fix(lib): fix potential command injection in `title` and `spectrum` functions

The `title` function unsafely prints its input without sanitization, which if used
with custom user code that calls it, it could trigger command injection.

The `spectrum_ls` and `spectrum_bls` could similarly be exploited if a variable is
changed in the user's shell environment with a carefully crafted value. This is
highly unlikely to occur (and if possible, other methods would be used instead),
but with this change the exploit of these two functions is now impossible.

lib/spectrum.zsh

@@ -20,16 +20,18 @@ done
 
 # Show all 256 colors with color number
 function spectrum_ls() {
+  setopt localoptions nopromptsubst
   local ZSH_SPECTRUM_TEXT=${ZSH_SPECTRUM_TEXT:-Arma virumque cano Troiae qui primus ab oris}
   for code in {000..255}; do
-    print -P -- "$code: $FG[$code]$ZSH_SPECTRUM_TEXT%{$reset_color%}"
+    print -P -- "$code: ${FG[$code]}${ZSH_SPECTRUM_TEXT}%{$reset_color%}"
   done
 }
 
 # Show all 256 colors where the background is set to specific color
 function spectrum_bls() {
+  setopt localoptions nopromptsubst
   local ZSH_SPECTRUM_TEXT=${ZSH_SPECTRUM_TEXT:-Arma virumque cano Troiae qui primus ab oris}
   for code in {000..255}; do
-    print -P -- "$code: $BG[$code]$ZSH_SPECTRUM_TEXT%{$reset_color%}"
+    print -P -- "$code: ${BG[$code]}${ZSH_SPECTRUM_TEXT}%{$reset_color%}"
   done
 }

lib/termsupport.zsh

@@ -7,8 +7,7 @@
 # (In screen, only short_tab_title is used)
 # Limited support for Apple Terminal (Terminal can't set window and tab separately)
 function title {
-  emulate -L zsh
-  setopt prompt_subst
+  setopt localoptions nopromptsubst
 
   # Don't set the title if inside emacs, unless using vterm
   [[ -n "$INSIDE_EMACS" && "$INSIDE_EMACS" != vterm ]] && return
@@ -48,13 +47,13 @@ fi
 
 # Runs before showing the prompt
 function omz_termsupport_precmd {
-  [[ "${DISABLE_AUTO_TITLE:-}" == true ]] && return
-  title $ZSH_THEME_TERM_TAB_TITLE_IDLE $ZSH_THEME_TERM_TITLE_IDLE
+  [[ "${DISABLE_AUTO_TITLE:-}" != true ]] || return
+  title "$ZSH_THEME_TERM_TAB_TITLE_IDLE" "$ZSH_THEME_TERM_TITLE_IDLE"
 }
 
 # Runs before executing the command
 function omz_termsupport_preexec {
-  [[ "${DISABLE_AUTO_TITLE:-}" == true ]] && return
+  [[ "${DISABLE_AUTO_TITLE:-}" != true ]] || return
 
   emulate -L zsh
   setopt extended_glob
@@ -97,10 +96,10 @@ function omz_termsupport_preexec {
   fi
 
   # cmd name only, or if this is sudo or ssh, the next cmd
-  local CMD=${1[(wr)^(*=*|sudo|ssh|mosh|rake|-*)]:gs/%/%%}
+  local CMD="${1[(wr)^(*=*|sudo|ssh|mosh|rake|-*)]:gs/%/%%}"
   local LINE="${2:gs/%/%%}"
 
-  title '$CMD' '%100>...>$LINE%<<'
+  title "$CMD" "%100>...>${LINE}%<<"
 }
 
 autoload -Uz add-zsh-hook