bashcheck

#!/usr/bin/env bash

#USAGE: bashcheck filename
#
#EXAMPLE: bashcheck ./bashcheck
#
#DESCRIPTION:
# Does a quick and dirty check of a bash script printing any potentially major
# problems to stdout, specifically it checks for:
#   +Assigning values to system variables in an unconstrained way, ie a way
#    that will have side effects on the callers environment.
#   +Assigning variables or defining functions using Built-in function names
#    or keywords.
#
# For more complete and systematic checking, I highly recommend 'shellcheck':
#    http://www.shellcheck.net/
#    https://github.com/koalaman/shellcheck
#
# Author: Stuart A. Knock
# Originally Written: 2015-11-23
# https://github.com/stuart-knock/bash-tools
#

#TODO: Cleanup output formatting.
#TODO: Consider using bashlogging

###############################################################################
########################## Configurable variables #############################
###############################################################################

#"Basic"|""|"Pernickety"
fussiness="Pernickety"

#The following set of variables define what to check for, you can add or remove
#items from the lists to suit your preferences.

#System variables to check for accidental overwrite
sysvars="auto_resume BASH BASH_ARGC BASH_ARGV BASH_ENV BASH_LINENO BASH_SOURCE
         BASH_VERSINFO BASH_VERSION BASH_VERSINFO CDPATH COLUMNS COMP_CWORD
         COMP_LINE COMP_POINT COMP_WORDS COMPREPLY CPU DIRSTACK DISPLAY EDITOR
         EUID FCEDIT FIGNORE FUNCNAME GLOBIGNORE GROUPS histchars HISTCMD
         HISTCONTROL HISTFILE HISTFILESIZE HISTIGNORE HISTSIZE HOME HOST
         HOSTFILE HOSTNAME HOSTTYPE IFS IGNOREEOF INPUTRC LANG LANGUAGE LC_ALL
         LC_COLLATE LC_CTYPE LC_MESSAGES LC_NUMERIC LESS LINENO LINES LOGNAME
         LS_COLORS MACHTYPE MAIL MAILCHECK MAILPATH MORE null OLDPWD OPTARG
         OPTERR OPTIND OSTYPE PAGER PATH PIPESTATUS POSIXLY_CORRECT PPID
         PROMPT_COMMAND PS1 PS2 PS4 PS3 PWD RANDOM REPLY SECONDS SHELL
         SHELLOPTS SHLVL TERM TIMEFORMAT TMOUT TMPDIR UID USER USERNAME
         XAUTHORITY"

#Built in and "standard" functions to check for overwrite or reassignment
builtins="agrep awk bash bind break caller case cat cd chmod chown command cp
          curl cut declare df dirs do done du echo egrep enable esac eval exec
          exit export false fi find for function getopts grep gzip hash head
          help id if in info let line ln local logout ls mapfile mkdir mv mysql
          popd print printf ps pushd pwd read readarray readonly return rm sed
          shift shopt sleep sort source su sudo tail tee test then tr true type
          typeset ulimit unalias uniq unset wait wc while who whoami xargs"

#TODO: switch to using bashlogging
#If "Enabled", display extra information for debugging purposes.
DEBUGMODE=""

###############################################################################
############################## Define Functions ###############################
##############################################################################
#TODO: Can't figure out how to prevent expansion of ${FUNCNAME} but still have
#  it properly expand inside the function when used as a printf format.
#ferrfmt='ERROR: ${FUNCNAME}(): %s\n'

#TODO: Allow for input variable, possibly a file or two, that adds variable and
#  function names to check just for this run. Useful for large projects where you
#  want to make sure no core variables or functions are being clobbered by other
#  parts of the script.

# Check a Bash script for variable definitions that may clobber system variables
check_assignment(){
  [[ "$DEBUGMODE" = "Enabled" ]] && printf '%s\n' "ENTERING: ${FUNCNAME}()"
  local errfmt="ERROR: ${FUNCNAME}(): %s\n"
  [[ "$#" != '1' ]] && { printf "$errfmt" "only supports one argument"; return 1; }
  local chkscrpt="$1"
  [[ -f "$chkscrpt" ]] || { printf "$errfmt" "can't find script: $chkscrpt"; return 1; }

  printf "Checking sysvars for possible overwriting:\n"

  #Convert sysvars variable into a regex.
  local overwritevars=$(printf "("$(printf '%s|' $sysvars)')=' | sed s/'|)='/')='/)

  #Match whole words followed immediately by "="
  grep --colour -nwE $overwritevars "$chkscrpt"
  if [[ "$?" != 0 ]]; then echo "No problems found"; else printf '\n'; fi

  #TODO: Exclude cases where the occurrence is commented or proceeded by local
  #      or a similar construct that protects the global variable.

  if [[ "$fussiness" == "Pernickety" ]] ; then
  	#While assigning a variable with an existing function name shouldn't cause
  	#any problem, it could make things confusing, so if we're being extra fussy
  	#we should avoid it.
    printf "Checking builtins for possible overwriting:\n"
    #Convert builtins variable into a regex.
  	local overwritevars=$(printf "("$(printf '%s|' $builtins)')=' | sed s/'|)='/')='/)
    #Match whole words followed immediately by "="
    grep --colour -nwE $overwritevars "$chkscrpt"
    if [[ "$?" != 0 ]]; then echo "  No problems found"; else printf '\n'; fi
  fi
  return 0
}

# Check a Bash script for value setting or function definitions using common
# function names or keywords, eg test, exit, local done
check_redefinition(){
  [[ "$DEBUGMODE" = "Enabled" ]] && printf '%s\n' "ENTERING: ${FUNCNAME}()"
  local errfmt="ERROR: ${FUNCNAME}(): %s\n"
  [[ "$#" != '1' ]] && { printf "$errfmt" "only supports one argument\n"; return 1; }
  local chkscrpt="$1"
  [[ -f "$chkscrpt" ]] || { printf "$errfmt" "can't find script: $chkscrpt\n"; return 1; }

  printf "Checking builtins for possible redefinition:\n"
  #Convert sysvars variable into a regex.
  local redeffuncs=$(printf "("$(printf '%s|' $builtins)')\s*\(\s*\)\s*\{' | sed s/'|)'/')'/)

  #Match whole words followed immediately by "(){", allowing for spaces before
  grep --colour -nwE $redeffuncs "$chkscrpt"
  if [[ "$?" != 0 ]]; then echo "  No problems found"; else printf '\n'; fi

  #TODO: Exclude cases where the occurrence is commented...

  return 0
}


###############################################################################
################################ Main Script ##################################
###############################################################################

# make sure filename supplied as command line arg else die
[[ "$#" != '1' ]] && { printf "  Usage: $0 filename\n"; exit 1; }

filename="$1"

printf "Running bashcheck on file: $filename\n"

check_assignment "$filename"
retCA="$?"

check_redefinition "$filename"
retCR="$?"

exit $((retCA||retCR))