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393 lines
12 KiB
393 lines
12 KiB
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set -euo pipefail
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# Assert that FILE exists and is executable
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#
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# assertExecutable FILE
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assertExecutable() {
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local file="$1"
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[[ -f "$file" && -x "$file" ]] || \
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die "Cannot wrap '$file' because it is not an executable file"
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}
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# Generate a binary executable wrapper for wrapping an executable.
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# The binary is compiled from generated C-code using gcc.
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# makeWrapper EXECUTABLE OUT_PATH ARGS
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# ARGS:
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# --argv0 NAME : set the name of the executed process to NAME
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# (if unset or empty, defaults to EXECUTABLE)
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# --inherit-argv0 : the executable inherits argv0 from the wrapper.
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# (use instead of --argv0 '$0')
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# --set VAR VAL : add VAR with value VAL to the executable's environment
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# --set-default VAR VAL : like --set, but only adds VAR if not already set in
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# the environment
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# --unset VAR : remove VAR from the environment
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# --chdir DIR : change working directory (use instead of --run "cd DIR")
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# --add-flags FLAGS : add FLAGS to invocation of executable
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# TODO(@ncfavier): --append-flags
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# --prefix ENV SEP VAL : suffix/prefix ENV with VAL, separated by SEP
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# --suffix
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# To troubleshoot a binary wrapper after you compiled it,
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# use the `strings` command or open the binary file in a text editor.
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makeWrapper() { makeBinaryWrapper "$@"; }
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makeBinaryWrapper() {
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local NIX_CFLAGS_COMPILE= NIX_CFLAGS_LINK=
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local original="$1"
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local wrapper="$2"
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shift 2
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assertExecutable "$original"
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mkdir -p "$(dirname "$wrapper")"
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makeDocumentedCWrapper "$original" "$@" | \
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@cc@ \
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-Wall -Werror -Wpedantic \
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-Wno-overlength-strings \
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-Os \
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-x c \
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-o "$wrapper" -
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}
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# Syntax: wrapProgram <PROGRAM> <MAKE-WRAPPER FLAGS...>
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wrapProgram() { wrapProgramBinary "$@"; }
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wrapProgramBinary() {
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local prog="$1"
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local hidden
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assertExecutable "$prog"
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hidden="$(dirname "$prog")/.$(basename "$prog")"-wrapped
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while [ -e "$hidden" ]; do
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hidden="${hidden}_"
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done
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mv "$prog" "$hidden"
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makeWrapper "$hidden" "$prog" --inherit-argv0 "${@:2}"
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}
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# Generate source code for the wrapper in such a way that the wrapper inputs
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# will still be readable even after compilation
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# makeDocumentedCWrapper EXECUTABLE ARGS
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# ARGS: same as makeWrapper
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makeDocumentedCWrapper() {
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local src docs
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src=$(makeCWrapper "$@")
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docs=$(docstring "$@")
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printf '%s\n\n' "$src"
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printf '%s\n' "$docs"
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}
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# makeCWrapper EXECUTABLE ARGS
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# ARGS: same as makeWrapper
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makeCWrapper() {
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local argv0 inherit_argv0 n params cmd main flagsBefore flags executable length
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local uses_prefix uses_suffix uses_assert uses_assert_success uses_stdio uses_asprintf
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executable=$(escapeStringLiteral "$1")
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params=("$@")
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length=${#params[*]}
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for ((n = 1; n < length; n += 1)); do
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p="${params[n]}"
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case $p in
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--set)
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cmd=$(setEnv "${params[n + 1]}" "${params[n + 2]}")
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main="$main$cmd"$'\n'
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n=$((n + 2))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 2 arguments"$'\n'
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;;
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--set-default)
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cmd=$(setDefaultEnv "${params[n + 1]}" "${params[n + 2]}")
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main="$main$cmd"$'\n'
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uses_stdio=1
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uses_assert_success=1
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n=$((n + 2))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 2 arguments"$'\n'
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;;
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--unset)
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cmd=$(unsetEnv "${params[n + 1]}")
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main="$main$cmd"$'\n'
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uses_stdio=1
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uses_assert_success=1
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n=$((n + 1))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 1 argument"$'\n'
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;;
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--prefix)
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cmd=$(setEnvPrefix "${params[n + 1]}" "${params[n + 2]}" "${params[n + 3]}")
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main="$main$cmd"$'\n'
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uses_prefix=1
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uses_asprintf=1
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uses_stdio=1
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uses_assert_success=1
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uses_assert=1
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n=$((n + 3))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 3 arguments"$'\n'
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;;
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--suffix)
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cmd=$(setEnvSuffix "${params[n + 1]}" "${params[n + 2]}" "${params[n + 3]}")
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main="$main$cmd"$'\n'
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uses_suffix=1
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uses_asprintf=1
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uses_stdio=1
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uses_assert_success=1
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uses_assert=1
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n=$((n + 3))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 3 arguments"$'\n'
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;;
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--chdir)
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cmd=$(changeDir "${params[n + 1]}")
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main="$main$cmd"$'\n'
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uses_stdio=1
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uses_assert_success=1
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n=$((n + 1))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 1 argument"$'\n'
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;;
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--add-flags)
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flags="${params[n + 1]}"
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flagsBefore="$flagsBefore $flags"
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uses_assert=1
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n=$((n + 1))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 1 argument"$'\n'
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;;
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--argv0)
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argv0=$(escapeStringLiteral "${params[n + 1]}")
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inherit_argv0=
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n=$((n + 1))
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[ $n -ge "$length" ] && main="$main#error makeCWrapper: $p takes 1 argument"$'\n'
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;;
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--inherit-argv0)
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# Whichever comes last of --argv0 and --inherit-argv0 wins
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inherit_argv0=1
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;;
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*) # Using an error macro, we will make sure the compiler gives an understandable error message
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main="$main#error makeCWrapper: Unknown argument ${p}"$'\n'
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;;
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esac
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done
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# shellcheck disable=SC2086
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[ -z "$flagsBefore" ] || main="$main"${main:+$'\n'}$(addFlags $flagsBefore)$'\n'$'\n'
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[ -z "$inherit_argv0" ] && main="${main}argv[0] = \"${argv0:-${executable}}\";"$'\n'
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main="${main}return execv(\"${executable}\", argv);"$'\n'
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[ -z "$uses_asprintf" ] || printf '%s\n' "#define _GNU_SOURCE /* See feature_test_macros(7) */"
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printf '%s\n' "#include <unistd.h>"
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printf '%s\n' "#include <stdlib.h>"
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[ -z "$uses_assert" ] || printf '%s\n' "#include <assert.h>"
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[ -z "$uses_stdio" ] || printf '%s\n' "#include <stdio.h>"
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[ -z "$uses_assert_success" ] || printf '\n%s\n' "#define assert_success(e) do { if ((e) < 0) { perror(#e); abort(); } } while (0)"
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[ -z "$uses_prefix" ] || printf '\n%s\n' "$(setEnvPrefixFn)"
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[ -z "$uses_suffix" ] || printf '\n%s\n' "$(setEnvSuffixFn)"
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printf '\n%s' "int main(int argc, char **argv) {"
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printf '\n%s' "$(indent4 "$main")"
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printf '\n%s\n' "}"
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}
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addFlags() {
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local result n flag flags var
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var="argv_tmp"
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flags=("$@")
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for ((n = 0; n < ${#flags[*]}; n += 1)); do
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flag=$(escapeStringLiteral "${flags[$n]}")
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result="$result${var}[$((n+1))] = \"$flag\";"$'\n'
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done
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printf '%s\n' "char **$var = calloc($((n+1)) + argc, sizeof(*$var));"
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printf '%s\n' "assert($var != NULL);"
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printf '%s\n' "${var}[0] = argv[0];"
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printf '%s' "$result"
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printf '%s\n' "for (int i = 1; i < argc; ++i) {"
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printf '%s\n' " ${var}[$n + i] = argv[i];"
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printf '%s\n' "}"
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printf '%s\n' "${var}[$n + argc] = NULL;"
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printf '%s\n' "argv = $var;"
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}
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# chdir DIR
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changeDir() {
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local dir
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dir=$(escapeStringLiteral "$1")
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printf '%s' "assert_success(chdir(\"$dir\"));"
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}
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# prefix ENV SEP VAL
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setEnvPrefix() {
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local env sep val
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env=$(escapeStringLiteral "$1")
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sep=$(escapeStringLiteral "$2")
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val=$(escapeStringLiteral "$3")
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printf '%s' "set_env_prefix(\"$env\", \"$sep\", \"$val\");"
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assertValidEnvName "$1"
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}
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# suffix ENV SEP VAL
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setEnvSuffix() {
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local env sep val
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env=$(escapeStringLiteral "$1")
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sep=$(escapeStringLiteral "$2")
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val=$(escapeStringLiteral "$3")
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printf '%s' "set_env_suffix(\"$env\", \"$sep\", \"$val\");"
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assertValidEnvName "$1"
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}
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# setEnv KEY VALUE
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setEnv() {
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local key value
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key=$(escapeStringLiteral "$1")
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value=$(escapeStringLiteral "$2")
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printf '%s' "putenv(\"$key=$value\");"
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assertValidEnvName "$1"
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}
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# setDefaultEnv KEY VALUE
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setDefaultEnv() {
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local key value
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key=$(escapeStringLiteral "$1")
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value=$(escapeStringLiteral "$2")
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printf '%s' "assert_success(setenv(\"$key\", \"$value\", 0));"
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assertValidEnvName "$1"
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}
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# unsetEnv KEY
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unsetEnv() {
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local key
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key=$(escapeStringLiteral "$1")
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printf '%s' "assert_success(unsetenv(\"$key\"));"
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assertValidEnvName "$1"
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}
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# Makes it safe to insert STRING within quotes in a C String Literal.
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# escapeStringLiteral STRING
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escapeStringLiteral() {
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local result
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result=${1//$'\\'/$'\\\\'}
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result=${result//\"/'\"'}
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result=${result//$'\n'/"\n"}
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result=${result//$'\r'/"\r"}
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printf '%s' "$result"
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}
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# Indents every non-empty line by 4 spaces. To avoid trailing whitespace, we don't indent empty lines
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# indent4 TEXT_BLOCK
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indent4() {
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printf '%s' "$1" | awk '{ if ($0 != "") { print " "$0 } else { print $0 }}'
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}
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assertValidEnvName() {
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case "$1" in
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*=*) printf '\n%s\n' "#error Illegal environment variable name \`$1\` (cannot contain \`=\`)";;
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"") printf '\n%s\n' "#error Environment variable name can't be empty.";;
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esac
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}
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setEnvPrefixFn() {
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printf '%s' "\
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void set_env_prefix(char *env, char *sep, char *prefix) {
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char *existing = getenv(env);
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if (existing) {
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char *val;
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assert_success(asprintf(&val, \"%s%s%s\", prefix, sep, existing));
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assert_success(setenv(env, val, 1));
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free(val);
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} else {
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assert_success(setenv(env, prefix, 1));
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}
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}
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"
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}
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setEnvSuffixFn() {
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printf '%s' "\
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void set_env_suffix(char *env, char *sep, char *suffix) {
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char *existing = getenv(env);
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if (existing) {
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char *val;
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assert_success(asprintf(&val, \"%s%s%s\", existing, sep, suffix));
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assert_success(setenv(env, val, 1));
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free(val);
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} else {
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assert_success(setenv(env, suffix, 1));
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}
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}
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"
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}
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# Embed a C string which shows up as readable text in the compiled binary wrapper
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# documentationString ARGS
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docstring() {
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printf '%s' "const char * DOCSTRING = \"$(escapeStringLiteral "
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# ------------------------------------------------------------------------------------
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# The C-code for this binary wrapper has been generated using the following command:
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makeCWrapper $(formatArgs "$@")
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# (Use \`nix-shell -p makeBinaryWrapper\` to get access to makeCWrapper in your shell)
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# ------------------------------------------------------------------------------------
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")\";"
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}
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# formatArgs EXECUTABLE ARGS
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formatArgs() {
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printf '%s' "$1"
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shift
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while [ $# -gt 0 ]; do
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case "$1" in
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--set)
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formatArgsLine 2 "$@"
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shift 2
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;;
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--set-default)
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formatArgsLine 2 "$@"
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shift 2
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;;
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--unset)
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formatArgsLine 1 "$@"
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shift 1
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;;
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--prefix)
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formatArgsLine 3 "$@"
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shift 3
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;;
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--suffix)
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formatArgsLine 3 "$@"
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shift 3
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;;
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--chdir)
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formatArgsLine 1 "$@"
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shift 1
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;;
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--add-flags)
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formatArgsLine 1 "$@"
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shift 1
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;;
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--argv0)
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formatArgsLine 1 "$@"
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shift 1
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;;
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--inherit-argv0)
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formatArgsLine 0 "$@"
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;;
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esac
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shift
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done
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printf '%s\n' ""
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}
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# formatArgsLine ARG_COUNT ARGS
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formatArgsLine() {
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local ARG_COUNT LENGTH
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ARG_COUNT=$1
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LENGTH=$#
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shift
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printf '%s' $' \\\n '"$1"
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shift
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while [ "$ARG_COUNT" -gt $((LENGTH - $# - 2)) ]; do
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printf ' %s' "${1@Q}"
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shift
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done
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}
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