lddsafe

#!/usr/bin/env bash
#
# lddsafe - Safely print shared library dependencies (similar to ldd).
# Author: Ricardo Garcia Gonzalez.
# Author: Ivan Mironov.
# License: Public domain code.
#

# Better for grep and expected output of other tools.
export LANG=C

# Expand globs to nothing when no match is found.
shopt -s nullglob

# Print error and exit.
die()
{
	echo "ERROR: $1" 1>&2
	exit 1
}

# Find required program.
findexec()
{
	which "$1" >/dev/null 2>/dev/null || die "$1 not found"
}

# Check file exists and is readable.
checkreadable()
{
	[ -r "$1" ] || die "$1 missing or not readable"
}

# Check for bash version.
[ -n "$BASH_VERSION" ] || die "Bash required"
[ ${BASH_VERSINFO[0]} -ge 4 ] || die "Bash version 4 or later required"

# Check needed programs.
findexec objdump
findexec readelf
findexec dirname
findexec sed

# Check needed files.
checkreadable /etc/ld.so.conf

# Check arguments.
[ "$1" == "-n" ] && recursive=0 || recursive=1
[ "$1" == "-n" ] && shift
if [ $# -eq 0 ]; then
	echo "Usage: $( basename $0 ) [-n] FILE..." 2>&1
	exit 1
fi
for arg in "$@"; do
	checkreadable "$1"
done

# Recursively print the list of files included from /etc/ld.so.conf.
ld_so_conf_deps()
{
	echo "$1"
	dirname="$( dirname "$1" )"
	patterns="$( sed -n 's/^include[\ \t]\+\(.\+\)$/\1/p' "$1" )"
	set -o noglob
	for pattern in $patterns; do
		set +o noglob
		case $pattern in
			/*)
				for file in $pattern; do
					ld_so_conf_deps "$file"
				done
				;;
			*)
				for file in $dirname/$pattern; do
					ld_so_conf_deps "$file"
				done
				;;
		esac
	done
	set +o noglob
}

# Additional library directories.
LD_LIBRARY_PATH_LIBS="${LD_LIBRARY_PATH//:/ }"
MORELIBDIRS="$( sed '/^include[\ \t]/d' $( ld_so_conf_deps /etc/ld.so.conf ) )"

# Search for a given library name.
searchlib()
{
	found=0
	for libdir in $LIBDIRS; do
		path="$libdir"/"$1"
		if [ -r "$path" ]; then
			found=1
			break
		fi
	done
	[ $found -eq 1 ] && echo "$path"
}

# Already visited libraries.
declare -A VISITEDLIBS

# Print dependency results, recursively.
recursivedeps()
{
	for lib in $( objdump -p "$1" | \
		      sed -n 's,^ *NEEDED \+\([^ ]\+\) *$,\1,p' ); do
		if [ ! "${VISITEDLIBS[$lib]}" ]; then
			VISITEDLIBS["$lib"]=1
			file=`searchlib "$lib"`
			if [ "$file" ]; then
				echo "	$lib => $file"
				[ $recursive -eq 1 ] && recursivedeps "$file"
			else
				echo "	$lib => not found"
			fi
		fi
	done
}

# Search symbol names in library directories.
for arg in "$@"; do
	# Print file name when more than one file given.
	[ $# -gt 1 ] && echo "${arg}:"

	# Set appropriate library search directories.
	class=$( readelf -h $arg 2>/dev/null | \
		 sed -n 's/^[ \t]*Class:[\ \t]\+\(.\+\)/\1/p' )
	if [ -z "$class" ]; then
		echo "$arg: not an ELF file" 2>&1
		continue
	fi
	if [ $class != ELF32 -a $class != ELF64 ]; then
		echo "$arg: unknown ELF format" 2>&1
		continue
	fi
	if [ $class == ELF64 ]; then
		if [ -d /lib64 ]; then
			stdlibs="/lib64 /usr/lib64"
		else
			stdlibs="/lib /usr/lib"
		fi
	else # $class == ELF32
		if [ -d /lib32 ]; then
			stdlibs="/lib32 /usr/lib32"
		else
			stdlibs="/lib /usr/lib"
		fi
	fi
	LIBDIRS="$LD_LIBRARY_PATH_LIBS $MORELIBDIRS $stdlibs"

	# Get a unique list of library dependencies for this argument.
	unset VISITEDLIBS
	declare -A VISITEDLIBS
	recursivedeps "$arg"
done
exit 0