ios: Add ScopedBackgroundTask to more flock file access.

Use ScopedBackgroundTask to prevent file lock termination from happening
when holding locked files in a shared AppGroup.

Bug: 1313555
Change-Id: Idc0105f8ecdb65c26214a7265a216b9d480ed01d
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3573184
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>

client/crash_report_database_mac.mm

@@ -43,6 +43,10 @@
 #include "util/misc/initialization_state_dcheck.h"
 #include "util/misc/metrics.h"
 
+#if BUILDFLAG(IS_IOS)
+#include "util/ios/scoped_background_task.h"
+#endif  // BUILDFLAG(IS_IOS)
+
 namespace crashpad {
 
 namespace {
@@ -182,6 +186,10 @@ class CrashReportDatabaseMac : public CrashReportDatabase {
     //! \brief Stores the flock of the file for the duration of
     //!     GetReportForUploading() and RecordUploadAttempt().
     base::ScopedFD lock_fd;
+#if BUILDFLAG(IS_IOS)
+    //! \brief Obtain a background task assertion while a flock is in use.
+    internal::ScopedBackgroundTask ios_background_task{"UploadReportMac"};
+#endif  // BUILDFLAG(IS_IOS)
   };
 
   //! \brief Locates a crash report in the database by UUID.

client/settings.cc

@@ -71,6 +71,30 @@ void Settings::ScopedLockedFileHandle::Destroy() {
 
 #else  // BUILDFLAG(IS_FUCHSIA)
 
+#if BUILDFLAG(IS_IOS)
+
+Settings::ScopedLockedFileHandle::ScopedLockedFileHandle(
+    const FileHandle& value)
+    : ScopedGeneric(value) {
+  ios_background_task_ = std::make_unique<internal::ScopedBackgroundTask>(
+      "ScopedLockedFileHandle");
+}
+
+Settings::ScopedLockedFileHandle::ScopedLockedFileHandle(
+    Settings::ScopedLockedFileHandle&& rvalue) {
+  ios_background_task_.reset(rvalue.ios_background_task_.release());
+  reset(rvalue.release());
+}
+
+Settings::ScopedLockedFileHandle& Settings::ScopedLockedFileHandle::operator=(
+    Settings::ScopedLockedFileHandle&& rvalue) {
+  ios_background_task_.reset(rvalue.ios_background_task_.release());
+  reset(rvalue.release());
+  return *this;
+}
+
+#endif  // BUILDFLAG(IS_IOS)
+
 namespace internal {
 
 // static
@@ -207,6 +231,10 @@ Settings::ScopedLockedFileHandle Settings::MakeScopedLockedFileHandle(
   }
   return ScopedLockedFileHandle(scoped.release(), base::FilePath());
 #else
+  // It's important to create the ScopedLockedFileHandle before calling
+  // LoggingLockFile on iOS, so a ScopedBackgroundTask is created *before*
+  // the LoggingLockFile call below.
+  ScopedLockedFileHandle handle(kInvalidFileHandle);
   if (scoped.is_valid()) {
     if (LoggingLockFile(
             scoped.get(), locking, FileLockingBlocking::kBlocking) !=
@@ -214,7 +242,8 @@ Settings::ScopedLockedFileHandle Settings::MakeScopedLockedFileHandle(
       scoped.reset();
     }
   }
-  return ScopedLockedFileHandle(scoped.release());
+  handle.reset(scoped.release());
+  return handle;
 #endif
 }
 

client/settings.h

@@ -24,6 +24,10 @@
 #include "util/misc/initialization_state.h"
 #include "util/misc/uuid.h"
 
+#if BUILDFLAG(IS_IOS)
+#include "util/ios/scoped_background_task.h"
+#endif  // BUILDFLAG(IS_IOS)
+
 namespace crashpad {
 
 namespace internal {
@@ -153,7 +157,24 @@ class Settings {
     FileHandle handle_;
     base::FilePath lockfile_path_;
   };
-#else  // BUILDFLAG(IS_FUCHSIA)
+#elif BUILDFLAG(IS_IOS)
+  // iOS needs to use ScopedBackgroundTask anytime a file lock is used.
+  class ScopedLockedFileHandle
+      : public base::ScopedGeneric<FileHandle,
+                                   internal::ScopedLockedFileHandleTraits> {
+   public:
+    using base::ScopedGeneric<
+        FileHandle,
+        internal::ScopedLockedFileHandleTraits>::ScopedGeneric;
+
+    ScopedLockedFileHandle(const FileHandle& value);
+    ScopedLockedFileHandle(ScopedLockedFileHandle&& rvalue);
+    ScopedLockedFileHandle& operator=(ScopedLockedFileHandle&& rvalue);
+
+   private:
+    std::unique_ptr<internal::ScopedBackgroundTask> ios_background_task_;
+  };
+#else
   using ScopedLockedFileHandle =
       base::ScopedGeneric<FileHandle, internal::ScopedLockedFileHandleTraits>;
 #endif  // BUILDFLAG(IS_FUCHSIA)