diff options
Diffstat (limited to 'Lib/subprocess.py')
| -rw-r--r-- | Lib/subprocess.py | 1141 |
1 files changed, 1141 insertions, 0 deletions
diff --git a/Lib/subprocess.py b/Lib/subprocess.py new file mode 100644 index 0000000..355529e --- /dev/null +++ b/Lib/subprocess.py @@ -0,0 +1,1141 @@ +# subprocess - Subprocesses with accessible I/O streams +# +# For more information about this module, see PEP 324. +# +# Copyright (c) 2003-2004 by Peter Astrand <astrand@lysator.liu.se> +# +# By obtaining, using, and/or copying this software and/or its +# associated documentation, you agree that you have read, understood, +# and will comply with the following terms and conditions: +# +# Permission to use, copy, modify, and distribute this software and +# its associated documentation for any purpose and without fee is +# hereby granted, provided that the above copyright notice appears in +# all copies, and that both that copyright notice and this permission +# notice appear in supporting documentation, and that the name of the +# author not be used in advertising or publicity pertaining to +# distribution of the software without specific, written prior +# permission. +# +# THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, +# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. +# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR +# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS +# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, +# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION +# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + +"""subprocess - Subprocesses with accessible I/O streams + +This module allows you to spawn processes and connect to their +input/output/error pipes and obtain their return codes under Unix. +This module intends to replace several other, older modules and +functions, like: + +os.system +os.spawn* +os.popen* +popen2.* +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(*args, **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"]) + + +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. + + +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 stdin 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) +output = p2.communicate()[0] + + +Replacing os.system() +--------------------- +sts = os.system("mycmd" + " myarg") +==> +p = Popen("mycmd" + " myarg", shell=True) +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 >>sys.stderr, "Child was terminated by signal", -retcode + else: + print >>sys.stderr, "Child returned", retcode +except OSError, e: + print >>sys.stderr, "Execution failed:", e + + +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"}) + + +Replacing os.popen* +------------------- +pipe = os.popen(cmd, mode='r', bufsize) +==> +pipe = Popen(cmd, shell=True, bufsize=bufsize, stdout=PIPE).stdout + +pipe = os.popen(cmd, mode='w', bufsize) +==> +pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin + + +(child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize) +==> +p = Popen(cmd, shell=True, bufsize=bufsize, + stdin=PIPE, stdout=PIPE, close_fds=True) +(child_stdin, child_stdout) = (p.stdin, p.stdout) + + +(child_stdin, + child_stdout, + child_stderr) = os.popen3(cmd, mode, bufsize) +==> +p = Popen(cmd, shell=True, bufsize=bufsize, + stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True) +(child_stdin, + child_stdout, + child_stderr) = (p.stdin, p.stdout, p.stderr) + + +(child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize) +==> +p = Popen(cmd, shell=True, bufsize=bufsize, + stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True) +(child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout) + + +Replacing popen2.* +------------------ +Note: If the cmd argument to popen2 functions is a string, the command +is executed through /bin/sh. If it is a list, the command is directly +executed. + +(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode) +==> +p = Popen(["somestring"], shell=True, bufsize=bufsize + stdin=PIPE, stdout=PIPE, close_fds=True) +(child_stdout, child_stdin) = (p.stdout, p.stdin) + + +(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode) +==> +p = Popen(["mycmd", "myarg"], bufsize=bufsize, + stdin=PIPE, stdout=PIPE, close_fds=True) +(child_stdout, child_stdin) = (p.stdout, p.stdin) + +The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen, +except that: + +* subprocess.Popen raises an exception if the execution fails +* the capturestderr argument is replaced with the stderr argument. +* stdin=PIPE and stdout=PIPE must be specified. +* popen2 closes all filedescriptors by default, but you have to specify + close_fds=True with subprocess.Popen. + + +""" + +import sys +mswindows = (sys.platform == "win32") + +import os +import types +import traceback + +if mswindows: + import threading + import msvcrt + try: + from _subprocess import * + class STARTUPINFO: + dwFlags = 0 + hStdInput = None + hStdOutput = None + hStdError = None + class pywintypes: + error = IOError + except ImportError: + 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 + from win32pipe import CreatePipe + from win32process import CreateProcess, STARTUPINFO, GetExitCodeProcess, STARTF_USESTDHANDLES, CREATE_NEW_CONSOLE + from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0 +else: + import select + import errno + import fcntl + import pickle + +__all__ = ["Popen", "PIPE", "STDOUT", "call"] + +try: + MAXFD = os.sysconf("SC_OPEN_MAX") +except: + MAXFD = 256 + +# True/False does not exist on 2.2.0 +try: + False +except NameError: + False = 0 + True = 1 + +_active = [] + +def _cleanup(): + for inst in _active[:]: + inst.poll() + +PIPE = -1 +STDOUT = -2 + + +def call(*args, **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(*args, **kwargs).wait() + + +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) + 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.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() + + if mswindows: + if preexec_fn != None: + raise ValueError("preexec_fn is not supported on Windows platforms") + if close_fds: + raise ValueError("close_fds is not supported on Windows platforms") + else: + # POSIX + if startupinfo != 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) + + if p2cwrite: + self.stdin = os.fdopen(p2cwrite, 'wb', bufsize) + if c2pread: + if universal_newlines: + self.stdout = os.fdopen(c2pread, 'rU', bufsize) + else: + self.stdout = os.fdopen(c2pread, 'rb', bufsize) + if errread: + if universal_newlines: + self.stderr = os.fdopen(errread, 'rU', bufsize) + else: + self.stderr = os.fdopen(errread, 'rb', bufsize) + + _active.append(self) + + + def _translate_newlines(self, data): + data = data.replace("\r\n", "\n") + data = data.replace("\r", "\n") + return data + + + 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 == None and stdout == None and stderr == None: + return (None, None, None, None, None, None) + + p2cread, p2cwrite = None, None + c2pread, c2pwrite = None, None + errread, errwrite = None, None + + if stdin == None: + p2cread = GetStdHandle(STD_INPUT_HANDLE) + elif stdin == PIPE: + p2cread, p2cwrite = CreatePipe(None, 0) + # Detach and turn into fd + p2cwrite = p2cwrite.Detach() + p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0) + elif type(stdin) == types.IntType: + p2cread = msvcrt.get_osfhandle(stdin) + else: + # Assuming file-like object + p2cread = msvcrt.get_osfhandle(stdin.fileno()) + p2cread = self._make_inheritable(p2cread) + + if stdout == None: + c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE) + elif stdout == PIPE: + c2pread, c2pwrite = CreatePipe(None, 0) + # Detach and turn into fd + c2pread = c2pread.Detach() + c2pread = msvcrt.open_osfhandle(c2pread, 0) + elif type(stdout) == types.IntType: + c2pwrite = msvcrt.get_osfhandle(stdout) + else: + # Assuming file-like object + c2pwrite = msvcrt.get_osfhandle(stdout.fileno()) + c2pwrite = self._make_inheritable(c2pwrite) + + if stderr == None: + errwrite = GetStdHandle(STD_ERROR_HANDLE) + elif 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 type(stderr) == types.IntType: + 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, types.StringTypes): + args = list2cmdline(args) + + if shell: + comspec = os.environ.get("COMSPEC", "cmd.exe") + args = comspec + " /c " + args + if GetVersion() >= 0x80000000L 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 + + # Process startup details + if startupinfo == None: + startupinfo = STARTUPINFO() + if not None in (p2cread, c2pwrite, errwrite): + startupinfo.dwFlags |= STARTF_USESTDHANDLES + startupinfo.hStdInput = p2cread + startupinfo.hStdOutput = c2pwrite + startupinfo.hStdError = errwrite + + # Start the process + try: + hp, ht, pid, tid = CreateProcess(executable, args, + None, None, # No special security + 1, # Must inherit handles to pass std handles + creationflags, + env, + cwd, + startupinfo) + except pywintypes.error, 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._handle = hp + self.pid = pid + ht.Close() + + # Child is launched. Close the parents 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 != None: + p2cread.Close() + if c2pwrite != None: + c2pwrite.Close() + if errwrite != None: + errwrite.Close() + + + def poll(self): + """Check if child process has terminated. Returns returncode + attribute.""" + if self.returncode == None: + if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0: + self.returncode = GetExitCodeProcess(self._handle) + _active.remove(self) + return self.returncode + + + def wait(self): + """Wait for child process to terminate. Returns returncode + attribute.""" + if self.returncode == None: + obj = WaitForSingleObject(self._handle, INFINITE) + self.returncode = GetExitCodeProcess(self._handle) + _active.remove(self) + return self.returncode + + + def _readerthread(self, fh, buffer): + buffer.append(fh.read()) + + + 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).""" + 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 != 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 != None: + stdout = stdout[0] + if stderr != 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 and hasattr(open, 'newlines'): + if stdout: + stdout = self._translate_newlines(stdout) + if stderr: + 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 == None: + pass + elif stdin == PIPE: + p2cread, p2cwrite = os.pipe() + elif type(stdin) == types.IntType: + p2cread = stdin + else: + # Assuming file-like object + p2cread = stdin.fileno() + + if stdout == None: + pass + elif stdout == PIPE: + c2pread, c2pwrite = os.pipe() + elif type(stdout) == types.IntType: + c2pwrite = stdout + else: + # Assuming file-like object + c2pwrite = stdout.fileno() + + if stderr == None: + pass + elif stderr == PIPE: + errread, errwrite = os.pipe() + elif stderr == STDOUT: + errwrite = c2pwrite + elif type(stderr) == types.IntType: + 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, types.StringTypes): + args = [args] + + if shell: + args = ["/bin/sh", "-c"] + args + + if executable == 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() + if self.pid == 0: + # Child + try: + # Close parent's pipe ends + if p2cwrite: + os.close(p2cwrite) + if c2pread: + os.close(c2pread) + if errread: + os.close(errread) + os.close(errpipe_read) + + # Dup fds for child + if p2cread: + os.dup2(p2cread, 0) + if c2pwrite: + os.dup2(c2pwrite, 1) + if errwrite: + os.dup2(errwrite, 2) + + # Close pipe fds. Make sure we doesn't close the same + # fd more than once. + if p2cread: + os.close(p2cread) + if c2pwrite and c2pwrite not in (p2cread,): + os.close(c2pwrite) + if errwrite and errwrite not in (p2cread, c2pwrite): + os.close(errwrite) + + # Close all other fds, if asked for + if close_fds: + self._close_fds(but=errpipe_write) + + if cwd != None: + os.chdir(cwd) + + if preexec_fn: + apply(preexec_fn) + + if env == 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 and p2cwrite: + os.close(p2cread) + if c2pwrite and c2pread: + os.close(c2pwrite) + if errwrite and errread: + 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 != "": + 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!") + + _active.remove(self) + + + def poll(self): + """Check if child process has terminated. Returns returncode + attribute.""" + if self.returncode == None: + try: + pid, sts = os.waitpid(self.pid, os.WNOHANG) + if pid == self.pid: + self._handle_exitstatus(sts) + except os.error: + pass + return self.returncode + + + def wait(self): + """Wait for child process to terminate. Returns returncode + attribute.""" + if self.returncode == None: + pid, sts = os.waitpid(self.pid, 0) + self._handle_exitstatus(sts) + return self.returncode + + + 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).""" + 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 = [] + + 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(), input[:512]) + input = input[bytes_written:] + if not input: + self.stdin.close() + write_set.remove(self.stdin) + + if self.stdout in rlist: + data = os.read(self.stdout.fileno(), 1024) + if 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 data == "": + self.stderr.close() + read_set.remove(self.stderr) + stderr.append(data) + + # All data exchanged. Translate lists into strings. + if stdout != None: + stdout = ''.join(stdout) + if stderr != None: + stderr = ''.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 and hasattr(open, 'newlines'): + if stdout: + stdout = self._translate_newlines(stdout) + if stderr: + 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, 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 >>sys.stderr, "Gosh. No error." + + +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() + + |