review: code simplification and cleanup

scripts/emit-release-fragment.sh

@@ -20,15 +20,25 @@ if [[ -n "${FRAG_FILE:-}" && -f "${FRAG_FILE}" ]]; then
   checksum="$(sha256sum "$FRAG_FILE" | cut -d' ' -f1)"
 fi
 
+json_escape() {
+  local s="$1"
+  s="${s//\\/\\\\}"
+  s="${s//\"/\\\"}"
+  s="${s//$'\n'/\\n}"
+  s="${s//$'\r'/\\r}"
+  s="${s//$'\t'/\\t}"
+  printf '%s' "$s"
+}
+
 cat > "$out" <<JSON
 {
-  "repo": "$FRAG_REPO",
-  "sha": "$FRAG_SHA",
-  "artifact": "$FRAG_ARTIFACT",
-  "digest": "${FRAG_DIGEST:-}",
+  "repo": "$(json_escape "$FRAG_REPO")",
+  "sha": "$(json_escape "$FRAG_SHA")",
+  "artifact": "$(json_escape "$FRAG_ARTIFACT")",
+  "digest": "$(json_escape "${FRAG_DIGEST:-}")",
   "sha256": "$checksum",
-  "publish_url": "${FRAG_URL:-}",
-  "run_id": "${FRAG_RUN_ID:-}"
+  "publish_url": "$(json_escape "${FRAG_URL:-}")",
+  "run_id": "$(json_escape "${FRAG_RUN_ID:-}")"
 }
 JSON
 echo "emit-release-fragment: wrote $out"