Bug 1783100 - Remove osfile.jsm usage from DevToolsUtils.js r=ochameau

Differential Revision: https://phabricator.services.mozilla.com/D163500

Author: brennie

devtools/client/debugger/test/mochitest/browser_dbg-features-source-text-content.js

@@ -420,15 +420,17 @@ add_task(async function testGarbageCollectedSourceTextContent() {
  * - it first loads fine so that it shows up
  * - initDebuggerWithAbsoluteURL will first load the document before the debugger
  * - so the debugger will have to fetch the html page content via a network request
- * - the test page will return a 404 error code on the second load attempt
+ * - the test page will return a connection reset error on the second load attempt
  */
 let loadCount = 0;
 httpServer.registerPathHandler(
-  "/200-then-404-page.html",
+  "/200-then-connection-reset.html",
   (request, response) => {
     loadCount++;
     if (loadCount > 1) {
-      response.setStatusLine(request.httpVersion, 404, "Not found");
+      response.seizePower();
+      response.bodyOutPutStream.close();
+      response.finish();
       return;
     }
     response.setStatusLine(request.httpVersion, 200, "OK");
@@ -440,17 +442,17 @@ add_task(async function testFailingHtmlSource() {
 
   // initDebuggerWithAbsoluteURL will first load the document once before the debugger,
   // then the debugger will have to fetch the html page content via a network request
-  // therefore the test page will return a 404 error code on the second load attempt
+  // therefore the test page will encounter a connection reset error on the second load attempt
   const dbg = await initDebuggerWithAbsoluteURL(
-    BASE_URL + "200-then-404-page.html",
-    "200-then-404-page.html"
+    BASE_URL + "200-then-connection-reset.html",
+    "200-then-connection-reset.html"
   );
 
   // We can't select the HTML page as its source content isn't fetched
   // (waitForSelectedSource doesn't resolve)
   // Note that it is important to load the page *before* opening the page
   // so that the thread actor has to request the page content and will fail
-  const source = findSource(dbg, "200-then-404-page.html");
+  const source = findSource(dbg, "200-then-connection-reset.html");
   await dbg.actions.selectLocation(
     getContext(dbg),
     { sourceId: source.id },

devtools/shared/DevToolsUtils.js

@@ -15,7 +15,6 @@ var {
 } = require("resource://devtools/shared/platform/stack.js");
 
 const lazy = {};
-ChromeUtils.defineModuleGetter(lazy, "OS", "resource://gre/modules/osfile.jsm");
 
 ChromeUtils.defineESModuleGetters(lazy, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
@@ -565,7 +564,23 @@ function mainThreadFetch(
         // to using the locale default encoding (bug 1181345).
 
         // Read and decode the data according to the locale default encoding.
-        const available = stream.available();
+
+        let available;
+        try {
+          available = stream.available();
+        } catch (ex) {
+          if (ex.name === "NS_BASE_STREAM_CLOSED") {
+            // Empty files cause NS_BASE_STREAM_CLOSED exception.
+            // If there was a real stream error, we would have already rejected above.
+            resolve({
+              content: "",
+              contentType: "text/plan",
+            });
+            return;
+          }
+
+          reject(ex);
+        }
         let source = NetUtil.readInputStreamToString(stream, available);
         stream.close();
 
@@ -639,35 +654,7 @@ function mainThreadFetch(
           sourceMapURL,
         });
       } catch (ex) {
-        const uri = request.originalURI;
-        if (
-          ex.name === "NS_BASE_STREAM_CLOSED" &&
-          uri instanceof Ci.nsIFileURL
-        ) {
-          // Empty files cause NS_BASE_STREAM_CLOSED exception. Use OS.File to
-          // differentiate between empty files and other errors (bug 1170864).
-          // This can be removed when bug 982654 is fixed.
-
-          uri.QueryInterface(Ci.nsIFileURL);
-          // Bug 1779574: IOUtils is not available in non-parent processes.
-          // eslint-disable-next-line mozilla/reject-osfile
-          const result = lazy.OS.File.read(uri.file.path).then(bytes => {
-            // Convert the bytearray to a String.
-            const decoder = new TextDecoder();
-            const content = decoder.decode(bytes);
-
-            // We can't detect the contentType without opening a channel
-            // and that failed already. This is the best we can do here.
-            return {
-              content,
-              contentType: "text/plain",
-            };
-          });
-
-          resolve(result);
-        } else {
-          reject(ex);
-        }
+        reject(ex);
       }
     };