From d59661ba17ae716b7a5a59d8d6913605a9081646 Mon Sep 17 00:00:00 2001
From: Your Name <you@example.com>
Date: Fri, 29 May 2020 23:54:14 -0400
Subject: [PATCH] Added specials and error checking

---
 share/adapters/chmod.sh | 54 ++++++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 14 deletions(-)
 mode change 100644 => 100755 share/adapters/chmod.sh

diff --git a/share/adapters/chmod.sh b/share/adapters/chmod.sh
old mode 100644
new mode 100755
index 13064d7..2eba35b
--- a/share/adapters/chmod.sh
+++ b/share/adapters/chmod.sh
@@ -3,6 +3,7 @@
 # Contributed by Erez Binyamin (github.com/ErezBinyamin)
 
 # Translate between chmod string and number
+# Inspired by http://permissions-calculator.org/
 # Contrib to chubin - cheat.sh
 chmod_calc(){
   p_s=""
@@ -10,23 +11,42 @@ chmod_calc(){
   R=()
   W=()
   X=()
+  S=()
+  setuid=' '
+  setgid=' '
+  sticky=' '
   # If permission number is given calc string
-  if [[ $1 =~ ^-?[0-9]+$ ]]
+  if [[ $1 =~ ^-?[0-9]+$ ]] && [ ${#1} -ge 2 ] && [ ${#1} -le 4 ]
   then
     p_n=$1
     for (( i=0; i<${#1}; i++ ))
     do
       num=$(echo "obase=2;${1:$i:1}" | bc | xargs printf '%03d')
-      [ ${num:0:1} -eq 1 ] && p_s+='r' || p_s+='-'
-      [ ${num:1:1} -eq 1 ] && p_s+='w' || p_s+='-'
-      [ ${num:2:1} -eq 1 ] && p_s+='x' || p_s+='-'
-      [ ${num:0:1} -eq 1 ] && R+=('X') || R+=(' ')
-      [ ${num:1:1} -eq 1 ] && W+=('X') || W+=(' ')
-      [ ${num:2:1} -eq 1 ] && X+=('X') || X+=(' ')
+      if [ ${#1} -eq 4 ] && [ $i -eq 0 ]
+      then
+        [ ${num:0:1} -eq 1 ] && setuid='X' || setuid=' '
+        [ ${num:1:1} -eq 1 ] && setgid='X' || setgid=' '
+        [ ${num:2:1} -eq 1 ] && sticky='X' || sticky=' '
+      else
+        [ ${num:0:1} -eq 1 ] && p_s+='r' || p_s+='-'
+        [ ${num:1:1} -eq 1 ] && p_s+='w' || p_s+='-'
+        if [[ $sticky == 'X' ]]
+        then
+          [ ${num:2:1} -eq 1 ] && p_s+='s' || p_s+='S'
+        else
+          [ ${num:2:1} -eq 1 ] && p_s+='x' || p_s+='-'
+        fi
+        [ ${num:0:1} -eq 1 ] && R+=('X') || R+=(' ')
+        [ ${num:1:1} -eq 1 ] && W+=('X') || W+=(' ')
+        [ ${num:2:1} -eq 1 ] && X+=('X') || X+=(' ')
+      fi
     done
   # If permission string is given calc number
-  else
+  elif [ ${#1} -le 9 ] && [ $(( ${#1} % 3 )) -eq 0 ] && [[ $1 =~ ^[r,w,x,s,S,-]+$ ]]
+  then
     p_s=$1
+    [[ ${p_s,,} =~ 's' ]] && p_n+="1" || p_n+="0"
+    [[ ${p_s,,} =~ 's' ]] && sticky='X'
     for (( i=0; i<${#1}; i+=0 ))
     do
       num=0
@@ -36,20 +56,26 @@ chmod_calc(){
       [[ ${1:$i:1} == 'w' ]] && W+=('X') || W+=(' ')
       [[ ${1:$((i++)):1} == 'w' ]] && let num++
       num=$(( num << 1 ))
-      [[ ${1:$i:1} == 'x' ]] && X+=('X') || X+=(' ')
-      [[ ${1:$((i++)):1} == 'x' ]] && let num++
+      [[ 'xs' =~ ${1:$i:1} ]] && X+=('X') || X+=(' ')
+      [[ 'Ss' =~ ${1:$i:1} ]] && S+=('X') || S+=(' ')
+      [[ 'xs' =~ ${1:$((i++)):1} ]] && let num++
       p_n+="$num"
     done
+  else
+    printf "Invalid permissions string: $1"
+    return 1
   fi
+  # Print Final results table
   printf "
 Linux Permissions String:\t${p_s}
 Linux Permissions Number:\t${p_n}
 
-Owner\t\tGroup\t\tPublic
+Special\t\tOwner\t\tGroup\t\tPublic
+
+Setuid     [$setuid]\tRead    [${R[0]}]\tRead    [${R[1]}]\tRead    [${R[2]}]
+Setgid     [$setgid]\tWrite   [${W[0]}]\tWrite   [${W[1]}]\tWrite   [${W[2]}]
+Sticky bit [$sticky]\tExecute [${X[0]}]\tExecute [${X[1]}]\tExecute [${X[2]}]
 
-Read    [${R[0]}]\tRead    [${R[1]}]\tRead    [${R[2]}]
-Write   [${W[0]}]\tWrite   [${W[1]}]\tWrite   [${W[2]}]
-Execute [${X[0]}]\tExecute [${X[1]}]\tExecute [${X[2]}]
 "
 }