Only dest dir longer than base dir not supported

Hello,

Have you experienced the mysterious error, “Only dest dir longer than base dir not supported”?

I have.

The Problem

When you build an rpm, the code is built in %{_builddir}, which usually evaluates as %{_topdir}/BUILD, which in turn evaluates as something like /home/you/rpmbuild/BUILD. The built code (if built with GCC) ends up with loads of /home/you/rpmbuild/BUILD paths embedded in it, and the script /usr/lib/rpm/debugedit rewrites these paths to /usr/src/debug so that the debuginfo rpms work. /usr/lib/rpm/debugedit cannot extend strings, it can only shrink them. If you are seeing “Only dest dir longer than base dir not supported” then, somewhere in your build system, %{_builddir} is defined as something that expands to a string shorter than /usr/src/debug.

Example

In my case, I was building a glibc rpm in a VM that turned out not to have enough disk. I created a new disk, mounted it on /mnt, and added the line %_topdir /mnt to my ~/.rpmmacros. The result? “Only dest dir longer than base dir not supported”. I fixed it by editing ~/.rpmmacros to say %_topdir /mnt/rpmbuild.

Briefly

/usr/src/debug       # the reference
/mnt/BUILD           # too short!
/mnt/rpmbuild/BUILD  # long enough

Thank you,
The Mgt.