subprocess.py: add call(), check_call(), check_output()

gevent/subprocess.py

@@ -7,7 +7,6 @@ import signal
 import traceback
 from gevent.event import Event
 from gevent.hub import get_hub
-from gevent.select import select
 from gevent.fileobject import FileObject
 from gevent.greenlet import Greenlet, joinall
 spawn = Greenlet.spawn
@@ -15,15 +14,15 @@ __subprocess__ = __import__('subprocess')
 
 
 # Standard functions and classes that this module re-implements in a gevent-aware way.
-__implements__ = ['Popen']
+__implements__ = ['Popen',
+                  'call',
+                  'check_call',
+                  'check_output']
 
 
 # Standard functions and classes that this module re-imports.
 __imports__ = ['PIPE',
                'STDOUT',
-               'call',
-               'check_call',
-               'check_output',
                'CalledProcessError',
                # Windows:
                'CREATE_NEW_CONSOLE',
@@ -40,7 +39,6 @@ __extra__ = ['MAXFD',
              '_eintr_retry_call',
              'STARTUPINFO',
              'pywintypes',
-             '_PIPE_BUF',
              'list2cmdline',
              '_subprocess',
              # Python 2.5 does not have _subprocess, so we don't use it
@@ -98,10 +96,68 @@ else:
     import fcntl
     import pickle
 
-    # When select or poll has indicated that the file is writable,
-    # we can write up to _PIPE_BUF bytes without risk of blocking.
-    # POSIX defines PIPE_BUF as >= 512.
-    _PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+
+def call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+    """
+    return Popen(*popenargs, **kwargs).wait()
+
+
+def check_call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete.  If
+    the exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+    """
+    retcode = call(*popenargs, **kwargs)
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise CalledProcessError(retcode, cmd)
+    return 0
+
+
+def check_output(*popenargs, **kwargs):
+    r"""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=STDOUT.
+
+    >>> check_output(["/bin/sh", "-c",
+    ...               "ls -l non_existent_file ; exit 0"],
+    ...              stderr=STDOUT)
+    'ls: non_existent_file: No such file or directory\n'
+    """
+    if 'stdout' in kwargs:
+        raise ValueError('stdout argument not allowed, it will be overridden.')
+    process = Popen(stdout=PIPE, *popenargs, **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
 
 
 class Popen(object):