#!/bin/sh -e
#
# is_elf_so_executable - checks whether the given ELF shared object
# should be treated as an executable.
#
# Not an every shared object is a library.
# For example, PIEs should be treated as executables.
#
# Copyright (C) 2003-2016  Dmitry V. Levin <ldv@altlinux.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#

[ $# -eq 1 ]
file="$1"; shift

# This dynamic linker used to have its entry point
# equal to the text segment start address.
[ -n "${file##*/lib64/ld-*.so}" ] || exit 0

section_header="$(readelf --wide --sections "$file" ||:)"
# An .interp section means it is an executable, see
# comm -12 <(grep -Fl .interp /usr/lib/ldscripts/*)
#          <(grep -Fle --shared /usr/lib/ldscripts/*)
if printf %s "$section_header" |grep -Fqs ' .interp '; then
	exit 0
fi

file_header="$(readelf --wide --file-header "$file" ||:)"
# Zero entry point is treated like no entry points.
entry="$(printf %s "$file_header" |
	sed -ne 's/^ \+Entry point address: \+0x0*\([1-9a-f][0-9a-f]*\)$/\1/p')"

# Zero text segment start address is treated like no text segments.
text="$(printf %s "$section_header" |
	sed -ne 's/^ *\[ *[0-9]\+\] \.text \+PROGBITS \+0*\([1-9a-f][0-9a-f]*\) \+.*/\1/p')"

# Missing entry point or text segment means it is not an executable.
# Also, if entry point and text segment start address are equal,
# it is not an executable.
[ -z "$entry" ] ||
[ -z "$text" ] ||
[ "$entry" = "$text" ] ||
exit 0

exit 1