Implement SysInfo::HardwareModelName() on iOS.

This allows the hardware_class field in UMA to be populated on
iOS (with values like "iPhone9,3"), which will allow us to stop
sending those strings in the cpu_architecture field which is
what's currently being done.

BUG=370104

Review-Url: https://codereview.chromium.org/2860663005
Cr-Commit-Position: refs/heads/master@{#469499}

base/sys_info.cc

@@ -49,7 +49,7 @@ bool SysInfo::IsLowEndDevice() {
 }
 #endif
 
-#if (!defined(OS_MACOSX) || defined(OS_IOS)) && !defined(OS_ANDROID)
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
 std::string SysInfo::HardwareModelName() {
   return std::string();
 }

base/sys_info.h

@@ -69,8 +69,9 @@ class BASE_EXPORT SysInfo {
 
   // Returns a descriptive string for the current machine model or an empty
   // string if the machine model is unknown or an error occured.
-  // e.g. "MacPro1,1" on Mac, or "Nexus 5" on Android. Only implemented on OS X,
-  // Android, and Chrome OS. This returns an empty string on other platforms.
+  // e.g. "MacPro1,1" on Mac, "iPhone9,3" on iOS or "Nexus 5" on Android. Only
+  // implemented on OS X, iOS, Android, and Chrome OS. This returns an empty
+  // string on other platforms.
   static std::string HardwareModelName();
 
   // Returns the name of the host operating system.

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 +111,20 @@ 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() {
+#if TARGET_OS_SIMULATOR
+  // On the simulator, "hw.machine" returns "i386" or "x86_64" which doesn't
+  // match the expected format, so supply a fake string here.
+  return "Simulator1,1";
+#else
+  // Note: This uses "hw.machine" instead of "hw.model" like the Mac code,
+  // because "hw.model" doesn't always return the right string on some devices.
+  return GetSysctlValue("hw.machine");
+#endif
 }
 
 }  // namespace base

base/sys_info_mac.mm

@@ -24,6 +24,23 @@
 
 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() {
   return "Mac OS X";
@@ -94,19 +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() {
-  char model[256];
-  size_t len = sizeof(model);
-  if (sysctlbyname("hw.model", model, &len, NULL, 0) == 0)
-    return std::string(model, 0, len);
-  return std::string();
+  return GetSysctlValue("hw.model");
 }
 
 }  // namespace base

base/sys_info_unittest.cc

@@ -7,6 +7,8 @@
 #include "base/environment.h"
 #include "base/files/file_util.h"
 #include "base/process/process_metrics.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
@@ -95,10 +97,17 @@ TEST_F(SysInfoTest, Uptime) {
   EXPECT_GT(up_time_2.InMicroseconds(), up_time_1.InMicroseconds());
 }
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-TEST_F(SysInfoTest, HardwareModelName) {
+#if defined(OS_MACOSX)
+TEST_F(SysInfoTest, HardwareModelNameFormatMacAndiOS) {
   std::string hardware_model = SysInfo::HardwareModelName();
-  EXPECT_FALSE(hardware_model.empty());
+  ASSERT_FALSE(hardware_model.empty());
+  // Check that the model is of the expected format "Foo,Bar" where "Bar" is
+  // a number.
+  std::vector<StringPiece> pieces =
+      SplitStringPiece(hardware_model, ",", KEEP_WHITESPACE, SPLIT_WANT_ALL);
+  ASSERT_EQ(2u, pieces.size()) << hardware_model;
+  int value;
+  EXPECT_TRUE(StringToInt(pieces[1], &value)) << hardware_model;
 }
 #endif