Accept non-fatal resource exceptions without generating crash reports

util/mach/exception_types.h

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_MACH_EXCEPTION_TYPES_H_
+#define CRASHPAD_UTIL_MACH_EXCEPTION_TYPES_H_
+
+#include <mach/mach.h>
+#include <sys/types.h>
+
+namespace crashpad {
+
+//! \brief Recovers the original exception, first exception code, and signal
+//!     from the encoded form of the first exception code delivered with
+//!     `EXC_CRASH` exceptions.
+//!
+//! `EXC_CRASH` exceptions are generated when the kernel has committed to
+//! terminating a process as a result of a core-generating POSIX signal and, for
+//! hardware exceptions, an earlier Mach exception. Information about this
+//! earlier exception and signal is made available to the `EXC_CRASH` handler
+//! via its `code[0]` parameter. This function recovers the original exception,
+//! the value of `code[0]` from the original exception, and the value of the
+//! signal responsible for process termination.
+//!
+//! \param[in] code_0 The first exception code (`code[0]`) passed to a Mach
+//!     exception handler in an `EXC_CRASH` exception. It is invalid to call
+//!     this function with an exception code from any exception other than
+//!     `EXC_CRASH`.
+//! \param[out] original_code_0 The first exception code (`code[0]`) passed to
+//!     the Mach exception handler for a hardware exception that resulted in the
+//!     generation of a POSIX signal that caused process termination. If the
+//!     signal that caused termination was not sent as a result of a hardware
+//!     exception, this will be `0`. Callers that do not need this value may
+//!     pass `nullptr`.
+//! \param[out] signal The POSIX signal that caused process termination. Callers
+//!     that do not need this value may pass `nullptr`.
+//!
+//! \return The original exception for a hardware exception that resulted in the
+//!     generation of a POSIX signal that caused process termination. If the
+//!     signal that caused termination was not sent as a result of a hardware
+//!     exception, this will be `0`.
+exception_type_t ExcCrashRecoverOriginalException(
+    mach_exception_code_t code_0,
+    mach_exception_code_t* original_code_0,
+    int* signal);
+
+//! \brief Determines whether an exception is a non-fatal `EXC_RESOURCE`.
+//!
+//! \param[in] exception The exception type as received by a Mach exception
+//!     handler.
+//! \param[in] code_0 The first exception code (`code[0]`) as received by a
+//!     Mach exception handler.
+//! \param[in] pid The process ID that the exception occurred in. In some cases,
+//!     process may need to be queried to determine whether an `EXC_RESOURCE`
+//!     exception is fatal.
+//!
+//! \return `true` if the exception is a non-fatal `EXC_RESOURCE`. `false`
+//!     otherwise. If the exception is `EXC_RESOURCE` of a recognized type but
+//!     it is not possible to determine whether it is fatal, returns `true`
+//!     under the assumption that all known `EXC_RESOURCE` exceptions are
+//!     non-fatal by default. If the exception is not `EXC_RESOURCE` or is an
+//!     unknown `EXC_RESOURCE` type, returns `false`.
+bool IsExceptionNonfatalResource(exception_type_t exception,
+                                 mach_exception_code_t code_0,
+                                 pid_t pid);
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_MACH_EXCEPTION_TYPES_H_