1 files changed, 139 insertions, 0 deletions
diff --git a/devtools/client/shared/source-map-loader/utils/fetchSourceMap.js b/devtools/client/shared/source-map-loader/utils/fetchSourceMap.js
new file mode 100644
index 0000000000..0fd8b15c25
--- /dev/null
+++ b/devtools/client/shared/source-map-loader/utils/fetchSourceMap.js
@@ -0,0 +1,139 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+"use strict";
+
+const {
+  networkRequest,
+} = require("resource://devtools/client/shared/source-map-loader/utils/network-request");
+
+const {
+  SourceMapConsumer,
+} = require("resource://devtools/client/shared/vendor/source-map/source-map.js");
+const {
+  getSourceMap,
+  setSourceMap,
+} = require("resource://devtools/client/shared/source-map-loader/utils/sourceMapRequests");
+const {
+  WasmRemap,
+} = require("resource://devtools/client/shared/source-map-loader/utils/wasmRemap");
+const {
+  convertToJSON,
+} = require("resource://devtools/client/shared/source-map-loader/wasm-dwarf/convertToJSON");
+
+// URLs which have been seen in a completed source map request.
+const originalURLs = new Set();
+
+function clearOriginalURLs() {
+  originalURLs.clear();
+}
+
+function hasOriginalURL(url) {
+  return originalURLs.has(url);
+}
+
+function resolveSourceMapURL(source) {
+  let { sourceMapBaseURL, sourceMapURL } = source;
+  sourceMapBaseURL = sourceMapBaseURL || "";
+  sourceMapURL = sourceMapURL || "";
+
+  if (!sourceMapBaseURL) {
+    // If the source doesn't have a URL, don't resolve anything.
+    return { resolvedSourceMapURL: sourceMapURL, baseURL: sourceMapURL };
+  }
+
+  let resolvedString;
+  let baseURL;
+
+  // When the sourceMap is a data: URL, fall back to using the source's URL,
+  // if possible. We don't use `new URL` here because it will be _very_ slow
+  // for large inlined source-maps, and we don't actually need to parse them.
+  if (sourceMapURL.startsWith("data:")) {
+    resolvedString = sourceMapURL;
+    baseURL = sourceMapBaseURL;
+  } else {
+    resolvedString = new URL(
+      sourceMapURL,
+      // If the URL is a data: URL, the sourceMapURL needs to be absolute, so
+      // we might as well pass `undefined` to avoid parsing a potentially
+      // very large data: URL for no reason.
+      sourceMapBaseURL.startsWith("data:") ? undefined : sourceMapBaseURL
+    ).toString();
+    baseURL = resolvedString;
+  }
+
+  return { resolvedSourceMapURL: resolvedString, baseURL };
+}
+
+async function _fetch(generatedSource, resolvedSourceMapURL, baseURL) {
+  let fetched = await networkRequest(resolvedSourceMapURL, {
+    loadFromCache: false,
+    // Blocking redirects on the sourceMappingUrl as its not easy to verify if the
+    // redirect protocol matches the supported ones.
+    allowRedirects: false,
+    sourceMapBaseURL: generatedSource.sourceMapBaseURL,
+  });
+
+  if (fetched.isDwarf) {
+    fetched = { content: await convertToJSON(fetched.content) };
+  }
+
+  // Create the source map and fix it up.
+  let map = await new SourceMapConsumer(fetched.content, baseURL);
+
+  if (generatedSource.isWasm) {
+    map = new WasmRemap(map);
+    // Check if experimental scope info exists.
+    if (fetched.content.includes("x-scopes")) {
+      const parsedJSON = JSON.parse(fetched.content);
+      map.xScopes = parsedJSON["x-scopes"];
+    }
+  }
+
+  // Extend the default map object with sourceMapBaseURL, used to check further
+  // network requests made for this sourcemap.
+  map.sourceMapBaseURL = generatedSource.sourceMapBaseURL;
+
+  if (map && map.sources) {
+    map.sources.forEach(url => originalURLs.add(url));
+  }
+
+  return map;
+}
+
+function fetchSourceMap(generatedSource, resolvedSourceMapURL, baseURL) {
+  const existingRequest = getSourceMap(generatedSource.id);
+
+  // If it has already been requested, return the request. Make sure
+  // to do this even if sourcemapping is turned off, because
+  // pretty-printing uses sourcemaps.
+  //
+  // An important behavior here is that if it's in the middle of
+  // requesting it, all subsequent calls will block on the initial
+  // request.
+  if (existingRequest) {
+    return existingRequest;
+  }
+
+  if (!generatedSource.sourceMapURL) {
+    return null;
+  }
+
+  // Fire off the request, set it in the cache, and return it.
+  const req = _fetch(generatedSource, resolvedSourceMapURL, baseURL);
+  // Make sure the cached promise does not reject, because we only
+  // want to report the error once.
+  setSourceMap(
+    generatedSource.id,
+    req.catch(() => null)
+  );
+  return req;
+}
+
+module.exports = {
+  fetchSourceMap,
+  hasOriginalURL,
+  clearOriginalURLs,
+  resolveSourceMapURL,
+};