Add unpack mode

README.md

@@ -1,20 +1,69 @@
-`packelf` was inspired by [the idea of Klaus D](https://askubuntu.com/a/546305). It is used to package the elf executable and its dependent libraries into a single executable.
+`packelf` was inspired by [the idea of Klaus D](https://askubuntu.com/a/546305). It is used to pack a ELF program and its dependent libraries into a single executable file.
-
 
 
 ## usage
 
 ```
-packelf.sh <ELF_SRC_PATH> <DST_PATH> [ADDITIONAL_LIBS ...]
+Usage: ./packelf.sh [-zjJn] <ELF_SRC_PATH> <DST_PATH> [ADDITIONAL_LIBS ...]
+      -zjJ    compress flag passed to tar, '-z' by default
+      -n      pack without compress
 ```
 
-
+First, pack a ELF program. For example, you can pack `ls` like this:
-
-## example
 
 ```
-~ # packelf.sh `which perf` /root/perf
+# ./packelf.sh /bin/ls /root/ls
-~ # /root/perf --version
+tar: Removing leading `/' from member names
-perf version 3.10.0-1160.49.1.el7.x86_64.debug
+'/bin/ls' was packed to '/root/ls'
+Just run '/root/ls ARGS...' to execute the command.
+Or run 'PACKELF_UNPACK_DIR=xxx /root/ls' to unpack it only.
 ```
 
+You can execute the packed program directly:
+
+```
+# /root/ls -lh /root/ls 
+-rwxr-xr-x 1 root root 1.3M May 21 08:35 /root/ls
+```
+
+However, every time the packed program is executed, an internal unpacking operation is performed automatically, which results in a slower startup of the program.
+
+If you need to execute the program many times and want to reduce the startup time, you can unpack the program before executing it.
+
+```
+# Run the packed program directly, it takes longer.
+~ # time bash -c 'for i in {1..100};do /root/ls >/dev/null; done'
+real    0m4.203s
+user    0m2.067s
+sys     0m3.093s
+
+# You can unpack it first.
+~ # PACKELF_UNPACK_DIR=/usr/local/bin /root/ls
+'ls' was unpacked to '/usr/local/bin'.
+You can run '/usr/local/bin/ls ARGS...' to execute the command.
+
+# ls and ls.res are generated after unpacking.
+~ # /usr/local/bin/ls -lh /usr/local/bin/ls*
+-rwxr-xr-x 1 root root 3.9K May 21 09:00 /usr/local/bin/ls
+/usr/local/bin/ls.res:
+total 3.0M
+-rwxr-xr-x 1 root root 175K May 21 09:00 ld-linux-x86-64.so.2
+-rwxr-xr-x 1 root root 2.0M May  3  2022 libc.so.6
+-rw-r--r-- 1 root root  15K May  3  2022 libdl.so.2
+-rw-r--r-- 1 root root 454K Feb  3  2018 libpcre.so.3
+-rwxr-xr-x 1 root root 142K May  3  2022 libpthread.so.0
+-rw-r--r-- 1 root root 152K Mar  1  2018 libselinux.so.1
+-rwxr-xr-x 1 root root 131K Jan 18  2018 ls
+
+# Running the unpacked launch script (/usr/local/bin/ls) will take much less time.
+~ # time bash -c 'for i in {1..100};do /usr/local/bin/ls >/dev/null; done'
+real    0m0.370s
+user    0m0.239s
+sys     0m0.133s
+```
+
+## dependence
+* sh
+* tar
+
+Note: If your tar doesn't support gzip, '-n' is needed when you pack a program.

packelf.sh

@@ -1,36 +1,148 @@
-#!/bin/bash
+#!/usr/bin/env sh
-set -eo pipefail
+#set -o pipefail # bash extension
+set -e
 
-[ $# -lt 2 ] && {
+# These vars will be modified automatically with sed
-    echo "usage: $0 <ELF_SRC_PATH> <DST_PATH> [ADDITIONAL_LIBS ...]"
+run_mode=packer
-    exit 1
+compress_flag=-z
+program=
+ld_so=
+
+load() {
+    script_path="$0"
+
+    while link_path=$(readlink "$script_path"); do
+        script_path="$link_path"
+    done
+
+    unpack_dir=$(dirname "$script_path")
+
+    exec "$unpack_dir/$program.res/$ld_so" \
+        --library-path "$unpack_dir/$program.res" \
+        "$unpack_dir/$program.res/$program" "$@"
+    # unreachable
 }
 
-src="$1"
+if [ "$run_mode" = loader ]; then
-dst="$2"
+    load "$@"
-shift
-shift
-
-libs="$(ldd "$src" | grep -F '/' | sed -E 's|[^/]*/([^ ]+).*?|/\1|')"
-ld_so="$(echo "$libs" | grep -F '/ld-linux-')"
-ld_so="$(basename "$ld_so")"
-program="$(basename "$src")"
-
-cat >"$dst" <<EOF
-#!/bin/bash
-tmp_dir="\$(mktemp -d)"
-check_path="\$tmp_dir/__check_permission__"
-trap 'rm -rf \$tmp_dir' 0 1 2 3 6
-if ! (touch "\$check_path" && chmod +x "\$check_path" && [ -x "\$check_path" ]); then
-    rm -rf "\$tmp_dir"
-    tmp_dir="\$(TMPDIR="\$(pwd)" mktemp -d)"
 fi
-sed '1,/^#__END__$/d' "\$0" | tar -xz -C "\$tmp_dir"
-sed -i 's@/etc/ld.so.preload@/etc/___so.preload@g' "\$tmp_dir/$ld_so"
-"\$tmp_dir/$ld_so" --library-path "\$tmp_dir" "\$tmp_dir/$program" "\$@"
-exit \$?
-#__END__
-EOF
 
-tar -czh --transform 's/.*\///g' "$src" $libs "$@" >>"$dst" 2> >(grep -v 'Removing leading' >&2)
+pack_help() {
-chmod +x "$dst"
+    echo "Usage: $0 [-zjJn] <ELF_SRC_PATH> <DST_PATH> [ADDITIONAL_LIBS ...]"
+    echo "      -zjJ    compress flag passed to tar, '-z' by default"
+    echo "      -n      pack without compress"
+}
+
+pack() {
+    [ $# -ge 2 ] || {
+        pack_help
+        exit 1
+    }
+
+    case $1 in
+        -z|-j|-J)
+            compress_flag=$1
+            shift
+        ;;
+        -n)
+            compress_flag=''
+            shift
+        ;;
+        -h|--help)
+            pack_help
+            exit 0
+        ;;
+        *)
+        ;;
+    esac
+
+    src="$1"
+    shift
+    dst="$1"
+    shift
+
+    libs="$(ldd "$src" | grep -F '/' | sed -E 's|[^/]*/([^ ]+).*?|/\1|')"
+    ld_so="$(echo "$libs" | grep -F '/ld-linux-')"
+    ld_so="$(basename "$ld_so")"
+    program="$(basename "$src")"
+
+    cat "$0" | sed -E \
+        -e 's/^run_mode=[^ ]*$/run_mode=unpacker/' \
+        -e 's/^compress_flag=[^ ]*$/compress_flag='"$compress_flag"'/' \
+        -e 's/^program=[^ ]*$/program='"$program"'/' \
+        -e 's/^ld_so=[^ ]*$/ld_so='"$ld_so"'/' \
+        >"$dst"
+
+    tar $compress_flag -ch \
+        --transform 's/.*\//'"$program"'.res\//' \
+        "$src" $libs "$@" \
+        >>"$dst" #\
+        #2> >(grep -v 'Removing leading' >&2) # bash extension
+
+    chmod +x "$dst"
+    echo "'$src' was packed to '$dst'"
+    echo "$dst" | grep -q / || dst="./$dst"
+    echo "Just run '$dst ARGS...' to execute the command."
+    echo "Or run 'PACKELF_UNPACK_DIR=xxx $dst' to unpack it only."
+}
+
+unpack() {
+    if [ -n "$PACKELF_UNPACK_DIR" ]; then
+        [ -d "$PACKELF_UNPACK_DIR" ] || {
+            echo "'$PACKELF_UNPACK_DIR' is not a dir."
+            exit 1
+        }
+        [ -e "$PACKELF_UNPACK_DIR/$program" ] && {
+            echo "'$PACKELF_UNPACK_DIR/$program' already exists, please remove it first."
+            exit 1
+        }
+        unpack_dir="$PACKELF_UNPACK_DIR"
+
+    else
+        if [ -n "$PACKELF_TMP_DIR" ]; then
+            unpack_dir="$PACKELF_TMP_DIR"
+        else
+            tmp_parent=/tmp/packelf_tmp
+            mkdir -p "$tmp_parent"
+            unpack_dir=$(mktemp -d -p "$tmp_parent" || echo "$tmp_parent")
+        fi
+
+        trap 'rm -rf "$unpack_dir"' 0 1 2 3 6 10 12 13 14 15
+    fi
+
+    check_path="$unpack_dir/__check_permission__"
+    if ! (echo > "$check_path" && chmod +x "$check_path" && [ -x "$check_path" ]); then
+        rm -rf "$unpack_dir"
+        tmp_parent="$(pwd)/packelf_tmp"
+        mkdir -p "$tmp_parent"
+        unpack_dir="$(mktemp -d -p "$tmp_parent"  || echo "$tmp_parent")"
+    fi
+
+    sed '1,/^#__END__$/d' "$0" | tar $compress_flag -x -C "$unpack_dir"
+    sed -i 's@/etc/ld.so.preload@/etc/___so.preload@g' "$unpack_dir/$program.res/$ld_so"
+
+    if [ -n "$PACKELF_UNPACK_DIR" ]; then
+        sed '/^#__END__$/,$d' "$0" > "$unpack_dir/$program"
+        sed -i -E 's/^run_mode=\w*$/run_mode=loader/' "$unpack_dir/$program"
+        chmod +x "$unpack_dir/$program"
+        echo "'$program' was unpacked to '$unpack_dir'."
+        echo "$unpack_dir" | grep -q / || unpack_dir="./$unpack_dir"
+        echo "You can run '$unpack_dir/$program ARGS...' to execute the command."
+
+    else
+        "$unpack_dir/$program.res/$ld_so" \
+            --library-path "$unpack_dir/$program.res" \
+            "$unpack_dir/$program.res/$program" "$@"
+        exit $?
+    fi
+}
+
+
+if [ "$run_mode" = unpacker ]; then
+    unpack "$@"
+else
+    pack "$@"
+fi
+
+exit 0
+#__END__