Fix BSD cpu count (#4466)

* Use sysctl to return the number of CPUs on BSD systems

See:
  http://man.openbsd.org/sysctl.3
  https://www.freebsd.org/cgi/man.cgi?query=sysctl&sektion=3

src/crystal/system.cr

@@ -0,0 +1,20 @@
+module Crystal
+  # :nodoc
+  module System
+    # Returns the hostname
+    # def self.hostname
+
+    # Returns the number of logical processors available to the system.
+    #
+    # def self.cpu_count
+  end
+end
+
+require "./system/unix/hostname"
+
+{% if flag?(:freebsd) || flag?(:openbsd) %}
+  require "./system/unix/sysctl_cpucount"
+{% else %}
+  # TODO: restrict on flag?(:unix) after crystal > 0.22.0 is released
+  require "./system/unix/sysconf_cpucount"
+{% end %}

src/crystal/system/unix/hostname.cr

@@ -0,0 +1,13 @@
+require "c/unistd"
+
+module Crystal::System
+  def self.hostname
+    String.new(255) do |buffer|
+      unless LibC.gethostname(buffer, LibC::SizeT.new(255)) == 0
+        raise Errno.new("Could not get hostname")
+      end
+      len = LibC.strlen(buffer)
+      {len, len}
+    end
+  end
+end

src/crystal/system/unix/sysconf_cpucount.cr

@@ -0,0 +1,9 @@
+{% skip_file if flag?(:openbsd) || flag?(:freebsd) %}
+
+require "c/unistd"
+
+module Crystal::System
+  def self.cpu_count
+    LibC.sysconf(LibC::SC_NPROCESSORS_ONLN)
+  end
+end

src/crystal/system/unix/sysctl_cpucount.cr

@@ -0,0 +1,17 @@
+{% skip_file unless flag?(:openbsd) || flag?(:freebsd) %}
+
+require "c/sysctl"
+
+module Crystal::System
+  def self.cpu_count
+    mib = Int32[LibC::CTL_HW, LibC::HW_NCPU]
+    ncpus = 0
+    size = sizeof(Int32).to_u64
+
+    if LibC.sysctl(mib, 2, pointerof(ncpus), pointerof(size), nil, 0) == 0
+      ncpus
+    else
+      -1
+    end
+  end
+end

src/lib_c/amd64-unknown-openbsd/c/sysctl.cr

@@ -0,0 +1,6 @@
+lib LibC
+  CTL_HW  = 6
+  HW_NCPU = 3
+
+  fun sysctl(name : Int*, namelen : UInt, oldp : Void*, oldlenp : SizeT*, newp : Void*, newlen : SizeT) : Int
+end

src/lib_c/amd64-unknown-openbsd/c/unistd.cr

@@ -2,12 +2,11 @@ require "./sys/types"
 require "./stdint"
 
 lib LibC
-  F_OK                =    0
-  R_OK                = 0x04
-  W_OK                = 0x02
-  X_OK                = 0x01
-  SC_CLK_TCK          =    3
-  SC_NPROCESSORS_ONLN =   58
+  F_OK       =    0
+  R_OK       = 0x04
+  W_OK       = 0x02
+  X_OK       = 0x01
+  SC_CLK_TCK =    3
 
   fun access(x0 : Char*, x1 : Int) : Int
   fun chdir(x0 : Char*) : Int

src/lib_c/x86_64-portbld-freebsd/c/sysctl.cr

@@ -0,0 +1,10 @@
+lib LibC
+  CTL_HW             =    6
+  CTL_KERN           =    1
+  HW_NCPU            =    3
+  KERN_PROC          =   14
+  KERN_PROC_PATHNAME =   12
+  PATH_MAX           = 1024
+
+  fun sysctl(name : Int*, namelen : UInt, oldp : Void*, oldlenp : SizeT*, newp : Void*, newlen : SizeT) : Int
+end

src/lib_c/x86_64-portbld-freebsd/c/unistd.cr

@@ -2,12 +2,11 @@ require "./sys/types"
 require "./stdint"
 
 lib LibC
-  F_OK                =    0
-  R_OK                = 0x04
-  W_OK                = 0x02
-  X_OK                = 0x01
-  SC_CLK_TCK          =    3
-  SC_NPROCESSORS_ONLN =   58
+  F_OK       =    0
+  R_OK       = 0x04
+  W_OK       = 0x02
+  X_OK       = 0x01
+  SC_CLK_TCK =    3
 
   fun access(x0 : Char*, x1 : Int) : Int
   fun chdir(x0 : Char*) : Int

src/process/executable_path.cr

@@ -72,13 +72,7 @@ end
   end
 
 {% elsif flag?(:freebsd) %}
-  lib LibC
-    PATH_MAX = 1024
-    CTL_KERN = 1
-    KERN_PROC = 14
-    KERN_PROC_PATHNAME = 12
-    fun sysctl(name : Int*, namelen : UInt, oldp : Void*, oldlenp : SizeT*, newp : Void*, newlen : SizeT) : Int
-  end
+  require "c/sysctl"
 
   class Process
     private def self.executable_path_impl

src/system.cr

@@ -1,22 +1,17 @@
-require "c/unistd"
+require "crystal/system"
 
 module System
   # Returns the hostname.
   #
-  # NOTE: Maximum of 253 characters are allowed, with 2 bytes reserved for storage.
+  # NOTE: Maximum of 253 characters are allowed, with 2 bytes reserved for
+  # storage.
   # In practice, many platforms will disallow anything longer than 63 characters.
   #
   # ```
   # System.hostname # => "host.example.org"
   # ```
   def self.hostname
-    String.new(255) do |buffer|
-      unless LibC.gethostname(buffer, LibC::SizeT.new(255)) == 0
-        raise Errno.new("Could not get hostname")
-      end
-      len = LibC.strlen(buffer)
-      {len, len}
-    end
+    Crystal::System.hostname
   end
 
   # Returns the number of logical processors available to the system.
@@ -25,6 +20,6 @@ module System
   # System.cpu_count # => 4
   # ```
   def self.cpu_count
-    LibC.sysconf(LibC::SC_NPROCESSORS_ONLN)
+    Crystal::System.cpu_count
   end
 end