1#!/bin/sh
2
3libkey() {
4	libkey="lib_symbols_$1"
5	patterns=[.+,/-]
6	replacement=_
7	while :; do
8		case " ${libkey} " in
9			*${patterns}*)
10				libkey="${libkey%%${patterns}*}${replacement}${libkey#*${patterns}}"
11				;;
12			*)
13				break
14				;;
15		esac
16	done
17	return 0
18}
19
20usage() {
21	cat <<-EOF
22	usage: $0 [-Uv] [-L LD_LIBRARY_PATH] file
23	       -L:       Specify an alternative LD_LIBRARY_PATH for the library resolution.
24	       -U:       Skip looking for unresolved symbols.
25	       -v:       Show which library each symbol is resolved to.
26	EOF
27	exit 0
28}
29
30ret=0
31CHECK_UNRESOLVED=1
32VERBOSE_RESOLVED=0
33while getopts "L:Uv" flag; do
34	case "${flag}" in
35		L) LIB_PATH="${OPTARG}" ;;
36		U) CHECK_UNRESOLVED=0 ;;
37		v) VERBOSE_RESOLVED=1 ;;
38		*) usage ;;
39	esac
40done
41shift $((OPTIND-1))
42
43if ! [ -f "$1" ]; then
44	echo "No such file or directory: $1" >&2
45	exit 1
46fi
47
48mime=$(file -L --mime-type $1)
49isbin=0
50case $mime in
51*application/x-executable|*application/x-pie-executable) isbin=1 ;;
52*application/x-sharedlib);;
53*) echo "Not an elf file" >&2 ; exit 1;;
54esac
55
56# Gather all symbols from the target
57unresolved_symbols=$(nm -u -D --format=posix "$1" | awk '$2 == "U" {print $1}' | tr '\n' ' ')
58[ ${isbin} -eq 1 ] && bss_symbols=$(nm -D --format=posix "$1" | awk '$2 == "B" && $4 != "" {print $1}' | tr '\n' ' ')
59if [ -n "${LIB_PATH}" ]; then
60	for libc in /lib/libc.so.*; do
61		LDD_ENV="LD_PRELOAD=${libc}"
62	done
63	LDD_ENV="${LDD_ENV} LD_LIBRARY_PATH=${LIB_PATH}"
64fi
65
66ldd_libs=$(env ${LDD_ENV} ldd $(realpath $1) | awk '{print $1 ":" $3}')
67
68# Check for useful libs
69list_libs=
70resolved_symbols=
71for lib in $(readelf -d $1 | awk '$2 ~ /\(?NEEDED\)?/ { sub(/\[/,"",$NF); sub(/\]/,"",$NF); print $NF }'); do
72	echo -n "checking if $lib is needed: "
73	if [ -n "${lib##/*}" ]; then
74		for libpair in ${ldd_libs}; do
75			case "${libpair}" in
76				${lib}:*) libpath="${libpair#*:}" && break ;;
77			esac
78		done
79	else
80		libpath="${lib}"
81	fi
82	list_libs="$list_libs $lib"
83	foundone=
84	lib_symbols="$(nm -D --defined-only --format=posix "${libpath}" | awk '$2 ~ /C|R|D|T|W|B|V/ {print $1}' | tr '\n' ' ')"
85	if [ ${CHECK_UNRESOLVED} -eq 1 ]; then
86		# Save the global symbols for this lib
87		libkey "${lib}"
88		setvar "${libkey}" "${lib_symbols}"
89	fi
90	for fct in ${lib_symbols}; do
91		case " ${unresolved_symbols} ${bss_symbols} " in
92			*\ ${fct}\ *) foundone="${fct}" && break ;;
93		esac
94	done
95	if [ -n "${foundone}" ]; then
96		echo "yes... ${foundone}"
97	else
98		echo "no"
99		ret=1
100	fi
101done
102
103if [ ${CHECK_UNRESOLVED} -eq 1 ]; then
104	# Add in crt1 symbols
105	list_libs="${list_libs} crt1.o"
106	lib_symbols="$(nm --defined-only --format=posix "/usr/lib/crt1.o" | awk '$2 ~ /C|R|D|T|W|B|V/ {print $1}' | tr '\n' ' ')"
107	# Save the global symbols for this lib
108	libkey "crt1.o"
109	setvar "${libkey}" "${lib_symbols}"
110
111	# Now search libs for all symbols and report missing ones.
112	for sym in ${unresolved_symbols}; do
113		found=0
114		for lib in ${list_libs}; do
115			libkey "${lib}"
116			eval "lib_symbols=\"\${${libkey}}\""
117			# lib_symbols now contains symbols for the lib.
118			case " ${lib_symbols} " in
119				*\ ${sym}\ *)
120					[ ${VERBOSE_RESOLVED} -eq 1 ] &&
121					    echo "Resolved symbol ${sym} from ${lib}"
122					found=1
123					break
124					;;
125			esac
126		done
127		if [ $found -eq 0 ]; then
128			echo "Unresolved symbol $sym"
129			ret=1
130		fi
131	done
132fi
133
134exit ${ret}
135