| # subprocess - Subprocesses with accessible I/O streams |
| # |
| # For more information about this module, see PEP 324. |
| # |
| # This module should remain compatible with Python 2.2, see PEP 291. |
| # |
| # Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se> |
| # |
| # Licensed to PSF under a Contributor Agreement. |
| # See http://www.python.org/2.4/license for licensing details. |
| |
| r"""subprocess - Subprocesses with accessible I/O streams |
| |
| This module allows you to spawn processes, connect to their |
| input/output/error pipes, and obtain their return codes. This module |
| intends to replace several other, older modules and functions, like: |
| |
| os.system |
| os.spawn* |
| commands.* |
| |
| Information about how the subprocess module can be used to replace these |
| modules and functions can be found below. |
| |
| |
| |
| Using the subprocess module |
| =========================== |
| This module defines one class called Popen: |
| |
| class Popen(args, bufsize=0, executable=None, |
| stdin=None, stdout=None, stderr=None, |
| preexec_fn=None, close_fds=False, shell=False, |
| cwd=None, env=None, universal_newlines=False, |
| startupinfo=None, creationflags=0): |
| |
| |
| Arguments are: |
| |
| args should be a string, or a sequence of program arguments. The |
| program to execute is normally the first item in the args sequence or |
| string, but can be explicitly set by using the executable argument. |
| |
| On UNIX, with shell=False (default): In this case, the Popen class |
| uses os.execvp() to execute the child program. args should normally |
| be a sequence. A string will be treated as a sequence with the string |
| as the only item (the program to execute). |
| |
| On UNIX, with shell=True: If args is a string, it specifies the |
| command string to execute through the shell. If args is a sequence, |
| the first item specifies the command string, and any additional items |
| will be treated as additional shell arguments. |
| |
| On Windows: the Popen class uses CreateProcess() to execute the child |
| program, which operates on strings. If args is a sequence, it will be |
| converted to a string using the list2cmdline method. Please note that |
| not all MS Windows applications interpret the command line the same |
| way: The list2cmdline is designed for applications using the same |
| rules as the MS C runtime. |
| |
| bufsize, if given, has the same meaning as the corresponding argument |
| to the built-in open() function: 0 means unbuffered, 1 means line |
| buffered, any other positive value means use a buffer of |
| (approximately) that size. A negative bufsize means to use the system |
| default, which usually means fully buffered. The default value for |
| bufsize is 0 (unbuffered). |
| |
| stdin, stdout and stderr specify the executed programs' standard |
| input, standard output and standard error file handles, respectively. |
| Valid values are PIPE, an existing file descriptor (a positive |
| integer), an existing file object, and None. PIPE indicates that a |
| new pipe to the child should be created. With None, no redirection |
| will occur; the child's file handles will be inherited from the |
| parent. Additionally, stderr can be STDOUT, which indicates that the |
| stderr data from the applications should be captured into the same |
| file handle as for stdout. |
| |
| If preexec_fn is set to a callable object, this object will be called |
| in the child process just before the child is executed. |
| |
| If close_fds is true, all file descriptors except 0, 1 and 2 will be |
| closed before the child process is executed. |
| |
| if shell is true, the specified command will be executed through the |
| shell. |
| |
| If cwd is not None, the current directory will be changed to cwd |
| before the child is executed. |
| |
| If env is not None, it defines the environment variables for the new |
| process. |
| |
| If universal_newlines is true, the file objects stdout and stderr are |
| opened as a text files, but lines may be terminated by any of '\n', |
| the Unix end-of-line convention, '\r', the Macintosh convention or |
| '\r\n', the Windows convention. All of these external representations |
| are seen as '\n' by the Python program. Note: This feature is only |
| available if Python is built with universal newline support (the |
| default). Also, the newlines attribute of the file objects stdout, |
| stdin and stderr are not updated by the communicate() method. |
| |
| The startupinfo and creationflags, if given, will be passed to the |
| underlying CreateProcess() function. They can specify things such as |
| appearance of the main window and priority for the new process. |
| (Windows only) |
| |
| |
| This module also defines two shortcut functions: |
| |
| 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"]) |
| |
| 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"]) |
| |
| Exceptions |
| ---------- |
| Exceptions raised in the child process, before the new program has |
| started to execute, will be re-raised in the parent. Additionally, |
| the exception object will have one extra attribute called |
| 'child_traceback', which is a string containing traceback information |
| from the childs point of view. |
| |
| The most common exception raised is OSError. This occurs, for |
| example, when trying to execute a non-existent file. Applications |
| 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. |
| |
| |
| Security |
| -------- |
| Unlike some other popen functions, this implementation will never call |
| /bin/sh implicitly. This means that all characters, including shell |
| metacharacters, can safely be passed to child processes. |
| |
| |
| Popen objects |
| ============= |
| Instances of the Popen class have the following methods: |
| |
| poll() |
| Check if child process has terminated. Returns returncode |
| attribute. |
| |
| wait() |
| Wait for child process to terminate. Returns returncode attribute. |
| |
| communicate(input=None) |
| Interact with process: Send data to stdin. Read data from stdout |
| and stderr, until end-of-file is reached. Wait for process to |
| terminate. The optional input argument should be a string to be |
| sent to the child process, or None, if no data should be sent to |
| the child. |
| |
| communicate() returns a tuple (stdout, stderr). |
| |
| Note: The data read is buffered in memory, so do not use this |
| method if the data size is large or unlimited. |
| |
| The following attributes are also available: |
| |
| stdin |
| If the stdin argument is PIPE, this attribute is a file object |
| that provides input to the child process. Otherwise, it is None. |
| |
| stdout |
| If the stdout argument is PIPE, this attribute is a file object |
| that provides output from the child process. Otherwise, it is |
| None. |
| |
| stderr |
| If the stderr argument is PIPE, this attribute is file object that |
| provides error output from the child process. Otherwise, it is |
| None. |
| |
| pid |
| The process ID of the child process. |
| |
| returncode |
| The child return code. A None value indicates that the process |
| hasn't terminated yet. A negative value -N indicates that the |
| child was terminated by signal N (UNIX only). |
| |
| |
| Replacing older functions with the subprocess module |
| ==================================================== |
| In this section, "a ==> b" means that b can be used as a replacement |
| for a. |
| |
| Note: All functions in this section fail (more or less) silently if |
| the executed program cannot be found; this module raises an OSError |
| exception. |
| |
| In the following examples, we assume that the subprocess module is |
| imported with "from subprocess import *". |
| |
| |
| Replacing /bin/sh shell backquote |
| --------------------------------- |
| output=`mycmd myarg` |
| ==> |
| output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0] |
| |
| |
| Replacing shell pipe line |
| ------------------------- |
| output=`dmesg | grep hda` |
| ==> |
| p1 = Popen(["dmesg"], stdout=PIPE) |
| p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE) |
| output = p2.communicate()[0] |
| |
| |
| Replacing os.system() |
| --------------------- |
| sts = os.system("mycmd" + " myarg") |
| ==> |
| p = Popen("mycmd" + " myarg", shell=True) |
| pid, sts = os.waitpid(p.pid, 0) |
| |
| Note: |
| |
| * Calling the program through the shell is usually not required. |
| |
| * It's easier to look at the returncode attribute than the |
| exitstatus. |
| |
| A more real-world example would look like this: |
| |
| try: |
| retcode = call("mycmd" + " myarg", shell=True) |
| if retcode < 0: |
| print("Child was terminated by signal", -retcode, file=sys.stderr) |
| else: |
| print("Child returned", retcode, file=sys.stderr) |
| except OSError as e: |
| print("Execution failed:", e, file=sys.stderr) |
| |
| |
| Replacing os.spawn* |
| ------------------- |
| P_NOWAIT example: |
| |
| pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg") |
| ==> |
| pid = Popen(["/bin/mycmd", "myarg"]).pid |
| |
| |
| P_WAIT example: |
| |
| retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg") |
| ==> |
| retcode = call(["/bin/mycmd", "myarg"]) |
| |
| |
| Vector example: |
| |
| os.spawnvp(os.P_NOWAIT, path, args) |
| ==> |
| Popen([path] + args[1:]) |
| |
| |
| Environment example: |
| |
| os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env) |
| ==> |
| Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"}) |
| """ |
| |
| import sys |
| mswindows = (sys.platform == "win32") |
| |
| import io |
| import os |
| import traceback |
| |
| # 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): |
| self.returncode = returncode |
| self.cmd = cmd |
| def __str__(self): |
| return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode) |
| |
| |
| if mswindows: |
| import threading |
| import msvcrt |
| if 0: # <-- change this to use pywin32 instead of the _subprocess driver |
| import pywintypes |
| from win32api import GetStdHandle, STD_INPUT_HANDLE, \ |
| STD_OUTPUT_HANDLE, STD_ERROR_HANDLE |
| from win32api import GetCurrentProcess, DuplicateHandle, \ |
| GetModuleFileName, GetVersion |
| from win32con import DUPLICATE_SAME_ACCESS, SW_HIDE |
| from win32pipe import CreatePipe |
| from win32process import CreateProcess, STARTUPINFO, \ |
| GetExitCodeProcess, STARTF_USESTDHANDLES, \ |
| STARTF_USESHOWWINDOW, CREATE_NEW_CONSOLE |
| from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0 |
| else: |
| from _subprocess import * |
| class STARTUPINFO: |
| dwFlags = 0 |
| hStdInput = None |
| hStdOutput = None |
| hStdError = None |
| wShowWindow = 0 |
| class pywintypes: |
| error = IOError |
| else: |
| import select |
| import errno |
| import fcntl |
| import pickle |
| |
| __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"] |
| |
| try: |
| MAXFD = os.sysconf("SC_OPEN_MAX") |
| except: |
| MAXFD = 256 |
| |
| _active = [] |
| |
| def _cleanup(): |
| for inst in _active[:]: |
| res = inst.poll(_deadstate=sys.maxint) |
| if res is not None and res >= 0: |
| try: |
| _active.remove(inst) |
| except ValueError: |
| # This can happen if two threads create a new Popen instance. |
| # It's harmless that it was already removed, so ignore. |
| pass |
| |
| PIPE = -1 |
| STDOUT = -2 |
| |
| |
| 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) |
| cmd = kwargs.get("args") |
| if cmd is None: |
| cmd = popenargs[0] |
| if retcode: |
| raise CalledProcessError(retcode, cmd) |
| return retcode |
| |
| |
| def list2cmdline(seq): |
| """ |
| Translate a sequence of arguments into a command line |
| string, using the same rules as the MS C runtime: |
| |
| 1) Arguments are delimited by white space, which is either a |
| space or a tab. |
| |
| 2) A string surrounded by double quotation marks is |
| interpreted as a single argument, regardless of white space |
| contained within. A quoted string can be embedded in an |
| argument. |
| |
| 3) A double quotation mark preceded by a backslash is |
| interpreted as a literal double quotation mark. |
| |
| 4) Backslashes are interpreted literally, unless they |
| immediately precede a double quotation mark. |
| |
| 5) If backslashes immediately precede a double quotation mark, |
| every pair of backslashes is interpreted as a literal |
| backslash. If the number of backslashes is odd, the last |
| backslash escapes the next double quotation mark as |
| described in rule 3. |
| """ |
| |
| # See |
| # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp |
| result = [] |
| needquote = False |
| for arg in seq: |
| bs_buf = [] |
| |
| # Add a space to separate this argument from the others |
| if result: |
| result.append(' ') |
| |
| needquote = (" " in arg) or ("\t" in arg) or arg == "" |
| if needquote: |
| result.append('"') |
| |
| for c in arg: |
| if c == '\\': |
| # Don't know if we need to double yet. |
| bs_buf.append(c) |
| elif c == '"': |
| # Double backspaces. |
| result.append('\\' * len(bs_buf)*2) |
| bs_buf = [] |
| result.append('\\"') |
| else: |
| # Normal char |
| if bs_buf: |
| result.extend(bs_buf) |
| bs_buf = [] |
| result.append(c) |
| |
| # Add remaining backspaces, if any. |
| if bs_buf: |
| result.extend(bs_buf) |
| |
| if needquote: |
| result.extend(bs_buf) |
| result.append('"') |
| |
| return ''.join(result) |
| |
| |
| class Popen(object): |
| def __init__(self, args, bufsize=0, executable=None, |
| stdin=None, stdout=None, stderr=None, |
| preexec_fn=None, close_fds=False, shell=False, |
| cwd=None, env=None, universal_newlines=False, |
| startupinfo=None, creationflags=0): |
| """Create new Popen instance.""" |
| _cleanup() |
| |
| self._child_created = False |
| if not isinstance(bufsize, int): |
| raise TypeError("bufsize must be an integer") |
| |
| if mswindows: |
| if preexec_fn is not None: |
| raise ValueError("preexec_fn is not supported on Windows " |
| "platforms") |
| if close_fds and (stdin is not None or stdout is not None or |
| stderr is not None): |
| raise ValueError("close_fds is not supported on Windows " |
| "platforms if you redirect stdin/stdout/stderr") |
| else: |
| # POSIX |
| if startupinfo is not None: |
| raise ValueError("startupinfo is only supported on Windows " |
| "platforms") |
| if creationflags != 0: |
| raise ValueError("creationflags is only supported on Windows " |
| "platforms") |
| |
| self.stdin = None |
| self.stdout = None |
| self.stderr = None |
| self.pid = None |
| self.returncode = None |
| self.universal_newlines = universal_newlines |
| |
| # Input and output objects. The general principle is like |
| # this: |
| # |
| # Parent Child |
| # ------ ----- |
| # p2cwrite ---stdin---> p2cread |
| # c2pread <--stdout--- c2pwrite |
| # errread <--stderr--- errwrite |
| # |
| # On POSIX, the child objects are file descriptors. On |
| # Windows, these are Windows file handles. The parent objects |
| # are file descriptors on both platforms. The parent objects |
| # are None when not using PIPEs. The child objects are None |
| # when not redirecting. |
| |
| (p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite) = self._get_handles(stdin, stdout, stderr) |
| |
| self._execute_child(args, executable, preexec_fn, close_fds, |
| cwd, env, universal_newlines, |
| startupinfo, creationflags, shell, |
| p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite) |
| |
| # On Windows, you cannot just redirect one or two handles: You |
| # either have to redirect all three or none. If the subprocess |
| # user has only redirected one or two handles, we are |
| # automatically creating PIPEs for the rest. We should close |
| # these after the process is started. See bug #1124861. |
| if mswindows: |
| if stdin is None and p2cwrite is not None: |
| os.close(p2cwrite) |
| p2cwrite = None |
| if stdout is None and c2pread is not None: |
| os.close(c2pread) |
| c2pread = None |
| if stderr is None and errread is not None: |
| os.close(errread) |
| errread = None |
| |
| if bufsize == 0: |
| bufsize = 1 # Nearly unbuffered (XXX for now) |
| if p2cwrite is not None: |
| self.stdin = io.open(p2cwrite, 'wb', bufsize) |
| if self.universal_newlines: |
| self.stdin = io.TextIOWrapper(self.stdin) |
| if c2pread is not None: |
| self.stdout = io.open(c2pread, 'rb', bufsize) |
| if universal_newlines: |
| self.stdout = io.TextIOWrapper(self.stdout) |
| if errread is not None: |
| self.stderr = io.open(errread, 'rb', bufsize) |
| if universal_newlines: |
| self.stderr = io.TextIOWrapper(self.stderr) |
| |
| |
| def _translate_newlines(self, data): |
| data = data.replace("\r\n", "\n") |
| data = data.replace("\r", "\n") |
| return str(data) |
| |
| |
| def __del__(self, sys=sys): |
| if not self._child_created: |
| # We didn't get to successfully create a child process. |
| return |
| # In case the child hasn't been waited on, check if it's done. |
| self.poll(_deadstate=sys.maxint) |
| if self.returncode is None and _active is not None: |
| # Child is still running, keep us alive until we can wait on it. |
| _active.append(self) |
| |
| |
| def communicate(self, input=None): |
| """Interact with process: Send data to stdin. Read data from |
| stdout and stderr, until end-of-file is reached. Wait for |
| process to terminate. The optional input argument should be a |
| string to be sent to the child process, or None, if no data |
| should be sent to the child. |
| |
| communicate() returns a tuple (stdout, stderr).""" |
| |
| # Optimization: If we are only using one pipe, or no pipe at |
| # all, using select() or threads is unnecessary. |
| if [self.stdin, self.stdout, self.stderr].count(None) >= 2: |
| stdout = None |
| stderr = None |
| if self.stdin: |
| if input: |
| self.stdin.write(input) |
| self.stdin.close() |
| elif self.stdout: |
| stdout = self.stdout.read() |
| elif self.stderr: |
| stderr = self.stderr.read() |
| self.wait() |
| return (stdout, stderr) |
| |
| return self._communicate(input) |
| |
| |
| if mswindows: |
| # |
| # Windows methods |
| # |
| def _get_handles(self, stdin, stdout, stderr): |
| """Construct and return tupel with IO objects: |
| p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite |
| """ |
| if stdin is None and stdout is None and stderr is None: |
| return (None, None, None, None, None, None) |
| |
| p2cread, p2cwrite = None, None |
| c2pread, c2pwrite = None, None |
| errread, errwrite = None, None |
| |
| if stdin is None: |
| p2cread = GetStdHandle(STD_INPUT_HANDLE) |
| if p2cread is not None: |
| pass |
| elif stdin is None or stdin == PIPE: |
| p2cread, p2cwrite = CreatePipe(None, 0) |
| # Detach and turn into fd |
| p2cwrite = p2cwrite.Detach() |
| p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0) |
| elif isinstance(stdin, int): |
| p2cread = msvcrt.get_osfhandle(stdin) |
| else: |
| # Assuming file-like object |
| p2cread = msvcrt.get_osfhandle(stdin.fileno()) |
| p2cread = self._make_inheritable(p2cread) |
| |
| if stdout is None: |
| c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE) |
| if c2pwrite is not None: |
| pass |
| elif stdout is None or stdout == PIPE: |
| c2pread, c2pwrite = CreatePipe(None, 0) |
| # Detach and turn into fd |
| c2pread = c2pread.Detach() |
| c2pread = msvcrt.open_osfhandle(c2pread, 0) |
| elif isinstance(stdout, int): |
| c2pwrite = msvcrt.get_osfhandle(stdout) |
| else: |
| # Assuming file-like object |
| c2pwrite = msvcrt.get_osfhandle(stdout.fileno()) |
| c2pwrite = self._make_inheritable(c2pwrite) |
| |
| if stderr is None: |
| errwrite = GetStdHandle(STD_ERROR_HANDLE) |
| if errwrite is not None: |
| pass |
| elif stderr is None or stderr == PIPE: |
| errread, errwrite = CreatePipe(None, 0) |
| # Detach and turn into fd |
| errread = errread.Detach() |
| errread = msvcrt.open_osfhandle(errread, 0) |
| elif stderr == STDOUT: |
| errwrite = c2pwrite |
| elif isinstance(stderr, int): |
| errwrite = msvcrt.get_osfhandle(stderr) |
| else: |
| # Assuming file-like object |
| errwrite = msvcrt.get_osfhandle(stderr.fileno()) |
| errwrite = self._make_inheritable(errwrite) |
| |
| return (p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite) |
| |
| |
| def _make_inheritable(self, handle): |
| """Return a duplicate of handle, which is inheritable""" |
| return DuplicateHandle(GetCurrentProcess(), handle, |
| GetCurrentProcess(), 0, 1, |
| DUPLICATE_SAME_ACCESS) |
| |
| |
| def _find_w9xpopen(self): |
| """Find and return absolut path to w9xpopen.exe""" |
| w9xpopen = os.path.join(os.path.dirname(GetModuleFileName(0)), |
| "w9xpopen.exe") |
| if not os.path.exists(w9xpopen): |
| # Eeek - file-not-found - possibly an embedding |
| # situation - see if we can locate it in sys.exec_prefix |
| w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix), |
| "w9xpopen.exe") |
| if not os.path.exists(w9xpopen): |
| raise RuntimeError("Cannot locate w9xpopen.exe, which is " |
| "needed for Popen to work with your " |
| "shell or platform.") |
| return w9xpopen |
| |
| |
| def _execute_child(self, args, executable, preexec_fn, close_fds, |
| cwd, env, universal_newlines, |
| startupinfo, creationflags, shell, |
| p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite): |
| """Execute program (MS Windows version)""" |
| |
| if not isinstance(args, basestring): |
| args = list2cmdline(args) |
| |
| # Process startup details |
| if startupinfo is None: |
| startupinfo = STARTUPINFO() |
| if None not in (p2cread, c2pwrite, errwrite): |
| startupinfo.dwFlags |= STARTF_USESTDHANDLES |
| startupinfo.hStdInput = p2cread |
| startupinfo.hStdOutput = c2pwrite |
| startupinfo.hStdError = errwrite |
| |
| if shell: |
| startupinfo.dwFlags |= STARTF_USESHOWWINDOW |
| startupinfo.wShowWindow = SW_HIDE |
| comspec = os.environ.get("COMSPEC", "cmd.exe") |
| args = comspec + " /c " + args |
| if (GetVersion() >= 0x80000000 or |
| os.path.basename(comspec).lower() == "command.com"): |
| # Win9x, or using command.com on NT. We need to |
| # use the w9xpopen intermediate program. For more |
| # information, see KB Q150956 |
| # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp) |
| w9xpopen = self._find_w9xpopen() |
| args = '"%s" %s' % (w9xpopen, args) |
| # Not passing CREATE_NEW_CONSOLE has been known to |
| # cause random failures on win9x. Specifically a |
| # dialog: "Your program accessed mem currently in |
| # use at xxx" and a hopeful warning about the |
| # stability of your system. Cost is Ctrl+C wont |
| # kill children. |
| creationflags |= CREATE_NEW_CONSOLE |
| |
| # Start the process |
| try: |
| hp, ht, pid, tid = CreateProcess(executable, args, |
| # no special security |
| None, None, |
| int(not close_fds), |
| creationflags, |
| env, |
| cwd, |
| startupinfo) |
| except pywintypes.error as e: |
| # Translate pywintypes.error to WindowsError, which is |
| # a subclass of OSError. FIXME: We should really |
| # translate errno using _sys_errlist (or simliar), but |
| # how can this be done from Python? |
| raise WindowsError(*e.args) |
| |
| # Retain the process handle, but close the thread handle |
| self._child_created = True |
| self._handle = hp |
| self.pid = pid |
| ht.Close() |
| |
| # Child is launched. Close the parent's copy of those pipe |
| # handles that only the child should have open. You need |
| # to make sure that no handles to the write end of the |
| # output pipe are maintained in this process or else the |
| # pipe will not close when the child process exits and the |
| # ReadFile will hang. |
| if p2cread is not None: |
| p2cread.Close() |
| if c2pwrite is not None: |
| c2pwrite.Close() |
| if errwrite is not None: |
| errwrite.Close() |
| |
| |
| def poll(self, _deadstate=None): |
| """Check if child process has terminated. Returns returncode |
| attribute.""" |
| if self.returncode is None: |
| if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0: |
| self.returncode = GetExitCodeProcess(self._handle) |
| return self.returncode |
| |
| |
| def wait(self): |
| """Wait for child process to terminate. Returns returncode |
| attribute.""" |
| if self.returncode is None: |
| obj = WaitForSingleObject(self._handle, INFINITE) |
| self.returncode = GetExitCodeProcess(self._handle) |
| return self.returncode |
| |
| |
| def _readerthread(self, fh, buffer): |
| buffer.append(fh.read()) |
| |
| |
| def _communicate(self, input): |
| stdout = None # Return |
| stderr = None # Return |
| |
| if self.stdout: |
| stdout = [] |
| stdout_thread = threading.Thread(target=self._readerthread, |
| args=(self.stdout, stdout)) |
| stdout_thread.setDaemon(True) |
| stdout_thread.start() |
| if self.stderr: |
| stderr = [] |
| stderr_thread = threading.Thread(target=self._readerthread, |
| args=(self.stderr, stderr)) |
| stderr_thread.setDaemon(True) |
| stderr_thread.start() |
| |
| if self.stdin: |
| if input is not None: |
| self.stdin.write(input) |
| self.stdin.close() |
| |
| if self.stdout: |
| stdout_thread.join() |
| if self.stderr: |
| stderr_thread.join() |
| |
| # All data exchanged. Translate lists into strings. |
| if stdout is not None: |
| stdout = stdout[0] |
| if stderr is not None: |
| stderr = stderr[0] |
| |
| # Translate newlines, if requested. We cannot let the file |
| # object do the translation: It is based on stdio, which is |
| # impossible to combine with select (unless forcing no |
| # buffering). |
| if self.universal_newlines: |
| if stdout is not None: |
| stdout = self._translate_newlines(stdout) |
| if stderr is not None: |
| stderr = self._translate_newlines(stderr) |
| |
| self.wait() |
| return (stdout, stderr) |
| |
| else: |
| # |
| # POSIX methods |
| # |
| def _get_handles(self, stdin, stdout, stderr): |
| """Construct and return tupel with IO objects: |
| p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite |
| """ |
| p2cread, p2cwrite = None, None |
| c2pread, c2pwrite = None, None |
| errread, errwrite = None, None |
| |
| if stdin is None: |
| pass |
| elif stdin == PIPE: |
| p2cread, p2cwrite = os.pipe() |
| elif isinstance(stdin, int): |
| p2cread = stdin |
| else: |
| # Assuming file-like object |
| p2cread = stdin.fileno() |
| |
| if stdout is None: |
| pass |
| elif stdout == PIPE: |
| c2pread, c2pwrite = os.pipe() |
| elif isinstance(stdout, int): |
| c2pwrite = stdout |
| else: |
| # Assuming file-like object |
| c2pwrite = stdout.fileno() |
| |
| if stderr is None: |
| pass |
| elif stderr == PIPE: |
| errread, errwrite = os.pipe() |
| elif stderr == STDOUT: |
| errwrite = c2pwrite |
| elif isinstance(stderr, int): |
| errwrite = stderr |
| else: |
| # Assuming file-like object |
| errwrite = stderr.fileno() |
| |
| return (p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite) |
| |
| |
| def _set_cloexec_flag(self, fd): |
| try: |
| cloexec_flag = fcntl.FD_CLOEXEC |
| except AttributeError: |
| cloexec_flag = 1 |
| |
| old = fcntl.fcntl(fd, fcntl.F_GETFD) |
| fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag) |
| |
| |
| def _close_fds(self, but): |
| for i in range(3, MAXFD): |
| if i == but: |
| continue |
| try: |
| os.close(i) |
| except: |
| pass |
| |
| |
| def _execute_child(self, args, executable, preexec_fn, close_fds, |
| cwd, env, universal_newlines, |
| startupinfo, creationflags, shell, |
| p2cread, p2cwrite, |
| c2pread, c2pwrite, |
| errread, errwrite): |
| """Execute program (POSIX version)""" |
| |
| if isinstance(args, basestring): |
| args = [args] |
| else: |
| args = list(args) |
| |
| if shell: |
| args = ["/bin/sh", "-c"] + args |
| |
| if executable is None: |
| executable = args[0] |
| |
| # For transferring possible exec failure from child to parent |
| # The first char specifies the exception type: 0 means |
| # OSError, 1 means some other error. |
| errpipe_read, errpipe_write = os.pipe() |
| self._set_cloexec_flag(errpipe_write) |
| |
| self.pid = os.fork() |
| self._child_created = True |
| if self.pid == 0: |
| # Child |
| try: |
| # Close parent's pipe ends |
| if p2cwrite is not None: |
| os.close(p2cwrite) |
| if c2pread is not None: |
| os.close(c2pread) |
| if errread is not None: |
| os.close(errread) |
| os.close(errpipe_read) |
| |
| # Dup fds for child |
| if p2cread is not None: |
| os.dup2(p2cread, 0) |
| if c2pwrite is not None: |
| os.dup2(c2pwrite, 1) |
| if errwrite is not None: |
| os.dup2(errwrite, 2) |
| |
| # Close pipe fds. Make sure we don't close the same |
| # fd more than once, or standard fds. |
| if p2cread is not None and p2cread not in (0,): |
| os.close(p2cread) |
| if c2pwrite is not None and c2pwrite not in (p2cread, 1): |
| os.close(c2pwrite) |
| if errwrite is not None and errwrite not in (p2cread, c2pwrite, 2): |
| os.close(errwrite) |
| |
| # Close all other fds, if asked for |
| if close_fds: |
| self._close_fds(but=errpipe_write) |
| |
| if cwd is not None: |
| os.chdir(cwd) |
| |
| if preexec_fn: |
| preexec_fn() |
| |
| if env is None: |
| os.execvp(executable, args) |
| else: |
| os.execvpe(executable, args, env) |
| |
| except: |
| exc_type, exc_value, tb = sys.exc_info() |
| # Save the traceback and attach it to the exception object |
| exc_lines = traceback.format_exception(exc_type, |
| exc_value, |
| tb) |
| exc_value.child_traceback = ''.join(exc_lines) |
| os.write(errpipe_write, pickle.dumps(exc_value)) |
| |
| # This exitcode won't be reported to applications, so it |
| # really doesn't matter what we return. |
| os._exit(255) |
| |
| # Parent |
| os.close(errpipe_write) |
| if p2cread is not None and p2cwrite is not None: |
| os.close(p2cread) |
| if c2pwrite is not None and c2pread is not None: |
| os.close(c2pwrite) |
| if errwrite is not None and errread is not None: |
| os.close(errwrite) |
| |
| # Wait for exec to fail or succeed; possibly raising exception |
| data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB |
| os.close(errpipe_read) |
| if data: |
| os.waitpid(self.pid, 0) |
| child_exception = pickle.loads(data) |
| raise child_exception |
| |
| |
| def _handle_exitstatus(self, sts): |
| if os.WIFSIGNALED(sts): |
| self.returncode = -os.WTERMSIG(sts) |
| elif os.WIFEXITED(sts): |
| self.returncode = os.WEXITSTATUS(sts) |
| else: |
| # Should never happen |
| raise RuntimeError("Unknown child exit status!") |
| |
| |
| def poll(self, _deadstate=None): |
| """Check if child process has terminated. Returns returncode |
| attribute.""" |
| if self.returncode is None: |
| try: |
| pid, sts = os.waitpid(self.pid, os.WNOHANG) |
| if pid == self.pid: |
| self._handle_exitstatus(sts) |
| except os.error: |
| if _deadstate is not None: |
| self.returncode = _deadstate |
| return self.returncode |
| |
| |
| def wait(self): |
| """Wait for child process to terminate. Returns returncode |
| attribute.""" |
| if self.returncode is None: |
| pid, sts = os.waitpid(self.pid, 0) |
| self._handle_exitstatus(sts) |
| return self.returncode |
| |
| |
| def _communicate(self, input): |
| if isinstance(input, str): # Unicode |
| input = input.encode("utf-8") # XXX What else? |
| read_set = [] |
| write_set = [] |
| stdout = None # Return |
| stderr = None # Return |
| |
| if self.stdin: |
| # Flush stdio buffer. This might block, if the user has |
| # been writing to .stdin in an uncontrolled fashion. |
| self.stdin.flush() |
| if input: |
| write_set.append(self.stdin) |
| else: |
| self.stdin.close() |
| if self.stdout: |
| read_set.append(self.stdout) |
| stdout = [] |
| if self.stderr: |
| read_set.append(self.stderr) |
| stderr = [] |
| |
| input_offset = 0 |
| while read_set or write_set: |
| rlist, wlist, xlist = select.select(read_set, write_set, []) |
| |
| if self.stdin in wlist: |
| # When select has indicated that the file is writable, |
| # we can write up to PIPE_BUF bytes without risk |
| # blocking. POSIX defines PIPE_BUF >= 512 |
| bytes_written = os.write(self.stdin.fileno(), buffer(input, input_offset, 512)) |
| input_offset += bytes_written |
| if input_offset >= len(input): |
| self.stdin.close() |
| write_set.remove(self.stdin) |
| |
| if self.stdout in rlist: |
| data = os.read(self.stdout.fileno(), 1024) |
| if not data: |
| self.stdout.close() |
| read_set.remove(self.stdout) |
| stdout.append(data) |
| |
| if self.stderr in rlist: |
| data = os.read(self.stderr.fileno(), 1024) |
| if not data: |
| self.stderr.close() |
| read_set.remove(self.stderr) |
| stderr.append(data) |
| |
| # All data exchanged. Translate lists into strings. |
| if stdout is not None: |
| stdout = b''.join(stdout) |
| if stderr is not None: |
| stderr = b''.join(stderr) |
| |
| # Translate newlines, if requested. We cannot let the file |
| # object do the translation: It is based on stdio, which is |
| # impossible to combine with select (unless forcing no |
| # buffering). |
| if self.universal_newlines: |
| if stdout is not None: |
| stdout = self._translate_newlines(stdout) |
| if stderr is not None: |
| stderr = self._translate_newlines(stderr) |
| |
| self.wait() |
| return (stdout, stderr) |
| |
| |
| def _demo_posix(): |
| # |
| # Example 1: Simple redirection: Get process list |
| # |
| plist = Popen(["ps"], stdout=PIPE).communicate()[0] |
| print("Process list:") |
| print(plist) |
| |
| # |
| # Example 2: Change uid before executing child |
| # |
| if os.getuid() == 0: |
| p = Popen(["id"], preexec_fn=lambda: os.setuid(100)) |
| p.wait() |
| |
| # |
| # Example 3: Connecting several subprocesses |
| # |
| print("Looking for 'hda'...") |
| p1 = Popen(["dmesg"], stdout=PIPE) |
| p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE) |
| print(repr(p2.communicate()[0])) |
| |
| # |
| # Example 4: Catch execution error |
| # |
| print() |
| print("Trying a weird file...") |
| try: |
| print(Popen(["/this/path/does/not/exist"]).communicate()) |
| except OSError as e: |
| if e.errno == errno.ENOENT: |
| print("The file didn't exist. I thought so...") |
| print("Child traceback:") |
| print(e.child_traceback) |
| else: |
| print("Error", e.errno) |
| else: |
| print("Gosh. No error.", file=sys.stderr) |
| |
| |
| def _demo_windows(): |
| # |
| # Example 1: Connecting several subprocesses |
| # |
| print("Looking for 'PROMPT' in set output...") |
| p1 = Popen("set", stdout=PIPE, shell=True) |
| p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE) |
| print(repr(p2.communicate()[0])) |
| |
| # |
| # Example 2: Simple execution of program |
| # |
| print("Executing calc...") |
| p = Popen("calc") |
| p.wait() |
| |
| |
| if __name__ == "__main__": |
| if mswindows: |
| _demo_windows() |
| else: |
| _demo_posix() |