#  Phusion Passenger - https://www.phusionpassenger.com/
#  Copyright (c) 2010-2013 Phusion
#
#  "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in
#  all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#  THE SOFTWARE.

require 'rbconfig'
PhusionPassenger.require_passenger_lib 'platform_info'

module PhusionPassenger

  module PlatformInfo
    # Returns the operating system's name. This name is in lowercase and contains no spaces,
    # and thus is suitable to be used in some kind of ID. It may contain a version number.
    # Linux is always identified as "linux". OS X is always identified as "macosx".
    # Identifiers for other operating systems may contain a version number, e.g. "freebsd10".
    def self.os_name
      if rb_config['target_os'] =~ /darwin/ && (sw_vers = find_command('sw_vers'))
        return "macosx"
      elsif rb_config['target_os'] =~ /^linux-/
        return "linux"
      else
        return rb_config['target_os']
      end
    end
    memoize :os_name

    # The current platform's shared library extension ('so' on most Unices).
    def self.library_extension
      if os_name == "macosx"
        return "bundle"
      else
        return "so"
      end
    end

    # Returns the `uname` command, or nil if `uname` cannot be found.
    # In addition to looking for `uname` in `PATH`, this method also looks
    # for `uname` in /bin and /usr/bin, just in case the user didn't
    # configure its PATH properly.
    def self.uname_command
      if result = find_command("uname")
        result
      elsif File.exist?("/bin/uname")
        return "/bin/uname"
      elsif File.exist?("/usr/bin/uname")
        return "/usr/bin/uname"
      else
        return nil
      end
    end

    # Returns a list of all CPU architecture names that the current machine CPU
    # supports. If there are multiple such architectures then the first item in
    # the result denotes that OS runtime's main/preferred architecture.
    #
    # This function normalizes some names. For example x86 is always reported
    # as "x86" regardless of whether the OS reports it as "i386" or "i686".
    # x86_64 is always reported as "x86_64" even if the OS reports it as "amd64".
    #
    # Please note that even if the CPU supports multiple architectures, the
    # operating system might not. For example most x86 CPUs nowadays also
    # support x86_64, but x86_64 Linux systems require various x86 compatibility
    # libraries to be installed before x86 executables can be run. This function
    # does not detect whether these compatibility libraries are installed.
    # The only guarantee that you have is that the OS can run executables in
    # the architecture denoted by the first item in the result.
    #
    # For example, on x86_64 Linux this function can return ["x86_64", "x86"].
    # This indicates that the CPU supports both of these architectures, and that
    # the OS's main/preferred architecture is x86_64. Most executables on the
    # system are thus be x86_64. It is guaranteed that the OS can run x86_64
    # executables, but not x86 executables per se.
    #
    # Another example: on MacOS X this function can return either
    # ["x86_64", "x86"] or ["x86", "x86_64"]. The former result indicates
    # OS X 10.6 (Snow Leopard) and beyond because starting from that version
    # everything is 64-bit by default. The latter result indicates an OS X
    # version older than 10.6.
    def self.cpu_architectures
      uname = uname_command
      raise "The 'uname' command cannot be found" if !uname
      if os_name == "macosx"
        arch = `#{uname} -p`.strip
        if arch == "i386"
          # Macs have been x86 since around 2007. I think all of them come with
          # a recent enough Intel CPU that supports both x86 and x86_64, and I
          # think every OS X version has both the x86 and x86_64 runtime installed.
          major, minor, *rest = `sw_vers -productVersion`.strip.split(".")
          major = major.to_i
          minor = minor.to_i
          if major >= 10 || (major == 10 && minor >= 6)
            # Since Snow Leopard x86_64 is the default.
            ["x86_64", "x86"]
          else
            # Before Snow Leopard x86 was the default.
            ["x86", "x86_64"]
          end
        else
          arch
        end
      else
        arch = `#{uname} -p`.strip
        # On some systems 'uname -p' returns something like
        # 'Intel(R) Pentium(R) M processor 1400MHz' or
        # 'Intel(R)_Xeon(R)_CPU___________X7460__@_2.66GHz'.
        if arch == "unknown" || arch =~ / / || arch =~ /Hz$/
          arch = `#{uname} -m`.strip
        end
        if arch =~ /^i.86$/
          arch = "x86"
        elsif arch == "amd64"
          arch = "x86_64"
        end

        if arch == "x86"
          # Most x86 operating systems nowadays are probably running on
          # a CPU that supports both x86 and x86_64, but we're not gonna
          # go through the trouble of checking that. The main architecture
          # is what we usually care about.
          ["x86"]
        elsif arch == "x86_64"
          # I don't think there's a single x86_64 CPU out there
          # that doesn't support x86 as well.
          ["x86_64", "x86"]
        else
          [arch]
        end
      end
    end
    memoize :cpu_architectures, true

    # Returns whether the OS's main CPU architecture supports the
    # x86/x86_64 sfence instruction.
    def self.supports_sfence_instruction?
      arch = cpu_architectures[0]
      return arch == "x86_64" || (arch == "x86" &&
        try_compile_and_run("Checking for sfence instruction support", :c, %Q{
          int
          main() {
            __asm__ __volatile__ ("sfence" ::: "memory");
            return 0;
          }
        }))
    end
    memoize :supports_sfence_instruction?, true

    # Returns whether the OS's main CPU architecture supports the
    # x86/x86_64 lfence instruction.
    def self.supports_lfence_instruction?
      arch = cpu_architectures[0]
      return arch == "x86_64" || (arch == "x86" &&
        try_compile_and_run("Checking for lfence instruction support", :c, %Q{
          int
          main() {
            __asm__ __volatile__ ("lfence" ::: "memory");
            return 0;
          }
        }))
    end
    memoize :supports_lfence_instruction?, true

    def self.requires_no_tls_direct_seg_refs?
      return File.exists?("/proc/xen/capabilities") && cpu_architectures[0] == "x86"
    end
    memoize :requires_no_tls_direct_seg_refs?, true
  end

end # module PhusionPassenger
