Changeset 267206 in webkit

Timestamp:

Sep 17, 2020 1:21:33 PM (4 years ago)

Author:

ddkilzer@apple.com

Message:

WebKit::XPCServiceEventHandler block should call exit() on the main thread
<​https://webkit.org/b/216594>
<rdar://problem/68053217>

Reviewed by Chris Dumez.

• Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm:

(WebKit::XPCServiceEventHandler):

• Call exit() on the main thread. I chose dispatch_sync() here so that if other crashes occur on the main thread, we will know if this background thread is waiting to call exit() at the same time. Also, if a different background thread calls exit() in the future with this block running on the main thread, we'll know where the block came from since the XPC handler thread will be waiting for the dispatch_sync() to return (instead of having a mysterious block calling exit() on the main thread and not knowing where it came from).
• Add logging (including simulated crash logs) when either of these exit() code paths is taken.

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm (modified) (3 diffs)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2020-09-17  David Kilzer  <ddkilzer@apple.com>
+
+        WebKit::XPCServiceEventHandler block should call exit() on the main thread
+        <https://webkit.org/b/216594>
+        <rdar://problem/68053217>
+
+        Reviewed by Chris Dumez.
+
+        * Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm:
+        (WebKit::XPCServiceEventHandler):
+        - Call exit() on the main thread. I chose dispatch_sync() here
+          so that if other crashes occur on the main thread, we will
+          know if this background thread is waiting to call exit() at
+          the same time. Also, if a different background thread calls
+          exit() in the future with this block running on the main
+          thread, we'll know where the block came from since the XPC
+          handler thread will be waiting for the dispatch_sync() to
+          return (instead of having a mysterious block calling exit() on
+          the main thread and not knowing where it came from).
+        - Add logging (including simulated crash logs) when either of
+          these exit() code paths is taken.
+
 2020-09-17  Hoa Dinh  <dvh@apple.com>
 

trunk/Source/WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm

@@ -27 +27 @@
 
 #import "HandleXPCEndpointMessages.h"
+#import "Logging.h"
 #import "WKCrashReporter.h"
 #import "XPCServiceEntryPoint.h"
@@ -48 +49 @@
         if (type == XPC_TYPE_ERROR) {
             if (event == XPC_ERROR_CONNECTION_INVALID || event == XPC_ERROR_TERMINATION_IMMINENT) {
+                RELEASE_LOG_FAULT(IPC, "Exiting: Received XPC event type: %s", event == XPC_ERROR_CONNECTION_INVALID ? "XPC_ERROR_CONNECTION_INVALID" : "XPC_ERROR_TERMINATION_IMMINENT");
                 // FIXME: Handle this case more gracefully.
-                exit(EXIT_FAILURE);
+                dispatch_sync(dispatch_get_main_queue(), ^{
+                    exit(EXIT_FAILURE);
+                });
             }
         } else {
@@ -73 +77 @@
                 InitializerFunction initializerFunctionPtr = reinterpret_cast<InitializerFunction>(CFBundleGetFunctionPointerForName(webKitBundle, entryPointFunctionName));
                 if (!initializerFunctionPtr) {
-                    NSLog(@"Unable to find entry point in WebKit.framework with name: %@", (__bridge NSString *)entryPointFunctionName);
-                    exit(EXIT_FAILURE);
+                    RELEASE_LOG_FAULT(IPC, "Exiting: Unable to find entry point in WebKit.framework with name: %s", [(__bridge NSString *)entryPointFunctionName UTF8String]);
+                    dispatch_sync(dispatch_get_main_queue(), ^{
+                        exit(EXIT_FAILURE);
+                    });
                 }