Generate an installation script

This commit adds a `-g` flag to rcup(1) to generate a standalone shell
script. This shell script can then be run again, even on different
computers, to recreate the symlinks.

This allows people to recreate the "download my dotfiles and run
./install.sh" instructions, but with generated code that they do not
need to maintain.

This provides us more freedom with lsrc(1): since rcm can be used to
generate a universal shell script, lsrc(1) now can be harder to install
-- it can depend on a compiler, for example -- because you only need to
install it on one machine.

The generated script is rather limited; this can be improved in future
commits, as desired.

2 files changed, 110 insertions, 13 deletions

diff --git a/bin/mkrc.in b/bin/mkrc.in
index 55a7cd8..8932926 100755
--- a/bin/mkrc.in
+++ b/bin/mkrc.in
@@ -101,8 +101,8 @@ for file in $files; do
   dotless="$(de_dot "$file")"
   dest="$(destination "$DOTFILES_DIR" "$dotless" $in_host "$tag")"
   mkdir -p "$dest/$(dirname "$dotless")"
-  $PRINT "Moving..."
+  $VERBOSE "Moving..."
   mv_v "$file" "$dest/$dotless"
-  $PRINT "Linking..."
+  $VERBOSE "Linking..."
   $INSTALL -d "$DOTFILES_DIR" -t "${tag:--}" $install_args "$dotless"
 done
diff --git a/bin/rcup.in b/bin/rcup.in
index 1823099..80e55f3 100755
--- a/bin/rcup.in
+++ b/bin/rcup.in
@@ -3,24 +3,107 @@
 : ${RCM_LIB:=$(dirname "$0")/../share/rcm}
 . "$RCM_LIB/rcm.sh"
 
+print_ln_v() {
+  $PRINT "handle_file_ln \"$1\" \"$2\""
+}
+
+print_cp_v() {
+  $PRINT "handle_file_cp \"$1\" \"$2\""
+}
+
+print_rm_v() {
+  :
+}
+
 link_or_copy() {
   $DEBUG "link_or_copy $1"
   local sigil="$1"
 
   if [ "x$sigil" = "xX" ]; then
-    echo "cp_v"
+    echo "$CP"
   else
     echo "$LN"
   fi
 }
 
+print_generated_preface() {
+  cat <<PREFACE
+#!/bin/sh
+#
+# Usage:
+#
+#    sh install.sh
+#
+# Environment variables: VERBOSE, CP, LN, MKDIR, RM, DIRNAME, XARGS.
+#
+#    env VERBOSE=1 sh install.sh
+#
+# DO NOT EDIT THIS FILE
+# 
+# This file is generated by rcm(7) as:
+#
+#   rcup $@
+#
+# To update it, re-run the above command.
+#
+: \${VERBOSE:=0}
+: \${CP:=/bin/cp}
+: \${LN:=/bin/ln}
+: \${MKDIR:=/bin/mkdir}
+: \${RM:=/bin/rm}
+: \${DIRNAME:=/usr/bin/dirname}
+: \${XARGS:=/usr/bin/xargs}
+verbose() {
+  if [ "\$VERBOSE" -gt 0 ]; then
+    echo "\$@"
+  fi
+}
+handle_file_cp() {
+  if [ -e "\$2" ]; then
+    printf "%s " "overwrite \$2? [yN]"
+    read overwrite
+    case "\$overwrite" in
+      y)
+        \$RM -rf "\$2"
+        ;;
+      *)
+        echo "skipping \$2"
+        return
+        ;;
+    esac
+  fi
+  verbose "'\$1' -> '\$2'"
+  \$DIRNAME "\$2" | \$XARGS \$MKDIR -p
+  \$CP -R "\$1" "\$2"
+}
+handle_file_ln() {
+  if [ -e "\$2" ]; then
+    printf "%s " "overwrite \$2? [yN]"
+    read overwrite
+    case "\$overwrite" in
+      y)
+        \$RM -rf "\$2"
+        ;;
+      *)
+        echo "skipping \$2"
+        return
+        ;;
+    esac
+  fi
+  verbose "'\$1' -> '\$2'"
+  \$DIRNAME "\$2" | \$XARGS \$MKDIR -p
+  \$LN -sf "\$1" "\$2"
+}
+PREFACE
+}
+
 link_file() {
   local src="$1"
   local dest="$2"
   local sigil="$3"
 
   if [ -h "$dest" ]; then
-    rm_v -f "$dest"
+    $RM -f "$dest"
   fi
 
   action="$(link_or_copy "$sigil")"
@@ -35,7 +118,7 @@ replace_file() {
 
   $DEBUG replace_file "$1" "$2" $3
 
-  rm_v -rf "$dest"
+  $RM -rf "$dest"
   link_file "$src" "$dest" "$sigil"
 }
 
@@ -56,13 +139,14 @@ handle_dir() {
 }
 
 handle_file() {
-  local src="$1"
-  local dest="$2"
-  local sigil="$3"
+  local generate="$1"
+  local src="$2"
+  local dest="$3"
+  local sigil="$4"
 
-  $DEBUG "handle_file $1 $2 $3"
+  $DEBUG "handle_file $1 $2 $3 $4"
 
-  if [ -e "$dest" ]; then
+  if [ "$generate" -ne 1 -a -e "$dest" ]; then
     if is_identical "$src" "$dest"; then
       $VERBOSE "identical $dest"
     elif [ $REPLACE_ALL -eq 1 ]; then
@@ -106,14 +190,18 @@ handle_command_line() {
   local symlink_dirs=
   local never_symlink_dirs=
   local hostname=
+  local generate=0
+  local args=$*
   REPLACE_ALL=0
+  GENERATE=
 
-  while getopts :CVqvfhikKI:x:S:s:t:d:B: opt; do
+  while getopts :CVqvfghikKI:x:S:s:t:d:B: opt; do
     case "$opt" in
       B) hostname="$OPTARG" ;;
       C) always_copy=1 ;;
       d) dotfiles_dirs="$dotfiles_dirs $OPTARG" ;;
       f) REPLACE_ALL=1 ;;
+      g) generate=1 ;;
       h) show_help ;;
       i) REPLACE_ALL=0 ;;
       I) includes="$includes $OPTARG" ;;
@@ -132,9 +220,18 @@ handle_command_line() {
   shift $(($OPTIND-1))
 
   LN="ln_v"
+  CP="cp_v"
+  RM="rm_v"
   if [ $always_copy -eq 1 ]; then
-    LN="cp_v"
+    LN="$CP"
+  fi
+  if [ "$generate" -eq 1 ]; then
+    LN="print_ln_v"
+    CP="print_cp_v"
+    RM="print_rm_v"
+    print_generated_preface $args
   fi
+  GENERATE="$generate"
 
   handle_common_flags rcup $version $verbosity
   hostname="$(determine_hostname "$hostname")"
@@ -191,7 +288,7 @@ for dest_and_src in $dests_and_srcs; do
     handle_dir "$dest"
   fi
 
-  handle_file "$src" "$dest" "$sigil"
+  handle_file "$GENERATE" "$src" "$dest" "$sigil"
 done
 
 run_hooks post up