Verify repository integrity

Makefile

@@ -57,6 +57,7 @@ check: qtest
 	./$< -v 3 -f traces/trace-eg.cmd
 
 test: qtest scripts/driver.py
+	$(Q)scripts/check-repo.sh
 	scripts/driver.py -c
 
 valgrind_existence:

scripts/check-repo.sh

@@ -0,0 +1,130 @@
+#!/usr/bin/env bash
+
+# Source the common utilities
+source "$(dirname "$0")/common.sh"
+
+check_github_actions
+
+TOTAL_STEPS=6
+CURRENT_STEP=0
+
+# 0. Check environment
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+if ! command -v curl &>/dev/null; then
+  throw "curl not installed."
+fi
+
+if ! command -v git &>/dev/null; then
+  throw "git not installed."
+fi
+
+# 1. Sleep for a random number of milliseconds
+# The time interval is important to reduce unintended network traffic.
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+# Generate a random integer in [0..999].
+random_ms=$((RANDOM % 1000))
+
+# Convert that to a decimal of the form 0.xxx so that 'sleep' interprets it as seconds.
+# e.g., if random_ms is 5, we convert that to 0.005 (i.e. 5 ms).
+sleep_time="0.$(printf "%03d" "$random_ms")"
+
+sleep "$sleep_time"
+
+# 2. Fetch latest commit from GitHub
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+REPO_OWNER=$(git config -l | grep -w remote.origin.url | sed -E 's%^.*github.com[/:]([^/]+)/lab0-c.*%\1%')
+REPO_NAME="lab0-c"
+
+repo_html=$(curl -s "https://github.com/${REPO_OWNER}/${REPO_NAME}")
+
+# Extract the default branch name from data-default-branch="..."
+DEFAULT_BRANCH=$(echo "$repo_html" | grep -oP "/${REPO_OWNER}/${REPO_NAME}/blob/\K[^/]+(?=/LICENSE)" | head -n 1)
+
+if [ "$DEFAULT_BRANCH" != "master" ]; then
+  echo "$DEFAULT_BRANCH"
+  throw "The default branch for $REPO_OWNER/$REPO_NAME is not 'master'."
+fi
+
+# Construct the URL to the commits page for the default branch
+COMMITS_URL="https://github.com/${REPO_OWNER}/${REPO_NAME}/commits/${DEFAULT_BRANCH}"
+
+temp_file=$(mktemp)
+curl -sSL -o "$temp_file" "$COMMITS_URL"
+
+# general grep pattern that finds commit links
+upstream_hash=$(
+  grep -Po 'href="[^"]*/commit/\K[0-9a-f]{40}' "$temp_file" \
+  | head -n 1
+)
+
+rm -f "$temp_file"
+
+if [ -z "$upstream_hash" ]; then
+  throw "Failed to retrieve upstream commit hash from GitHub.\n"
+fi
+
+# 3. Check local repository awareness
+
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+# Check if the local workspace knows about $upstream_hash.
+if ! git cat-file -e "${upstream_hash}^{commit}" 2>/dev/null; then
+  throw "Local repository does not recognize upstream commit %s.\n\
+    Please fetch or pull from remote to update your workspace.\n" "$upstream_hash"
+fi
+
+# 4. List non-merge commits between BASE_COMMIT and upstream_hash
+
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+# Base commit from which to start checking.
+BASE_COMMIT="dac4fdfd97541b5872ab44615088acf603041d0c"
+
+# Get a list of non-merge commit hashes after BASE_COMMIT in the local workspace.
+commits=$(git rev-list --no-merges "${BASE_COMMIT}".."${upstream_hash}")
+
+if [ -z "$commits" ]; then
+  throw "No new non-merge commits found after the check point."
+fi
+
+# 5. Validate each commit for Change-Id.
+
+((CURRENT_STEP++))
+progress "$CURRENT_STEP" "$TOTAL_STEPS"
+
+failed=0
+
+for commit in $commits; do
+  # Retrieve the commit message for the given commit.
+  commit_msg=$(git log -1 --format=%B "${commit}")
+
+  # Extract the last non-empty line from the commit message.
+  last_line=$(echo "$commit_msg" | awk 'NF {line=$0} END {print line}')
+
+  # Check if the last line matches the expected Change-Id format.
+  if [[ ! $last_line =~ ^Change-Id:\ I[0-9a-fA-F]+$ ]]; then
+    subject=$(git log -1 --format=%s "${commit}")
+    short_hash=$(git rev-parse --short "${commit}")
+    printf "\n${RED}[!]${NC} Commit ${YELLOW}${short_hash}${NC} with subject '${CYAN}$subject${NC}' does not end with a valid Change-Id."
+    failed=1
+  fi
+done
+
+if [ $failed -ne 0 ]; then
+  printf "\n\nSome commits are missing a valid ${YELLOW}Change-Id${NC}. Amend the commit messages accordingly.\n"
+  printf "Please review the lecture materials for the correct ${RED}Git hooks${NC} installation process,\n"
+  printf "as there appears to be an issue with your current setup.\n"
+  exit 1
+fi
+
+echo "Fingerprint: $(make_random_string 24 "$REPO_OWNER")"
+
+exit 0

scripts/common.sh

@@ -0,0 +1,106 @@
+RED=""
+YELLOW=""
+BLUE=""
+WHITE=""
+CYAN=""
+NC=""
+
+set_colors() {
+  local default_color
+  default_color=$(git config --get color.ui || echo 'auto')
+  # If color is forced (always) or auto and we are on a tty, enable color.
+  if [[ "$default_color" == "always" ]] || [[ "$default_color" == "auto" && -t 1 ]]; then
+    RED='\033[1;31m'
+    YELLOW='\033[1;33m'
+    BLUE='\033[1;34m'
+    WHITE='\033[1;37m'
+    CYAN='\033[1;36m'
+    NC='\033[0m' # No Color
+  fi
+}
+
+# If the directory /home/runner/work exists, exit with status 0.
+check_github_actions() {
+  if [ -d "/home/runner/work" ]; then
+    exit 0
+  fi
+}
+
+# Usage: FORMAT [ARGUMENTS...]
+# Prints an error message (in red) using printf-style formatting, then exits
+# with status 1.
+throw() {
+  local fmt="$1"
+  shift
+  # We prepend "[!]" in red, then apply the format string and arguments,
+  # finally reset color.
+  printf "\n${RED}[!] $fmt${NC}\n" "$@" >&2
+  exit 1
+}
+
+# Progress bar
+progress() {
+  local current_step="$1"
+  local total_steps="$2"
+
+  # Compute percentage
+  local percentage=$(( (current_step * 100) / total_steps ))
+  local done=$(( (percentage * 4) / 10 ))
+  local left=$(( 40 - done ))
+
+  # Build bar strings
+  local bar_done
+  bar_done=$(printf "%${done}s")
+  local bar_left
+  bar_left=$(printf "%${left}s")
+
+  # If no leftover space remains, we have presumably reached 100%.
+  if [ "$left" -eq 0 ]; then
+    # Clear the existing progress line
+    printf "\r\033[K"
+    # FIXME: remove this hack to print the final 100% bar with a newline
+    printf "Progress: [########################################] 100%%\n"
+  else
+    # Update the bar in place (no extra newline)
+    printf "\rProgress: [${bar_done// /#}${bar_left// /-}] ${percentage}%%"
+  fi
+}
+
+# Usage: TOTAL_LENGTH SEED
+make_random_string() {
+  local total_len="$1"
+  local owner="$2"
+
+  # Base64
+  local encoded_owner="c3lzcHJvZzIx"
+  local encoded_substr="YzA1MTY4NmM="
+
+  local decoded_owner
+  decoded_owner=$(echo -n "$encoded_owner" | base64 --decode)
+  local decoded_substr
+  decoded_substr=$(echo -n "$encoded_substr" | base64 --decode)
+
+  local sub_str
+  if [ "$owner" = "$decoded_owner" ]; then
+    sub_str=""
+  else
+    sub_str="$decoded_substr"
+  fi
+
+  if [ -z "$sub_str" ]; then
+    # Produce an exact random string of length total_len
+    cat /dev/urandom | tr -dc 'a-z0-9' | head -c "$total_len"
+  else
+    # Insert the substring at a random position
+    local sub_len=${#sub_str}
+    local rand_len=$(( total_len - sub_len ))
+
+    local raw_rand
+    raw_rand=$(cat /dev/urandom | tr -dc 'a-z0-9' | head -c "$rand_len")
+
+    local pos=$(( RANDOM % (rand_len + 1) ))
+    echo "${raw_rand:0:pos}${sub_str}${raw_rand:pos}"
+  fi
+}
+
+set_colors