script: Enhance validations in utxo_snapshot.sh

- Ensure that the snapshot height is higher than the pruned block height when the node is pruned.
- Validate the correctness of the file path and check if the file already exists.
- Make network activity disablement optional for the user.
- Ensure the reconsiderblock command is triggered on exit, even in the case of user interruption (Ctrl-C).

Co-authored-by: Chris Heyes <22148308+hazeycode@users.noreply.github.com>
Co-authored-by: Sjors Provoost <sjors@sprovoost.nl>

contrib/devtools/utxo_snapshot.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2019 The Bitcoin Core developers
+# Copyright (c) 2019-2023 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
@@ -8,6 +8,8 @@ export LC_ALL=C
 
 set -ueo pipefail
 
+NETWORK_DISABLED=false
+
 if (( $# < 3 )); then
   echo 'Usage: utxo_snapshot.sh <generate-at-height> <snapshot-out-path> <bitcoin-cli-call ...>'
   echo
@@ -26,9 +28,60 @@ OUTPUT_PATH="${1}"; shift;
 # Most of the calls we make take a while to run, so pad with a lengthy timeout.
 BITCOIN_CLI_CALL="${*} -rpcclienttimeout=9999999"
 
+# Check if the node is pruned and get the pruned block height
+PRUNED=$( ${BITCOIN_CLI_CALL} getblockchaininfo | awk '/pruneheight/ {print $2}' | tr -d ',' )
+
+if (( GENERATE_AT_HEIGHT < PRUNED )); then
+  echo "Error: The requested snapshot height (${GENERATE_AT_HEIGHT}) should be greater than the pruned block height (${PRUNED})."
+  exit 1
+fi
+
+# Early exit if file at OUTPUT_PATH already exists
+if [[ -e "$OUTPUT_PATH" ]]; then
+  (>&2 echo "Error: $OUTPUT_PATH already exists or is not a valid path.")
+  exit 1
+fi
+
+# Validate that the path is correct
+if [[ "${OUTPUT_PATH}" != "-" && ! -d "$(dirname "${OUTPUT_PATH}")" ]]; then
+  (>&2 echo "Error: The directory $(dirname "${OUTPUT_PATH}") does not exist.")
+  exit 1
+fi
+
+function cleanup {
+  (>&2 echo "Restoring chain to original height; this may take a while")
+  ${BITCOIN_CLI_CALL} reconsiderblock "${PIVOT_BLOCKHASH}"
+
+  if $NETWORK_DISABLED; then
+    (>&2 echo "Restoring network activity")
+    ${BITCOIN_CLI_CALL} setnetworkactive true
+  fi
+}
+
+function early_exit {
+  (>&2 echo "Exiting due to Ctrl-C")
+  cleanup
+  exit 1
+}
+
+# Prompt the user to disable network activity
+read -p "Do you want to disable network activity (setnetworkactive false) before running invalidateblock? (Y/n): " -r
+if [[ "$REPLY" =~ ^[Yy]*$ || -z "$REPLY" ]]; then
+  # User input is "Y", "y", or Enter key, proceed with the action
+  NETWORK_DISABLED=true
+  (>&2 echo "Disabling network activity")
+  ${BITCOIN_CLI_CALL} setnetworkactive false
+else
+  (>&2 echo "Network activity remains enabled")
+fi
+
 # Block we'll invalidate/reconsider to rewind/fast-forward the chain.
 PIVOT_BLOCKHASH=$($BITCOIN_CLI_CALL getblockhash $(( GENERATE_AT_HEIGHT + 1 )) )
 
+# Trap for normal exit and Ctrl-C
+trap cleanup EXIT
+trap early_exit INT
+
 (>&2 echo "Rewinding chain back to height ${GENERATE_AT_HEIGHT} (by invalidating ${PIVOT_BLOCKHASH}); this may take a while")
 ${BITCOIN_CLI_CALL} invalidateblock "${PIVOT_BLOCKHASH}"
 
@@ -39,6 +92,3 @@ else
   (>&2 echo "Generating UTXO snapshot...")
   ${BITCOIN_CLI_CALL} dumptxoutset "${OUTPUT_PATH}"
 fi
-
-(>&2 echo "Restoring chain to original height; this may take a while")
-${BITCOIN_CLI_CALL} reconsiderblock "${PIVOT_BLOCKHASH}"