On Mon, 4 Mar 2024 23:44:14 GMT, Erik Joelsson <er...@openjdk.org> wrote:
>> Executables and dynamic libraries on Linux can encode a search path that the >> dynamic linker will use when looking up library dependencies, generally >> referred to as an "rpath". In the JDK we use this with the $ORIGIN feature >> to set search paths relative to the location of the binary itself. Typically >> executables in the bin/ directory have the rpath "$ORIGIN/../lib" to find >> libjli.so. Most of the libraries in lib/ have rpath set to just "$ORIGIN" to >> find each other. >> >> There are two different types of such rpaths, RPATH and RUNPATH. The former >> is the earlier incantation but RUNPATH has been around since about 2003 and >> has been default in prominent Linux distros for a long time, and now also >> seems to be default in the linker directly from binutils. The toolchain used >> by Oracle defaulted to RPATH until at least JDK 11, but since then with some >> toolchain upgrade, the default was flipped to RUNPATH. >> >> The main (relevant in this case) difference between the two is that RPATH is >> considered before the LD_LIBRARY_PATH environment variable, while RUNPATH is >> only considered after LD_LIBRARY_PATH. For libraries that are part of a >> Linux distribution, letting users, or the system, control and override >> builtin rpaths with LD_LIBRARY_PATH seems like a reasonable thing to prefer. >> However, for the JDK, there really is no usecase for having an externally >> configured LD_LIBRARY_PATH potentially getting in the way of the JDK >> libraries finding each other correctly. If a user environment sets >> LD_LIBRARY_PATH, and there is a library in that path with the same name as a >> JDK library (e.g. libnet.so or some other generically named library) that >> external library will be loaded instead of the JDK internal library and that >> is basically guaranteed to break the JDK. There is no supported usecase that >> I can think of for injecting other versions of such libraries in a JDK >> distribution. >> >> I propose that we explicitly configure the JDK build to set RPATH instead of >> RUNPATH for Linux binaries. This is done with the linker flag >> "--disable-new-dtags". > > Erik Joelsson has updated the pull request incrementally with one additional > commit since the last revision: > > bug ref Thanks for the further explanation and adding the comment. LGTM. ------------- Marked as reviewed by dholmes (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/18050#pullrequestreview-1916027301
