/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/ is in libpetsc-complex-3.7.7-dbg 3.7.7+dfsg1-2build5.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/bagimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/characteristicimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmdaimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmforestimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmlabelimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmmbimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmnetworkimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmpatchimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dmpleximpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/drawimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/dtimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/fortranimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/isimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kernels/
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kernels/blockinvert.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kernels/blockmatmult.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kernels/blocktranspose.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kernels/petscaxpy.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/kspimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/linesearchimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/logimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/matimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/matorderimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/pcgamgimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/pcimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/pcmgimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/petscdsimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/petscfeimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/petscfptimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/petscfvimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/petscimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/sfimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/snesimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/taoimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/taolinesearchimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/tsimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/vecimpl.h
/usr/lib/petscdir/3.7.7/x86_64-linux-gnu-complex-debug/include/petsc/private/viewerimpl.h