Drop support for the --interface flag of unset-static-ip script (#1719)

Related #1710.

[As discussed in the
issue](#1710 (comment)),
this PR drops support for the `--interface` flag of the
`unset-static-ip` script. Instead of allowing to selectively unset
interface configurations, the `unset-static-ip` script now only allows
to remove all/any custom IP configs. We didn’t find to have a need for
the selective unsetting, and can therefore spare the complexity.

## Notes

- I noticed we accidentally forgot to parse the `--help` flag, and we
also forgot to document the `--help` and `--quiet` flags in the usage
description. I’ve fixed both.
- I dropped the “Examples” section from the help output, because without
the `--interface` flag the usage seems trivial enough to me.
- Using the `--interface` flag now produces an error, just in case
someone relied on it.
- The code for eliminating the marker sections is now the same as [the
code in the `change-hostname` privileged
script](https://github.com/tiny-pilot/tinypilot/blob/8e99d5a666df12d851b14dd4276e8b95ab958493/debian-pkg/opt/tinypilot-privileged/scripts/change-hostname#L62-L79)
– except for the `dhcpcd_original` variable name. Both instances will
later be replaced by a call to the [upcoming unified
script](#1710).
- Heads-up: this PR will (probably) conflict with
tiny-pilot/tinypilot-pro#1175, as both touch the
tail of the `unset-static-ip` script. It should be trivial to resolve
this, though.
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---------

Co-authored-by: Jan Heuermann <[email protected]>

debian-pkg/opt/tinypilot-privileged/scripts/set-static-ip

@@ -22,6 +22,10 @@ Sets a static local IP address for the TinyPilot device.
                       Defaults to eth0.
   --help:             Display this help text.
 
+Note: there can only be one custom static IP configuration at a time. Running
+      this script will clear any potentially existing custom configuration
+      that might have been added previously by this script.
+
 Examples:
 
 1. Set static IP to 10.0.105 on a 10.0.0.x network.
@@ -134,7 +138,7 @@ fi
 set -u
 
 # Use the unset-static-ip script to remove any existing configuration.
-"${SCRIPT_DIR}/unset-static-ip" --quiet --interface "${INTERFACE}"
+"${SCRIPT_DIR}/unset-static-ip" --quiet
 
 # Only proceed if no other configuration exists.
 if grep -q "^interface ${INTERFACE}" "${CONFIG_FILE}" ; then

debian-pkg/opt/tinypilot-privileged/scripts/unset-static-ip

@@ -1,29 +1,17 @@
 #!/bin/bash
 #
-# Reverts changes made by the set-static-ip script.
+# Reverts any changes made by the set-static-ip script.
 
 # Exit on first error.
 set -e
 
 print_help() {
   cat << EOF
-Usage: ${0##*/} [--interface name]
+Usage: ${0##*/} [--quiet] [--help]
 
-Reverts changes made by the set-static-ip script.
-  --interface name: Optional. The interface to configure (e.g., eth0). Defaults
-                    to eth0.
-  --quiet:          Optional. Surpress the confirmation message.
+Reverts any changes made by the set-static-ip script.
+  --quiet:          Suppress the confirmation message.
   --help:           Display this help text.
-
-Examples:
-
-1. Unset the static IP address on the default eth0 interface.
-unset-static-ip
-
-2. Quietly unset a static IP address on the wlan0 interface.
-unset-static-ip \\
-  --interface wlan0
-
 EOF
 }
 
@@ -34,7 +22,7 @@ readonly CONFIG_FILE="/etc/dhcpcd.conf"
 . "${SCRIPT_DIR}/lib/markers.sh"
 
 # Parse command-line arguments.
-if ! NEW_ARGS=$(getopt -q -o "" -l "quiet,interface:" -- "$@"); then
+if ! NEW_ARGS=$(getopt -q -o "" -l "quiet,help,interface:" -- "$@"); then
   print_help
   exit 1
 fi
@@ -48,15 +36,13 @@ while true; do
       shift 1
       ;;
     --interface)
-      if [[ -z "${INTERFACE}" ]] ; then
-        readonly INTERFACE="$2"
-      else
-        echo "Only one interface should be provided using --interface" >&2
-        echo "For help on using this tool:" >&2
-        echo "  unset-static-ip --help" >&2
-        exit 1
-      fi
-      shift 2
+      # See https://github.com/tiny-pilot/tinypilot/issues/1710#issuecomment-1885680744.
+      echo 'The --interface flag is no longer supported' >&2
+      exit 1
+      ;;
+    --help)
+      print_help
+      exit
       ;;
     --)
       shift
@@ -65,11 +51,6 @@ while true; do
   esac
 done
 
-# Default interface.
-if [[ -z "${INTERFACE}" ]] ; then
-  readonly INTERFACE="eth0"
-fi
-
 # Default to not quiet.
 if [[ -z "${QUIET}" ]] ; then
   readonly QUIET="false"
@@ -78,35 +59,24 @@ fi
 # Exit on unset variable
 set -u
 
-# Remove any existing auto-generated configuration for the interface.
+# Remove any existing auto-generated configuration as populated by the
+# set-static-ip script.
 dhcpcd_original=()
-section=()
-interface_matched="false"
+is_in_marker_section='false'
 while IFS= read -r line; do
-  if [[ "${#section[@]}" -ne 0 ]] && [[ "${line}" == "${MARKER_END}" ]]; then
-    section+=("${line}")
-    if [[ "${interface_matched}" == "false" ]] ; then
-      dhcpcd_original=("${dhcpcd_original[@]}" "${section[@]}")
-    fi
-    section=()
-    interface_matched="false"
+  if "${is_in_marker_section}" && [[ "${line}" == "${MARKER_END}" ]]; then
+    is_in_marker_section='false'
     continue
   fi
-  if [[ "${#section[@]}" -ne 0 ]] || [[ "${line}" == "${MARKER_START}" ]]; then
-    if [[ "${line}" == "interface ${INTERFACE}" ]] ; then
-      interface_matched="true"
-    fi
-    section+=("${line}")
+  if "${is_in_marker_section}" || [[ "${line}" == "${MARKER_START}" ]]; then
+    is_in_marker_section='true'
     continue
   fi
   dhcpcd_original+=("${line}")
 done < "${CONFIG_FILE}"
 
-if [[ "${#section[@]}" -ne 0 ]] ; then
-  echo "The contents of ${CONFIG_FILE} are not in the expected format." >&2
-  echo "Auto-generated changes may have been manually edited." >&2
-  echo "" >&2
-  echo "Remove the relevant configuration manually to proceed." >&2
+if "${is_in_marker_section}"; then
+  echo 'Unclosed marker section' >&2
   exit 1
 fi
 
@@ -120,7 +90,6 @@ echo "${OLD_CONFIG_FILE}" | sudo tee "${CONFIG_FILE}" > /dev/null
 # Changes require a reboot so prompt the user.
 if [[ "${QUIET}" == "false" ]] ; then
   echo "Any changes made by the set-static-ip script have been reverted."
-  echo "  Interface: ${INTERFACE}"
   echo ""
   echo "Reboot your TinyPilot device to apply the changes."
 fi