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