During the src_unpack, src_compile, src_test and src_install phases, operates inside a sandbox. This is a special environment which attempts to help prevent badly written ebuilds (or ebuilds working with badly written build systems) accidentally writing outside of permitted locations.

All packages must build correctly when sandbox is active. Packages must not achieve this by using sneaky tricks to make sandbox warnings not show up — the sandbox is there to ensure that binary packages will work correctly, and that a badly written Makefile won't cause problems. Using addwrite is generally not the correct solution.

See Sandbox functions reference for details on sandbox-related functions. See Handling access violations for suggestions on fixing sandbox-related build problems.