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In some cases, sensitive to readline version and the user's environment, gdb might emit escape codes while run under python's pexpect (i.e. testing pretty printers). This patch, suggested by Jan, helps isolate the test from the user's environment. Tested on RHEL 7 x86_64 with DTS 7 and EPEL, which is one magic combination of components that triggers this bug.
373 lines
12 KiB
Python
373 lines
12 KiB
Python
# Common functions and variables for testing the Python pretty printers.
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#
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# Copyright (C) 2016-2019 Free Software Foundation, Inc.
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# This file is part of the GNU C Library.
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#
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# The GNU C Library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# The GNU C Library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with the GNU C Library; if not, see
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# <http://www.gnu.org/licenses/>.
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"""These tests require PExpect 4.0 or newer.
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Exported constants:
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PASS, FAIL, UNSUPPORTED (int): Test exit codes, as per evaluate-test.sh.
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"""
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import os
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import re
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from test_printers_exceptions import *
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PASS = 0
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FAIL = 1
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UNSUPPORTED = 77
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gdb_bin = 'gdb'
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gdb_options = '-q -nx'
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gdb_invocation = '{0} {1}'.format(gdb_bin, gdb_options)
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pexpect_min_version = 4
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gdb_min_version = (7, 8)
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encoding = 'utf-8'
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try:
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import pexpect
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except ImportError:
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print('PExpect 4.0 or newer must be installed to test the pretty printers.')
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exit(UNSUPPORTED)
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pexpect_version = pexpect.__version__.split('.')[0]
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if int(pexpect_version) < pexpect_min_version:
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print('PExpect 4.0 or newer must be installed to test the pretty printers.')
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exit(UNSUPPORTED)
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if not pexpect.which(gdb_bin):
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print('gdb 7.8 or newer must be installed to test the pretty printers.')
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exit(UNSUPPORTED)
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timeout = 5
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TIMEOUTFACTOR = os.environ.get('TIMEOUTFACTOR')
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if TIMEOUTFACTOR:
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timeout = int(TIMEOUTFACTOR)
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# Otherwise GDB is run in interactive mode and readline may send escape
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# sequences confusing output for pexpect.
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os.environ["TERM"]="dumb"
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try:
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# Check the gdb version.
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version_cmd = '{0} --version'.format(gdb_invocation, timeout=timeout)
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gdb_version_out = pexpect.run(version_cmd, encoding=encoding)
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# The gdb version string is "GNU gdb <PKGVERSION><version>", where
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# PKGVERSION can be any text. We assume that there'll always be a space
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# between PKGVERSION and the version number for the sake of the regexp.
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version_match = re.search(r'GNU gdb .* ([1-9]+)\.([0-9]+)', gdb_version_out)
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if not version_match:
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print('The gdb version string (gdb -v) is incorrectly formatted.')
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exit(UNSUPPORTED)
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gdb_version = (int(version_match.group(1)), int(version_match.group(2)))
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if gdb_version < gdb_min_version:
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print('gdb 7.8 or newer must be installed to test the pretty printers.')
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exit(UNSUPPORTED)
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# Check if gdb supports Python.
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gdb_python_cmd = '{0} -ex "python import os" -batch'.format(gdb_invocation,
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timeout=timeout)
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gdb_python_error = pexpect.run(gdb_python_cmd, encoding=encoding)
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if gdb_python_error:
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print('gdb must have python support to test the pretty printers.')
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print('gdb output: {!r}'.format(gdb_python_error))
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exit(UNSUPPORTED)
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# If everything's ok, spawn the gdb process we'll use for testing.
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gdb = pexpect.spawn(gdb_invocation, echo=False, timeout=timeout,
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encoding=encoding)
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gdb_prompt = u'\(gdb\)'
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gdb.expect(gdb_prompt)
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except pexpect.ExceptionPexpect as exception:
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print('Error: {0}'.format(exception))
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exit(FAIL)
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def test(command, pattern=None):
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"""Sends 'command' to gdb and expects the given 'pattern'.
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If 'pattern' is None, simply consumes everything up to and including
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the gdb prompt.
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Args:
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command (string): The command we'll send to gdb.
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pattern (raw string): A pattern the gdb output should match.
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Returns:
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string: The string that matched 'pattern', or an empty string if
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'pattern' was None.
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"""
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match = ''
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gdb.sendline(command)
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if pattern:
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# PExpect does a non-greedy match for '+' and '*'. Since it can't look
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# ahead on the gdb output stream, if 'pattern' ends with a '+' or a '*'
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# we may end up matching only part of the required output.
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# To avoid this, we'll consume 'pattern' and anything that follows it
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# up to and including the gdb prompt, then extract 'pattern' later.
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index = gdb.expect([u'{0}.+{1}'.format(pattern, gdb_prompt),
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pexpect.TIMEOUT])
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if index == 0:
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# gdb.after now contains the whole match. Extract the text that
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# matches 'pattern'.
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match = re.match(pattern, gdb.after, re.DOTALL).group()
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elif index == 1:
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# We got a timeout exception. Print information on what caused it
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# and bail out.
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error = ('Response does not match the expected pattern.\n'
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'Command: {0}\n'
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'Expected pattern: {1}\n'
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'Response: {2}'.format(command, pattern, gdb.before))
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raise pexpect.TIMEOUT(error)
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else:
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# Consume just the the gdb prompt.
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gdb.expect(gdb_prompt)
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return match
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def init_test(test_bin, printer_files, printer_names):
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"""Loads the test binary file and the required pretty printers to gdb.
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Args:
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test_bin (string): The name of the test binary file.
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pretty_printers (list of strings): A list with the names of the pretty
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printer files.
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"""
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# Load all the pretty printer files. We're assuming these are safe.
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for printer_file in printer_files:
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test('source {0}'.format(printer_file))
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# Disable all the pretty printers.
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test('disable pretty-printer', r'0 of [0-9]+ printers enabled')
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# Enable only the required printers.
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for printer in printer_names:
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test('enable pretty-printer {0}'.format(printer),
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r'[1-9][0-9]* of [1-9]+ printers enabled')
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# Finally, load the test binary.
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test('file {0}'.format(test_bin))
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# Disable lock elision.
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test('set environment GLIBC_TUNABLES glibc.elision.enable=0')
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def go_to_main():
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"""Executes a gdb 'start' command, which takes us to main."""
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test('start', r'main')
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def get_line_number(file_name, string):
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"""Returns the number of the line in which 'string' appears within a file.
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Args:
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file_name (string): The name of the file we'll search through.
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string (string): The string we'll look for.
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Returns:
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int: The number of the line in which 'string' appears, starting from 1.
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"""
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number = -1
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with open(file_name) as src_file:
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for i, line in enumerate(src_file):
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if string in line:
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number = i + 1
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break
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if number == -1:
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raise NoLineError(file_name, string)
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return number
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def break_at(file_name, string, temporary=True, thread=None):
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"""Places a breakpoint on the first line in 'file_name' containing 'string'.
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'string' is usually a comment like "Stop here". Notice this may fail unless
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the comment is placed inline next to actual code, e.g.:
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...
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/* Stop here */
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...
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may fail, while:
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...
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some_func(); /* Stop here */
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...
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will succeed.
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If 'thread' isn't None, the breakpoint will be set for all the threads.
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Otherwise, it'll be set only for 'thread'.
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Args:
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file_name (string): The name of the file we'll place the breakpoint in.
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string (string): A string we'll look for inside the file.
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We'll place a breakpoint on the line which contains it.
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temporary (bool): Whether the breakpoint should be automatically deleted
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after we reach it.
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thread (int): The number of the thread we'll place the breakpoint for,
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as seen by gdb. If specified, it should be greater than zero.
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"""
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if not thread:
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thread_str = ''
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else:
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thread_str = 'thread {0}'.format(thread)
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if temporary:
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command = 'tbreak'
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break_type = 'Temporary breakpoint'
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else:
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command = 'break'
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break_type = 'Breakpoint'
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line_number = str(get_line_number(file_name, string))
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test('{0} {1}:{2} {3}'.format(command, file_name, line_number, thread_str),
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r'{0} [0-9]+ at 0x[a-f0-9]+: file {1}, line {2}\.'.format(break_type,
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file_name,
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line_number))
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def continue_cmd(thread=None):
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"""Executes a gdb 'continue' command.
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If 'thread' isn't None, the command will be applied to all the threads.
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Otherwise, it'll be applied only to 'thread'.
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Args:
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thread (int): The number of the thread we'll apply the command to,
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as seen by gdb. If specified, it should be greater than zero.
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"""
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if not thread:
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command = 'continue'
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else:
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command = 'thread apply {0} continue'.format(thread)
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test(command)
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def next_cmd(count=1, thread=None):
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"""Executes a gdb 'next' command.
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If 'thread' isn't None, the command will be applied to all the threads.
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Otherwise, it'll be applied only to 'thread'.
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Args:
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count (int): The 'count' argument of the 'next' command.
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thread (int): The number of the thread we'll apply the command to,
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as seen by gdb. If specified, it should be greater than zero.
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"""
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if not thread:
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command = 'next'
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else:
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command = 'thread apply {0} next'
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test('{0} {1}'.format(command, count))
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def select_thread(thread):
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"""Selects the thread indicated by 'thread'.
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Args:
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thread (int): The number of the thread we'll switch to, as seen by gdb.
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This should be greater than zero.
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"""
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if thread > 0:
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test('thread {0}'.format(thread))
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def get_current_thread_lwpid():
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"""Gets the current thread's Lightweight Process ID.
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Returns:
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string: The current thread's LWP ID.
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"""
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# It's easier to get the LWP ID through the Python API than the gdb CLI.
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command = 'python print(gdb.selected_thread().ptid[1])'
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return test(command, r'[0-9]+')
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def set_scheduler_locking(mode):
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"""Executes the gdb 'set scheduler-locking' command.
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Args:
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mode (bool): Whether the scheduler locking mode should be 'on'.
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"""
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modes = {
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True: 'on',
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False: 'off'
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}
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test('set scheduler-locking {0}'.format(modes[mode]))
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def test_printer(var, to_string, children=None, is_ptr=True):
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""" Tests the output of a pretty printer.
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For a variable called 'var', this tests whether its associated printer
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outputs the expected 'to_string' and children (if any).
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Args:
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var (string): The name of the variable we'll print.
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to_string (raw string): The expected output of the printer's 'to_string'
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method.
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children (map {raw string->raw string}): A map with the expected output
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of the printer's children' method.
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is_ptr (bool): Whether 'var' is a pointer, and thus should be
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dereferenced.
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"""
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if is_ptr:
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var = '*{0}'.format(var)
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test('print {0}'.format(var), to_string)
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if children:
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for name, value in children.items():
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# Children are shown as 'name = value'.
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test('print {0}'.format(var), r'{0} = {1}'.format(name, value))
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def check_debug_symbol(symbol):
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""" Tests whether a given debugging symbol exists.
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If the symbol doesn't exist, raises a DebugError.
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Args:
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symbol (string): The symbol we're going to check for.
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"""
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try:
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test('ptype {0}'.format(symbol), r'type = {0}'.format(symbol))
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except pexpect.TIMEOUT:
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# The symbol doesn't exist.
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raise DebugError(symbol)
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