compat/subprocess.py

   1 # subprocess - Subprocesses with accessible I/O streams
   2 #
   3 # For more information about this module, see PEP 324.
   4 #
   5 # Copyright (c) 2003-2004 by Peter Astrand <astrand@lysator.liu.se>
   6 #
   7 # By obtaining, using, and/or copying this software and/or its
   8 # associated documentation, you agree that you have read, understood,
   9 # and will comply with the following terms and conditions:
  10 #
  11 # Permission to use, copy, modify, and distribute this software and
  12 # its associated documentation for any purpose and without fee is
  13 # hereby granted, provided that the above copyright notice appears in
  14 # all copies, and that both that copyright notice and this permission
  15 # notice appear in supporting documentation, and that the name of the
  16 # author not be used in advertising or publicity pertaining to
  17 # distribution of the software without specific, written prior
  18 # permission.
  19 #
  20 # THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  21 # INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  22 # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  23 # CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
  24 # OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  25 # NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  26 # WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  27 #
  28 # Use of this file within git is permitted under GPLv2.
  29 #
  30
  31 r"""subprocess - Subprocesses with accessible I/O streams
  32
  33 This module allows you to spawn processes, connect to their
  34 input/output/error pipes, and obtain their return codes.  This module
  35 intends to replace several other, older modules and functions, like:
  36
  37 os.system
  38 os.spawn*
  39 os.popen*
  40 popen2.*
  41 commands.*
  42
  43 Information about how the subprocess module can be used to replace these
  44 modules and functions can be found below.
  45
  46
  47
  48 Using the subprocess module
  49 ===========================
  50 This module defines one class called Popen:
  51
  52 class Popen(args, bufsize=0, executable=None,
  53             stdin=None, stdout=None, stderr=None,
  54             preexec_fn=None, close_fds=False, shell=False,
  55             cwd=None, env=None, universal_newlines=False,
  56             startupinfo=None, creationflags=0):
  57
  58
  59 Arguments are:
  60
  61 args should be a string, or a sequence of program arguments.  The
  62 program to execute is normally the first item in the args sequence or
  63 string, but can be explicitly set by using the executable argument.
  64
  65 On UNIX, with shell=False (default): In this case, the Popen class
  66 uses os.execvp() to execute the child program.  args should normally
  67 be a sequence.  A string will be treated as a sequence with the string
  68 as the only item (the program to execute).
  69
  70 On UNIX, with shell=True: If args is a string, it specifies the
  71 command string to execute through the shell.  If args is a sequence,
  72 the first item specifies the command string, and any additional items
  73 will be treated as additional shell arguments.
  74
  75 On Windows: the Popen class uses CreateProcess() to execute the child
  76 program, which operates on strings.  If args is a sequence, it will be
  77 converted to a string using the list2cmdline method.  Please note that
  78 not all MS Windows applications interpret the command line the same
  79 way: The list2cmdline is designed for applications using the same
  80 rules as the MS C runtime.
  81
  82 bufsize, if given, has the same meaning as the corresponding argument
  83 to the built-in open() function: 0 means unbuffered, 1 means line
  84 buffered, any other positive value means use a buffer of
  85 (approximately) that size.  A negative bufsize means to use the system
  86 default, which usually means fully buffered.  The default value for
  87 bufsize is 0 (unbuffered).
  88
  89 stdin, stdout and stderr specify the executed programs' standard
  90 input, standard output and standard error file handles, respectively.
  91 Valid values are PIPE, an existing file descriptor (a positive
  92 integer), an existing file object, and None.  PIPE indicates that a
  93 new pipe to the child should be created.  With None, no redirection
  94 will occur; the child's file handles will be inherited from the
  95 parent.  Additionally, stderr can be STDOUT, which indicates that the
  96 stderr data from the applications should be captured into the same
  97 file handle as for stdout.
  98
  99 If preexec_fn is set to a callable object, this object will be called
 100 in the child process just before the child is executed.
 101
 102 If close_fds is true, all file descriptors except 0, 1 and 2 will be
 103 closed before the child process is executed.
 104
 105 if shell is true, the specified command will be executed through the
 106 shell.
 107
 108 If cwd is not None, the current directory will be changed to cwd
 109 before the child is executed.
 110
 111 If env is not None, it defines the environment variables for the new
 112 process.
 113
 114 If universal_newlines is true, the file objects stdout and stderr are
 115 opened as a text files, but lines may be terminated by any of '\n',
 116 the Unix end-of-line convention, '\r', the Macintosh convention or
 117 '\r\n', the Windows convention.  All of these external representations
 118 are seen as '\n' by the Python program.  Note: This feature is only
 119 available if Python is built with universal newline support (the
 120 default).  Also, the newlines attribute of the file objects stdout,
 121 stdin and stderr are not updated by the communicate() method.
 122
 123 The startupinfo and creationflags, if given, will be passed to the
 124 underlying CreateProcess() function.  They can specify things such as
 125 appearance of the main window and priority for the new process.
 126 (Windows only)
 127
 128
 129 This module also defines two shortcut functions:
 130
 131 call(*args, **kwargs):
 132     Run command with arguments.  Wait for command to complete, then
 133     return the returncode attribute.
 134
 135     The arguments are the same as for the Popen constructor.  Example:
 136
 137     retcode = call(["ls", "-l"])
 138
 139
 140 Exceptions
 141 ----------
 142 Exceptions raised in the child process, before the new program has
 143 started to execute, will be re-raised in the parent.  Additionally,
 144 the exception object will have one extra attribute called
 145 'child_traceback', which is a string containing traceback information
 146 from the childs point of view.
 147
 148 The most common exception raised is OSError.  This occurs, for
 149 example, when trying to execute a non-existent file.  Applications
 150 should prepare for OSErrors.
 151
 152 A ValueError will be raised if Popen is called with invalid arguments.
 153
 154
 155 Security
 156 --------
 157 Unlike some other popen functions, this implementation will never call
 158 /bin/sh implicitly.  This means that all characters, including shell
 159 metacharacters, can safely be passed to child processes.
 160
 161
 162 Popen objects
 163 =============
 164 Instances of the Popen class have the following methods:
 165
 166 poll()
 167     Check if child process has terminated.  Returns returncode
 168     attribute.
 169
 170 wait()
 171     Wait for child process to terminate.  Returns returncode attribute.
 172
 173 communicate(input=None)
 174     Interact with process: Send data to stdin.  Read data from stdout
 175     and stderr, until end-of-file is reached.  Wait for process to
 176     terminate.  The optional stdin argument should be a string to be
 177     sent to the child process, or None, if no data should be sent to
 178     the child.
 179
 180     communicate() returns a tuple (stdout, stderr).
 181
 182     Note: The data read is buffered in memory, so do not use this
 183     method if the data size is large or unlimited.
 184
 185 The following attributes are also available:
 186
 187 stdin
 188     If the stdin argument is PIPE, this attribute is a file object
 189     that provides input to the child process.  Otherwise, it is None.
 190
 191 stdout
 192     If the stdout argument is PIPE, this attribute is a file object
 193     that provides output from the child process.  Otherwise, it is
 194     None.
 195
 196 stderr
 197     If the stderr argument is PIPE, this attribute is file object that
 198     provides error output from the child process.  Otherwise, it is
 199     None.
 200
 201 pid
 202     The process ID of the child process.
 203
 204 returncode
 205     The child return code.  A None value indicates that the process
 206     hasn't terminated yet.  A negative value -N indicates that the
 207     child was terminated by signal N (UNIX only).
 208
 209
 210 Replacing older functions with the subprocess module
 211 ====================================================
 212 In this section, "a ==> b" means that b can be used as a replacement
 213 for a.
 214
 215 Note: All functions in this section fail (more or less) silently if
 216 the executed program cannot be found; this module raises an OSError
 217 exception.
 218
 219 In the following examples, we assume that the subprocess module is
 220 imported with "from subprocess import *".
 221
 222
 223 Replacing /bin/sh shell backquote
 224 ---------------------------------
 225 output=`mycmd myarg`
 226 ==>
 227 output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]
 228
 229
 230 Replacing shell pipe line
 231 -------------------------
 232 output=`dmesg | grep hda`
 233 ==>
 234 p1 = Popen(["dmesg"], stdout=PIPE)
 235 p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
 236 output = p2.communicate()[0]
 237
 238
 239 Replacing os.system()
 240 ---------------------
 241 sts = os.system("mycmd" + " myarg")
 242 ==>
 243 p = Popen("mycmd" + " myarg", shell=True)
 244 sts = os.waitpid(p.pid, 0)
 245
 246 Note:
 247
 248 * Calling the program through the shell is usually not required.
 249
 250 * It's easier to look at the returncode attribute than the
 251   exitstatus.
 252
 253 A more real-world example would look like this:
 254
 255 try:
 256     retcode = call("mycmd" + " myarg", shell=True)
 257     if retcode < 0:
 258         print >>sys.stderr, "Child was terminated by signal", -retcode
 259     else:
 260         print >>sys.stderr, "Child returned", retcode
 261 except OSError, e:
 262     print >>sys.stderr, "Execution failed:", e
 263
 264
 265 Replacing os.spawn*
 266 -------------------
 267 P_NOWAIT example:
 268
 269 pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
 270 ==>
 271 pid = Popen(["/bin/mycmd", "myarg"]).pid
 272
 273
 274 P_WAIT example:
 275
 276 retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
 277 ==>
 278 retcode = call(["/bin/mycmd", "myarg"])
 279
 280
 281 Vector example:
 282
 283 os.spawnvp(os.P_NOWAIT, path, args)
 284 ==>
 285 Popen([path] + args[1:])
 286
 287
 288 Environment example:
 289
 290 os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
 291 ==>
 292 Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
 293
 294
 295 Replacing os.popen*
 296 -------------------
 297 pipe = os.popen(cmd, mode='r', bufsize)
 298 ==>
 299 pipe = Popen(cmd, shell=True, bufsize=bufsize, stdout=PIPE).stdout
 300
 301 pipe = os.popen(cmd, mode='w', bufsize)
 302 ==>
 303 pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin
 304
 305
 306 (child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize)
 307 ==>
 308 p = Popen(cmd, shell=True, bufsize=bufsize,
 309           stdin=PIPE, stdout=PIPE, close_fds=True)
 310 (child_stdin, child_stdout) = (p.stdin, p.stdout)
 311
 312
 313 (child_stdin,
 314  child_stdout,
 315  child_stderr) = os.popen3(cmd, mode, bufsize)
 316 ==>
 317 p = Popen(cmd, shell=True, bufsize=bufsize,
 318           stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
 319 (child_stdin,
 320  child_stdout,
 321  child_stderr) = (p.stdin, p.stdout, p.stderr)
 322
 323
 324 (child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize)
 325 ==>
 326 p = Popen(cmd, shell=True, bufsize=bufsize,
 327           stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
 328 (child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout)
 329
 330
 331 Replacing popen2.*
 332 ------------------
 333 Note: If the cmd argument to popen2 functions is a string, the command
 334 is executed through /bin/sh.  If it is a list, the command is directly
 335 executed.
 336
 337 (child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
 338 ==>
 339 p = Popen(["somestring"], shell=True, bufsize=bufsize
 340           stdin=PIPE, stdout=PIPE, close_fds=True)
 341 (child_stdout, child_stdin) = (p.stdout, p.stdin)
 342
 343
 344 (child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
 345 ==>
 346 p = Popen(["mycmd", "myarg"], bufsize=bufsize,
 347           stdin=PIPE, stdout=PIPE, close_fds=True)
 348 (child_stdout, child_stdin) = (p.stdout, p.stdin)
 349
 350 The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
 351 except that:
 352
 353 * subprocess.Popen raises an exception if the execution fails
 354 * the capturestderr argument is replaced with the stderr argument.
 355 * stdin=PIPE and stdout=PIPE must be specified.
 356 * popen2 closes all filedescriptors by default, but you have to specify
 357   close_fds=True with subprocess.Popen.
 358
 359
 360 """
 361
 362 import sys
 363 mswindows = (sys.platform == "win32")
 364
 365 import os
 366 import types
 367 import traceback
 368
 369 if mswindows:
 370     import threading
 371     import msvcrt
 372     if 0: # <-- change this to use pywin32 instead of the _subprocess driver
 373         import pywintypes
 374         from win32api import GetStdHandle, STD_INPUT_HANDLE, \
 375                              STD_OUTPUT_HANDLE, STD_ERROR_HANDLE
 376         from win32api import GetCurrentProcess, DuplicateHandle, \
 377                              GetModuleFileName, GetVersion
 378         from win32con import DUPLICATE_SAME_ACCESS, SW_HIDE
 379         from win32pipe import CreatePipe
 380         from win32process import CreateProcess, STARTUPINFO, \
 381                                  GetExitCodeProcess, STARTF_USESTDHANDLES, \
 382                                  STARTF_USESHOWWINDOW, CREATE_NEW_CONSOLE
 383         from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0
 384     else:
 385         from _subprocess import *
 386         class STARTUPINFO:
 387             dwFlags = 0
 388             hStdInput = None
 389             hStdOutput = None
 390             hStdError = None
 391         class pywintypes:
 392             error = IOError
 393 else:
 394     import select
 395     import errno
 396     import fcntl
 397     import pickle
 398
 399 __all__ = ["Popen", "PIPE", "STDOUT", "call"]
 400
 401 try:
 402     MAXFD = os.sysconf("SC_OPEN_MAX")
 403 except:
 404     MAXFD = 256
 405
 406 # True/False does not exist on 2.2.0
 407 try:
 408     False
 409 except NameError:
 410     False = 0
 411     True = 1
 412
 413 _active = []
 414
 415 def _cleanup():
 416     for inst in _active[:]:
 417         inst.poll()
 418
 419 PIPE = -1
 420 STDOUT = -2
 421
 422
 423 def call(*args, **kwargs):
 424     """Run command with arguments.  Wait for command to complete, then
 425     return the returncode attribute.
 426
 427     The arguments are the same as for the Popen constructor.  Example:
 428
 429     retcode = call(["ls", "-l"])
 430     """
 431     return Popen(*args, **kwargs).wait()
 432
 433
 434 def list2cmdline(seq):
 435     """
 436     Translate a sequence of arguments into a command line
 437     string, using the same rules as the MS C runtime:
 438
 439     1) Arguments are delimited by white space, which is either a
 440        space or a tab.
 441
 442     2) A string surrounded by double quotation marks is
 443        interpreted as a single argument, regardless of white space
 444        contained within.  A quoted string can be embedded in an
 445        argument.
 446
 447     3) A double quotation mark preceded by a backslash is
 448        interpreted as a literal double quotation mark.
 449
 450     4) Backslashes are interpreted literally, unless they
 451        immediately precede a double quotation mark.
 452
 453     5) If backslashes immediately precede a double quotation mark,
 454        every pair of backslashes is interpreted as a literal
 455        backslash.  If the number of backslashes is odd, the last
 456        backslash escapes the next double quotation mark as
 457        described in rule 3.
 458     """
 459
 460     # See
 461     # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
 462     result = []
 463     needquote = False
 464     for arg in seq:
 465         bs_buf = []
 466
 467         # Add a space to separate this argument from the others
 468         if result:
 469             result.append(' ')
 470
 471         needquote = (" " in arg) or ("\t" in arg)
 472         if needquote:
 473             result.append('"')
 474
 475         for c in arg:
 476             if c == '\\':
 477                 # Don't know if we need to double yet.
 478                 bs_buf.append(c)
 479             elif c == '"':
 480                 # Double backspaces.
 481                 result.append('\\' * len(bs_buf)*2)
 482                 bs_buf = []
 483                 result.append('\\"')
 484             else:
 485                 # Normal char
 486                 if bs_buf:
 487                     result.extend(bs_buf)
 488                     bs_buf = []
 489                 result.append(c)
 490
 491         # Add remaining backspaces, if any.
 492         if bs_buf:
 493             result.extend(bs_buf)
 494
 495         if needquote:
 496             result.extend(bs_buf)
 497             result.append('"')
 498
 499     return ''.join(result)
 500
 501
 502 class Popen(object):
 503     def __init__(self, args, bufsize=0, executable=None,
 504                  stdin=None, stdout=None, stderr=None,
 505                  preexec_fn=None, close_fds=False, shell=False,
 506                  cwd=None, env=None, universal_newlines=False,
 507                  startupinfo=None, creationflags=0):
 508         """Create new Popen instance."""
 509         _cleanup()
 510
 511         if not isinstance(bufsize, (int, long)):
 512             raise TypeError("bufsize must be an integer")
 513
 514         if mswindows:
 515             if preexec_fn is not None:
 516                 raise ValueError("preexec_fn is not supported on Windows "
 517                                  "platforms")
 518             if close_fds:
 519                 raise ValueError("close_fds is not supported on Windows "
 520                                  "platforms")
 521         else:
 522             # POSIX
 523             if startupinfo is not None:
 524                 raise ValueError("startupinfo is only supported on Windows "
 525                                  "platforms")
 526             if creationflags != 0:
 527                 raise ValueError("creationflags is only supported on Windows "
 528                                  "platforms")
 529
 530         self.stdin = None
 531         self.stdout = None
 532         self.stderr = None
 533         self.pid = None
 534         self.returncode = None
 535         self.universal_newlines = universal_newlines
 536
 537         # Input and output objects. The general principle is like
 538         # this:
 539         #
 540         # Parent                   Child
 541         # ------                   -----
 542         # p2cwrite   ---stdin--->  p2cread
 543         # c2pread    <--stdout---  c2pwrite
 544         # errread    <--stderr---  errwrite
 545         #
 546         # On POSIX, the child objects are file descriptors.  On
 547         # Windows, these are Windows file handles.  The parent objects
 548         # are file descriptors on both platforms.  The parent objects
 549         # are None when not using PIPEs. The child objects are None
 550         # when not redirecting.
 551
 552         (p2cread, p2cwrite,
 553          c2pread, c2pwrite,
 554          errread, errwrite) = self._get_handles(stdin, stdout, stderr)
 555
 556         self._execute_child(args, executable, preexec_fn, close_fds,
 557                             cwd, env, universal_newlines,
 558                             startupinfo, creationflags, shell,
 559                             p2cread, p2cwrite,
 560                             c2pread, c2pwrite,
 561                             errread, errwrite)
 562
 563         if p2cwrite:
 564             self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
 565         if c2pread:
 566             if universal_newlines:
 567                 self.stdout = os.fdopen(c2pread, 'rU', bufsize)
 568             else:
 569                 self.stdout = os.fdopen(c2pread, 'rb', bufsize)
 570         if errread:
 571             if universal_newlines:
 572                 self.stderr = os.fdopen(errread, 'rU', bufsize)
 573             else:
 574                 self.stderr = os.fdopen(errread, 'rb', bufsize)
 575
 576         _active.append(self)
 577
 578
 579     def _translate_newlines(self, data):
 580         data = data.replace("\r\n", "\n")
 581         data = data.replace("\r", "\n")
 582         return data
 583
 584
 585     if mswindows:
 586         #
 587         # Windows methods
 588         #
 589         def _get_handles(self, stdin, stdout, stderr):
 590             """Construct and return tupel with IO objects:
 591             p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
 592             """
 593             if stdin == None and stdout == None and stderr == None:
 594                 return (None, None, None, None, None, None)
 595
 596             p2cread, p2cwrite = None, None
 597             c2pread, c2pwrite = None, None
 598             errread, errwrite = None, None
 599
 600             if stdin == None:
 601                 p2cread = GetStdHandle(STD_INPUT_HANDLE)
 602             elif stdin == PIPE:
 603                 p2cread, p2cwrite = CreatePipe(None, 0)
 604                 # Detach and turn into fd
 605                 p2cwrite = p2cwrite.Detach()
 606                 p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0)
 607             elif type(stdin) == types.IntType:
 608                 p2cread = msvcrt.get_osfhandle(stdin)
 609             else:
 610                 # Assuming file-like object
 611                 p2cread = msvcrt.get_osfhandle(stdin.fileno())
 612             p2cread = self._make_inheritable(p2cread)
 613
 614             if stdout == None:
 615                 c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE)
 616             elif stdout == PIPE:
 617                 c2pread, c2pwrite = CreatePipe(None, 0)
 618                 # Detach and turn into fd
 619                 c2pread = c2pread.Detach()
 620                 c2pread = msvcrt.open_osfhandle(c2pread, 0)
 621             elif type(stdout) == types.IntType:
 622                 c2pwrite = msvcrt.get_osfhandle(stdout)
 623             else:
 624                 # Assuming file-like object
 625                 c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
 626             c2pwrite = self._make_inheritable(c2pwrite)
 627
 628             if stderr == None:
 629                 errwrite = GetStdHandle(STD_ERROR_HANDLE)
 630             elif stderr == PIPE:
 631                 errread, errwrite = CreatePipe(None, 0)
 632                 # Detach and turn into fd
 633                 errread = errread.Detach()
 634                 errread = msvcrt.open_osfhandle(errread, 0)
 635             elif stderr == STDOUT:
 636                 errwrite = c2pwrite
 637             elif type(stderr) == types.IntType:
 638                 errwrite = msvcrt.get_osfhandle(stderr)
 639             else:
 640                 # Assuming file-like object
 641                 errwrite = msvcrt.get_osfhandle(stderr.fileno())
 642             errwrite = self._make_inheritable(errwrite)
 643
 644             return (p2cread, p2cwrite,
 645                     c2pread, c2pwrite,
 646                     errread, errwrite)
 647
 648
 649         def _make_inheritable(self, handle):
 650             """Return a duplicate of handle, which is inheritable"""
 651             return DuplicateHandle(GetCurrentProcess(), handle,
 652                                    GetCurrentProcess(), 0, 1,
 653                                    DUPLICATE_SAME_ACCESS)
 654
 655
 656         def _find_w9xpopen(self):
 657             """Find and return absolut path to w9xpopen.exe"""
 658             w9xpopen = os.path.join(os.path.dirname(GetModuleFileName(0)),
 659                                     "w9xpopen.exe")
 660             if not os.path.exists(w9xpopen):
 661                 # Eeek - file-not-found - possibly an embedding
 662                 # situation - see if we can locate it in sys.exec_prefix
 663                 w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix),
 664                                         "w9xpopen.exe")
 665                 if not os.path.exists(w9xpopen):
 666                     raise RuntimeError("Cannot locate w9xpopen.exe, which is "
 667                                        "needed for Popen to work with your "
 668                                        "shell or platform.")
 669             return w9xpopen
 670
 671
 672         def _execute_child(self, args, executable, preexec_fn, close_fds,
 673                            cwd, env, universal_newlines,
 674                            startupinfo, creationflags, shell,
 675                            p2cread, p2cwrite,
 676                            c2pread, c2pwrite,
 677                            errread, errwrite):
 678             """Execute program (MS Windows version)"""
 679
 680             if not isinstance(args, types.StringTypes):
 681                 args = list2cmdline(args)
 682
 683             # Process startup details
 684             default_startupinfo = STARTUPINFO()
 685             if startupinfo == None:
 686                 startupinfo = default_startupinfo
 687             if not None in (p2cread, c2pwrite, errwrite):
 688                 startupinfo.dwFlags |= STARTF_USESTDHANDLES
 689                 startupinfo.hStdInput = p2cread
 690                 startupinfo.hStdOutput = c2pwrite
 691                 startupinfo.hStdError = errwrite
 692
 693             if shell:
 694                 default_startupinfo.dwFlags |= STARTF_USESHOWWINDOW
 695                 default_startupinfo.wShowWindow = SW_HIDE
 696                 comspec = os.environ.get("COMSPEC", "cmd.exe")
 697                 args = comspec + " /c " + args
 698                 if (GetVersion() >= 0x80000000L or
 699                         os.path.basename(comspec).lower() == "command.com"):
 700                     # Win9x, or using command.com on NT. We need to
 701                     # use the w9xpopen intermediate program. For more
 702                     # information, see KB Q150956
 703                     # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
 704                     w9xpopen = self._find_w9xpopen()
 705                     args = '"%s" %s' % (w9xpopen, args)
 706                     # Not passing CREATE_NEW_CONSOLE has been known to
 707                     # cause random failures on win9x.  Specifically a
 708                     # dialog: "Your program accessed mem currently in
 709                     # use at xxx" and a hopeful warning about the
 710                     # stability of your system.  Cost is Ctrl+C wont
 711                     # kill children.
 712                     creationflags |= CREATE_NEW_CONSOLE
 713
 714             # Start the process
 715             try:
 716                 hp, ht, pid, tid = CreateProcess(executable, args,
 717                                          # no special security
 718                                          None, None,
 719                                          # must inherit handles to pass std
 720                                          # handles
 721                                          1,
 722                                          creationflags,
 723                                          env,
 724                                          cwd,
 725                                          startupinfo)
 726             except pywintypes.error, e:
 727                 # Translate pywintypes.error to WindowsError, which is
 728                 # a subclass of OSError.  FIXME: We should really
 729                 # translate errno using _sys_errlist (or simliar), but
 730                 # how can this be done from Python?
 731                 raise WindowsError(*e.args)
 732
 733             # Retain the process handle, but close the thread handle
 734             self._handle = hp
 735             self.pid = pid
 736             ht.Close()
 737
 738             # Child is launched. Close the parent's copy of those pipe
 739             # handles that only the child should have open.  You need
 740             # to make sure that no handles to the write end of the
 741             # output pipe are maintained in this process or else the
 742             # pipe will not close when the child process exits and the
 743             # ReadFile will hang.
 744             if p2cread != None:
 745                 p2cread.Close()
 746             if c2pwrite != None:
 747                 c2pwrite.Close()
 748             if errwrite != None:
 749                 errwrite.Close()
 750
 751
 752         def poll(self):
 753             """Check if child process has terminated.  Returns returncode
 754             attribute."""
 755             if self.returncode == None:
 756                 if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0:
 757                     self.returncode = GetExitCodeProcess(self._handle)
 758                     _active.remove(self)
 759             return self.returncode
 760
 761
 762         def wait(self):
 763             """Wait for child process to terminate.  Returns returncode
 764             attribute."""
 765             if self.returncode == None:
 766                 obj = WaitForSingleObject(self._handle, INFINITE)
 767                 self.returncode = GetExitCodeProcess(self._handle)
 768                 _active.remove(self)
 769             return self.returncode
 770
 771
 772         def _readerthread(self, fh, buffer):
 773             buffer.append(fh.read())
 774
 775
 776         def communicate(self, input=None):
 777             """Interact with process: Send data to stdin.  Read data from
 778             stdout and stderr, until end-of-file is reached.  Wait for
 779             process to terminate.  The optional input argument should be a
 780             string to be sent to the child process, or None, if no data
 781             should be sent to the child.
 782
 783             communicate() returns a tuple (stdout, stderr)."""
 784             stdout = None # Return
 785             stderr = None # Return
 786
 787             if self.stdout:
 788                 stdout = []
 789                 stdout_thread = threading.Thread(target=self._readerthread,
 790                                                  args=(self.stdout, stdout))
 791                 stdout_thread.setDaemon(True)
 792                 stdout_thread.start()
 793             if self.stderr:
 794                 stderr = []
 795                 stderr_thread = threading.Thread(target=self._readerthread,
 796                                                  args=(self.stderr, stderr))
 797                 stderr_thread.setDaemon(True)
 798                 stderr_thread.start()
 799
 800             if self.stdin:
 801                 if input != None:
 802                     self.stdin.write(input)
 803                 self.stdin.close()
 804
 805             if self.stdout:
 806                 stdout_thread.join()
 807             if self.stderr:
 808                 stderr_thread.join()
 809
 810             # All data exchanged.  Translate lists into strings.
 811             if stdout != None:
 812                 stdout = stdout[0]
 813             if stderr != None:
 814                 stderr = stderr[0]
 815
 816             # Translate newlines, if requested.  We cannot let the file
 817             # object do the translation: It is based on stdio, which is
 818             # impossible to combine with select (unless forcing no
 819             # buffering).
 820             if self.universal_newlines and hasattr(open, 'newlines'):
 821                 if stdout:
 822                     stdout = self._translate_newlines(stdout)
 823                 if stderr:
 824                     stderr = self._translate_newlines(stderr)
 825
 826             self.wait()
 827             return (stdout, stderr)
 828
 829     else:
 830         #
 831         # POSIX methods
 832         #
 833         def _get_handles(self, stdin, stdout, stderr):
 834             """Construct and return tupel with IO objects:
 835             p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
 836             """
 837             p2cread, p2cwrite = None, None
 838             c2pread, c2pwrite = None, None
 839             errread, errwrite = None, None
 840
 841             if stdin == None:
 842                 pass
 843             elif stdin == PIPE:
 844                 p2cread, p2cwrite = os.pipe()
 845             elif type(stdin) == types.IntType:
 846                 p2cread = stdin
 847             else:
 848                 # Assuming file-like object
 849                 p2cread = stdin.fileno()
 850
 851             if stdout == None:
 852                 pass
 853             elif stdout == PIPE:
 854                 c2pread, c2pwrite = os.pipe()
 855             elif type(stdout) == types.IntType:
 856                 c2pwrite = stdout
 857             else:
 858                 # Assuming file-like object
 859                 c2pwrite = stdout.fileno()
 860
 861             if stderr == None:
 862                 pass
 863             elif stderr == PIPE:
 864                 errread, errwrite = os.pipe()
 865             elif stderr == STDOUT:
 866                 errwrite = c2pwrite
 867             elif type(stderr) == types.IntType:
 868                 errwrite = stderr
 869             else:
 870                 # Assuming file-like object
 871                 errwrite = stderr.fileno()
 872
 873             return (p2cread, p2cwrite,
 874                     c2pread, c2pwrite,
 875                     errread, errwrite)
 876
 877
 878         def _set_cloexec_flag(self, fd):
 879             try:
 880                 cloexec_flag = fcntl.FD_CLOEXEC
 881             except AttributeError:
 882                 cloexec_flag = 1
 883
 884             old = fcntl.fcntl(fd, fcntl.F_GETFD)
 885             fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag)
 886
 887
 888         def _close_fds(self, but):
 889             for i in range(3, MAXFD):
 890                 if i == but:
 891                     continue
 892                 try:
 893                     os.close(i)
 894                 except:
 895                     pass
 896
 897
 898         def _execute_child(self, args, executable, preexec_fn, close_fds,
 899                            cwd, env, universal_newlines,
 900                            startupinfo, creationflags, shell,
 901                            p2cread, p2cwrite,
 902                            c2pread, c2pwrite,
 903                            errread, errwrite):
 904             """Execute program (POSIX version)"""
 905
 906             if isinstance(args, types.StringTypes):
 907                 args = [args]
 908
 909             if shell:
 910                 args = ["/bin/sh", "-c"] + args
 911
 912             if executable == None:
 913                 executable = args[0]
 914
 915             # For transferring possible exec failure from child to parent
 916             # The first char specifies the exception type: 0 means
 917             # OSError, 1 means some other error.
 918             errpipe_read, errpipe_write = os.pipe()
 919             self._set_cloexec_flag(errpipe_write)
 920
 921             self.pid = os.fork()
 922             if self.pid == 0:
 923                 # Child
 924                 try:
 925                     # Close parent's pipe ends
 926                     if p2cwrite:
 927                         os.close(p2cwrite)
 928                     if c2pread:
 929                         os.close(c2pread)
 930                     if errread:
 931                         os.close(errread)
 932                     os.close(errpipe_read)
 933
 934                     # Dup fds for child
 935                     if p2cread:
 936                         os.dup2(p2cread, 0)
 937                     if c2pwrite:
 938                         os.dup2(c2pwrite, 1)
 939                     if errwrite:
 940                         os.dup2(errwrite, 2)
 941
 942                     # Close pipe fds.  Make sure we doesn't close the same
 943                     # fd more than once.
 944                     if p2cread:
 945                         os.close(p2cread)
 946                     if c2pwrite and c2pwrite not in (p2cread,):
 947                         os.close(c2pwrite)
 948                     if errwrite and errwrite not in (p2cread, c2pwrite):
 949                         os.close(errwrite)
 950
 951                     # Close all other fds, if asked for
 952                     if close_fds:
 953                         self._close_fds(but=errpipe_write)
 954
 955                     if cwd != None:
 956                         os.chdir(cwd)
 957
 958                     if preexec_fn:
 959                         apply(preexec_fn)
 960
 961                     if env == None:
 962                         os.execvp(executable, args)
 963                     else:
 964                         os.execvpe(executable, args, env)
 965
 966                 except:
 967                     exc_type, exc_value, tb = sys.exc_info()
 968                     # Save the traceback and attach it to the exception object
 969                     exc_lines = traceback.format_exception(exc_type,
 970                                                            exc_value,
 971                                                            tb)
 972                     exc_value.child_traceback = ''.join(exc_lines)
 973                     os.write(errpipe_write, pickle.dumps(exc_value))
 974
 975                 # This exitcode won't be reported to applications, so it
 976                 # really doesn't matter what we return.
 977                 os._exit(255)
 978
 979             # Parent
 980             os.close(errpipe_write)
 981             if p2cread and p2cwrite:
 982                 os.close(p2cread)
 983             if c2pwrite and c2pread:
 984                 os.close(c2pwrite)
 985             if errwrite and errread:
 986                 os.close(errwrite)
 987
 988             # Wait for exec to fail or succeed; possibly raising exception
 989             data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB
 990             os.close(errpipe_read)
 991             if data != "":
 992                 os.waitpid(self.pid, 0)
 993                 child_exception = pickle.loads(data)
 994                 raise child_exception
 995
 996
 997         def _handle_exitstatus(self, sts):
 998             if os.WIFSIGNALED(sts):
 999                 self.returncode = -os.WTERMSIG(sts)
1000             elif os.WIFEXITED(sts):
1001                 self.returncode = os.WEXITSTATUS(sts)
1002             else:
1003                 # Should never happen
1004                 raise RuntimeError("Unknown child exit status!")
1005
1006             _active.remove(self)
1007
1008
1009         def poll(self):
1010             """Check if child process has terminated.  Returns returncode
1011             attribute."""
1012             if self.returncode == None:
1013                 try:
1014                     pid, sts = os.waitpid(self.pid, os.WNOHANG)
1015                     if pid == self.pid:
1016                         self._handle_exitstatus(sts)
1017                 except os.error:
1018                     pass
1019             return self.returncode
1020
1021
1022         def wait(self):
1023             """Wait for child process to terminate.  Returns returncode
1024             attribute."""
1025             if self.returncode == None:
1026                 pid, sts = os.waitpid(self.pid, 0)
1027                 self._handle_exitstatus(sts)
1028             return self.returncode
1029
1030
1031         def communicate(self, input=None):
1032             """Interact with process: Send data to stdin.  Read data from
1033             stdout and stderr, until end-of-file is reached.  Wait for
1034             process to terminate.  The optional input argument should be a
1035             string to be sent to the child process, or None, if no data
1036             should be sent to the child.
1037
1038             communicate() returns a tuple (stdout, stderr)."""
1039             read_set = []
1040             write_set = []
1041             stdout = None # Return
1042             stderr = None # Return
1043
1044             if self.stdin:
1045                 # Flush stdio buffer.  This might block, if the user has
1046                 # been writing to .stdin in an uncontrolled fashion.
1047                 self.stdin.flush()
1048                 if input:
1049                     write_set.append(self.stdin)
1050                 else:
1051                     self.stdin.close()
1052             if self.stdout:
1053                 read_set.append(self.stdout)
1054                 stdout = []
1055             if self.stderr:
1056                 read_set.append(self.stderr)
1057                 stderr = []
1058
1059             while read_set or write_set:
1060                 rlist, wlist, xlist = select.select(read_set, write_set, [])
1061
1062                 if self.stdin in wlist:
1063                     # When select has indicated that the file is writable,
1064                     # we can write up to PIPE_BUF bytes without risk
1065                     # blocking.  POSIX defines PIPE_BUF >= 512
1066                     bytes_written = os.write(self.stdin.fileno(), input[:512])
1067                     input = input[bytes_written:]
1068                     if not input:
1069                         self.stdin.close()
1070                         write_set.remove(self.stdin)
1071
1072                 if self.stdout in rlist:
1073                     data = os.read(self.stdout.fileno(), 1024)
1074                     if data == "":
1075                         self.stdout.close()
1076                         read_set.remove(self.stdout)
1077                     stdout.append(data)
1078
1079                 if self.stderr in rlist:
1080                     data = os.read(self.stderr.fileno(), 1024)
1081                     if data == "":
1082                         self.stderr.close()
1083                         read_set.remove(self.stderr)
1084                     stderr.append(data)
1085
1086             # All data exchanged.  Translate lists into strings.
1087             if stdout != None:
1088                 stdout = ''.join(stdout)
1089             if stderr != None:
1090                 stderr = ''.join(stderr)
1091
1092             # Translate newlines, if requested.  We cannot let the file
1093             # object do the translation: It is based on stdio, which is
1094             # impossible to combine with select (unless forcing no
1095             # buffering).
1096             if self.universal_newlines and hasattr(open, 'newlines'):
1097                 if stdout:
1098                     stdout = self._translate_newlines(stdout)
1099                 if stderr:
1100                     stderr = self._translate_newlines(stderr)
1101
1102             self.wait()
1103             return (stdout, stderr)
1104
1105
1106 def _demo_posix():
1107     #
1108     # Example 1: Simple redirection: Get process list
1109     #
1110     plist = Popen(["ps"], stdout=PIPE).communicate()[0]
1111     print "Process list:"
1112     print plist
1113
1114     #
1115     # Example 2: Change uid before executing child
1116     #
1117     if os.getuid() == 0:
1118         p = Popen(["id"], preexec_fn=lambda: os.setuid(100))
1119         p.wait()
1120
1121     #
1122     # Example 3: Connecting several subprocesses
1123     #
1124     print "Looking for 'hda'..."
1125     p1 = Popen(["dmesg"], stdout=PIPE)
1126     p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
1127     print repr(p2.communicate()[0])
1128
1129     #
1130     # Example 4: Catch execution error
1131     #
1132     print
1133     print "Trying a weird file..."
1134     try:
1135         print Popen(["/this/path/does/not/exist"]).communicate()
1136     except OSError, e:
1137         if e.errno == errno.ENOENT:
1138             print "The file didn't exist.  I thought so..."
1139             print "Child traceback:"
1140             print e.child_traceback
1141         else:
1142             print "Error", e.errno
1143     else:
1144         print >>sys.stderr, "Gosh.  No error."
1145
1146
1147 def _demo_windows():
1148     #
1149     # Example 1: Connecting several subprocesses
1150     #
1151     print "Looking for 'PROMPT' in set output..."
1152     p1 = Popen("set", stdout=PIPE, shell=True)
1153     p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE)
1154     print repr(p2.communicate()[0])
1155
1156     #
1157     # Example 2: Simple execution of program
1158     #
1159     print "Executing calc..."
1160     p = Popen("calc")
1161     p.wait()
1162
1163
1164 if __name__ == "__main__":
1165     if mswindows:
1166         _demo_windows()
1167     else:
1168         _demo_posix()