally we'd avoid configuration information from the gcc/ directory needing to be used in target libraries at all). > Other than libgcov libgomp, libcilkrts, libmpx and libstdc++ > are similarly affected (they use fopen on the 32bit multilib) > but not fixed. libubsan, libasan, libssp, libbacktrace and libgfortran > use open. While libgfortran configury has AC_SYS_LARGEFILE, the > open use leaks in through libbacktrace (ubsan/asan might have the > same issue, didn't investigate). libbacktrace lacks AC_SYS_LARGEFILE. In general, watch out for off_t etc. as part of the ABI for such libraries (in which case AC_SYS_LARGEFILE could break the ABI). And if the code uses fseek/ftell, it needs to change to fseeko/ftello (where available) to handle large offsets. -- Joseph S. Myers jos...@codesourcery.com
