GCC fix: Don’t use arraysize() on packed structs

While compiling, for example, minidump_exception_writer.cc:

In file included from ../../minidump/minidump_exception_writer.h:26:0,
                 from ../../minidump/minidump_exception_writer.cc:15:
../../minidump/minidump_exception_writer.cc: In member function ‘void crashpad::MinidumpExceptionWriter::SetExceptionInformation(const std::vector<long unsigned int>&)’:
../../minidump/minidump_exception_writer.cc:67:44: error: cannot bind packed field ‘((crashpad::MinidumpExceptionWriter*)this)->crashpad::MinidumpExceptionWriter::exception_.MINIDUMP_EXCEPTION_STREAM::ExceptionRecord.MINIDUMP_EXCEPTION::ExceptionInformation’ to ‘long unsigned int (&)[15]’
       arraysize(exception_.ExceptionRecord.ExceptionInformation);
                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~^
../../third_party/mini_chromium/mini_chromium/base/macros.h:41:50: note: in definition of macro ‘arraysize’
 #define arraysize(array) (sizeof(ArraySizeHelper(array)))

Tested with:
 - GCC 4.9 from NDK r13 targeting arm with SDK 16
 - GCC 4.9 from NDK r13 targeting arm64 with SDK 21
 - GCC 6.2 targeting x86_64

BUG=crashpad:30

Change-Id: I63963b277a309b4715148215f51902c33ba13b5a
Reviewed-on: https://chromium-review.googlesource.com/409694
Reviewed-by: Scott Graham <scottmg@chromium.org>

minidump/minidump_exception_writer.cc

@@ -21,6 +21,7 @@
 #include "minidump/minidump_context_writer.h"
 #include "snapshot/exception_snapshot.h"
 #include "util/file/file_writer.h"
+#include "util/misc/arraysize_unsafe.h"
 
 namespace crashpad {
 
@@ -64,7 +65,7 @@ void MinidumpExceptionWriter::SetExceptionInformation(
 
   const size_t parameters = exception_information.size();
   const size_t kMaxParameters =
-      arraysize(exception_.ExceptionRecord.ExceptionInformation);
+      ARRAYSIZE_UNSAFE(exception_.ExceptionRecord.ExceptionInformation);
   CHECK_LE(parameters, kMaxParameters);
 
   exception_.ExceptionRecord.NumberParameters =

minidump/minidump_misc_info_writer.cc

@@ -26,6 +26,7 @@
 #include "snapshot/process_snapshot.h"
 #include "snapshot/system_snapshot.h"
 #include "util/file/file_writer.h"
+#include "util/misc/arraysize_unsafe.h"
 #include "util/numeric/in_range_cast.h"
 #include "util/numeric/safe_assignment.h"
 
@@ -295,7 +296,7 @@ void MinidumpMiscInfoWriter::SetTimeZone(uint32_t time_zone_id,
 
   internal::MinidumpWriterUtil::AssignUTF8ToUTF16(
       misc_info_.TimeZone.StandardName,
-      arraysize(misc_info_.TimeZone.StandardName),
+      ARRAYSIZE_UNSAFE(misc_info_.TimeZone.StandardName),
       standard_name);
 
   misc_info_.TimeZone.StandardDate = standard_date;
@@ -303,7 +304,7 @@ void MinidumpMiscInfoWriter::SetTimeZone(uint32_t time_zone_id,
 
   internal::MinidumpWriterUtil::AssignUTF8ToUTF16(
       misc_info_.TimeZone.DaylightName,
-      arraysize(misc_info_.TimeZone.DaylightName),
+      ARRAYSIZE_UNSAFE(misc_info_.TimeZone.DaylightName),
       daylight_name);
 
   misc_info_.TimeZone.DaylightDate = daylight_date;
@@ -320,10 +321,12 @@ void MinidumpMiscInfoWriter::SetBuildString(
   misc_info_.Flags1 |= MINIDUMP_MISC4_BUILDSTRING;
 
   internal::MinidumpWriterUtil::AssignUTF8ToUTF16(
-      misc_info_.BuildString, arraysize(misc_info_.BuildString), build_string);
+      misc_info_.BuildString,
+      ARRAYSIZE_UNSAFE(misc_info_.BuildString),
+      build_string);
   internal::MinidumpWriterUtil::AssignUTF8ToUTF16(
       misc_info_.DbgBldStr,
-      arraysize(misc_info_.DbgBldStr),
+      ARRAYSIZE_UNSAFE(misc_info_.DbgBldStr),
       debug_build_string);
 }
 

minidump/minidump_system_info_writer.cc

@@ -20,6 +20,7 @@
 #include "minidump/minidump_string_writer.h"
 #include "snapshot/system_snapshot.h"
 #include "util/file/file_writer.h"
+#include "util/misc/arraysize_unsafe.h"
 #include "util/misc/implicit_cast.h"
 
 namespace crashpad {
@@ -196,7 +197,7 @@ void MinidumpSystemInfoWriter::SetCPUX86Vendor(uint32_t ebx,
          system_info_.ProcessorArchitecture ==
              kMinidumpCPUArchitectureX86Win64);
 
-  static_assert(arraysize(system_info_.Cpu.X86CpuInfo.VendorId) == 3,
+  static_assert(ARRAYSIZE_UNSAFE(system_info_.Cpu.X86CpuInfo.VendorId) == 3,
                 "VendorId must have 3 elements");
 
   system_info_.Cpu.X86CpuInfo.VendorId[0] = ebx;
@@ -254,7 +255,8 @@ void MinidumpSystemInfoWriter::SetCPUOtherFeatures(uint64_t features_0,
          system_info_.ProcessorArchitecture !=
              kMinidumpCPUArchitectureX86Win64);
 
-  static_assert(arraysize(system_info_.Cpu.OtherCpuInfo.ProcessorFeatures) == 2,
+  static_assert(
+      ARRAYSIZE_UNSAFE(system_info_.Cpu.OtherCpuInfo.ProcessorFeatures) == 2,
       "ProcessorFeatures must have 2 elements");
 
   system_info_.Cpu.OtherCpuInfo.ProcessorFeatures[0] = features_0;

util/misc/arraysize_unsafe.h

@@ -0,0 +1,27 @@
+// Copyright 2016 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_MISC_ARRAYSIZE_UNSAFE_H_
+#define CRASHPAD_UTIL_MISC_ARRAYSIZE_UNSAFE_H_
+
+//! \file
+
+//! \brief Not the safest way of computing an array’s size…
+//!
+//! `#%include "base/macros.h"` and use its `arraysize()` instead. This macro
+//! should only be used in rare situations where `arraysize()` does not
+//! function.
+#define ARRAYSIZE_UNSAFE(array) (sizeof(array) / sizeof(array[0]))
+
+#endif  // CRASHPAD_UTIL_MISC_ARRAYSIZE_UNSAFE_H_

util/misc/arraysize_unsafe_test.cc

@@ -0,0 +1,73 @@
+// Copyright 2016 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.
+
+#include "util/misc/arraysize_unsafe.h"
+
+#include "gtest/gtest.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+TEST(ArraySizeUnsafe, ArraySizeUnsafe) {
+  char c0[0];
+  static_assert(ARRAYSIZE_UNSAFE(c0) == 0, "c0");
+
+  char c1[1];
+  static_assert(ARRAYSIZE_UNSAFE(c1) == 1, "c1");
+
+  char c2[2];
+  static_assert(ARRAYSIZE_UNSAFE(c2) == 2, "c2");
+
+  char c4[4];
+  static_assert(ARRAYSIZE_UNSAFE(c4) == 4, "c4");
+
+  int i0[0];
+  static_assert(ARRAYSIZE_UNSAFE(i0) == 0, "i0");
+
+  int i1[1];
+  static_assert(ARRAYSIZE_UNSAFE(i1) == 1, "i1");
+
+  int i2[2];
+  static_assert(ARRAYSIZE_UNSAFE(i2) == 2, "i2");
+
+  int i4[4];
+  static_assert(ARRAYSIZE_UNSAFE(i4) == 4, "i4");
+
+  long l8[8];
+  static_assert(ARRAYSIZE_UNSAFE(l8) == 8, "l8");
+
+  int l9[9];
+  static_assert(ARRAYSIZE_UNSAFE(l9) == 9, "l9");
+
+  struct S {
+    char c;
+    int i;
+    long l;
+    bool b;
+  };
+
+  S s0[0];
+  static_assert(ARRAYSIZE_UNSAFE(s0) == 0, "s0");
+
+  S s1[1];
+  static_assert(ARRAYSIZE_UNSAFE(s1) == 1, "s1");
+
+  S s10[10];
+  static_assert(ARRAYSIZE_UNSAFE(s10) == 10, "s10");
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad

util/util.gyp

@@ -84,6 +84,7 @@
         'mach/task_for_pid.h',
         'mach/task_memory.cc',
         'mach/task_memory.h',
+        'misc/arraysize_unsafe.h',
         'misc/clock.h',
         'misc/clock_mac.cc',
         'misc/clock_posix.cc',

util/util_test.gyp

@@ -55,6 +55,7 @@
         'mach/scoped_task_suspend_test.cc',
         'mach/symbolic_constants_mach_test.cc',
         'mach/task_memory_test.cc',
+        'misc/arraysize_unsafe_test.cc',
         'misc/clock_test.cc',
         'misc/initialization_state_dcheck_test.cc',
         'misc/initialization_state_test.cc',