From 83a40c51809cdac3c7d58731b555dc95cdc5c5bf Mon Sep 17 00:00:00 2001
From: Martin Robinson <mrobinson@igalia.com>
Date: Fri, 30 Aug 2024 10:00:34 +0200
Subject: [PATCH] script: Stop using legacy `time` for
 `Document::reflow_timeout` (#33258)

Use `std::time` from the Rust standard library instead. This is one step
toward removing our use of the legacy `time` crate which has security
issues.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
---
 components/script/dom/document.rs        | 39 +++++++++++++-----------
 components/script/dom/htmlbodyelement.rs |  9 +++---
 2 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index c8adb924aec..2f42a3cfe60 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -327,7 +327,7 @@ pub struct Document {
     /// The current active HTML parser, to allow resuming after interruptions.
     current_parser: MutNullableDom<ServoParser>,
     /// When we should kick off a reflow. This happens during parsing.
-    reflow_timeout: Cell<Option<u64>>,
+    reflow_timeout: Cell<Option<Instant>>,
     /// The cached first `base` element with an `href` attribute.
     base_element: MutNullableDom<HTMLBaseElement>,
     /// This field is set to the document itself for inert documents.
@@ -898,27 +898,32 @@ impl Document {
 
     /// Reflows and disarms the timer if the reflow timer has expired.
     pub fn reflow_if_reflow_timer_expired(&self) {
-        if let Some(reflow_timeout) = self.reflow_timeout.get() {
-            if time::precise_time_ns() < reflow_timeout {
-                return;
-            }
+        let Some(reflow_timeout) = self.reflow_timeout.get() else {
+            return;
+        };
 
-            self.reflow_timeout.set(None);
-            self.window
-                .reflow(ReflowGoal::Full, ReflowReason::RefreshTick);
+        if Instant::now() < reflow_timeout {
+            return;
         }
+
+        self.reflow_timeout.set(None);
+        self.window
+            .reflow(ReflowGoal::Full, ReflowReason::RefreshTick);
     }
 
-    /// Schedules a reflow to be kicked off at the given `timeout` (in `time::precise_time_ns()`
-    /// units). This reflow happens even if the event loop is busy. This is used to display initial
-    /// page content during parsing.
-    pub fn set_reflow_timeout(&self, timeout: u64) {
-        if let Some(existing_timeout) = self.reflow_timeout.get() {
-            if existing_timeout < timeout {
-                return;
-            }
+    /// Schedules a reflow to be kicked off at the given [`Duration`] in the future. This reflow
+    /// happens even if the event loop is busy. This is used to display initial page content during
+    /// parsing.
+    pub fn set_reflow_timeout(&self, duration: Duration) {
+        let new_reflow_time = Instant::now() + duration;
+
+        // Do not schedule a timeout that is longer than the one that is currently queued.
+        if matches!(self.reflow_timeout.get(), Some(existing_timeout) if existing_timeout < new_reflow_time)
+        {
+            return;
         }
-        self.reflow_timeout.set(Some(timeout))
+
+        self.reflow_timeout.set(Some(new_reflow_time))
     }
 
     /// Remove any existing association between the provided id and any elements in this document.
diff --git a/components/script/dom/htmlbodyelement.rs b/components/script/dom/htmlbodyelement.rs
index a5b18210e1a..bc544e5491a 100644
--- a/components/script/dom/htmlbodyelement.rs
+++ b/components/script/dom/htmlbodyelement.rs
@@ -2,6 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use std::time::Duration;
+
 use dom_struct::dom_struct;
 use embedder_traits::EmbedderMsg;
 use html5ever::{local_name, namespace_url, ns, LocalName, Prefix};
@@ -23,9 +25,8 @@ use crate::dom::htmlelement::HTMLElement;
 use crate::dom::node::{document_from_node, window_from_node, BindContext, Node};
 use crate::dom::virtualmethods::VirtualMethods;
 
-/// How long we should wait before performing the initial reflow after `<body>` is parsed, in
-/// nanoseconds.
-const INITIAL_REFLOW_DELAY: u64 = 200_000_000;
+/// How long we should wait before performing the initial reflow after `<body>` is parsed.
+const INITIAL_REFLOW_DELAY: Duration = Duration::from_millis(200);
 
 #[dom_struct]
 pub struct HTMLBodyElement {
@@ -155,7 +156,7 @@ impl VirtualMethods for HTMLBodyElement {
 
         let window = window_from_node(self);
         let document = window.Document();
-        document.set_reflow_timeout(time::precise_time_ns() + INITIAL_REFLOW_DELAY);
+        document.set_reflow_timeout(INITIAL_REFLOW_DELAY);
         if window.is_top_level() {
             let msg = EmbedderMsg::HeadParsed;
             window.send_to_embedder(msg);