tor-browser

commit 3a6d85e46efe2c20748ba17e33f50f9fab584845
parent d89acdce02035974ba540c785e797a6996e99b51
Author: Florian Quèze <florian@queze.net>
Date:   Fri, 14 Nov 2025 11:17:12 +0000

Bug 1989077 - Increase the buffer size used in nsNetUtil.cpp, r=necko-reviewers,valentin.

Differential Revision: https://phabricator.services.mozilla.com/D265133

Diffstat:
M
modules/libpref/init/StaticPrefList.yaml
 | 
7
+++++++
M
netwerk/base/nsNetUtil.cpp
 | 
21
++++++++++++++-------

2 files changed, 21 insertions(+), 7 deletions(-)
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
@@ -13285,6 +13285,13 @@
   value: true
   mirror: always
 
+# Default buffer size for buffered stream operations. The actual value used will
+# be floored to the nearest power of two.
+- name: network.buffer.default_size
+  type: RelaxedAtomicUint32
+  value: 65536
+  mirror: always
+
 # See the full list of values in nsICookieService.idl.
 - name: network.cookie.cookieBehavior
   type: RelaxedAtomicInt32
diff --git a/netwerk/base/nsNetUtil.cpp b/netwerk/base/nsNetUtil.cpp
@@ -16,6 +16,7 @@
 #include "mozilla/Encoding.h"
 #include "mozilla/LoadContext.h"
 #include "mozilla/LoadInfo.h"
+#include "mozilla/MathAlgorithms.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/StaticPrefs_browser.h"
 #include "mozilla/StaticPrefs_network.h"
@@ -1398,7 +1399,11 @@ Result<nsCOMPtr<nsIInputStream>, nsresult> NS_NewBufferedInputStream(
 
 namespace {
 
-#define BUFFER_SIZE 8192
+// Returns the buffer size from the pref, floored to the nearest power of two.
+static uint32_t GetBufferSize() {
+  uint32_t prefValue = StaticPrefs::network_buffer_default_size();
+  return uint32_t(1) << FloorLog2(prefValue);
+}
 
 class BufferWriter final : public nsIInputStreamCallback {
  public:
@@ -1423,8 +1428,9 @@ class BufferWriter final : public nsIInputStreamCallback {
     // Let's make the inputStream buffered if it's not.
     if (!NS_InputStreamIsBuffered(mInputStream)) {
       nsCOMPtr<nsIInputStream> bufferedStream;
-      nsresult rv = NS_NewBufferedInputStream(
-          getter_AddRefs(bufferedStream), mInputStream.forget(), BUFFER_SIZE);
+      nsresult rv =
+          NS_NewBufferedInputStream(getter_AddRefs(bufferedStream),
+                                    mInputStream.forget(), GetBufferSize());
       NS_ENSURE_SUCCESS(rv, rv);
 
       mInputStream = bufferedStream;
@@ -1517,7 +1523,7 @@ class BufferWriter final : public nsIInputStreamCallback {
       }
 
       uint64_t offset = mWrittenData;
-      uint64_t length = mCount == -1 ? BUFFER_SIZE : mCount;
+      uint64_t length = mCount == -1 ? GetBufferSize() : mCount;
 
       // Let's try to read data directly.
       uint32_t writtenData;
@@ -1603,15 +1609,16 @@ class BufferWriter final : public nsIInputStreamCallback {
 
     MOZ_ASSERT(mCount == -1);
 
-    if (mBufferSize >= mWrittenData + BUFFER_SIZE) {
+    uint32_t bufSize = GetBufferSize();
+    if (mBufferSize >= mWrittenData + bufSize) {
       // The buffer is big enough.
       return true;
     }
 
     CheckedUint32 bufferSize =
-        std::max<uint32_t>(static_cast<uint32_t>(mWrittenData), BUFFER_SIZE);
+        std::max<uint32_t>(static_cast<uint32_t>(mWrittenData), bufSize);
     while (bufferSize.isValid() &&
-           bufferSize.value() < mWrittenData + BUFFER_SIZE) {
+           bufferSize.value() < mWrittenData + bufSize) {
       bufferSize *= 2;
     }