Implement SysInfo::HardwareModelName() on iOS.

base/sys_info_ios.mm

Index: base/sys_info_ios.mm
diff --git a/base/sys_info_ios.mm b/base/sys_info_ios.mm
index 9a329b9f0924bbdefce908cd51de4a6488c574f0..e544848abbea62bb31ff068b2ce74bf0e7d361db 100644
--- a/base/sys_info_ios.mm
+++ b/base/sys_info_ios.mm
@@ -20,6 +20,23 @@
 
 namespace base {
 
+namespace {
+
+// Queries sysctlbyname() for the given key and returns the value from the
+// system or the empty string on failure.
+std::string GetSysctlValue(const char* key_name) {
+  char value[256];
+  size_t len = arraysize(value);
+  if (sysctlbyname(key_name, &value, &len, nullptr, 0) == 0) {
+    DCHECK_GE(len, 1u);
+    DCHECK_EQ('\0', value[len - 1]);
+    return std::string(value, len - 1);
+  }
+  return std::string();
+}
+
+}  // namespace
+
 // static
 std::string SysInfo::OperatingSystemName() {
   static dispatch_once_t get_system_name_once;
@@ -94,11 +111,12 @@ int64_t SysInfo::AmountOfAvailablePhysicalMemory() {
 
 // 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;
-  return std::string();
+  return GetSysctlValue("machdep.cpu.brand_string");
+}
+
+// static
+std::string SysInfo::HardwareModelName() {
+  return GetSysctlValue("hw.model");

[pkl (ping after 24h if needed), 2017/05/04 19:50:22]

I patched this CL and tested it on a real device (iPhone5S).
hw.model returns some strange string "N53AP". On simulator, it returns
"MacPro6,1".

Based on https://gist.github.com/Tokuriku/9708472cbe1095030c8b
I tried "hw.machine". That returns "iPhone6,2" on device and "x86_64" on
simulator.
I think "hw.machine" is the better key to use here.

Is there a unit test that we can add to run only on iOS devices to be sure that
the returned value is somewhat "sane"?

[Alexei Svitkine (slow), 2017/05/04 20:01:41]

Wow - that's pretty strange. Thanks for checking!

I can expand the test SysInfoTest.HardwareModelName - which should run on Mac
and iOS - to specifically look for the pattern "Foo,Bar". Let's see if that
works and matches the pattern. Will also use hw.machine. I'll ping the CL when
it's ready for another look.

 }
 
 }  // namespace base