Merged revisions 67511,67536-67537,67543 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r67511 | vinay.sajip | 2008-12-04 00:22:58 +0100 (Thu, 04 Dec 2008) | 1 line

  Issue #4384: Added logging integration with warnings module using captureWarnings(). This change includes a NullHandler which does nothing; it will be of use to library developers who want to avoid the "No handlers could be found for logger XXX" message which can appear if the library user doesn't configure logging.
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  r67536 | gregory.p.smith | 2008-12-04 21:21:09 +0100 (Thu, 04 Dec 2008) | 3 lines

  Adds a subprocess.check_call_output() function to return the output from a
  process on success or raise an exception on error.
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  r67537 | vinay.sajip | 2008-12-04 21:32:18 +0100 (Thu, 04 Dec 2008) | 1 line

  Took Nick Coghlan's advice about importing warnings globally in logging, to avoid the possibility of race conditions: "This could deadlock if a thread spawned as a side effect of importing a module happens to trigger a warning. warnings is pulled into sys.modules as part of the interpreter startup - having a global 'import warnings' shouldn't have any real effect on logging's import time."
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  r67543 | gregory.p.smith | 2008-12-05 03:27:01 +0100 (Fri, 05 Dec 2008) | 2 lines

  rename the new check_call_output to check_output.  its less ugly.
........

4 files changed, 179 insertions, 17 deletions

diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index 499c954..cce6ea0 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -23,7 +23,8 @@ Copyright (C) 2001-2008 Vinay Sajip. All Rights Reserved.
 To use, simply 'import logging' and log away!
 """
 
-import sys, os, time, io, traceback
+import sys, os, time, io, traceback, warnings
+
 __all__ = ['BASIC_FORMAT', 'BufferingFormatter', 'CRITICAL', 'DEBUG', 'ERROR',
            'FATAL', 'FileHandler', 'Filter', 'Filterer', 'Formatter', 'Handler',
            'INFO', 'LogRecord', 'Logger', 'Manager', 'NOTSET', 'PlaceHolder',
@@ -42,8 +43,8 @@ except ImportError:
 
 __author__  = "Vinay Sajip <vinay_sajip@red-dove.com>"
 __status__  = "production"
-__version__ = "0.5.0.5"
-__date__    = "24 January 2008"
+__version__ = "0.5.0.6"
+__date__    = "03 December 2008"
 
 #---------------------------------------------------------------------------
 #   Miscellaneous module data
@@ -1483,3 +1484,56 @@ except ImportError: # for Python versions < 2.0
             old_exit(status)
 
     sys.exit = exithook
+
+# Null handler
+
+class NullHandler(Handler):
+    """
+    This handler does nothing. It's intended to be used to avoid the
+    "No handlers could be found for logger XXX" one-off warning. This is
+    important for library code, which may contain code to log events. If a user
+    of the library does not configure logging, the one-off warning might be
+    produced; to avoid this, the library developer simply needs to instantiate
+    a NullHandler and add it to the top-level logger of the library module or
+    package.
+    """
+    def emit(self, record):
+        pass
+
+# Warnings integration
+
+_warnings_showwarning = None
+
+def _showwarning(message, category, filename, lineno, file=None, line=None):
+    """
+    Implementation of showwarnings which redirects to logging, which will first
+    check to see if the file parameter is None. If a file is specified, it will
+    delegate to the original warnings implementation of showwarning. Otherwise,
+    it will call warnings.formatwarning and will log the resulting string to a
+    warnings logger named "py.warnings" with level logging.WARNING.
+    """
+    if file is not None:
+        if _warnings_showwarning is not None:
+            _warnings_showwarning(message, category, filename, lineno, file, line)
+    else:
+        s = warnings.formatwarning(message, category, filename, lineno, line)
+        logger = getLogger("py.warnings")
+        if not logger.handlers:
+            logger.addHandler(NullHandler())
+        logger.warning("%s", s)
+
+def captureWarnings(capture):
+    """
+    If capture is true, redirect all warnings to the logging package.
+    If capture is False, ensure that warnings are not redirected to logging
+    but to their original destinations.
+    """
+    global _warnings_showwarning
+    if capture:
+        if _warnings_showwarning is None:
+            _warnings_showwarning = warnings.showwarning
+            warnings.showwarning = _showwarning
+    else:
+        if _warnings_showwarning is not None:
+            warnings.showwarning = _warnings_showwarning
+            _warnings_showwarning = None
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index ac92185..b47ebb8 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -104,7 +104,7 @@ appearance of the main window and priority for the new process.
 (Windows only)
 
 
-This module also defines four shortcut functions:
+This module also defines some shortcut functions:
 
 call(*popenargs, **kwargs):
     Run command with arguments.  Wait for command to complete, then
@@ -151,6 +151,17 @@ getoutput(cmd):
     >>> subprocess.getoutput('ls /bin/ls')
     '/bin/ls'
 
+check_output(*popenargs, **kwargs):
+   Run command with arguments and return its output as a byte string.
+
+   If the exit code was non-zero it raises a CalledProcessError.  The
+   CalledProcessError object will have the return code in the returncode
+   attribute and output in the output attribute.
+
+   The arguments are the same as for the Popen constructor.  Example:
+
+      output = subprocess.check_output(["ls", "-l", "/dev/null"])
+
 
 Exceptions
 ----------
@@ -166,8 +177,8 @@ should prepare for OSErrors.
 
 A ValueError will be raised if Popen is called with invalid arguments.
 
-check_call() will raise CalledProcessError, if the called process
-returns a non-zero return code.
+check_call() and check_output() will raise CalledProcessError, if the
+called process returns a non-zero return code.
 
 
 Security
@@ -321,12 +332,15 @@ import signal
 
 # Exception classes used by this module.
 class CalledProcessError(Exception):
-    """This exception is raised when a process run by check_call() returns
-    a non-zero exit status.  The exit status will be stored in the
-    returncode attribute."""
-    def __init__(self, returncode, cmd):
+    """This exception is raised when a process run by check_call() or
+    check_output() returns a non-zero exit status.
+    The exit status will be stored in the returncode attribute;
+    check_output() will also store the output in the output attribute.
+    """
+    def __init__(self, returncode, cmd, output=None):
         self.returncode = returncode
         self.cmd = cmd
+        self.output = output
     def __str__(self):
         return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
 
@@ -364,7 +378,7 @@ else:
     import pickle
 
 __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
-           "getoutput", "CalledProcessError"]
+           "getoutput", "check_output", "CalledProcessError"]
 
 try:
     MAXFD = os.sysconf("SC_OPEN_MAX")
@@ -410,12 +424,45 @@ def check_call(*popenargs, **kwargs):
     check_call(["ls", "-l"])
     """
     retcode = call(*popenargs, **kwargs)
-    cmd = kwargs.get("args")
-    if cmd is None:
-        cmd = popenargs[0]
     if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
         raise CalledProcessError(retcode, cmd)
-    return retcode
+    return 0
+
+
+def check_output(*popenargs, **kwargs):
+    """Run command with arguments and return its output as a byte string.
+
+    If the exit code was non-zero it raises a CalledProcessError.  The
+    CalledProcessError object will have the return code in the returncode
+    attribute and output in the output attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    >>> check_output(["ls", "-l", "/dev/null"])
+    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
+
+    The stdout argument is not allowed as it is used internally.
+    To capture standard error in the result, use stderr=subprocess.STDOUT.
+
+    >>> check_output(["/bin/sh", "-c",
+                      "ls -l non_existant_file ; exit 0"],
+                     stderr=subprocess.STDOUT)
+    'ls: non_existant_file: No such file or directory\n'
+    """
+    if 'stdout' in kwargs:
+        raise ValueError('stdout argument not allowed, it will be overridden.')
+    process = Popen(*popenargs, stdout=PIPE, **kwargs)
+    output, unused_err = process.communicate()
+    retcode = process.poll()
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise CalledProcessError(retcode, cmd, output=output)
+    return output
 
 
 def list2cmdline(seq):
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index c99a650..c179d14 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -18,7 +18,7 @@
 
 """Test harness for the logging module. Run all tests.
 
-Copyright (C) 2001-2002 Vinay Sajip. All Rights Reserved.
+Copyright (C) 2001-2008 Vinay Sajip. All Rights Reserved.
 """
 
 import logging
@@ -44,6 +44,7 @@ import threading
 import time
 import types
 import unittest
+import warnings
 import weakref
 
 
@@ -885,6 +886,32 @@ class EncodingTest(BaseTest):
             if os.path.isfile(fn):
                 os.remove(fn)
 
+class WarningsTest(BaseTest):
+    def test_warnings(self):
+        logging.captureWarnings(True)
+        warnings.filterwarnings("always", category=UserWarning)
+        try:
+            file = io.StringIO()
+            h = logging.StreamHandler(file)
+            logger = logging.getLogger("py.warnings")
+            logger.addHandler(h)
+            warnings.warn("I'm warning you...")
+            logger.removeHandler(h)
+            s = file.getvalue()
+            h.close()
+            self.assertTrue(s.find("UserWarning: I'm warning you...\n") > 0)
+
+            #See if an explicit file uses the original implementation
+            file = io.StringIO()
+            warnings.showwarning("Explicit", UserWarning, "dummy.py", 42, file,
+                                 "Dummy line")
+            s = file.getvalue()
+            file.close()
+            self.assertEqual(s, "dummy.py:42: UserWarning: Explicit\n  Dummy line\n")
+        finally:
+            warnings.resetwarnings()
+            logging.captureWarnings(False)
+
 # Set the locale to the platform-dependent default.  I have no idea
 # why the test does this, but in any case we save the current locale
 # first and restore it at the end.
@@ -893,7 +920,7 @@ def test_main():
     run_unittest(BuiltinLevelsTest, BasicFilterTest,
                     CustomLevelsAndFiltersTest, MemoryHandlerTest,
                     ConfigFileTest, SocketHandlerTest, MemoryTest,
-                    EncodingTest)
+                    EncodingTest, WarningsTest)
 
 if __name__ == "__main__":
     test_main()
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index f4f1cd5..eb4e759 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -73,6 +73,40 @@ class ProcessTestCase(unittest.TestCase):
         else:
             self.fail("Expected CalledProcessError")
 
+    def test_check_output(self):
+        # check_output() function with zero return code
+        output = subprocess.check_output(
+                [sys.executable, "-c", "print('BDFL')"])
+        self.assertTrue(b'BDFL' in output)
+
+    def test_check_output_nonzero(self):
+        # check_call() function with non-zero return code
+        try:
+            subprocess.check_output(
+                    [sys.executable, "-c", "import sys; sys.exit(5)"])
+        except subprocess.CalledProcessError as e:
+            self.assertEqual(e.returncode, 5)
+        else:
+            self.fail("Expected CalledProcessError")
+
+    def test_check_output_stderr(self):
+        # check_output() function stderr redirected to stdout
+        output = subprocess.check_output(
+                [sys.executable, "-c", "import sys; sys.stderr.write('BDFL')"],
+                stderr=subprocess.STDOUT)
+        self.assertTrue(b'BDFL' in output)
+
+    def test_check_output_stdout_arg(self):
+        # check_output() function stderr redirected to stdout
+        try:
+            output = subprocess.check_output(
+                    [sys.executable, "-c", "print('will not be run')"],
+                    stdout=sys.stdout)
+        except ValueError as e:
+            self.assertTrue('stdout' in e.args[0])
+        else:
+            self.fail("Expected ValueError when stdout arg supplied.")
+
     def test_call_kwargs(self):
         # call() function with keyword args
         newenv = os.environ.copy()