Resolve symlinked java command to find home#6639
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headius merged 8 commits intojruby:jruby-9.2from Mar 30, 2021
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On many Linux systems, the installed `java` command will live in /usr/bin and point via a chain of symlinks to the actual JDK home installation under (for example) /usr/lib/jvm/<java-home>. This symlinking interferes with our detecting where Java actually lives, leading to issues like jruby#6637. This patch uses existing logic for resolving a trail of symlinks, allowing us to dig down to the actual binary `java` and from there determine its JAVA_HOME. Fixes jruby#6637. See also jruby/jruby-launcher#34 which will need a similar fix in C.
These should be visible from within the launched JRuby process.
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First attempt at a test failed, indicating that the JDK installs on Ubuntu also symlink |
There is no standard way in POSIX shell to determine the target of a symlink, so we are forced to use readlink.
export will hide the failure of the command on the RHS used as the value, so export only the variable names.
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Additional improvements thanks to @mrnoname1000:
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From de400b6:
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headius
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Mar 31, 2021
I decided I am not comfortable with this change, since it would mean launching a subprocess JRuby with a different home or Java would require *clearing* these variables rather than just pointing at a new jruby or java executable. See #6639.
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This PR fixes #6637 by fully resolving any symlinks between the
javacommand (found from$JAVACMDorjavain PATH) before using that command's path to determine$JAVA_HOME.The issue affects systems without
$JAVA_HOMEset, but that have ajavacommand in PATH that resolves to a$JAVA_HOME/bin/javathrough a series of symlinks (e.g. CentOS).This PR also exports
JRUBY_HOME,JAVACMD, andJAVA_HOMEso they will be seen by the JRuby process and subprocesses, avoiding recalculating this home or accidentally using a different JDK for additional JRuby launches.I have added a test case for the symlink situation.