Implement System for Win32

spec/std/system_spec.cr

@@ -4,16 +4,21 @@ require "system"
 describe System do
   describe "hostname" do
     it "returns current hostname" do
-      shell_hostname = `hostname`.strip
-      $?.success?.should be_true # The hostname command has to be available
+      shell_hostname = `hostname`.strip # Workaround for inability to execute shell commands on Windows.
+      $?.success?.should be_true        # The hostname command has to be available
       hostname = System.hostname
       hostname.should eq(shell_hostname)
     end
   end
 
   describe "cpu_count" do
     it "returns current CPU count" do
-      shell_cpus = `getconf _NPROCESSORS_ONLN 2>/dev/null || nproc --all 2>/dev/null || grep -sc '^processor' /proc/cpuinfo || sysctl -n hw.ncpu 2>/dev/null`.to_i
+      shell_cpus = 0
+      {% if flag?(:win32) %}
+        shell_cpus = ENV["NUMBER_OF_PROCESSORS"].to_i
+      {% elsif flag?(:unix) %}
+        shell_cpus = `getconf _NPROCESSORS_ONLN 2>/dev/null || nproc --all 2>/dev/null || grep -sc '^processor' /proc/cpuinfo || sysctl -n hw.ncpu 2>/dev/null`.to_i
+      {% end %}
       cpu_count = System.cpu_count
       cpu_count.should eq(shell_cpus)
     end

src/crystal/system.cr

@@ -8,10 +8,17 @@ module Crystal::System
   # def self.cpu_count
 end
 
-require "./system/unix/hostname"
+{% if flag?(:unix) %}
+  require "./system/unix/hostname"
 
-{% if flag?(:freebsd) || flag?(:openbsd) %}
+  {% if flag?(:freebsd) || flag?(:openbsd) %}
   require "./system/unix/sysctl_cpucount"
-{% elsif flag?(:unix) %}
-  require "./system/unix/sysconf_cpucount"
+  {% else %}
+    require "./system/unix/sysconf_cpucount"
+  {% end %}
+{% elsif flag?(:win32) %}
+  require "./system/win32/hostname"
+  require "./system/win32/cpucount"
+{% else %}
+  {% raise "No Crystal::System implementation available" %}
 {% end %}

src/crystal/system/win32/cpucount.cr

@@ -0,0 +1,8 @@
+require "c/sysinfoapi"
+
+module Crystal::System
+  def self.cpu_count
+    LibC.GetNativeSystemInfo(out system_info)
+    system_info.dwNumberOfProcessors
+  end
+end

src/crystal/system/win32/hostname.cr

@@ -0,0 +1,16 @@
+require "c/sysinfoapi"
+
+module Crystal::System
+  def self.hostname
+    retry_wstr_buffer do |buffer, small_buf|
+      name_size = buffer.size.to_u
+      if LibC.GetComputerNameExW(LibC::COMPUTER_NAME_FORMAT::ComputerNameDnsHostname, buffer, pointerof(name_size)) != 0
+        break String.from_utf16(buffer[0, name_size])
+      elsif small_buf && name_size > 0
+        next name_size
+      else
+        raise WinError.new("GetComputerNameExW")
+      end
+    end
+  end
+end

src/lib_c/x86_64-windows-msvc/c/sysinfoapi.cr

@@ -0,0 +1,45 @@
+require "c/winnt"
+require "c/win_def"
+require "c/int_safe"
+
+lib LibC
+  fun GetNativeSystemInfo(system_info : SYSTEM_INFO*)
+
+  struct PROCESSOR_INFO
+    wProcessorArchitecture : WORD
+    wReserved : WORD
+  end
+
+  union OEM_PROCESSOR_INFO
+    dwOemId : DWORD
+    processorInfo : PROCESSOR_INFO
+  end
+
+  struct SYSTEM_INFO
+    oemProcessorInfo : OEM_PROCESSOR_INFO
+    dwPageSize : DWORD
+    lpMinimumApplicationAddress : Void*
+    lpMaximumApplicationAddress : Void*
+    dwActiveProcessorMask : DWORD*
+    dwNumberOfProcessors : DWORD
+    dwProcessorType : DWORD
+    dwAllocationGranularity : DWORD
+    wProcessorLevel : WORD
+    wProcessorRevision : WORD
+  end
+
+  fun GetComputerNameExW(computer_name_format : COMPUTER_NAME_FORMAT,
+                         machine_name : LPWSTR,
+                         machine_name_size : DWORD*) : BOOLEAN
+
+  enum COMPUTER_NAME_FORMAT
+    ComputerNameNetBIOS
+    ComputerNameDnsHostname
+    ComputerNameDnsDomain
+    ComputerNameDnsFullyQualified
+    ComputerNamePhysicalNetBIOS
+    ComputerNamePhysicalDnsHostname
+    ComputerNamePhysicalDomain
+    ComputerNamePhysicalDnsFullyQualified
+  end
+end