+
−/* Open a stream to a sub-process.
+
−   Copyright (C) 2009-2013 Free Software Foundation, Inc.
+
−
+
−   This program is free software: you can redistribute it and/or modify
+
−   it under the terms of the GNU General Public License as published by
+
−   the Free Software Foundation; either version 3 of the License, or
+
−   (at your option) any later version.
+
−
+
−   This program is distributed in the hope that it will be useful,
+
−   but WITHOUT ANY WARRANTY; without even the implied warranty of
+
−   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+
−   GNU General Public License for more details.
+
−
+
−   You should have received a copy of the GNU General Public License
+
−   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
−
+
−/* Written by Eric Blake <ebb9@byu.net>, 2009.  */
+
−
+
−#include <config.h>
+
−
+
−/* Specification.  */
+
−#include <stdio.h>
+
−
+
−#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+
−/* Native Windows API.  */
+
−
+
−# include <string.h>
+
−
+
−FILE *
+
−popen (const char *filename, const char *mode)
+
−{
+
−  /* Use binary mode by default.  */
+
−  if (strcmp (mode, "r") == 0)
+
−    mode = "rb";
+
−  else if (strcmp (mode, "w") == 0)
+
−    mode = "wb";
+
−
+
−  return _popen (filename, mode);
+
−}
+
−
+
−#else
+
−
+
−# include <errno.h>
+
−# include <fcntl.h>
+
−# include <stdlib.h>
+
−# include <unistd.h>
+
−
+
−# undef popen
+
−
+
−FILE *
+
−rpl_popen (const char *filename, const char *mode)
+
−{
+
−  /* All other platforms have popen and fcntl.
+
−     The bug of the child clobbering its own file descriptors if stdin
+
−     or stdout was closed in the parent can be worked around by
+
−     opening those two fds as close-on-exec to begin with.  */
+
−  /* Cygwin 1.5.x also has a bug where the popen fd is improperly
+
−     marked close-on-exec, and if the application undoes this, then
+
−     the fd leaks into subsequent popen calls.  We could work around
+
−     this by maintaining a list of all fd's opened by popen, and
+
−     temporarily marking them cloexec around the real popen call, but
+
−     we would also have to override pclose, and the bookkeeping seems
+
−     extreme given that cygwin 1.7 no longer has the bug.  */
+
−  FILE *result;
+
−  int cloexec0 = fcntl (STDIN_FILENO, F_GETFD);
+
−  int cloexec1 = fcntl (STDOUT_FILENO, F_GETFD);
+
−  int saved_errno;
+
−
+
−  /* If either stdin or stdout was closed (that is, fcntl failed),
+
−     then we open a dummy close-on-exec fd to occupy that slot.  That
+
−     way, popen's internal use of pipe() will not contain either fd 0
+
−     or 1, overcoming the fact that the child process blindly calls
+
−     close() on the parent's end of the pipe without first checking
+
−     whether it is clobbering the fd just placed there via dup2(); the
+
−     exec will get rid of the dummy fd's in the child.  Fortunately,
+
−     closed stderr in the parent does not cause problems in the
+
−     child.  */
+
−  if (cloexec0 < 0)
+
−    {
+
−      if (open ("/dev/null", O_RDONLY) != STDIN_FILENO
+
−          || fcntl (STDIN_FILENO, F_SETFD,
+
−                    fcntl (STDIN_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
+
−        abort ();
+
−    }
+
−  if (cloexec1 < 0)
+
−    {
+
−      if (open ("/dev/null", O_RDONLY) != STDOUT_FILENO
+
−          || fcntl (STDOUT_FILENO, F_SETFD,
+
−                    fcntl (STDOUT_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
+
−        abort ();
+
−    }
+
−  result = popen (filename, mode);
+
−  /* Now, close any dummy fd's created in the parent.  */
+
−  saved_errno = errno;
+
−  if (cloexec0 < 0)
+
−    close (STDIN_FILENO);
+
−  if (cloexec1 < 0)
+
−    close (STDOUT_FILENO);
+
−  errno = saved_errno;
+
−  return result;
+
−}
+
−
+
−#endif