Update ds-identify to pass shellcheck (#979)

This patch updates the ds-identify file to pass the
popular shell linter, shellcheck. Updates include:

* Global ignore for error code 3043, the warning about
  the "local" keyword not being POSIX compliant. This
  keyword is used everywhere and cannot be easily removed.

* Point-of-use ignore for error code 3013, the warning
  about the "-nt" comparator not being POSIX compliant.
  There's no POSIX compliant way to compare timestamps
  on two files without forking a new process, so this
  comparator remains.

* Several point-of-use ignores for error code 2254, the
  warning about quoting parameters. These warnings are
  ignored for the *_matches functions where wildcard
  tokens are expected to be used. Quoting the parameters
  would prevent the desired globbing and cause calls
  to these functions with wildcards to fail.

* A point-of-use ignore for error code 2086 for the
  same reason as the above ignore -- allowing globbing
  to take place for matching.

* Quoted parameters in the remainder of the locations
  where it was safe to do so and did not break the
  tests.

1 files changed, 20 insertions, 15 deletions

diff --git a/tools/ds-identify b/tools/ds-identify
index f509f566..63d2f0c8 100755
--- a/tools/ds-identify
+++ b/tools/ds-identify
@@ -1,5 +1,5 @@
 #!/bin/sh
-# shellcheck disable=2015,2039,2162,2166
+# shellcheck disable=2015,2039,2162,2166,3043
 #
 # ds-identify is configured via /etc/cloud/ds-identify.cfg
 # or on the kernel command line. It takes the following inputs:
@@ -615,6 +615,7 @@ read_pid1_product_name() {
 
 dmi_chassis_asset_tag_matches() {
     is_container && return 1
+    # shellcheck disable=2254
     case "${DI_DMI_CHASSIS_ASSET_TAG}" in
         $1) return 0;;
     esac
@@ -623,6 +624,7 @@ dmi_chassis_asset_tag_matches() {
 
 dmi_product_name_matches() {
     is_container && return 1
+    # shellcheck disable=2254
     case "${DI_DMI_PRODUCT_NAME}" in
         $1) return 0;;
     esac
@@ -631,6 +633,7 @@ dmi_product_name_matches() {
 
 dmi_product_serial_matches() {
     is_container && return 1
+    # shellcheck disable=2254
     case "${DI_DMI_PRODUCT_SERIAL}" in
         $1) return 0;;
     esac
@@ -764,7 +767,7 @@ check_config() {
         while read line; do
             line=${line%%#*}
             case "$line" in
-                $key:\ *|$key:)
+                $key:\ *|"${key}":)
                     ret=${line#*:};
                     ret=${ret# };
                     found=$((found+1))
@@ -812,6 +815,7 @@ dscheck_NoCloud() {
         check_seed_dir "$d" meta-data user-data && return ${DS_FOUND}
         check_writable_seed_dir "$d" meta-data user-data && return ${DS_FOUND}
     done
+    # shellcheck disable=2086
     if has_fs_with_label $fslabel; then
         return ${DS_FOUND}
     fi
@@ -1239,11 +1243,11 @@ dscheck_AltCloud() {
         ctype="${DI_DMI_PRODUCT_NAME}"
     fi
     case "$ctype" in
-        ${match_rhev})
+        "${match_rhev}")
             probe_floppy || return ${DS_NOT_FOUND}
             dev="/dev/floppy"
             ;;
-        ${match_vsphere})
+        "${match_vsphere}")
             block_dev_with_label CDROM || return ${DS_NOT_FOUND}
             dev="$_RET"
             ;;
@@ -1309,6 +1313,7 @@ is_ibm_provisioning() {
         msg="config '$pcfg' exists."
         is_prov=true
         if [ -f "$logf" ]; then
+            # shellcheck disable=3013
             if [ "$logf" -nt "$PATH_PROC_1_ENVIRON" ]; then
                 msg="$msg log '$logf' from current boot."
             else
@@ -1324,7 +1329,7 @@ is_ibm_provisioning() {
 }
 
 is_ibm_cloud() {
-    cached "${_IS_IBM_CLOUD}" && return ${_IS_IBM_CLOUD}
+    cached "${_IS_IBM_CLOUD}" && return "${_IS_IBM_CLOUD}"
     local ret=1
     if [ "$DI_VIRT" = "xen" ]; then
         if is_ibm_provisioning; then
@@ -1640,10 +1645,10 @@ parse_policy() {
     for tok in "$@"; do
         val=${tok#*=}
         case "$tok" in
-            $DI_ENABLED|$DI_DISABLED|search|report) mode=$tok;;
+            "${DI_ENABLED}"|"${DI_DISABLED}"|search|report) mode=$tok;;
             found=all|found=first) found=$val;;
             maybe=all|maybe=none) maybe=$val;;
-            notfound=$DI_ENABLED|notfound=$DI_DISABLED) notfound=$val;;
+            notfound="${DI_ENABLED}"|notfound="${DI_DISABLED}") notfound=$val;;
             found=*)
                parse_warn found "$val" "${_def_found}"
                found=${_def_found};;
@@ -1724,11 +1729,11 @@ _main() {
     fi
 
     case "$DI_MODE" in
-        $DI_DISABLED)
+        "${DI_DISABLED}")
             debug 1 "mode=$DI_DISABLED. returning $ret_dis"
             return $ret_dis
             ;;
-        $DI_ENABLED)
+        "${DI_ENABLED}")
             debug 1 "mode=$DI_ENABLED. returning $ret_en"
             return $ret_en;;
         search|report) :;;
@@ -1768,11 +1773,11 @@ _main() {
         $dscheck_fn
         ret="$?"
         case "$ret" in
-            $DS_FOUND)
+            "${DS_FOUND}")
                 debug 1 "check for '$ds' returned found";
                 exfound_cfg="${exfound_cfg:+${exfound_cfg}${CR}}${_RET_excfg}"
                 found="${found} $ds";;
-            $DS_MAYBE)
+            "${DS_MAYBE}")
                 debug 1 "check for '$ds' returned maybe";
                 exmaybe_cfg="${exmaybe_cfg:+${exmaybe_cfg}${CR}}${_RET_excfg}"
                 maybe="${maybe} $ds";;
@@ -1811,16 +1816,16 @@ _main() {
     local basemsg="No ds found [mode=$DI_MODE, notfound=$DI_ON_NOTFOUND]."
     local msg="" ret=3
     case "$DI_MODE:$DI_ON_NOTFOUND" in
-        report:$DI_DISABLED)
+        report:"${DI_DISABLED}")
             msg="$basemsg Would disable cloud-init [$ret_dis]"
             ret=$ret_en;;
-        report:$DI_ENABLED)
+        report:"${DI_ENABLED}")
             msg="$basemsg Would enable cloud-init [$ret_en]"
             ret=$ret_en;;
-        search:$DI_DISABLED)
+        search:"${DI_DISABLED}")
             msg="$basemsg Disabled cloud-init [$ret_dis]"
             ret=$ret_dis;;
-        search:$DI_ENABLED)
+        search:"${DI_ENABLED}")
             msg="$basemsg Enabled cloud-init [$ret_en]"
             ret=$ret_en;;
         *) error "Unexpected result";;