Implement SysInfo::HardwareModelName() on iOS.

base/sys_info_ios.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/sys_info.h"
 
 #include <mach/mach.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <sys/sysctl.h>
@@ skipping 78 matching lines @@
     return 0;
   // We should add inactive file-backed memory also but there is no such
   // information from iOS unfortunately.
   return static_cast<int64_t>(info.free + info.speculative) * 1024;
 }
 
 // static
 std::string SysInfo::CPUModelName() {
   char name[256];
   size_t len = arraysize(name);
-  if (sysctlbyname("machdep.cpu.brand_string", &name, &len, NULL, 0) == 0)
-    return name;
+  if (sysctlbyname("machdep.cpu.brand_string", &name, &len, nullptr, 0) == 0) {
+    DCHECK_GE(len, 1u);
+    DCHECK_EQ('\0', name[len - 1]);

[Mark Mentovai, 2017/05/04 16:52:45]

You don’t have to write things backwards like this anymore.

You never did for DCHECK, but gtest’s ASSERT_EQ/EXPECT_EQ did have an (expected,
actual) ordering. This has recently changed, and it’s just (val1, val2)
everywhere now, so you can write these in whatever way you find natural.

[Alexei Svitkine (slow), 2017/05/04 17:10:18]

Interesting.

I guess I'm very used to having the constant be to the left that I do find that
way natural for these statements. Also I think JUnit which we in Chrome for
Android Java code still requires the expected, actual ordering and so I like the
consistency. So kept as-is.

+    return std::string(name, len - 1);
+  }
   return std::string();
 }
 
+// static
+std::string SysInfo::HardwareModelName() {
+  char model[256];
+  size_t len = sizeof(model);
+  if (sysctlbyname("hw.model", model, &len, nullptr, 0) == 0) {

[Mark Mentovai, 2017/05/04 16:52:45]

Since these two functions are identical other than the first parameter to
sysctlbyname, maybe you want to refactor them to both call into a common
function.

[Alexei Svitkine (slow), 2017/05/04 17:10:18]

Done.

+    DCHECK_GE(len, 1u);
+    DCHECK_EQ('\0', model[len - 1]);
+    return std::string(model, len - 1);
+  }
+  return std::string();
+}
+
 }  // namespace base