summaryrefslogtreecommitdiffstats
path: root/tools/shld.sh
blob: 3117ccfe99d1687fe49c815fab9ee8380087f846 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
#!/bin/sh
#
# Shell command language linker
#
# Copyright (C) 2015, 2019  Patrick "P. J." McDermott
#
# 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 3 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, see <http://www.gnu.org/licenses/>.

set -u

VERSION='0.3.0'

die()
{
	local fmt="${1}"
	shift 1

	printf "shld: ${fmt}\n" "${@}" >&2
	exit 2
}

link()
{
	local make_executable="${1}"
	local interpreter="${2}"
	local entry_point="${3}"
	local libs="${4}"
	local output="${5}"
	shift 5
	local input=

	# Open output file.
	if ! exec 3>"${output}~"; then
		die 'Cannot open file "%s"' "${output}~"
	fi

	# Write magic number and interpreter path.
	if ${make_executable}; then
		printf '#!%s\n' "${interpreter}" >&3
	fi

	# Write __init() function.
	cat >&3 <<-'EOF'
		__init_funcs=''
		__init()
		{
			__init_funcs="${__init_funcs} ${1}"
		}
		EOF

	# Write __DT_NEEDED list and basic RTLD.
	printf "__DT_NEEDED='%s'\n" "${libs}" >&3
	cat >&3 <<-'EOF'
		: ${SHLD_LIBRARY_PATH:=${LIBDATADIR}}
		for __lib in ${__DT_NEEDED}; do
			__found=false
			IFS=':'
			for __el in ${SHLD_LIBRARY_PATH}; do
				if __f="$(cat "${__el}/${__lib}" 2>/dev/null)"
				then
					eval "${__f}"
					__found=true
					break
				fi
			done
			unset IFS
			if ! ${__found}; then
				printf "%s: error while loading shell $(: \
					)shared libraries: %s: cannot open $(: \
					)shell shared object file\n" \
					"${0}" "${__lib}" >&2
				exit 127
			fi
		done
		unset __lib __el __found
		EOF

	# Read input files.
	for input in "${@}"; do
		if ! cat "${input}" >&3; then
			die 'Cannot read file "%s"' "${input}"
		fi
	done

	# Add call to init functions.
	cat >&3 <<-'EOF'
		for __func in ${__init_funcs}; do
			${__func}
		done
		EOF

	# Add call to entry point.
	if ${make_executable}; then
		printf '%s "${@}"\n' "${entry_point}" >&3
	fi

	# Close output file, make it executable, and set its name.
	exec 3>&-
	if ${make_executable}; then
		if ! chmod a+x "${output}~"; then
			die 'Cannot set mode of file "%s"' "${output}~"
		fi
	fi
	if ! mv "${output}~" "${output}"; then
		die 'Cannot rename file to "%s"' "${output}"
	fi
}

usage()
{
	printf 'Usage: %s [option ...] <file>...\n' "${0}"
}

help()
{
	usage
	cat <<EOF
Options:
  -h           Display this information
  -V           Display linker version information
  -l <lib>     Add <lib> to the list of libraries to load at run time
  -I <interp>  Make an executable and use <interp> as the interpreter for your
               program, instead of the default of "/bin/sh"
  -e <entry>   Make an executable and use <entry> as the function for beginning
               execution of your program, instead of the default of "main"
  -o <output>  Use <output> as the name of the program produced by shld, instead
               of the default of "out.sh"
EOF
}

version()
{
	cat <<EOF
shld ${VERSION}
Copyright (C) 2015  Patrick "P. J." McDermott
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
EOF
}

main()
{
	local opt=
	local libs=''
	local make_executable=false
	local interpreter='/bin/sh'
	local entry_point='main'
	local output='out.sh'

	while getopts 'hVl:I:e:o:' opt; do
		case "${opt}" in
			'h')
				help
				exit
				;;
			'V')
				version
				exit
				;;
			'l')
				libs="${libs}${OPTARG} "
				;;
			'I')
				interpreter="${OPTARG}"
				make_executable=true
				;;
			'e')
				entry_point="${OPTARG}"
				make_executable=true
				;;
			'o')
				output="${OPTARG}"
				;;
		esac
	done
	shift $(($OPTIND - 1))

	if [ ${#} -lt 1 ]; then
		usage >&2
		exit 1
	fi

	link "${make_executable}" "${interpreter}" "${entry_point}" "${libs}" \
		"${output}" "${@}"
}

main "${@}"