Improve git hook installer

Before installing git hooks, ensure this repository is forked from
sysprog21/lab0-c properly.

scripts/install-git-hooks

@@ -7,7 +7,13 @@ fi
 
 ACCOUNT=$(git config -l | grep -w remote.origin.url | sed -e 's/^.*github.com[\/:]\(.*\)\/lab0-c.*/\1/')
 
-CURL_RES=$(curl -s \
+CURL=$(which curl)
+if [ $? -ne 0 ]; then
+    echo "[!] curl not installed." >&2
+    exit 1
+fi
+
+CURL_RES=$(${CURL} -s \
 -H "Accept: application/vnd.github.v3+json" \
 https://api.github.com/repos/${ACCOUNT}/lab0-c/actions/workflows)
 
@@ -18,8 +24,22 @@ case ${TOTAL_COUNT} in
         exit 1
 esac
 
+if [[ "${ACCOUNT}" != "sysprog21" ]]; then
+    REPO_FORKED=$(${CURL} -s \
+    -H "Accept: application/vnd.github.v3+json" \
+    https://api.github.com/repos/${ACCOUNT}/lab0-c | grep -m 1 fork)
+    case ${REPO_FORKED} in
+        *true*)
+            ;;
+        *)
+            echo "Your repository MUST be forked from sysprog21/lab0-c"
+            exit 1
+    esac
+fi
+
 if [ ${TOTAL_COUNT} -eq "0" ]; then
     echo "Fatal: GitHub Actions MUST be activated."
+    open https://github.com/${ACCOUNT}/lab0-c/actions
     echo "Check this article: https://docs.github.com/en/actions/managing-workflow-runs/disabling-and-enabling-a-workflow"
     echo "Then, execute 'make' again."
     exit 1