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-rwxr-xr-xtools/shld.sh157
1 files changed, 157 insertions, 0 deletions
diff --git a/tools/shld.sh b/tools/shld.sh
new file mode 100755
index 0000000..e1dff5f
--- /dev/null
+++ b/tools/shld.sh
@@ -0,0 +1,157 @@
+#!/bin/sh
+#
+# Shell command language linker
+#
+# Copyright (C) 2015 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='0.1.0'
+
+output='out.sh'
+make_executable=true
+interpreter='/bin/sh'
+entry_point='main'
+
+die()
+{
+ local fmt="${1}"
+ shift 1
+
+ printf "shld: ${fmt}\n" "${@}" >&2
+ exit 2
+}
+
+link()
+{
+ 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} ${1}"
+ }
+ EOF
+
+ # Read input files.
+ for input in "${@}"; 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
+ -I <interp> Use <interp> as the interpreter for your program, instead of the
+ default of "/bin/sh"
+ -e <entry> 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 ${VERSION}
+Copyright (C) 2015 Patrick "P. J." McDermott
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+EOF
+}
+
+main()
+{
+ while getopts 'hVI:e:o:' opt; do
+ case "${opt}" in
+ 'h')
+ help
+ exit
+ ;;
+ 'V')
+ version
+ exit
+ ;;
+ 'I')
+ interpreter="${OPTARG}"
+ ;;
+ 'e')
+ entry_point="${OPTARG}"
+ ;;
+ 'o')
+ output="${OPTARG}"
+ ;;
+ esac
+ done
+ shift $(($OPTIND - 1))
+
+ if [ ${#} -lt 1 ]; then
+ usage >&2
+ exit 1
+ fi
+
+ link "${@}"
+}
+
+main "${@}"