lib/tools.exp

#!/usr/bin/expect

# This file provides many valuable expect procedures like handle_timeout and
# handle_eof.

my_source [list print.tcl]


proc handle_timeout { description } {

  # Print timeout error message to stderr and exit 1.

  # Description of argument(s):
  # description                     A description of what was being expected
  #                                 (e.g. "an SOL login prompt").

  global spawn_id
  global expect_out

  set timeout [get_stack_var timeout {} 2]

  if { $timeout == 1 } {
    set seconds "second"
  } else {
    set seconds "seconds"
  }

  puts stderr ""
  print_error "Did not get ${description} after $timeout ${seconds}.\n"
  # Using uplevel to be able to access expect_out.
  if { [ catch {uplevel { puts stderr [sprint_var expect_out]}} result ] } {
    puts stderr [sprint_varx expect_out "<not set>"]
  }
  # If caller has exit_proc defined, call it.  Otherwise, just call exit.
  if { [info procs "exit_proc"] != "" } {
    exit_proc 1
  }
  exit 1

}


proc handle_eof { description } {

  # Print end-of-file error message to stderr and exit 1.

  # Description of argument(s):
  # description                     A description of what was being expected
  #                                 (e.g. "an SOL login prompt").

  global spawn_id

  puts stderr ""
  print_error "Reached end of file before getting $description.\n"
  # Using uplevel to be able to access expect_out.
  if { [ catch {uplevel { puts stderr [sprint_var expect_out]}} result ] } {
    puts stderr [sprint_varx expect_out "<not set>"]
  }
  # If caller has exit_proc defined, call it.  Otherwise, just call exit.
  if { [info procs "exit_proc"] != "" } {
    exit_proc 1
  }
  exit 1

}


proc expect_wrap {pattern_list message {timeout 15} {fail_on_timeout 1}} {

  # Run the expect command for the caller and return the list index of the
  # matching pattern.

  # This function offers the following benefits over calling the expect
  # command directly:
  # - It makes program debug easier.  When the program is run with --debug=1,
  # this function prints useful debug output.
  # - It will do standardized timeout and eof handling.

  # Description of argument(s):
  # pattern_list                    A list of patterns to be matched.  If one
  #                                 of the patterns matches, the list index of
  #                                 the matching item will be returned.  By
  #                                 default, each pattern is presumed to be a
  #                                 regex.  If the caller wishes to, they may
  #                                 precede each pattern with either of the
  #                                 following: "-re ", "-gl " or "-ex " in
  #                                 order to explicitly choose the kind of
  #                                 match to be done..
  # message                         A message explaining what is being
  #                                 expected (e.g. "an SOL login prompt").
  #                                 This will be included in output messages.
  # timeout                         The expect timeout value.
  # fail_on_timeout                 A flag governing the behavior when the
  #                                 expect command results in a timeout.
  #                                 If set to 1, this procedure will print an
  #                                 error message to standard error and exit
  #                                 the program with a non-zero return code.
  #                                 If set to 0, it will return
  #                                 [expect_wrap_timeout].

  # Example usage:
  #   set result [expect_wrap\
  #     [list $bad_user_pw_regex "sh: xauth: command not found"]\
  #     "an SOL prompt" 10]
  #
  #   switch $result {
  #     0 {
  #       puts stderr "" ; print_error "Invalid username or password.\n"
  #       exit_proc 1
  #     }
  #     1 {
  #       dict set state ssh_logged_in 1
  #     }
  #   }

  global spawn_id
  global expect_out

  # Recognized flags.
  set flags [list "-re" "-ex" "-gl"]

  # This helps debug efforts by removing leftover, stale entries.
  array unset expect_out \[1-9\],string

  # Prepare the expect statement.
  append cmd_buf "global spawn_id\n"
  append cmd_buf "global expect_out\n"
  append cmd_buf "expect {\n"
  set ix 0
  foreach pattern $pattern_list {
    # Check to see whether the caller has specified a flag (e.g. "-re",
    # "-ex", etc.) at the beginning of the pattern.
    set tokens [split $pattern " "]
    if { [lsearch $flags [lindex $tokens 0]] != -1 } {
      # Caller specified a flag.
      set flag [lindex $tokens 0]
      # Strip the flag from the pattern.
      set pattern [string range $pattern 4 end]
    } else {
      set flag "-re"
    }
    append cmd_buf "  ${flag} {$pattern} {set expect_result $ix}\n"
    incr ix
  }

  if { $fail_on_timeout } {
    append cmd_buf "  timeout {handle_timeout \$message}\n"
  } else {
    append cmd_buf "  timeout {set expect_result \[expect_wrap_timeout\]}\n"
  }
  append cmd_buf "  eof {handle_eof \$message}\n"
  append cmd_buf "}\n"

  dprint_timen "Expecting $message."
  dprint_issuing "\n${cmd_buf}"
  eval ${cmd_buf}

  dprintn ; dprint_vars expect_out expect_result

  return $expect_result

}

proc expect_wrap_timeout {} {

  # Return constant value of 1000.

  return 1000

}


proc send_wrap {buffer {add_lf 1}} {

  # Send the buffer to the spawned process.

  # This function offers the following benefits over calling the send command
  # directly:
  # - It makes program debug easier.  When the program is run with --debug=1,
  # this function prints useful debug output.

  # Description of argument(s):
  # buffer                          The string to be sent to the spawned
  #                                 process.
  # add_lf                          Send a line feed after sending the buffer.

  # Example usage.
  # Close the ssh session.
  #   send_wrap "~."
  #
  #   set expect_result [expect_wrap\
  #     [list "Connection to $host closed"]\
  #     "a connection closed message" 5]

  global spawn_id
  global expect_out

  set cmd_buf "send -- {${buffer}}"
  dprint_issuing
  eval ${cmd_buf}

  if { $add_lf } {
    send -- "\n"
    set cmd_buf "send -- \"\\n\""
    dprint_issuing
    eval ${cmd_buf}
  }

}