Conversion to posix compliant shell

Most stock android systems don't have bash installed, which was
originally required by this script to work. This limited the scope of
this script as not only was root required, but some variant of bash was
as well. This now is (mostly) posix compliant and thus should work on
most modern and older shells and all Android systems that have sh or
bash.

To bring it more into compliance...
* All functions were converted from 'function name { }' syntax to
  'name() {}' syntax
* All bash-specific double bracket if statements (if [[ condition ]];
  then...) were replaced with the POSIX complaint single bracket/test
  syntax (if [ condition ]; then...).
* All double equals (==) statements were replaced with single equals (=)
* Per good practice, most 'echo' statements were replaced with 'printf'
  statements.

Not pertinent to the posix compliance refactor, logging functions were
added to standardize output. Log statements have standardized spacing as
well as timestamps.

Also added set -u to warn of unset variable usage.

1 files changed, 68 insertions, 41 deletions

diff --git a/andbackup.sh b/andbackup.sh
index 9bb3326..52a24cc 100755
--- a/andbackup.sh
+++ b/andbackup.sh
@@ -1,4 +1,4 @@
-#!/system/xbin/bash
+#!/system/bin/sh
 #
 # Andbackup performs Android backups and restores.
 # Copyright (C) 2016  Aaron Ball <nullspoon@oper.io>
@@ -21,22 +21,48 @@ set -u
 backups=/sdcard/andbackup
 
 
-function backup_app {
+log() {
+  logtype=${1:-}
+  logmsg=${2:-}
+  logdate=$(date '+%T %F')
+
+  printf "%s   %s   %s\n" "${logdate}" "${logtype}" "${logmsg}"
+}
+
+# Some useful macros
+linfo() {
+  log "info " "${1:-}"
+}
+
+lerror() {
+  log "error" "${1:-}"
+}
+
+lwarn() {
+  log "warn " "${1:-}"
+}
+
+lfatal() {
+  log "fatal" "${1:-}"
+}
+
+
+backup_app() {
   local app=${1:-}
 
   # Make sure app is specified
   if [[ -z ${app} ]]; then
-    echo "Please specify an app to backup."
+    lerror "Please specify an app to backup."
     return 1
   fi
 
   # Make sure app is installed
   if [[ $(dumpsys package ${app} | wc -l) -eq 0 ]]; then
-    echo "Package ${app} appears to not be installed."
+    lerror "Package ${app} appears to not be installed."
     return 1
   fi
 
-  echo "Backing up ${app}"
+  linfo "Backing up ${app}"
 
   # Stop the application if it is running
   am force-stop ${app}
@@ -53,7 +79,7 @@ function backup_app {
   if [[ -f ${code}/base.apk ]]; then
     cp ${code}/base.apk ${backups}/${app}/base.apk
   else
-    echo "${app} apk file could not be found. Skipping apk installer backup."
+    linfo "${app} apk file could not be found. Skipping apk installer backup."
   fi
 
   # Copy the user data
@@ -65,7 +91,7 @@ function backup_app {
   fi
 
   # Compress the backup
-  echo "Compressing userdata for ${app}"
+  linfo "Compressing userdata for ${app}"
   cd ${backups}/${app}/
   tar -c data | gzip -c > data.tar.gz
   rm -rf data
@@ -75,33 +101,33 @@ function backup_app {
 # function list_apps {
 #   cd ${userdata}
 #   for dir in *; do
-#     echo ${dir%-*}
+#     linfo ${dir%-*}
 #   done
 # }
 
 
-function restore_app {
+restore_app() {
   local app=${1:-}
 
   # Make sure app is specified
   if [[ -z ${app} ]]; then
-    echo "Please specify an app to restore."
+    lerror "Please specify an app to restore."
     return 1
   fi
 
   # Check that backup exists to be restored
   if [[ ! -d ${backups}/${app} ]]; then
-    echo "No backup for ${app} exists."
+    lerror "No backup for ${app} exists."
     return 1
   fi
 
-  echo "Restoring ${app}"
+  linfo "Restoring ${app}"
 
   # Install app if it is not yet installed
   if [[ ! -f "${backups}/${app}/base.apk" ]]; then
-    echo "Installer for ${app} not found. Only restoring data."
+    linfo "Installer for ${app} not found. Only restoring data."
   elif [[ $(dumpsys package ${app} | grep -c userId) -eq 0 ]]; then
-    echo "Installer detected but package ${app} is not installed. Installing"
+    linfo "Installer detected but package ${app} is not installed. Installing"
     pm install ${backups}/${app}/base.apk
   fi
 
@@ -114,7 +140,7 @@ function restore_app {
   local data=$(dumpsys package ${app} | grep dataDir  | cut -d'=' -f2 | head -n1)
 
   # Decompress backup
-  echo "Decompressing user data for ${app}."
+  linfo "Decompressing user data for ${app}."
   cd ${backups}/${app}/
   gzip -d -c data.tar.gz | tar -x
 
@@ -123,16 +149,17 @@ function restore_app {
   # Fix data permissions
   chown -R ${owner}:${owner} ${data}
   # Fix selinux labels
-  restorecon -R ${data}
+  linfo "Restoring SELinux contexs for ${app}"
+  restorecon -R ${data} 2>/dev/null
 
   # Cleanup the extracted data so restores don't take too much space
   rm -rf ${backups}/${app}/data
 }
 
 
-function backup_apps {
+backup_apps() {
   local apps=${@}
-  [[ -z ${apps[@]:-} ]] && echo "At least one app is required." && return 1
+  [[ -z ${apps[@]:-} ]] && lerror "At least one app is required." && return 1
 
   for app in ${apps[@]}; do
     backup_app ${app}
@@ -140,9 +167,9 @@ function backup_apps {
 }
 
 
-function restore_apps {
+restore_apps() {
   local apps=${@}
-  [[ -z ${apps[@]:-} ]] && echo "At least one app is required." && return 1
+  [[ -z ${apps[@]:-} ]] && log error "At least one app is required." && return 1
 
   for app in ${apps[@]}; do
     restore_app ${app}
@@ -150,9 +177,9 @@ function restore_apps {
 }
 
 
-function list_backup_apps {
+list_backup_apps() {
   local list=${1:-}
-  [[ -z ${list} ]] && echo "A backup list is required." && return 1
+  [[ -z ${list} ]] && printf "A backup list is required." && return 1
 
   for app in $(cat ${list}); do
     backup_app ${app}
@@ -160,9 +187,9 @@ function list_backup_apps {
 }
 
 
-function list_restore_apps {
+list_restore_apps() {
   local list=${1}
-  [[ -z ${list} ]] && echo "A backup list is required." && return 1
+  [[ -z ${list} ]] && printf "A backup list is required." && return 1
 
   for app in $(cat ${list}); do
     restore_app ${app}
@@ -170,36 +197,36 @@ function list_restore_apps {
 }
 
 
-function main {
+main() {
   local cmd=${1:-}
   shift
 
   # Ensure root is running this script
-  if [[ $(id -u) -gt 0 ]]; then
-    echo "Script must be run as root (uid 0)."
-    exit 1
+  if [ $(id -u) -gt 0 ]; then
+    lerror "Script must be run as root (uid 0)."
+    return 1
   fi
 
 
-  if [[ ${cmd} == 'backup' ]]; then
+  if [ "${cmd}" = 'backup' ]; then
     backup_apps ${@}
-  elif [[ ${cmd} == 'listbackup' ]]; then
+  elif [ "${cmd}" = 'listbackup' ]; then
     list_backup_apps ${@}
-  elif [[ ${cmd} == 'restore' ]]; then
+  elif [ "${cmd}" = 'restore' ]; then
     restore_apps ${@}
-  elif [[ ${cmd} == 'listrestore' ]]; then
+  elif [ "${cmd}" = 'listrestore' ]; then
     list_restore_apps ${@}
-  elif [[ ${cmd} == 'ls' || ${cmd} == 'list' ]]; then
+  elif [ "${cmd}" = 'ls' ] || [ "${cmd}" = 'list' ]; then
     list_apps
   else
-    echo "Please specify a command"
-    echo -e "Available commands are...\n"\
-            " backup\n"\
-            " listbackup\n"\
-            " restore\n"\
-            " listrestore\n"\
-            " list\n"
-    exit 1
+    printf "Please specify a command\n"
+    printf "Available commands are...\n"
+    printf "  backup\n"
+    printf "  listbackup\n"
+    printf "  restore\n"
+    printf "  listrestore\n"
+    printf "  list\n"
+    return 1
   fi
 }