#!/bin/bash

# A function that finds needed libraries and interpreters.
#
function find_requires() {
	local dir
	local dirs=$@

	# Find interpreters of all files in the dirs and skip those we provide
	# ourself.
	local interpreter
	local interpreters
	for interpreter in $(find_interpreters ${dirs}); do
		local found=0
		for dir in ${dirs}; do
			if [ -e "${dir}/${interpreter}" ]; then
				found=1
				break
			fi
		done

		[ "${found}" = "0" ] && interpreters="${interpreters} ${interpreter}"
	done

	# Find NEEDED libs and add them to a list if they are not provided by any
	# other file in dirs.
	local neededs
	for file in $(find_elf_files ${dirs}); do
		for needed in $(file_get_needed ${file}); do
			neededs="${neededs} ${needed}"
		done
	done

	# Find all symlink destinations
	local links=$(find_symlink_destinations ${dirs})

	# Others
	local others=$(find_python_requires ${dirs})
	others="${others} $(find_weak_symbols_requires ${dirs})"
	others="${others} $(find_perl_requires ${dirs})"

	# Get provides, because packages should not depend on features they provide
	# by themselves.
	local provides=$(find_provides ${dirs})

	# Return a sorted and unique(!) list
	local require
	local requires
	for require in $(listsort ${PKG_DEPS} ${interpreters} ${neededs} ${links} ${others}); do
		[ "${require:0:3}" = "ld-" ] && continue
		listmatch ${require} ${provides} || requires="${requires} ${require}"
	done

	echo ${requires}
}

function find_provides() {
	local dirs=$@

	local file
	local sonames
	for file in $(find_elf_files ${dirs}); do
		sonames="${sonames} $(file_get_soname ${file})"
	done
	sonames=$(listsort ${sonames})

	# Others
	local others=$(find_python_provides ${dirs})
	others="${others} $(find_weak_symbols_provides ${dirs})"
	others="${others} $(find_perl_provides ${dirs})"

	listsort ${PKG_PROVIDES} ${sonames} ${others}
}

function find_interpreters() {
	local dirs=$@

	log DEBUG "Searching for interpreters in ${dirs}"

	local file
	local interpreter
	local interpreters
	for file in $(find ${dirs} -type f 2>/dev/null); do
		# Get interpreter information from file.
		interpreter=$(file_get_interpreter ${file})

		# Skip the file silently if the result was empty.
		[ -z "${interpreter}" ] && continue

		# Skip invalid interpreters that don't start with a slash.
		if [ "${interpreter:0:1}" != "/" ]; then
			log WARNING "Skipping invalid interpreter \"${interpreter}\" from \"${file}\"."
			continue
		fi

		if ! listmatch ${interpreter} ${INTERPRETERS_TO_BE_SKIPPED}; then
			interpreters="${interpreters} ${interpreter}"
		fi
	done

	interpreters=$(listsort ${interpreters})

	log DEBUG "find_interpreters ${dirs}: ${interpreters}"

	echo "${interpreters}"
}

# Find the destinations of all symlinks and adds a dependency for that.
#
function find_symlink_destinations() {
        local dir=$@

        local link
        local links
        for link in $(find ${dir} -type l 2>/dev/null); do
                link="$(readlink -m ${link})"
                [ -e "${link}" ] && continue

                link="${link#${dir}}"
                links="${links} ${link}"
        done

        echo ${links}
}

function find_python_provides() {
	local dir=${1}

	local file
	for file in $(find ${dir}/usr/bin/python* 2>/dev/null); do
		file=$(basename ${file})
		file=${file#python}

		if [ -n "${file}" ]; then
			echo "python-api=${file}"
		fi
	done
}

function find_python_requires() {
	local dir=${1}

	local file
	for file in $(find ${dir}/usr/lib -maxdepth 1 2>/dev/null); do
		file=$(basename ${file})

		if [ "${file:0:6}" = "python" ]; then
			file=${file#python}

			if [ -n "${file}" ]; then
				echo "python-api=${file}"
			fi
		fi
	done
}

function find_perl_files() {
	local extension
	for extension in pm pl; do
		find $@ -name "*.${extension}" 2>/dev/null
	done
}

function find_perl_provides() {
	[ -x "/usr/bin/perl" ] || return 0
	${BASEDIR}/perl.prov $(find_perl_files $@) | sort -u
}

function find_perl_requires() {
	[ -x "/usr/bin/perl" ] || return 0
	${BASEDIR}/perl.req $(find_perl_files $@) | sort -u
}

function find_weak_symbols_provides() {
	local dirs=$@

	local file
	local soname
	local symbol
	for file in $(find_elf_files ${dirs}); do
		soname=$(file_get_soname ${file})
		[ -z "${soname}" ] && continue

		for symbol in $(objdump -p ${file} | grep -E "^[0-9]+" | awk '{ print $4 }'); do
			[ "${symbol}" = "${soname}" ] && continue
			[ "${symbol}" = "GLIBC_PRIVATE" ] && continue

			echo "${soname}(${symbol})"
		done
	done | sort -u
}

function find_weak_symbols_requires() {
	local dirs=$@

	local file
	for file in $(find_elf_files ${dirs}); do
	    objdump -p ${file} | awk 'BEGIN { START=0; LIBNAME=""; }
			/^$/ { START=0; }
			/^Dynamic Section:$/ { START=1; }
			(START==1) && /NEEDED/ {
				print $2;
			}
			(START==2) && /^[A-Za-z]/ { START=3; }
			/^Version References:$/ { START=2; }
			(START==2) && /required from/ {
			    sub(/:/, "", $3);
			    LIBNAME=$3;
			}
			(START==2) && (LIBNAME!="") && ($4!="") && (($4~/^GLIBC_*/) || ($4~/^GCC_*/)) {
			    print LIBNAME "(" $4 ")";
			}'
	done | grep -v "GLIBC_PRIVATE" | sort -u
}