fix permissions subcommand

bin/terractl

@@ -79,6 +79,8 @@ Admin commands:
   cmd <name> <console command...>          send a console command (e.g. save, say hi)
   reinstall <name> [--clean]               re-unpack server on next start
                                            (--clean also re-downloads tModLoader's .NET)
+  fix-perms <name>                         give all of an instance's files back to the
+                                           '$SVC_USER' user, with the usual modes (run as root)
   mods <name> [list]                       show installed mods and whether they're enabled
   mods <name> add <file.tmod|folder>...    install mods (and ModConfigs) and enable them
   mods <name> enable|disable <mod>...      change which installed mods load
@@ -1119,6 +1121,28 @@ cmd_reinstall() {
   echo "server/ will be re-unpacked on next start: $(hint group restart "$name")"
 }
 
+# Gives every file of an instance back to the service user, with the modes the
+# service creates files with (UMask=0027): the terraria group can read but not
+# change them, others get nothing. For files copied in as root, or with odd
+# modes (e.g. 'cp -a' or 'scp -p'). Symlinks are left alone, never followed.
+cmd_fix_perms() {
+  local name=$1 dir; shift
+  [[ $# -eq 0 ]] || die "usage: terractl fix-perms <name>"
+  [[ $EUID -eq 0 ]] || die "fix-perms must be run as root: sudo terractl fix-perms $name"
+  dir=$(inst_dir "$name")
+  [[ -f $dir/instance.conf && ! -L $dir ]] || die "no instance '$name'"
+  chown -R -h "$SVC_USER:$SVC_USER" "$dir"
+  # X: directories, and files that were already executable for someone
+  chmod -R u+rwX,u-s,g=rX,o= "$dir"
+  # The server binaries must stay executable, whatever happened to them
+  if [[ -d $dir/server ]]; then
+    find "$dir/server" -maxdepth 1 -type f \
+      \( -name TerrariaServer.bin.x86_64 -o -name TerrariaServer -o -name '*.sh' \) \
+      -exec chmod u+x,g+x {} +
+  fi
+  echo "'$name': all files owned by $SVC_USER:$SVC_USER, readable by the '$SVC_USER' group, private to everyone else"
+}
+
 # key=value facts, one per line, for people and for terractl-remote (copy, move,
 # tab completion). Without a name: this host. Repeated keys are lists.
 cmd_info() {
@@ -1218,6 +1242,7 @@ case $command in
   mods)      cmd_mods "$@" ;;
   new)       cmd_new "$@" ;;
   reinstall) cmd_reinstall "$@" ;;
+  fix-perms) cmd_fix_perms "$@" ;;
   delete)    cmd_delete "$@" ;;
   rename)    cmd_rename "$@" ;;
   export)    cmd_export "$@" ;;