update-godep-licenses.sh: various fixes and cleanups.

The file was analyzed with shellcheck, and various issues fixed. Most of
the problems were just cleanups, but also potential bugs were fixed.

Many variables were quoted with double quotes to prevent globbing. The
local_files array expansion was quoted so that any file names with
potential spaces in the filename would not be re-split. The empty
default value was removed from the list processing. POSIX standard "grep
-E" was used instead of egrep.

hack/update-godep-licenses.sh

@@ -74,10 +74,10 @@ process_content () {
   # Start search at package root
   case ${package} in
     github.com/*|golang.org/*|bitbucket.org/*)
-     package_root=$(echo ${package} |awk -F/ '{ print $1"/"$2"/"$3 }')
+     package_root=$(echo "${package}" |awk -F/ '{ print $1"/"$2"/"$3 }')
      ;;
     go4.org/*)
-     package_root=$(echo ${package} |awk -F/ '{ print $1 }')
+     package_root=$(echo "${package}" |awk -F/ '{ print $1 }')
      ;;
     gopkg.in/*)
      # Root of gopkg.in package always ends with '.v(number)' and my contain
@@ -85,10 +85,10 @@ process_content () {
      # - gopkg.in/yaml.v2
      # - gopkg.in/inf.v0
      # - gopkg.in/square/go-jose.v2
-     package_root=$(echo ${package} |grep -oh '.*\.v[0-9]')
+     package_root=$(echo "${package}" |grep -oh '.*\.v[0-9]')
      ;;
     *)
-     package_root=$(echo ${package} |awk -F/ '{ print $1"/"$2 }')
+     package_root=$(echo "${package}" |awk -F/ '{ print $1"/"$2 }')
      ;;
   esac
 
@@ -98,7 +98,7 @@ process_content () {
       [[ -d ${DEPS_DIR}/${dir_root} ]] || continue
 
       # One (set) of these is fine
-      find ${DEPS_DIR}/${dir_root} \
+      find "${DEPS_DIR}/${dir_root}" \
           -xdev -follow -maxdepth ${find_maxdepth} \
           -type f "${find_names[@]}"
     done | sort -u))
@@ -107,9 +107,14 @@ process_content () {
   local f
   index="${package}-${type}"
   if [[ -z "${CONTENT[${index}]-}" ]]; then
-    for f in ${local_files[@]-}; do
+    for f in "${local_files[@]-}"; do
+      if [[ -z "$f" ]]; then
+        # Set the default value and then check it to prevent
+        # accessing potentially empty array
+        continue
+      fi
       # Find some copyright info in any file and break
-      if egrep -i -wq "${ensure_pattern}" "${f}"; then
+      if grep -E -i -wq "${ensure_pattern}" "${f}"; then
         CONTENT[${index}]="${f}"
         break
       fi
@@ -151,19 +156,17 @@ declare -Ag CONTENT
 echo "================================================================================"
 echo "= Kubernetes licensed under: ="
 echo
-cat ${LICENSE_ROOT}/LICENSE
+cat "${LICENSE_ROOT}/LICENSE"
 echo
-echo "= LICENSE $(cat ${LICENSE_ROOT}/LICENSE | md5sum | awk '{print $1}')"
+echo "= LICENSE $(cat "${LICENSE_ROOT}/LICENSE" | md5sum | awk '{print $1}')"
 echo "================================================================================"
 ) > ${TMP_LICENSE_FILE}
 
 # Loop through every package in Godeps.json
-for PACKAGE in $(cat Godeps/Godeps.json | \
-                 jq -r ".Deps[].ImportPath" | \
-                 sort -f); do
-  process_content ${PACKAGE} LICENSE
-  process_content ${PACKAGE} COPYRIGHT
-  process_content ${PACKAGE} COPYING
+for PACKAGE in $(jq -r ".Deps[].ImportPath" < Godeps/Godeps.json | sort -f); do
+  process_content "${PACKAGE}" LICENSE
+  process_content "${PACKAGE}" COPYRIGHT
+  process_content "${PACKAGE}" COPYING
 
   # display content
   echo
@@ -195,7 +198,7 @@ __EOF__
   cat "${file}"
 
   echo
-  echo "= ${file} $(cat ${file} | md5sum | awk '{print $1}')"
+  echo "= ${file} $(cat "${file}" | md5sum | awk '{print $1}')"
   echo "================================================================================"
   echo
 done >> ${TMP_LICENSE_FILE}