|
| 1 | +# Written to test interrupted system calls interfering with our many buffered |
| 2 | +# IO implementations. http://bugs.python.org/issue12268 |
| 3 | +# |
| 4 | +# It was suggested that this code could be merged into test_io and the tests |
| 5 | +# made to work using the same method as the existing signal tests in test_io. |
| 6 | +# I was unable to get single process tests using alarm or setitimer that way |
| 7 | +# to reproduce the EINTR problems. This process based test suite reproduces |
| 8 | +# the problems prior to the issue12268 patch reliably on Linux and OSX. |
| 9 | +# - gregory.p.smith |
| 10 | + |
| 11 | +import os |
| 12 | +import select |
| 13 | +import signal |
| 14 | +import subprocess |
| 15 | +import sys |
| 16 | +from test.support import run_unittest |
| 17 | +import time |
| 18 | +import unittest |
| 19 | + |
| 20 | +# Test import all of the things we're about to try testing up front. |
| 21 | +from _io import FileIO |
| 22 | + |
| 23 | + |
| 24 | +@unittest.skipUnless(os.name == 'posix', 'tests requires a posix system.') |
| 25 | +class TestFileIOSignalInterrupt(unittest.TestCase): |
| 26 | + def setUp(self): |
| 27 | + self._process = None |
| 28 | + |
| 29 | + def tearDown(self): |
| 30 | + if self._process and self._process.poll() is None: |
| 31 | + try: |
| 32 | + self._process.kill() |
| 33 | + except OSError: |
| 34 | + pass |
| 35 | + |
| 36 | + def _generate_infile_setup_code(self): |
| 37 | + """Returns the infile = ... line of code for the reader process. |
| 38 | +
|
| 39 | + subclasseses should override this to test different IO objects. |
| 40 | + """ |
| 41 | + return ('import _io ;' |
| 42 | + 'infile = _io.FileIO(sys.stdin.fileno(), "rb")') |
| 43 | + |
| 44 | + def fail_with_process_info(self, why, stdout=b'', stderr=b'', |
| 45 | + communicate=True): |
| 46 | + """A common way to cleanup and fail with useful debug output. |
| 47 | +
|
| 48 | + Kills the process if it is still running, collects remaining output |
| 49 | + and fails the test with an error message including the output. |
| 50 | +
|
| 51 | + Args: |
| 52 | + why: Text to go after "Error from IO process" in the message. |
| 53 | + stdout, stderr: standard output and error from the process so |
| 54 | + far to include in the error message. |
| 55 | + communicate: bool, when True we call communicate() on the process |
| 56 | + after killing it to gather additional output. |
| 57 | + """ |
| 58 | + if self._process.poll() is None: |
| 59 | + time.sleep(0.1) # give it time to finish printing the error. |
| 60 | + try: |
| 61 | + self._process.terminate() # Ensure it dies. |
| 62 | + except OSError: |
| 63 | + pass |
| 64 | + if communicate: |
| 65 | + stdout_end, stderr_end = self._process.communicate() |
| 66 | + stdout += stdout_end |
| 67 | + stderr += stderr_end |
| 68 | + self.fail('Error from IO process %s:\nSTDOUT:\n%sSTDERR:\n%s\n' % |
| 69 | + (why, stdout.decode(), stderr.decode())) |
| 70 | + |
| 71 | + def _test_reading(self, data_to_write, read_and_verify_code): |
| 72 | + """Generic buffered read method test harness to validate EINTR behavior. |
| 73 | +
|
| 74 | + Also validates that Python signal handlers are run during the read. |
| 75 | +
|
| 76 | + Args: |
| 77 | + data_to_write: String to write to the child process for reading |
| 78 | + before sending it a signal, confirming the signal was handled, |
| 79 | + writing a final newline and closing the infile pipe. |
| 80 | + read_and_verify_code: Single "line" of code to read from a file |
| 81 | + object named 'infile' and validate the result. This will be |
| 82 | + executed as part of a python subprocess fed data_to_write. |
| 83 | + """ |
| 84 | + infile_setup_code = self._generate_infile_setup_code() |
| 85 | + # Total pipe IO in this function is smaller than the minimum posix OS |
| 86 | + # pipe buffer size of 512 bytes. No writer should block. |
| 87 | + assert len(data_to_write) < 512, 'data_to_write must fit in pipe buf.' |
| 88 | + |
| 89 | + # Start a subprocess to call our read method while handling a signal. |
| 90 | + self._process = subprocess.Popen( |
| 91 | + [sys.executable, '-u', '-c', |
| 92 | + 'import signal, sys ;' |
| 93 | + 'signal.signal(signal.SIGINT, ' |
| 94 | + 'lambda s, f: sys.stderr.write("$\\n")) ;' |
| 95 | + + infile_setup_code + ' ;' + |
| 96 | + 'sys.stderr.write("Worm Sign!\\n") ;' |
| 97 | + + read_and_verify_code + ' ;' + |
| 98 | + 'infile.close()' |
| 99 | + ], |
| 100 | + stdin=subprocess.PIPE, stdout=subprocess.PIPE, |
| 101 | + stderr=subprocess.PIPE) |
| 102 | + |
| 103 | + # Wait for the signal handler to be installed. |
| 104 | + worm_sign = self._process.stderr.read(len(b'Worm Sign!\n')) |
| 105 | + if worm_sign != b'Worm Sign!\n': # See also, Dune by Frank Herbert. |
| 106 | + self.fail_with_process_info('while awaiting a sign', |
| 107 | + stderr=worm_sign) |
| 108 | + self._process.stdin.write(data_to_write) |
| 109 | + |
| 110 | + signals_sent = 0 |
| 111 | + rlist = [] |
| 112 | + # We don't know when the read_and_verify_code in our child is actually |
| 113 | + # executing within the read system call we want to interrupt. This |
| 114 | + # loop waits for a bit before sending the first signal to increase |
| 115 | + # the likelihood of that. Implementations without correct EINTR |
| 116 | + # and signal handling usually fail this test. |
| 117 | + while not rlist: |
| 118 | + rlist, _, _ = select.select([self._process.stderr], (), (), 0.05) |
| 119 | + self._process.send_signal(signal.SIGINT) |
| 120 | + signals_sent += 1 |
| 121 | + if signals_sent > 200: |
| 122 | + self._process.kill() |
| 123 | + self.fail('reader process failed to handle our signals.') |
| 124 | + # This assumes anything unexpected that writes to stderr will also |
| 125 | + # write a newline. That is true of the traceback printing code. |
| 126 | + signal_line = self._process.stderr.readline() |
| 127 | + if signal_line != b'$\n': |
| 128 | + self.fail_with_process_info('while awaiting signal', |
| 129 | + stderr=signal_line) |
| 130 | + |
| 131 | + # We append a newline to our input so that a readline call can |
| 132 | + # end on its own before the EOF is seen and so that we're testing |
| 133 | + # the read call that was interrupted by a signal before the end of |
| 134 | + # the data stream has been reached. |
| 135 | + stdout, stderr = self._process.communicate(input=b'\n') |
| 136 | + if self._process.returncode: |
| 137 | + self.fail_with_process_info( |
| 138 | + 'exited rc=%d' % self._process.returncode, |
| 139 | + stdout, stderr, communicate=False) |
| 140 | + # PASS! |
| 141 | + |
| 142 | + # String format for the read_and_verify_code used by read methods. |
| 143 | + _READING_CODE_TEMPLATE = ( |
| 144 | + 'got = infile.{read_method_name}() ;' |
| 145 | + 'expected = {expected!r} ;' |
| 146 | + 'assert got == expected, (' |
| 147 | + '"{read_method_name} returned wrong data.\\n"' |
| 148 | + '"got data %r\\nexpected %r" % (got, expected))' |
| 149 | + ) |
| 150 | + |
| 151 | + def test_readline(self): |
| 152 | + """readline() must handle signals and not lose data.""" |
| 153 | + self._test_reading( |
| 154 | + data_to_write=b'hello, world!', |
| 155 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 156 | + read_method_name='readline', |
| 157 | + expected=b'hello, world!\n')) |
| 158 | + |
| 159 | + def test_readlines(self): |
| 160 | + """readlines() must handle signals and not lose data.""" |
| 161 | + self._test_reading( |
| 162 | + data_to_write=b'hello\nworld!', |
| 163 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 164 | + read_method_name='readlines', |
| 165 | + expected=[b'hello\n', b'world!\n'])) |
| 166 | + |
| 167 | + def test_readall(self): |
| 168 | + """readall() must handle signals and not lose data.""" |
| 169 | + self._test_reading( |
| 170 | + data_to_write=b'hello\nworld!', |
| 171 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 172 | + read_method_name='readall', |
| 173 | + expected=b'hello\nworld!\n')) |
| 174 | + # read() is the same thing as readall(). |
| 175 | + self._test_reading( |
| 176 | + data_to_write=b'hello\nworld!', |
| 177 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 178 | + read_method_name='read', |
| 179 | + expected=b'hello\nworld!\n')) |
| 180 | + |
| 181 | + |
| 182 | +class TestBufferedIOSignalInterrupt(TestFileIOSignalInterrupt): |
| 183 | + def _generate_infile_setup_code(self): |
| 184 | + """Returns the infile = ... line of code to make a BufferedReader.""" |
| 185 | + return ('infile = open(sys.stdin.fileno(), "rb") ;' |
| 186 | + 'import _io ;assert isinstance(infile, _io.BufferedReader)') |
| 187 | + |
| 188 | + def test_readall(self): |
| 189 | + """BufferedReader.read() must handle signals and not lose data.""" |
| 190 | + self._test_reading( |
| 191 | + data_to_write=b'hello\nworld!', |
| 192 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 193 | + read_method_name='read', |
| 194 | + expected=b'hello\nworld!\n')) |
| 195 | + |
| 196 | + |
| 197 | +class TestTextIOSignalInterrupt(TestFileIOSignalInterrupt): |
| 198 | + def _generate_infile_setup_code(self): |
| 199 | + """Returns the infile = ... line of code to make a TextIOWrapper.""" |
| 200 | + return ('infile = open(sys.stdin.fileno(), "rt", newline=None) ;' |
| 201 | + 'import _io ;assert isinstance(infile, _io.TextIOWrapper)') |
| 202 | + |
| 203 | + def test_readline(self): |
| 204 | + """readline() must handle signals and not lose data.""" |
| 205 | + self._test_reading( |
| 206 | + data_to_write=b'hello, world!', |
| 207 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 208 | + read_method_name='readline', |
| 209 | + expected='hello, world!\n')) |
| 210 | + |
| 211 | + def test_readlines(self): |
| 212 | + """readlines() must handle signals and not lose data.""" |
| 213 | + self._test_reading( |
| 214 | + data_to_write=b'hello\r\nworld!', |
| 215 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 216 | + read_method_name='readlines', |
| 217 | + expected=['hello\n', 'world!\n'])) |
| 218 | + |
| 219 | + def test_readall(self): |
| 220 | + """read() must handle signals and not lose data.""" |
| 221 | + self._test_reading( |
| 222 | + data_to_write=b'hello\nworld!', |
| 223 | + read_and_verify_code=self._READING_CODE_TEMPLATE.format( |
| 224 | + read_method_name='read', |
| 225 | + expected="hello\nworld!\n")) |
| 226 | + |
| 227 | + |
| 228 | +def test_main(): |
| 229 | + test_cases = [ |
| 230 | + tc for tc in globals().values() |
| 231 | + if isinstance(tc, type) and issubclass(tc, unittest.TestCase)] |
| 232 | + run_unittest(*test_cases) |
| 233 | + |
| 234 | + |
| 235 | +if __name__ == '__main__': |
| 236 | + test_main() |
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