procutil: unroll uin/uout loop in protectstdio()

I'll change uout to be redirected to stderr.

mercurial/utils/procutil.py

@@ -1,358 +1,359
 # procutil.py - utility for managing processes and executable environment
 #
 #  Copyright 2005 K. Thananchayan <[e-mail]>
 #  Copyright 2005-2007 Matt Mackall <[e-mail]>
 #  Copyright 2006 Vadim Gelfer <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import contextlib
 import imp
 import io
 import os
 import signal
 import subprocess
 import sys
 import tempfile
 import time
 
 from ..i18n import _
 
 from .. import (
     encoding,
     error,
     policy,
     pycompat,
 )
 
 osutil = policy.importmod(r'osutil')
 
 stderr = pycompat.stderr
 stdin = pycompat.stdin
 stdout = pycompat.stdout
 
 def isatty(fp):
     try:
         return fp.isatty()
     except AttributeError:
         return False
 
 # glibc determines buffering on first write to stdout - if we replace a TTY
 # destined stdout with a pipe destined stdout (e.g. pager), we want line
 # buffering
 if isatty(stdout):
     stdout = os.fdopen(stdout.fileno(), r'wb', 1)
 
 if pycompat.iswindows:
     from .. import windows as platform
     stdout = platform.winstdout(stdout)
 else:
     from .. import posix as platform
 
 explainexit = platform.explainexit
 findexe = platform.findexe
 _gethgcmd = platform.gethgcmd
 getuser = platform.getuser
 getpid = os.getpid
 hidewindow = platform.hidewindow
 popen = platform.popen
 quotecommand = platform.quotecommand
 readpipe = platform.readpipe
 setbinary = platform.setbinary
 setsignalhandler = platform.setsignalhandler
 shellquote = platform.shellquote
 shellsplit = platform.shellsplit
 spawndetached = platform.spawndetached
 sshargs = platform.sshargs
 testpid = platform.testpid
 
 try:
     setprocname = osutil.setprocname
 except AttributeError:
     pass
 try:
     unblocksignal = osutil.unblocksignal
 except AttributeError:
     pass
 
 closefds = pycompat.isposix
 
 def popen2(cmd, env=None, newlines=False):
     # Setting bufsize to -1 lets the system decide the buffer size.
     # The default for bufsize is 0, meaning unbuffered. This leads to
     # poor performance on Mac OS X: http://bugs.python.org/issue4194
     p = subprocess.Popen(cmd, shell=True, bufsize=-1,
                          close_fds=closefds,
                          stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                          universal_newlines=newlines,
                          env=env)
     return p.stdin, p.stdout
 
 def popen3(cmd, env=None, newlines=False):
     stdin, stdout, stderr, p = popen4(cmd, env, newlines)
     return stdin, stdout, stderr
 
 def popen4(cmd, env=None, newlines=False, bufsize=-1):
     p = subprocess.Popen(cmd, shell=True, bufsize=bufsize,
                          close_fds=closefds,
                          stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE,
                          universal_newlines=newlines,
                          env=env)
     return p.stdin, p.stdout, p.stderr, p
 
 def pipefilter(s, cmd):
     '''filter string S through command CMD, returning its output'''
     p = subprocess.Popen(cmd, shell=True, close_fds=closefds,
                          stdin=subprocess.PIPE, stdout=subprocess.PIPE)
     pout, perr = p.communicate(s)
     return pout
 
 def tempfilter(s, cmd):
     '''filter string S through a pair of temporary files with CMD.
     CMD is used as a template to create the real command to be run,
     with the strings INFILE and OUTFILE replaced by the real names of
     the temporary files generated.'''
     inname, outname = None, None
     try:
         infd, inname = tempfile.mkstemp(prefix='hg-filter-in-')
         fp = os.fdopen(infd, r'wb')
         fp.write(s)
         fp.close()
         outfd, outname = tempfile.mkstemp(prefix='hg-filter-out-')
         os.close(outfd)
         cmd = cmd.replace('INFILE', inname)
         cmd = cmd.replace('OUTFILE', outname)
         code = os.system(cmd)
         if pycompat.sysplatform == 'OpenVMS' and code & 1:
             code = 0
         if code:
             raise error.Abort(_("command '%s' failed: %s") %
                               (cmd, explainexit(code)))
         with open(outname, 'rb') as fp:
             return fp.read()
     finally:
         try:
             if inname:
                 os.unlink(inname)
         except OSError:
             pass
         try:
             if outname:
                 os.unlink(outname)
         except OSError:
             pass
 
 _filtertable = {
     'tempfile:': tempfilter,
     'pipe:': pipefilter,
 }
 
 def filter(s, cmd):
     "filter a string through a command that transforms its input to its output"
     for name, fn in _filtertable.iteritems():
         if cmd.startswith(name):
             return fn(s, cmd[len(name):].lstrip())
     return pipefilter(s, cmd)
 
 def mainfrozen():
     """return True if we are a frozen executable.
 
     The code supports py2exe (most common, Windows only) and tools/freeze
     (portable, not much used).
     """
     return (pycompat.safehasattr(sys, "frozen") or # new py2exe
             pycompat.safehasattr(sys, "importers") or # old py2exe
             imp.is_frozen(u"__main__")) # tools/freeze
 
 _hgexecutable = None
 
 def hgexecutable():
     """return location of the 'hg' executable.
 
     Defaults to $HG or 'hg' in the search path.
     """
     if _hgexecutable is None:
         hg = encoding.environ.get('HG')
         mainmod = sys.modules[r'__main__']
         if hg:
             _sethgexecutable(hg)
         elif mainfrozen():
             if getattr(sys, 'frozen', None) == 'macosx_app':
                 # Env variable set by py2app
                 _sethgexecutable(encoding.environ['EXECUTABLEPATH'])
             else:
                 _sethgexecutable(pycompat.sysexecutable)
         elif (os.path.basename(
             pycompat.fsencode(getattr(mainmod, '__file__', ''))) == 'hg'):
             _sethgexecutable(pycompat.fsencode(mainmod.__file__))
         else:
             exe = findexe('hg') or os.path.basename(sys.argv[0])
             _sethgexecutable(exe)
     return _hgexecutable
 
 def _sethgexecutable(path):
     """set location of the 'hg' executable"""
     global _hgexecutable
     _hgexecutable = path
 
 def _testfileno(f, stdf):
     fileno = getattr(f, 'fileno', None)
     try:
         return fileno and fileno() == stdf.fileno()
     except io.UnsupportedOperation:
         return False # fileno() raised UnsupportedOperation
 
 def isstdin(f):
     return _testfileno(f, sys.__stdin__)
 
 def isstdout(f):
     return _testfileno(f, sys.__stdout__)
 
 def protectstdio(uin, uout):
     """Duplicate streams and redirect original to null if (uin, uout) are
     stdio
 
     Returns (fin, fout) which point to the original (uin, uout) fds, but
     may be copy of (uin, uout). The returned streams can be considered
     "owned" in that print(), exec(), etc. never reach to them.
     """
     uout.flush()
-    newfiles = []
     nullfd = os.open(os.devnull, os.O_RDWR)
-    for f, sysf, mode in [(uin, stdin, r'rb'),
-                          (uout, stdout, r'wb')]:
-        if f is sysf:
-            newfd = os.dup(f.fileno())
-            os.dup2(nullfd, f.fileno())
-            f = os.fdopen(newfd, mode)
-        newfiles.append(f)
+    fin, fout = uin, uout
+    if uin is stdin:
+        newfd = os.dup(uin.fileno())
+        os.dup2(nullfd, uin.fileno())
+        fin = os.fdopen(newfd, r'rb')
+    if uout is stdout:
+        newfd = os.dup(uout.fileno())
+        os.dup2(nullfd, uout.fileno())
+        fout = os.fdopen(newfd, r'wb')
     os.close(nullfd)
-    return tuple(newfiles)
+    return fin, fout
 
 def restorestdio(uin, uout, fin, fout):
     """Restore (uin, uout) streams from possibly duplicated (fin, fout)"""
     uout.flush()
     for f, uif in [(fin, uin), (fout, uout)]:
         if f is not uif:
             os.dup2(f.fileno(), uif.fileno())
             f.close()
 
 @contextlib.contextmanager
 def protectedstdio(uin, uout):
     """Run code block with protected standard streams"""
     fin, fout = protectstdio(uin, uout)
     try:
         yield fin, fout
     finally:
         restorestdio(uin, uout, fin, fout)
 
 def shellenviron(environ=None):
     """return environ with optional override, useful for shelling out"""
     def py2shell(val):
         'convert python object into string that is useful to shell'
         if val is None or val is False:
             return '0'
         if val is True:
             return '1'
         return pycompat.bytestr(val)
     env = dict(encoding.environ)
     if environ:
         env.update((k, py2shell(v)) for k, v in environ.iteritems())
     env['HG'] = hgexecutable()
     return env
 
 def system(cmd, environ=None, cwd=None, out=None):
     '''enhanced shell command execution.
     run with environment maybe modified, maybe in different dir.
 
     if out is specified, it is assumed to be a file-like object that has a
     write() method. stdout and stderr will be redirected to out.'''
     try:
         stdout.flush()
     except Exception:
         pass
     cmd = quotecommand(cmd)
     env = shellenviron(environ)
     if out is None or isstdout(out):
         rc = subprocess.call(cmd, shell=True, close_fds=closefds,
                              env=env, cwd=cwd)
     else:
         proc = subprocess.Popen(cmd, shell=True, close_fds=closefds,
                                 env=env, cwd=cwd, stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
         for line in iter(proc.stdout.readline, ''):
             out.write(line)
         proc.wait()
         rc = proc.returncode
     if pycompat.sysplatform == 'OpenVMS' and rc & 1:
         rc = 0
     return rc
 
 def gui():
     '''Are we running in a GUI?'''
     if pycompat.isdarwin:
         if 'SSH_CONNECTION' in encoding.environ:
             # handle SSH access to a box where the user is logged in
             return False
         elif getattr(osutil, 'isgui', None):
             # check if a CoreGraphics session is available
             return osutil.isgui()
         else:
             # pure build; use a safe default
             return True
     else:
         return pycompat.iswindows or encoding.environ.get("DISPLAY")
 
 def hgcmd():
     """Return the command used to execute current hg
 
     This is different from hgexecutable() because on Windows we want
     to avoid things opening new shell windows like batch files, so we
     get either the python call or current executable.
     """
     if mainfrozen():
         if getattr(sys, 'frozen', None) == 'macosx_app':
             # Env variable set by py2app
             return [encoding.environ['EXECUTABLEPATH']]
         else:
             return [pycompat.sysexecutable]
     return _gethgcmd()
 
 def rundetached(args, condfn):
     """Execute the argument list in a detached process.
 
     condfn is a callable which is called repeatedly and should return
     True once the child process is known to have started successfully.
     At this point, the child process PID is returned. If the child
     process fails to start or finishes before condfn() evaluates to
     True, return -1.
     """
     # Windows case is easier because the child process is either
     # successfully starting and validating the condition or exiting
     # on failure. We just poll on its PID. On Unix, if the child
     # process fails to start, it will be left in a zombie state until
     # the parent wait on it, which we cannot do since we expect a long
     # running process on success. Instead we listen for SIGCHLD telling
     # us our child process terminated.
     terminated = set()
     def handler(signum, frame):
         terminated.add(os.wait())
     prevhandler = None
     SIGCHLD = getattr(signal, 'SIGCHLD', None)
     if SIGCHLD is not None:
         prevhandler = signal.signal(SIGCHLD, handler)
     try:
         pid = spawndetached(args)
         while not condfn():
             if ((pid in terminated or not testpid(pid))
                 and not condfn()):
                 return -1
             time.sleep(0.1)
         return pid
     finally:
         if prevhandler is not None:
             signal.signal(signal.SIGCHLD, prevhandler)