tor-browser

commit 6670c30e05cd77aa6aa716957793f0e5dcbaeab4
parent 5278a541b3b5cbf16190208389f2fb904d4914b3
Author: Markus Stange <mstange.moz@gmail.com>
Date:   Thu, 23 Oct 2025 20:44:35 +0000

Bug 1996126 - Make nsCocoaFeatures::macOSVersion() handle concurrent calls. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D269881

Diffstat:
M
widget/cocoa/nsCocoaFeatures.h
 | 
4
+---
M
widget/cocoa/nsCocoaFeatures.mm
 | 
30
+++++++++++++++++++-----------

2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/widget/cocoa/nsCocoaFeatures.h b/widget/cocoa/nsCocoaFeatures.h
@@ -42,9 +42,7 @@ class nsCocoaFeatures {
 
  private:
   nsCocoaFeatures() = delete;  // Prevent instantiation.
-  static void InitializeVersionNumbers();
-
-  static int32_t mOSVersion;
+  static int32_t ComputeVersion();
 };
 
 #endif  // nsCocoaFeatures_h_
diff --git a/widget/cocoa/nsCocoaFeatures.mm b/widget/cocoa/nsCocoaFeatures.mm
@@ -34,10 +34,12 @@
 #include "nsDebug.h"
 #include "nsObjCExceptions.h"
 
+#include <atomic>
 #import <Cocoa/Cocoa.h>
 #include <sys/sysctl.h>
 
-/*static*/ int32_t nsCocoaFeatures::mOSVersion = 0;
+// The lazily-initialized version. 0 before initialization, non-zero after.
+static std::atomic<int32_t> sOSVersion = 0;
 
 // This should not be called with unchecked aMajor, which should be >= 10.
 inline int32_t AssembleVersion(int32_t aMajor, int32_t aMinor,
@@ -117,8 +119,8 @@ int32_t nsCocoaFeatures::GetVersion(int32_t aMajor, int32_t aMinor,
   return macOSVersion;
 }
 
-/*static*/ void nsCocoaFeatures::InitializeVersionNumbers() {
-  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+/*static*/ int32_t nsCocoaFeatures::ComputeVersion() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
 
   // Provide an autorelease pool to avoid leaking Cocoa objects,
   // as this gets called before the main autorelease pool is in place.
@@ -126,19 +128,25 @@ int32_t nsCocoaFeatures::GetVersion(int32_t aMajor, int32_t aMinor,
 
   int major, minor, bugfix;
   GetSystemVersion(major, minor, bugfix);
-  mOSVersion = GetVersion(major, minor, bugfix);
+  return GetVersion(major, minor, bugfix);
 
-  NS_OBJC_END_TRY_IGNORE_BLOCK;
+  NS_OBJC_END_TRY_BLOCK_RETURN(0);
 }
 
 /* static */ int32_t nsCocoaFeatures::macOSVersion() {
-  // Don't let this be called while we're first setting the value...
-  MOZ_ASSERT((mOSVersion & MACOS_VERSION_MASK) >= 0);
-  if (!mOSVersion) {
-    mOSVersion = -1;
-    InitializeVersionNumbers();
+  int32_t version = sOSVersion.load(std::memory_order_relaxed);
+  if (version != 0) {
+    return version;
   }
-  return mOSVersion;
+
+  // Compute the version. Multiple threads might do the computation
+  // concurrently. That's ok; they will all compute the same value.
+  version = ComputeVersion();
+  if (version != 0) {
+    sOSVersion.store(version, std::memory_order_relaxed);
+  }
+
+  return version;
 }
 
 /* static */ int32_t nsCocoaFeatures::macOSVersionMajor() {