Method: MakeMakefile#pkg_config

Defined in:
lib/mkmf.rb

#pkg_config(pkg, option = nil) ⇒ Object

Returns compile/link information about an installed library in a tuple of [cflags, ldflags, libs], by using the command found first in the following commands:

  1. If --with-{pkg}-config={command} is given via command line option: {command} {option}

  2. {pkg}-config {option}

  3. pkg-config {option} {pkg}

Where option is, for instance, --cflags.

The values obtained are appended to $CFLAGS, $LDFLAGS and $libs.

If an option argument is given, the config command is invoked with the option and a stripped output string is returned without modifying any of the global values mentioned above.



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# File 'lib/mkmf.rb', line 1753

def pkg_config(pkg, option=nil)
  if pkgconfig = with_config("#{pkg}-config") and find_executable0(pkgconfig)
    # iff package specific config command is given
  elsif ($PKGCONFIG ||=
         (pkgconfig = with_config("pkg-config", ("pkg-config" unless CROSS_COMPILING))) &&
         find_executable0(pkgconfig) && pkgconfig) and
      system("#{$PKGCONFIG} --exists #{pkg}")
    # default to pkg-config command
    pkgconfig = $PKGCONFIG
    get = proc {|opt|
      opt = IO.popen("#{$PKGCONFIG} --#{opt} #{pkg}", err:[:child, :out], &:read)
      opt.strip if $?.success?
    }
  elsif find_executable0(pkgconfig = "#{pkg}-config")
    # default to package specific config command, as a last resort.
  else
    pkgconfig = nil
  end
  if pkgconfig
    get ||= proc {|opt|
      opt = IO.popen("#{pkgconfig} --#{opt}", err:[:child, :out], &:read)
      opt.strip if $?.success?
    }
  end
  orig_ldflags = $LDFLAGS
  if get and option
    get[option]
  elsif get and try_ldflags(ldflags = get['libs'])
    if incflags = get['cflags-only-I']
      $INCFLAGS << " " << incflags
      cflags = get['cflags-only-other']
    else
      cflags = get['cflags']
    end
    libs = get['libs-only-l']
    ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
    $CFLAGS += " " << cflags
    $CXXFLAGS += " " << cflags
    $LDFLAGS = [orig_ldflags, ldflags].join(' ')
    $libs += " " << libs
    Logging::message "package configuration for %s\n", pkg
    Logging::message "cflags: %s\nldflags: %s\nlibs: %s\n\n",
                     cflags, ldflags, libs
    [cflags, ldflags, libs]
  else
    Logging::message "package configuration for %s is not found\n", pkg
    nil
  end
end