return true
      }
    } else {
      return false
    }
  }

  #
  # NOTE: This procedure attempts to verify the OpenPGP signature file that
  #       is associated with the specified file.  The forcePgp parameter is
  #       used to force verification attempts to be performed even when the
  #       file does not appear to be an OpenPGP signature file.
  #
  proc maybeVerifyOpenPgpSignature { fileName forcePgp } {
    #
    # NOTE: Is this temporary package file actually just an OpenPGP
    #       signature file?  If so, skip it.
    #
    if {$forcePgp || \
        [isOpenPgpSignatureFileName $fileName true]} then {
      #
      # NOTE: Attempt to verify the OpenPGP signature.  If this fails,
      #       an error is raised.
      #
      ::PackageRepository::probeForOpenPgpInstallation
      ::PackageRepository::openPgpMustBeInstalled

      if {![::PackageRepository::verifyOpenPgpSignature \
          $fileName]} then {
        error [appendArgs \
            "bad OpenPGP signature \"" $fileName \"]
      }
    }
  }

  #
  # NOTE: This procedure returns the auto-path for the language specified by
  #       the language argument.  An empty list is returned if the auto-path
  #       does not exist in the target language.  This procedure may raise
  #       script errors.
  #
  proc getAutoPath { language } {

  #       a package index file.  The language argument must be one of the
  #       literal strings "eagle", "tcl", or "client".  The fileNames argument
  #       must be the list of file names to be downloaded.  The package name,
  #       if one can be detected, is returned; otherwise, an empty string will
  #       be returned.
  #
  proc guessPackageNameFromFileNames { language fileNames } {
    set packageIndexFileName [getPackageIndexFileName $language]
    set packageIndexFileNameOnly [getPackageIndexFileName $language]

    if {[string length $packageIndexFileName] > 0} then {
    if {[string length $packageIndexFileNameOnly] > 0} then {
      foreach fileName $fileNames {
        set fileNameOnly [file tail $fileName]

        if {$fileNameOnly eq $packageIndexFileName} then {
        if {$fileNameOnly eq $packageIndexFileNameOnly} then {
          set directory [file dirname $fileName]

          if {[string length $directory] > 0} then {
            return [file tail $directory]
          }
        }
      }

    #
    writeFile $localFileName [getPackageFile $uri]

    #
    # NOTE: Is use of OpenPGP for signature verification enabled?  Also,
    #       did we just download an OpenPGP signature file?
    #
    if {$usePgp && ($forcePgp || \
    if {$usePgp} then {
        [isOpenPgpSignatureFileName $localFileName true])} then {
      #
      # NOTE: Attempt to verify the OpenPGP signature.  If this fails,
      #       an error is raised.
      # NOTE: Maybe attempt to verify the OpenPGP signature.  If this
      #       fails, an error is raised.
      #
      ::PackageRepository::probeForOpenPgpInstallation
      ::PackageRepository::openPgpMustBeInstalled

      if {![::PackageRepository::verifyOpenPgpSignature $localFileName]} then {
      maybeVerifyOpenPgpSignature $localFileName $forcePgp
        error [appendArgs \
            "bad OpenPGP signature \"" $localFileName \"]
      }
    }
  }

  #
  # NOTE: This procedure downloads a single file from the package file server,
  #       writing its contents to the specified local file name.  It can also
  #       verify the OpenPGP signatures.  When an OpenPGP signature file is

        set downloadDirectories [list $persistentDirectory]
      } else {
        #
        # NOTE: Check each unique download directory for a package index
        #       file.  If a directory has a package index for the target
        #       language, add to the auto-path for the target language.
        #
        set packageIndexFileName [getPackageIndexFileName $language]
        set packageIndexFileNameOnly [getPackageIndexFileName $language]

        if {[string length $packageIndexFileName] > 0} then {
        if {[string length $packageIndexFileNameOnly] > 0} then {
          foreach downloadDirectory $downloadDirectories {
            if {[file exists [file join \
                $downloadDirectory $packageIndexFileName]]} then {
                $downloadDirectory $packageIndexFileNameOnly]]} then {
              addToAutoPath $language $downloadDirectory
            }
          }
        }
      }
    }

    #
    # NOTE: Always return the list of directories that were actually added
    #       to the auto-path, if any.
    #
    return $downloadDirectories
  }

  #
  # NOTE: This procedure adds temporary package directories to the auto-path
  #       of the specified language (i.e. native Tcl or Eagle).  Directories
  #       will not be added if already present.  The language argument must
  #       be the literal string "eagle" or the literal string "tcl".  The
  #       pattern argument is the optional pattern to match against each of
  #       the candidate temporary package directories.  If the pattern is an
  #       empty string then all candidate temporary package directories will
  #       be added to the auto-path; otherwise, the pattern will be matched
  #       against the final portion of the temporary package directory name
  #       and only those temporary package directories that actually match
  #       the pattern will be added to the auto-path.  The options argument
  #       must be a dictionary of name/value pairs.  This procedure does not
  #       currently support any options.  This procedure may raise script
  #       errors.  This procedure assumes the local temporary directory is
  #       writable only by applications that are implicitly trusted by the
  #       current user.  If this assumption does not hold on your platform,
  #       DO NOT USE THIS PROCEDURE AS IT MAY BE UNSAFE.
  #
  # <public>
  proc maybeAddTemporaryPackagesToAutoPath { language options {pattern *} } {
    variable temporaryRootDirectory
    variable verboseTemporaryDirectory

    #
    # NOTE: Initially, no temporary package directories have been added
    #       to the auto-path.
    #
    set result [list]; set packageNames [list]

    #
    # NOTE: What is the package index file name for this language?  Each
    #       candidate temporary package directory will be checked to see
    #       if it contains this file; otherwise, it will not be added to
    #       the auto-path.
    #
    set packageIndexFileNameOnly [getPackageIndexFileName $language]

    #
    # HACK: Obtain the list of candidate temporary package directories
    #       that may need to be added to the auto-path.  The prefix we
    #       use here is considered "well-known" by this package.
    #
    set directories(1) [glob -nocomplain -types {d} \
        [file join $temporaryRootDirectory pkgd_lib_*]]

    foreach directory(1) $directories(1) {
      set directories(2) [glob -nocomplain -types {d} \
          [file join $directory(1) *]]

      foreach directory(2) $directories(2) {
        set directoryNameOnly(2) [file tail $directory(2)]
        set packageName $directoryNameOnly(2); # HACK: Well-known.

        if {[lsearch -exact $packageNames $packageName] == -1} then {
          if {[string length $pattern] == 0 || \
              [string match $pattern $directoryNameOnly(2)]} then {
            if {[string length $packageIndexFileNameOnly] == 0 || \
                [file exists [file join $directory(2) \
                    $packageIndexFileNameOnly]]} then {
              if {[maybeAddToAutoPath $language $directory(2)]} then {
                lappend packageNames $directoryNameOnly(2)
                lappend result $directory(2)

                if {$verboseTemporaryDirectory} then {
                  pkgLog [appendArgs \
                      "added temporary package directory named \"" \
                      $directory(2) "\" to auto-path..."]
                }
              }
            }
          }
        }
      }
    }

    return $result
  }

  #
  # NOTE: This package requires the package repository client package.
  #
  package require Eagle.Package.Repository

  #