#!/usr/bin/env bash
#
# Summary: Rewrite an unpacked Python's rpaths so it runs from its prefix
#
# Usage: pyenv binary relocate <prefix>
#
#   Rewrites the rpaths of a Python tree that was unpacked into <prefix> so the
#   interpreter and its extension modules load the bundled libraries from their
#   new location rather than the path it was built at. Requires patchelf.
#
#   The definition that `pyenv binary generate-installer' produces calls this
#   after `install_package ... copy' has laid the tree down.
#
set -e
[ -n "$PYENV_DEBUG" ] && set -x

if [ "$1" = "--complete" ]; then
  exit
fi

prefix="$1"
if [ -z "$prefix" ]; then
  pyenv-help --usage binary-relocate >&2
  exit 1
fi

# patchelf can add an rpath and write one of any length; chrpath can only shorten
# an existing one, which is not enough to relocate every build, so require it.
if ! command -v patchelf >/dev/null 2>&1; then
  echo "pyenv-binary: need patchelf to relocate the binary" >&2
  exit 1
fi

# The interpreter loads libpython from ../lib. Patch every ELF binary in bin/ so
# this holds whatever the interpreter is named (python3, python2.7, ...); the
# scripts alongside it (pip, idle) are not ELF, so `--print-rpath' fails on them
# and they are skipped. A tree with no interpreter at all did not unpack the way
# we expect, so treat that as an error rather than quietly relocating nothing.
found=0
for file in "$prefix"/bin/*; do
  [[ -f $file && -x $file && ! -L $file ]] || continue
  patchelf --print-rpath "$file" >/dev/null 2>&1 || continue
  patchelf --set-rpath "$prefix/lib" "$file"
  found=1
done
if [ "$found" -eq 0 ]; then
  echo "pyenv-binary: found no interpreter to relocate under \`${prefix}/bin'" >&2
  exit 1
fi

# The extension modules CPython built are the only other objects with an rpath
# into the old prefix, so point them at lib/ as well. Anything a wheel installed
# carries an rpath of its own, often into a bundled library directory beside it,
# and would stop loading if we overwrote it. Each match is an ELF object we expect
# to patch, so let a failure stop us rather than swallow it.
while IFS= read -r so; do
  patchelf --set-rpath "$prefix/lib" "$so"
done < <(find "$prefix" -path '*/lib-dynload/*.so')